3.0   Modifications

3.1   General

3.1.1    What basics will I need for making modifications to my Neon?

You'll need the basics of mechanical maintenance on your car. Read the maintenance section of this FAQ, & get a service manual (prerferably the Chrysler FSM). A good resource is the book High-Performance Dodge Neon Builder's Handbook by Mike Ancas & Mike Carpenter, published by S-A Design (ISBN 1932494022).

3.1.2    Will aftermarket parts void my warranty?  What about Mopar Performance parts?

This question does not have a hard-and-fast answer.  Dealers will be instantly suspicious if you show up driving a heavily modified car and complaining about defects.  Just how suspicious depends upon the dealer.

Adding aftermarket parts does not automatically void your entire warranty.  For instance, having an Iceman will not affect coverage of suspension, transmission, or electrical problems.  However, if you spin a bearing and the analysis shows dirt in the oil, you are probably out of luck.  If there is an issue, technically the burden is on the dealer to prove that the particular part caused the problem.  Realistically, though, you are starting out with one strike against you.

There is a continuing myth that Mopar Performance parts will not affect warranty coverage.  This is not true.  As far as Chrysler is concerned, Mopar Performance is just like any other aftermarket supplier.  The 'Mother Parts' catalog carries a disclaimer stating the following:

"Competition parts are sold 'as is' without any warranty whatsoever...  Chrysler Corporation vehicle and parts warranties are voided if the vehicle or part is used for competition or if they fail as a result of modification."

Yes, installing a Mopar Performance piece qualifies as a modification to the original car.  In fact, until the 2000 catalog came out, MP parts themselves were not even warranted against defects.  While they still void the car's warranty, most defective parts are now covered.

3.1.3    What is 'Rice'?

Generally, being 'ricey' centers around having a lot of Touring style appearance items without any actual performance modifications, but that's not the whole story. Just adding gargantuan exhaust tips, tall spoilers, multitudinous stickers, ground effects, driving lights, hood pins, huge wheels (and calling them rims), etc. doesn't  automatically mean you are 'rice'.  Style, after all, is a personal thing.

Rice is more of an attitude problem.  Ricers confuse appearance with reality, and convince themselves that a car that looks fast is fast.  Talking the talk without enough performance work to walk the walk is what makes someone a true Riceboy or Ricegirl.

The term 'rice' itself derives from the predominantly Japanese cars favored by the early trendsetters of this style, and the graphics of untranslatable Asian characters that they often carry.  It is not a reference to Asian people in general.

3.2   Engine

3.2.1    General

3.2.1.1    What aftermarket hop-ups are available for each engine?

The Neon aftermarket changes on a weekly basis.  Because more items are coming into production all the time, we recommend that interested folks check the current opinions to be found on the Neon message boards elsewhere on this site.  Some Neon-specific manufacturers have appeared; Mopar Performance has begun shipping its new line of Neon parts, and the car is attracting attention from some companies previously interested in imports only.   Opinions vary widely on the effectiveness of each modification, however:

"When it comes to modifying Neon engines for more power, in my opinion, I wouldn't waste any money on a throttle body, header, ignition system, or any of that typical aftermarket bolt-on stuff... the Chrysler engine guys are horsepower junkies just like the rest of us, and they did the best they could with what they were given."

- Erich Heuschele, from an article in Grassroots Motorsports, July/August 1998

However, one bolt-on everybody agrees on is a cold air induction system.  Also from the same article:

"An intake kit  [is] worth a few horsepower throughout the rpm band, and make[s] the engine much more consistent."  -E. H.

3.2.1.2    What is a basic plan for increasing SOHC performance?

The SOHC has the reputation of being the DOHC's 'little brother'.  However, due to some under-reporting of the SOHC's power figures, and some over-reporting of the DOHC's, the difference is not as huge as it might seem.  Contrary to some opinions, the first step in upgrading a SOHC is not "sell it and buy a DOHC".  Below is a 10-step program for getting more performance out of your single overhead cam engine:

1. Remove the black weatherstripping from the back edge of the hood.  This adds 1hp and is the most cost-effective mod, since it's free.  Approximately 10-15 degrees cooler underhood temperature means more power, too.  One consideration:  with the seal removed, an underhood leak can spray coolant steam over the windshield, causing visibility problems.
2. Muffler.  Replacing the restrictive, one-outlet muffler with something that flows better will add 3 to 4hp.  Once you have upgraded the muffler, exhaust is no longer the bottleneck in the SOHC engine.
3. Plugs and wires.  Replace the stock Champion plugs every 10-20,000 miles.  Fresh cheap plugs do much more for the Neon than expensive ones.
4. Cold air intake.  Installing a CAI ($100-300) replaces the stock airbox and the restrictive snorkel.  Horsepower increase varies by manufacturer and installation, but is typically between 4hp and 8hp across the middle and upper band.
5. Throttle body.  For an MTX car, install the throttle body from an ATX car ($35-75, get it from a junkyard).  This modification is only effective in conjunction with a cold air intake.  Over-bored TBs are also available, larger than the ATX throttle body.  This step is not a critical option.
6. Cam/cam gears.  Replace the '96 and later cam with the original '95 SOHC spec.  This cam ($140) adds about 4hp; it is available as either an over-the-counter part, or as a Mopar Performance piece.  MP also offers an even hotter cam, adding about 6hp; however, idle quality will be noticeably affected.  If replacing the cam, use MP valve springs as well.  This package is labor-intensive and can be expensive to install.
7. Computer.  Install a revised PCM unit ($200-400), which alters spark and fuel tables as well as raising the rev limiter.  Aftermarket PCMs may not meet emissions requirements, and are not available for all models.  Certain units may require a header or other upgrades as well.
8. Header.  Install a header ($150-300).  This improves engine breathing and reduces backpressure in the exhaust system.
9. Underdrive pulley.  Replace the stock accessory pulley with an underdrive unit ($180).
10. Headwork.  The SOHC responds particularly well to porting and polishing the cylinder head for better flow ($500-900), especially in conjunction with #6 and #9 above.  The only reason that headwork comes in at #10 is due to the expense and inconvenience of having it done.

There are plenty of other items which can be modified on the SOHC to improve performance; however, most of them fall into the realm of "serious folks only".  As mentioned above, this list is geared toward the do-it-yourselfer.

3.2.1.3    What is a basic plan for increasing DOHC performance?

The DOHC does have some advantages that help squeeze a few extra horses out of it.  Its main bonus  is the additional 500 rpm redline over the SOHC.  Because of differences in the two engines, the modification lists are somewhat different.  Below is a 10-step program for getting more performance out of your dual overhead cam engine:

1. Remove the black weatherstripping from the back edge of the hood.  This adds 1hp and is the most cost-effective mod, since it's free.  Approximately 10-15 degrees cooler underhood temperature means more power, too.  One consideration:  with the seal removed, an underhood leak can spray coolant steam over the windshield, causing visibility problems.
2. Plugs and wires.  Replace the stock Champion plugs with exactly the same thing (a buck apiece), and do it every 10-20,000 miles.  Fresh cheap plugs do much more for the Neon than expensive ones.
3. Cold air intake.  Installing a CAI ($100-300) replaces the stock airbox and the restrictive snorkel.  Horsepower increase varies by manufacturer and installation, but is typically between 4hp and 8hp across the middle and upper band.
4. Throttle body.  For an MTX car, install the throttle body from an ATX car ($35-75, get it from a junkyard).  This modification is only effective in conjunction with a cold air intake.  Over-bored TBs are also available, larger than the ATX throttle body.  This step is not a critical option.
5. Computer.  Install a revised PCM unit ($200-400), which alters spark and fuel tables as well as raising the rev limiter.  Aftermarket PCMs may not meet emissions requirements, and are not available for all models.  Certain units may require a header or other upgrades as well.
6. Header.  Install a header ($150-300).  This improves engine breathing and reduces backpressure in the exhaust system.
7. Intake manifold.  Polish the inside of the intake manifold, which is somewhat rough cast aluminum.  This can be done by hand, done professionally, or by the extrude-hone method, which is fairly expensive.
8. Underdrive pulley.  Replace the stock accessory pulley with an underdrive unit ($180).
9. Cam gears/cam.  Cam gears allow easier adjustment of the valve timing, which can improve performance.  MP also offers hotter cams; however, idle quality will be noticeably affected.  If replacing the cams, use MP valve springs as well.  This package is labor-intensive and can be expensive to install.
10. Headwork.  As with the SOHC, the DOHC head responds well to porting and polishing.  The only reason that headwork comes in at #10 is due to the expense and inconvenience of having it done.

There are plenty of other items which can be modified on the DOHC to improve performance; however, most of them fall into the realm of "serious folks only".  As mentioned above, this list is geared toward the do-it-yourselfer.

3.2.1.4    A discussion of fuel injection control by the stock PCM.

"There are two types of fuel (injector pulsewidth) adaptives: short term and long term.

Short term basically follows the O2 sensor signal and slightly modifies the pulsewidth in order to keep the O2 sensor switching between rich (lack of O2, or high volts) and lean (lotsa O2, or low volts) states. Short term adaptive is only operating when you are in a closed loop mode, and is therefore not operating at WOT or immediately after a cold start. When the engine is fairly well warmed up (coolant temp above 170 deg F), short term typically runs back and forth over a range between +5% and -5% of base calculated injector pulsewidth. Short term has the authority to go to a maximum of + or - 25% of base calculated pulsewidth.

Long term adaptive is used under all conditions, but the learned values contained in the table can only be updated under closed loop operating conditions with coolant temp above 170 deg F. So, the values in the long term adaptive table are used to alter the pulsewidth even when in open loop immediately after a cold start, but the values themselves cannot change until coolant temp reaches 170. Long term also has the authority to go to a maximum of + or - 25% of base calculated pulsewidth.

Long term "learns" a value when the short term adaptive strays significantly from zero percent pulsewidth correction *and* coolant temp is above 170 F. Long term moves in the direction that short term is going; for example, if short term (due to O2 sensor feedback) has to go to +8%, then long term will start incrementing (in 1% steps) in the positive direction until it covers the movement of short term. Long term always tries to keep short term within +/- 3% pulsewidth change. One little quirk of the 4-cylinder PCMs is that long term will not "learn" when you are above 3400 RPM. The PCM will still use the pulsewidth correction percentages in the appropriate adaptive cell, but it will not change those values above 3400 RPM. In that situation, short term can and does stray farther from the zero line.

Long term is intended to adapt the PCM's pulsewidth equation to the particular components on your car: fuel injectors, fuel pump/pressure, engine compression, intake/exhaust airflow, the gas you buy, etc. As you know, these are a few of the items affecting the engine's Volumetric Efficiency (VE). Of course, this is necessary because all powertrains of the same spec are not identical since there are production tolerances involved. Long term adpative is also expressed in terms of a percentage change to the calculated base injector pulsewidth.

The long term adaptive table is assembled by RPM and MAP paramaters. There are (If I remember correctly) 16 "cells" to cover the following conditions: idle drive (automatics only), idle neutral, the vacuum range from high to low with RPM below approximately 2000, the vacuum range from high to low with RPM above approx 2000, deceleration below approx 2000 RPM and decel above approx 2000 RPM. The 4-cylinder fuel injection training book is one of the few published sources which actually spells out what MAP and RPM parameters it takes to be "in" a given cell.

The DRB III scan tool (and presumably a good professional aftermarket scan tool) will show the long term table if you look under "adaptive memory monitor" under engine.

A DOHC PCM might be really interesting to try on a more aggressively cammed SOHC Neon. The "hotter" of the two listed Mopar Performance cams supposedly pulls nicely up to at least 7000 RPM, which would mesh nicely with the DOHC's rev limiter. By contrast, the stock '95 Neon SOHC cam doesn't require revving past 6100 RPM on 2-3 and 3-4 shifts. Even if you retarded the stock '95 cam, I doubt that the powerband would be shifted enough to require more than 6500 RPM shift points for the 2-3 and 3-4 shifts. I'm sure that the aftermarket would be more than happy to grind up all sorts of alternative cams that would really zing at higher RPM, with the expected loss at lower RPM.

The adaptives may cover your closed-loop fuel needs (altering fuel pressure and/or injector flow rate may also be necessary) and the presumably greater ignition advance of the DOHC PCM would be interesting. Both the DOHC and SOHC run a knock sensor in stock form."

- Greg Smith

3.2.1.5    What spark plugs and wires should I use?

Replace the stock Champion plugs with exactly the same thing (a buck apiece), and do it every 10-20,000 miles.  Fresh cheap plugs do much more for the Neon than expensive ones.   Gimmick plugs like Splitfires, +Fours, etc. have not been proven superior, and in some instances hinder performance.  Platinum plugs may seem to last longer, but many owners don't think they perform as well.

Replace the plug wires with 8mm or 8.5mm wires from Mopar Performance, Magnecore, Crane, or others ($30-60).  These do not actually add power, but do tend to smooth out uneven spots in the power curve.  It is not worth changing the plug wires until the older ones are ready for replacement (40,000 miles or so).  Really expensive plug wires such as Nology HotWires have not been proven to offer a performance gain.

3.2.1.6    What does an underdrive pulley do?

An underdrive pulley reduces the power transmitted to accessories such as the alternator, A/C, and power steering, thus freeing up more power to send to the wheels.  UDPs are also usually lighter than the original unit, which helps reduce rotating mass.  It does not *add* power to the engine.  Several are available from various manufacturers such as AF/X ($200) and Unorthodox Racing.

The accessoriy pulley is located in a very difficult place to reach, and is an interference fit on the shaft, making it extremely tight.  Removal requires a special puller tool, which can be bought from Miller Tools or rented from your local automotive store.  The replacement pulley must be heated enough to expand before it will seat properly on the shaft.  Consequently it can be extremely difficult to install, and is probably beyond the ability of your average do-it-yourselfer with limited facilities.

Please note that the stock unit is called an 'accessory pulley', not an 'underdrive pulley'.  It is also referred to as a "harmonic balancer" and a "crank damper".  Part of its job is to reduce vibration in the crankshaft, though it is not designed to balance the crank like a tire weight does.  Be aware that aftermarket underdrive pulleys (no matter how well they are balanced and manufactured) have not been long-term tested for effects on crankshaft and bearing life.

3.2.1.7    What aftermarket computers (or 'chips') are available?

A common upgrade among both Japanese and German cars, reprogrammed engine controllers have only come to the Neon recently.  The two most common are the AF/X unit ($350, plus exchange) modified by Gary Howell's development company, and the recently-released Mopar Performance unit ($200-300, no core charge).  These computers contain modified ignition and fuel information tables, which the controller uses to vary the spark timing and the quantity of fuel delivered by the injection system.  In most cases they also raise the built-in rev and speed limiters.

These units are not cheap, but do offer real performance gains, especially in conjunction with other modifications such as intake or flow improvements.  For the AF/X unit,  various 'stages' are available, some of which are not emissions-legal.  All of the Mopar Performance controllers are emissions exempt.  Also, most will require 92 octane gas or better to prevent detonation or 'pinging', which can be very harmful to the engine.

The PCM is specific to year and type of engine & transmission. Also, 1995 & 1996 PCM's are different, & cars from those years cannot use the PCM from a car of another year. The PCM's from 1997 to 1999 are interchangeable with cars from the same period having the same engine & transmission.

The AF/X unit is not currently available for '95 m/y cars because it lacks a fan control circuit.  The MP computer is available for the '95, but is not available for ATX cars because it cannot control torque convertor lockup. See the table below for the Mopar Performance part numbers (part status information courtesy of Jim Waleke).

A company called JET offers "reprogrammed" engine control units ($400).  However, analysis has determined that the only modification performed by JET was to place a sticker on the PCM case - the programming remained identical to stock.  The Venom 400, another aftermarket computer, also has not been proven to significantly help performance.  The Venom unit is a 'piggyback' computer that operates at partial throttle positions, but has no effect when the regular PCM goes into 'open loop' mode at wide open throttle.

The part numbers for OEM controllers in the table below are only for cars using US (Federal) controllers.
California, RHD, leaded fuel, & other export models were shipped with different controllers.

1995 Neon Engine Controllers
Manufacturer	Part number	Engine	Transmission	Rev limiter rpm	Speed limiter mph	Market	Notes
OEM	5293 461	SOHC	MTX	6750	118
OEM	5293 471	SOHC	ATX	6750	118
OEM		SOHC	MTX	6750	none		Competition Package
Mopar Performance	P5007033	SOHC	MTX	7400			mtx only, emissions exempt, available as of March, 2007
OEM	5269 718	DOHC	MTX	7250	118
OEM	4699 036	DOHC	ATX	6750	118
OEM		DOHC	MTX	7250	none		Competition Package
Mopar Performance	P5007034	DOHC	MTX	7600			mtx only, emissions exempt, available as of March, 2007
1996 Neon Engine Controllers
Manufacturer	Part number	Engine	Transmission	Rev limiter rpm	Speed limiter mph	Market	Notes
OEM	4699 053	SOHC	MTX	6750	118
OEM	4700 055	SOHC	ATX	6750	118
OEM	5293 072	SOHC	MTX	6750	130		Competition Pacage
Mopar Performance	P5007035	SOHC	MTX	7400			mtx only, emissions exempt, available as of March, 2007
AF/X "Street"	AFXNC96SSA	SOHC	ATX	7800	none
AF/X "Race"	AFXNC96RSM	SOHC	MTX	7800	none
AF/X "Race"	AFXNC96RS	SOHC	ATX	7800	none
OEM		DOHC	MTX	7250	118
OEM	4699 060	DOHC	ATX	6750	118
OEM	5269 609	DOHC	MTX	7250	130		Competition Package
Mopar Performance	P5007036	DOHC	MTX	7600			mtx only, emissions exempt, available as of March, 2007
AF/X "Street"	AFX96DOHCSSM	DOHC	MTX	7800	none
AF/X "Street"	AFX96DOHCSSA	DOHC	ATX	7800	none
AF/X "Race"	AFXNC96RD96	DOHC	MTX	7800	none
AF/X "Race"	AFXNC96RD	DOHC	ATX	7800	none
1997-1999 Neon Engine Controllers
Manufacturer	Part number	Engine	Transmission	Rev limiter rpm	Speed limiter mph	Market	Notes
OEM	5269 991AC (97 m/y mfd. to 9/16/96) 5269 991AD (97 m/y mfd. after 9/16/96) 5269 815AD (98 m/y) ( ? ) (99 m/y)	SOHC	MTX	6750	118
OEM	5269 995AC (97 m/y) 5269 819AD (98 m/y) ( ? ) (99 m/y)	SOHC	ATX	6750	118
OEM	5269 993AB (97 m/y) 5269 817AC (98 m/y) 5269 817AD (99 m/y)	SOHC	MTX	6750	130		Competitive package
Mopar Performance	P5007037	SOHC	MTX	7400			mtx only, emissions exempt, available as of March, 2007
AF/X "Street"	AFXNC9799SSM	SOHC	MTX	7800	none
AF/X "Street"	AFXNC9799SSA	SOHC	ATX	7800	none
AF/X "Race"	AFXNC9799RSM	SOHC	MTX	7800	none
AF/X "Race"	AFXNC9799RSA	SOHC	ATX	7800	none
OEM	5269 998AC (97 m/y) 5269 825AC (98 m/y) 5269 825AD (99 m/y)	DOHC	MTX	7250	118
OEM	5293 005AC(97 m/y) 5293 065AB (98 m/y) 5293 065AD (99 m/y)	DOHC	ATX	6750	118
OEM	5293 004AC (97 m/y)	DOHC	MTX	7250	130		Competitive package
Mopar Performance	P5007038	DOHC	MTX	7600			mtx only, emissions exempt, available as of March, 2007
AF/X "Street"	AFXNC9799SDM	DOHC	MTX	7800	none
AF/X "Race"	AFXNC9799RD	DOHC	MTX	7800	none
AF/X "Race"	AFXNC9799RA	DOHC	ATX	7800	none

3.2.1.8    Won't I get in trouble for switching the PCM?  I thought they tracked mileage or something.

A:      The '95 m/y Neon was not required to be fully OBD-II compliant, and does not track mileage.  '96 and newer cars, however, do store a variable that contains the vehicle mileage.  This is used to set the 'Maintenance Required' light at specified intervals, and may not exactly agree with the odometer reading.  Below are some additional words on the subject:

"I don't know how this issue keeps coming up, but there is no mileage or VIN related legal problem with installing a new PCM in a used vehicle.

For example:  an injector driver in your 1998 Neon's PCM fails -- what does the dealer do under warranty to fix it?  They install a new PCM with the appropriate 1998 Neon programming.  Once the new PCM is installed, the tech needs to use the DRB III scan tool to program the car's VIN into the PCM and enter the odometer mileage intro the SRI (service reminder indicator) mileage counter in the PCM.  However, the SRI mileage counter in the PCM is not used for anything except as a reference for the dealer's MDS2 diagnostic system.  Therefore, in this scenario the '98 Neon would leave the shop with a new PCM containing the car's VIN and the current mileage in the SRI counter.

Mopar Performance is currently selling emissions-exempted performance controllers for various '96-98 Dodge trucks.  Since the OBD II laws (Clean Air Act of 1990) apply to light trucks as well as cars, I have to believe that the Mopar management and the massive corporate legal staff checked out the legality of selling a performance controller for these vehicles.  I do not think that there is a legal requirement to update the mileage counter in the PCM; a customer could install a performance PCM on their own without running afoul of the law."

-Greg Smith

Some people have claimed that the Mopar Performance computer will set the CEL unless it is flashed by the dealer, but this is not the case.  If the PCM is setting a code it is a symptom of some other issue.

3.2.1.9    What does replacing the motor mount do?

The stock motor mounts (p/n ATX - 4668182, MTX - 4668183) are fairly soft, in an effort to reduce noise and vibration.  This allows a lot of engine movement, interfering with quick launches and fast shifting.  It also leads to wheel hop, where the front tire(s) shake rapidly up and down during a racing launch.  Extended wheel hop can damage engine and transmission mounting points, and other components.

Replacing the front motor mount (FMM) in particular is an easy way to reduce this problem.  Stiffer mounts are available via the aftermarket, as well as "Rexified" stock mounts, which have plastic inserts to firm up the OEM unit.  It is even possible to use solid mounts. All of these will improve shifting and launch quality, reducing wheel hop.  However, expect to feel increased vibration from the engine, particularly at idle.

3.2.1.10    I want to replace the oil gauge. What size thread is on the engine oil pressure sensor?

The Neon engine's oil sensor has a 3/8" NPT thread.

3.2.2    Air Intake

3.2.2.1    What is the difference between the SOHC and DOHC intake manifolds?

The DOHC's intake manifold is made from cast aluminum, which means that it can be polished and ported to match the head.  Even if headwork is not planned, it is recommended that the intake manifold runners be polished or extrude honed inside to remove casting roughness.  The intake manifold is much easier to remove and polish than the cylinder head.

SOHC owners are at a disadvantage, except for a few lucky '96 m/y cars.  The SOHC's intake manifold is made from plastic, which cannot be modified this way.  However, due to a supplier problem early in the '96 m/y manufacturing run, a small number of SOHCs got an aluminum intake manifold which can be polished and ported.  Oddly enough these were painted black to match the plastic piece rather than left natural metallic like the DOHC manifold.  This is one reason why more high-performance parts are available for the DOHC.

The SOHC's plastic intake manifold does have some advantages, however.  In its stock form it is smoother inside than the aluminum DOHC manifold, though not as smooth as a polished one.  Plastic is also several pounds lighter, and transfers less heat to the intake air.

3.2.2.2    What is the significance of the throttle body?  How do they differ between cars?

On a fuel-injected engine, the throttle body takes the place of the carburetor.  This is where the gas pedal moves a butterfly valve that varies the amount of air let into the engine, and thus determines engine speed.

ATX Neons have a slightly larger bore to the throttle body than MTX Neons do.  This is because a small flange was added around the rim of the MTX throttle body to restrict air flow at low throttle positions; this was done in an effort to make the manual transmission car more forgiving of poor throttle/clutch technique.  Switching to the ATX throttle body may cause the car to be more jumpy and difficult to drive smoothly.

If done in conjunction with a cold air intake, switching to the larger ATX TB seems to improve acceleration for the MTX car, though it has not been completely quantified.  The throttle body is available from junkyards ($35-75); however, when making the swap be sure to retain the sensors that came with the original car because the different transmissions use different types of sensor.  Cruise control mechanicals complicate the swap as well.  Also, retain the original throttle plate shaft from the manual transmission TB, which helps limit the jumpiness that was engineered out of the MTX in the first place.

Over-bored TBs (larger than the ATX unit) are available through Nemo, Howell, and others.  Both manual and automatic cars can benefit from an over-bored throttle body; however, this is only effective in conjunction with a cold air intake.  Note that homemade oversize TBs sometimes reuse the OEM throttle plate, meaning that the restriction has not been removed.  Buy one from a reputable dealer instead.

3.2.2.3    How can I upgrade my intake system?

The purpose of an aftermarket Cold Air Intake (CAI) is to draw cooler air for combustion than the stock intake does. These are cone-type filters that draw cooler air from another location, usually near the front of the battery, & route the air via a tube to the throttle body. A simple & effective modification; the only drawback is consideration of water ingestion. Replacing the stock intake with a CAI may require other modifications; some are:

• Relocation of the battery to the trunk or
• Modification of the battery mounting tray to retain the stock battery location. Battery tray modification is usually relocation of the battery temp sensor, removal of the battery cooling ductwork, & cutting away sections of the battery tray which are in the way of the CAI.
• Provision for the valve cover breather. The stock setup has a small hose running from the valve cover to the intake pipe, & some CAI intake tubes do not have a place to attach this hose. Typical solutions are to attach a nipple to the new intake tube & attach the hose there, or to just remove the small hose from the valve cover & place an inexpensive small filter there. These small filters can be usually be found in the accessory aisle at an auto parts store - an example is the K&N filter part #62-1320.
• Modification of the CAI tube for atx: The Iceman & 3.0 setup will fit cars with an automatic transmission, but usually for clearance of the battery & fans the section across the tube's U-bend must be cut, turned, &/or extended with an inserted section of pipe.
• Removal of the snow diverter: some CAI systems will collide with the flat plastic duct attached to the underside of the hood, requiring its removal.

Choices for aftermarket air intake systems are:

3.2.2.3.1    Iceman (approx. $200, no longer available as of 2006): The intake pipe snakes down from the throttle body to a filter located under the battery & behind the lower left side of the front fascia. The Iceman ships with a replacement steel mounting tray which moves the battery up and back for clearance. The replacement battery tray is nice but not essential: battery tray modification will work. The Iceman has a nipple for attachment of the tube from the valve cover breather. Requires modification for ATX cars, & can be subject to water ingestion. Replacement filter is K&N filter RU-3130, or K&N Xtreme RX-4140.

3.2.2.3.2    Mopar Performance (no longer available as of 2006): It's a rebadged Iceman kit; a bit more expensive and absolutely no different from Knight Engineering's original Iceman.

3.2.2.3.3    Early style AEM intake: as Iceman. No battery tray is supplied, so battery tray modification is required.

3.2.2.3.4    Kirk (approx $200): The Kirk unit is a very short U-shaped pipe that places the cone filter up high, approximately in the front part of the stock battery location, & specifies relocation of the battery to the trunk. The stock battery location can be retained, however, by attaching to the back of the battery tray a smaller battery (such as a gelcell or the Odyssey PC680MJT), & modifying the battery tray. These smaller batteries usually are sufficient for ordinary use, but may be inadequate for cars requiring starts in extreme cold or if power-hungry electrical accessories have been added. Provision for the valve cover breather must be made. Does not need modification for ATX cars, & is not prone to water ingestion.

3.2.2.3.5    Quikpipe (approx. $120, no longer available as of 2006): positions the filter behind the battery approximately near the engine controller. This location does not draw air as cool as the front-mounted units, & the Quikpipe's filter is smaller than the front-mounted units. However, the Quikpipe can be effective, is less expensive than some others, and does not require any modification to the battery. Does not need modification for ATX cars, & is not prone to water ingestion.

3.2.2.3.6    3.0 CAI (approx. $35): A very successful do-it-yourself CAI similar in style & performance to the Iceman. Parts required are one J-shaped intake tube taken from a salvage-yard mid-1990s Chrysler product with the 3.0 litre V6 (such as a Dodge Caravan), a K&N open-element cone filter available at auto parts stores, a short (6" or 7") length of 2.5" diameter aluminum or exhaust pipe, & three hose clamps. One end of the short pipe is inserted into the end of the long section of the tube &secured with a clamp, the filter is attached to the other end of the pipe with a clamp, & the assembly is attached to the throttle body with a clamp. A variety of filters will work; the requirement is that it must have a 2.5" opening for attachment. K&N part number RU-3130 will do. Provision for the valve cover breather must be made, battery tray modification is often required, requires modification for ATX cars, & can be subject to water ingestion if the filter is positioned very low. A page showing how this CAI is constructed is maintained in the Archived Posts section in the neons.org forums.

3.2.2.3.7    Other CAI sytems: inexpensive home-built CAI's have been constructed using an open-element cone fliter, a little creativity, and other auto intake tubes or some ABS pipe (PVC gives off noxious gases when heated and should not be used).  All of these units will perform similarly; the major differences come from other factors.

3.2.2.3.8    Warm Air Intakes: Focuz, Ractive, Weapon R, later style AEM, & many eBay intakes are deprecated as Warm Air Intakes, as they locate the cone filter at the back of the engine where the stock airbox is. This position draws air from above the exhaust manifold, which is actually warmer than the air ducted to the stock setup when the intake snorkel is in place. With their polished or anodized tubes, the accent is on show rather than go. They are also very subject to water ingestion. These intakes have with some work been modified by some owners to reposition the filter to the usual CAI locations for better performance.

3.2.2.4    What is a K&N filter, and what will it do for performance?

K&N manufactures high-flow air filter replacements commonly found on race cars.  They have a screen-covered, woven cotton filter element that is soaked in special oil to trap dirt particles.  Rather than being replaced, the filter is cleaned regularly using a cleaning kit.  If maintained, one filter will last the lifetime of the car.  Other manufacturers, such as Amsoil, make a similar product using oiled foam.  Opinions vary about which type is better, but I prefer the K&N because of its tighter weave.

K&N filters come in two main applications for the Neon.  First, there is the 'drop in' style (p/n 33-2087, about $35) which is a direct replacement for the paper element, and sits in the stock airbox.  The drop in filter will provide a modest performance gain, mostly noticeable as quicker throttle response.  Second, there is the 'cone' style (p/n varies by size) open element filter, which is typically used as part of a cold-air induction system.

Note that cone-style filters are not legal for SCCA Stock classes.  However, they are permitted in Street Touring and Street Prepared classes.  The drop-in type is legal in all Stock classes.

3.2.2.5    Can I install a cold air intake if I have an automatic transmission?

On ATX cars, the larger transmission will inhibit the airflow improvement to some extent.  Also, The Iceman and AEM must be shortened by 3 to 5 inches so that the filter element fits above the transmission.  Automatic transmission owners may want to consider the Quikpipe, which is less expensive and easier to install, but nearly as effective as a shortened Iceman.  The cruise control unit, which is located behind the front fascia on the left side, also reduces the flow of cool air to these units.  The Kirk/Nemo kit is more effective for the ATX as well.

3.2.2.6    Is water a problem for a cold air intake, or not?

One item of which you should be aware:  some CAIs (the Iceman in particular) sit quite low and may inhale water under some circumstances.  Many vendors claim this is not an issue, but there are documented cases of major engine damage.  It does not take much water to hydrolock an engine - less than a cup full can cause serious pain to pistons, connecting rods, and the block.  If you live somewhere wet, and want to play it safe, go with the Quikpipe or the more expensive Kirk/Nemo kit.

The Focuz, Ractive, and Weapon R intakes are equally in danger from water ingestion, as they can be hit by water splashing off the firewall.  They are even more susceptible to hydrolock than the front-mounted style because the intake piping runs downhill to the throttle body, rather than uphill.  These intakes are not recommended.

3.2.2.7    Will removing the air intake snorkle give more power?

The '96-up m/y snorkle, which passes right over the motor, significantly increases the charge temperature of the incoming air.  Simply removing the snorkle and using the stock airbox has not been shown to give a measurable increase in performance.  However, it does put the air intake in about the same position as the '95 m/y SOHC, which has slightly better performance than later SOHCs.  It is also much noisier, which is why the snorkle design was changed in the first place.

If you do remove the snorkle, or have a '95 SOHC, there is a simple modification that is good for about 1 hp.  Just remove the soft black weatherstrip at the rear edge of the hood.  This allows high-pressure air from the base of the cowl to get under the hood at the rear of the engine, right where the airbox sits.  The downside is that this will increase the temperature of the air brought in through the fresh air vents. Also, an underhood coolant leak can cause sticky white steam to blow over the windshield, impairing visibility.

3.2.2.8    How does the PCV relate to my cool new intake setup?

Many people, when installing the Iceman or other cold air induction setups, buy a small filter to put over the breather fitting on the valve cover.  This is not a good idea, since under certain conditions the breather will splatter oil out through this filter.

Most kits come with a small fitting that must be drilled and tapped into the intake tube.  The PCV hose is then attached to this fitting, which allows the cranckase to breath filtered air.  DOHC owners should also install the oil restrictor plug in this hose.

3.2.2.9    What K&N filter do I use as a replacement on my Iceman intake?

The Iceman originally came with a K&N RU-3130 filter; K&N Xtreme filter RX-4140 may also be used as a replacement.

3.2.3    Exhaust

3.2.3.1    What is the theory behind header design?

"Headers function in different ways.  Lets go with the 'scavenge' effect first.  On a four stroke, four cylinder engine, you have a cylinder firing every 180 degrees of crankshaft rotation.  That means each of the 4 cylinders is at a different stage in the four stroke cycle.  Because of valve overlap, the exhaust valve on a cylinder is still open for a very short period of time while the piston is starting down on its intake stroke, thus pulling vacuum on the exhaust system.  Now, that small amount of vacuum can be used to help pull the exhaust from another cylinder, or 'scavenge'.  The length of the tubes from the head to the collector determine the rpm where maximum scavenging occurs.

The stock manifold is short, thus scavenging occurs low in the rpm band; the Pacesetter header which is longer scavenges most in the mid range; and some other brands which are a long tube design are more for the upper rpm range.  What this scavenging does is increase the torque in the area of maximum scavenging.  So for normal putting around town the stock manifold is the best choice; that is one of the reasons the factory uses that length. The mid-range is the best for most general performance use where acceleration drops into the mid-range rpms and climbs back up.  Drag racing and road racing would be two common examples of this.  The long tube design is for sustained high rpm running, such as land speed records or Goody's Dash series cars running at Daytona where speeds remain constant with little or no acceleration.  The long tube can increase the maximum speed of the a car by increasing the torque at high rpms, but has little use on the street.

Headers also reduce exhaust restrictions by making more gradual bends.  Look at the stock manifold: the bends are more harsh; if you drill and tap a hole in one of those bends you will read a pressure increase in the turns.  The headers have less of a bend, so the pressure is reduced.  Reduced pressure in the exhaust system equals increased power.  The piston coming up on the exhaust stroke pushes the exhaust out of that cylinder; since the piston on the power stroke is driving the piston on the exhaust stroke, it takes engine power to push the exhaust out.  The more restrictive the exhaust flow, the more power the engine has to use.  Therefore if we reduce the restriction by adding a header, less power is required to push out the exhaust.  That "extra" power now can be used at the wheels to accelerate the car.

The addition of headers will do one other thing - it will effectively lean out the fuel mixture.  If you add only the header you will gain power, but in order to get the full benefit of the header you will have to richen the fuel mixture.  This should be done because the air/fuel ratio from the factory is set to the lean side in order to meet emission standards.  [Editorís Note:  this statement is not entirely correct.]  The header will push it more into the lean side; power comes with a richer mixture.  The only way to richen the fuel mixture on the Neon is to have the computer reprogrammed.

[other sources maintain that naturally aspirated Neons do not run lean, even with normal bolt-on modifications.  Also, one other point of header design Gary doesn't mention:  headers are configured in certain ways to make the runners for all cylinders close to equal in length.  This improves consistency of air/fuel flow across all cylinders.  -- Duke Cunningham]

In short I recommend a header that will enhance mid range torque, such as the Pacesetter Header.  In addition one should consider having the computer reprogrammed to richen the fuel mixture, to make a better combination."

- Gary Howell

3.2.3.2    How can I upgrade my exhaust piping and muffler?  Which muffler is best?

Exhaust system changes are probably the most popular modification among Neon enthusiasts; they vary widely in both cost and effectiveness.  Some performance gains can be had for cheap, but it takes money to look good.

The stock piping is fairly well laid out and produced; it is mandrel bent and adequately sized at 2-1/4" diameter (which looks like a water main compared to stock Honda pipes).  It is not necessary to replace the stock catalytic converter or the rest of the piping until after some serious engine modification has improved flow through the engine itself.  Borla makes a high-quality, stainless steel cat-back system ($300); Dynomax makes a 2-1/2" mandrel bent cat-back system that is cheaper, but is mild steel and will rust out.

In its stock form, the bottleneck in the SOHC's flow is on the exhaust side.  Fortunately for SOHC owners, the only change necessary is the simple switch to a stock DOHC muffler ($30-50).  These are usually available used on the Neons.org For Sale board; they should also be available at the local junk yard.  The DOHC's twin-outlet muffler is slightly louder, with a little more rumble, but it is quieter than any aftermarket muffler.  Other mufflers certainly look better, but will not offer the SOHC any performance gain over the DOHC unit.  Note that the stock clamp is actually part of the muffler, not a separate piece.  Once it is loosened, simply pull the muffler off of the pipe.

For DOHC owners, switching to an aftermarket muffler will provide only slight performance gains, since the stock DOHC's bottleneck is on the intake side rather than the exhaust.  However, it can improve looks considerably.

The next step up on the cost-effectiveness scale is either the Dynomax or the Walker Ultraflow, both of which are aluminized steel with stainless tips ($70-90).  The Dynomax looks like an OEM DOHC unit, with twin slightly oversized 2-1/2" tips; the Walker has a single 2-1/2" outlet and will need an additional pipe to exit the rear of the car.  The Dynomax has been dyno proven to add a small power gain for both the SOHC and the DOHC.  It is notably louder and deeper than the original equipment, with a moderate boom at around 3000 rpm.

For more aesthetically-oriented folks, the Thermal ($250) and Vibrant ($220) offer polished-stainless looks with the sound and fury of mighty 4" tips (of course the rest of the piping is still 2-1/4").  The Thermal has two outlets exiting the right side of the car; the Vibrant has one each side for that "dual exhaust" look.  Neither of these mufflers offers a performance improvement over the less-expensive models listed above; however, they certainly look better.  Sound for both is comparable to the Dynomax: notably louder than the stock unit, but without the 'coffee can' buzz common to some Asian-market mufflers.

Borla ($200 muffler, $300 cat-back) and Pacesetter ($175 cat-back) were two of the earliest makers of performance exhaust for the Neon.  Borla's design has a large single outlet with the trademark "intercooled" tip while Pacesetter's dual look was copied by Vibrant.  While the Borla is a high-quality stainless steel piece, the painted-steel Pacesetter has some reputation for low quality and quickly rusting out.  While both are still made, neither is currently popular.

SuperTrapp makes a version of their unique multiple-disc muffler that fits the Neon.  Opinion on the SuperTrapp varies widely; some have good success while others claim no addition or are not satisfied with quality.  The SuperTrapp offers "tunable" noise (and theoretically power) level by adding and subtracting discs to the tube-like muffler body.

3.2.3.3    What about a header and cat?

Several companies make headers for the Neon in both SOHC and DOHC flavors (the head bolts are different so the two are not interchangeable); Pacesetter and Kirk are the two most popular.  A header improves airflow through the engine and can help "scavenge" the exhaust waste from the cylinders.  See the essay on header theory for more information.

The second-generation Pacesetter is an improved design, but occasional bad things are said about quality.  Pacesetter's header is designed to improve midrange torque, which is helpful for drag racing.  This piece will work with the OEM catalytic convertor in place.   The Kirk unit appears to be of somewhat better quality but is aimed at improving high-rpm power; it is more suited to road racing.  Because of its long-tube design, the Kirk header requires modification to the catalytic convertor location and therefore to the exhaust piping.  Mopar Performance offers both street and track headers, as well, based on these two designs.

High-flow catalytic convertors ('cats') are also available from Random Technologies and others; it is also possible to 'gut' the OEM unit.  Typically they do not offer performance gains for street use and are effective only in the later stages of a build-up program when other more significant bottlenecks have been removed.

3.2.4    Cylinder Head

3.2.4.1    What do 'porting', 'polishing', and 'headwork' mean?

Headwork means modifying the original cylinder head, which is the top part of the engine containing the combustion chambers, valvetrain, and passages where air/fuel mix flows in and exhaust gases flow out.  Typically this is done by two seperate processes called 'porting' and 'polishing'.

Porting means that the openings at each end of the head are bored out to a larger diameter in order to improve flow.  Often they are 'port matched' to the intake manifold or exhaust manifold/header, meaning that any offsets or misalignments between the two parts are machined out.  Sometimes the valve openings are modified as well.

Polishing means that the inside of each passage is polished from a rough cast surface to a smooth finish.  This reduces drag as the combustion gases move along the walls and therefor increases the velocity of the air/fuel mixture.  This can be done by hand, or by a process called 'extrude honing' in which an abrasive paste is pumped through at high pressure.  Extrude honing is very effective but expensive.

A third form of head modification is called 'decking'.  The bottom face of the head (which joins the block) is milled or ground down in order to reduce the combustion chamber volume, which increases compression.

3.2.4.2    What do cam gears do?

Cam gears replace the fixed factory gears at the end of the camshaft, which carry the upper end of the timing belt.  They are used to tune the valve timing relative to the crank.  To make this job easier, they are indexed with decimal degree markings and are designed to allow precise adjustment.  This can be done using the stock pulley; however, it is not nearly as easy.  Cam gears do not add any power themselves - they are merely a tuning tool.  Because of variation in each engine, cam timing is not perfectly adjusted at the factory.  Most engines can benefit from some degree of fine tuning.

On the SOHC, a cam gear is used to adjust the cam timing relative to the crank position, since the intake/exhaust overlap is fixed.  Advancing the cam will increase low-end power; however, it can cause the upper end to fall off dramatically.  Conversely, retarding the cam will improve high-end power at the cost of low-rev grunt.

Cam gears are also used to adjust the relative timing of intake and exhaust valves on the DOHC.   As a rule of thumb, the general method of tuning is to retard the exhaust cam in small steps with multiple timed or dyno runs between.  Continue retarding until performance stops improving, then advance slightly.

This kind of tuning is by necessity a compromise.  Otherwise, manufacturers would simply set the cam for maximum power at the factory!  Which method you choose depends entirely on the type of performance for which you're looking.

3.2.5    Forced Air Induction

3.2.5.1    I need boost!

Moving beyond normal bolt-ons like those above means finding a way to force more air/fuel mix into the engine than it can inhale naturally.  The two main methods of applying boost pressure to the intake are turbocharging and supercharging.  These two units accomplish the same goal, a dramatic increase in power, by somewhat different means.  This discussion will be very limited, because the details could be an FAQ unto themselves.  Both systems are very expensive, with kit prices starting around $3000 - not including installation or improvements to other engine components to compensate for the added stress.

Turbocharging utilizes exhaust gas to spin a turbine, which drives (via a shaft) an impeller to force air/fuel into the intake system.  Turbos are very efficient because they utilize wasted energy; however, they can be finicky to install and maintain.  Also, turbocharging creates a large amount of heat, which must be dealt with effectively.  Several kits are currently available; they range from near-prototypes to complete packages. The first true kit was developed by Hahn Racecraft, and enjoys an excellent reputation for quality.  Turbocharger installation is beyond the amateur mechanic and requires a professional.  Due to differences in the intake manifold, among other things, the Hahn kit is available only for the DOHC.

Supercharging uses a belt-driven compressor, which come in several varieties such as the screw, centrifugal, and roots types.  Boost is available even at very low rpm; however, the 'blower' itself adds a parasitic load to the engine approximately equal to an extra air conditioner.  No supercharger kit is currently shipping, though Rimmer Engineering and Jackson Racing (both big in the Import scene) are said to be developing Neon kits.  Rimmers product is said to be close to release; however, development problems have set the project back several times.  Typically, supercharger installation is feasible to a skilled amateur with good facilities; this is an advantage for the system.

Both systems benefit greatly from an intercooler, which is usually added as part of a 'Stage Two' system.  Physics dictates that compressing a gas also heats it; hot air is less dense than cool air and does not burn as well.  An intercooler is, in essence, an additional radiator through which the intake air is piped before entering the throttle body.  This cools the air to a better charge temperature and improves combustion.

3.2.5.2    A few words about the problems involved with adding boost to the Neon.

"Recently, several folks on the list have been contemplating a supercharger or turbo setup for the Neon.  I have been thinking about the feasibility of this a bit, and I thought I'd share some info.

Since the Neon uses a speed-density fuel injection system, it does not directly measure the amount of air flowing into the intake manifold. Instead, it measures the intake air temperature, manifold vacuum, barometric pressure and RPM to *calculate* the amount of air flowing into the engine.  Since the PCM would have no way to know about the increased airflow resulting from a turbo or supercharger, you can't just bolt on a turbo/supercharger and expect the car to run properly.

I was thinking about the aftermarket supercharger kits that some companies offer for the Dodge Magnum V8s.  How do they get around the limitations of a speed-density system?  What are they using for a MAP sensor?  Do they have custom software?  To find some answers, I spoke with someone from the Mopar Performance tech line.

The guy that I spoke with told me that the aftermarket V8 supercharger kits they have tested did not use modified software -- they just relied on an additional fuel pump to keep up.  I was told that in spite of the additional fuel pressure, trucks with these kits run very lean with 6 psi boost, which results in (at least) a blown head gasket sooner or later.  I was told that Mopar Performance does NOT endorse any of these supercharger kits because of this issue.

I asked about the supercharged Neon GTS concept car.  I was told that they basically just bolted that car together as a show vehicle and knew that the fuel/air ratio would not be correct when under boost. They knew that the drivability would not be correct, but it doesn't matter since the car is a show vehicle that is rarely driven.

We both agreed that you couldn't get a super/turbo setup to run properly without (at least) a turbo-style MAP sensor and significant PCM software changes.  The Mopar Perf guy said that some folks who race trucks in SuperStock drag racing are finding that the PCM has a hard time keeping up with some of the cams that they run.

I just thought you'd all like to know..."

- Greg Smith

3.2.5.3    Which is better, turbo- or supercharging?

In general, turbocharging is a better system because its potential maximum power is higher than the supercharger.  However, supercharger systems have some advantages in their favor.  Which system is right for you will depend upon your application.

The turbocharger's effectiveness increases with rpm, so that power increases smoothly.  In a front wheel drive car like the Neon, this means that traction is not overwhelmed at the launch, and the power is effectively put down after the car has begun moving.  For racing applications with a small engine, the turbo's even power delivery and high top-end performance give it a clear advantage over the blower.

However, the supercharger excels for a predominantly street-driven car, because its constant boost adds the low-end torque missing from nearly all smaller engines.  The 80/20 rule applies here - the supercharger will give most of its power gain in the rev range where most people spend 80% of their driving time.  Additionally, the installation is simpler, meaning that the average street performance car driver has a hope of being able to 'do it yourself'.

3.2.6    Nitrous Oxide

3.2.6.1    What about nitrous oxide?

Nitrous oxide is like steroids for your engine:  it'll make you strong, but ultimately it's unhealthy and leads to premature death.  Nitrous oxide does not actually burn in the engine.  Rather, rapid cooling caused by the expanding gas drastically increases the density of the air/fuel mixture, allowing more into the engine.  This leads to large (50 to 150hp) but short-lived (measured in seconds) boosts in horsepower.

Nitrous systems can cause many problems.  The engine will run lean, causing melted pistons, unless a carefully managed program is followed to deliver additional fuel.  The increased internal stresses often result in crank, rod, or piston failure.  Also, nitrous systems by design operate under very high pressure (thousands of pounds per square inch) and improper installation is a serious safety hazard.  It must be a professionally designed and installed system.

This is not to say that the 'throttle in a bottle' is not a highly effective method of improving short-term performance.  However, it should only be considered for racing applications, or by those who (like most racers) consider engine replacement a 'routine maintenance item'.

3.2.7    Engine Swap

3.2.7.1    Choices for engine swap

Engine Data Comparison
	2.0 SOHC 1995 only	2.0 SOHC 1996-9	2.0 DOHC 1995-9	PL2k SOHC 2000-2	PL2k SOHC 2003-2006	Magnum SOHC	2.4 DOHC (Stratus)	SRT-4 Turbo
Chrysler Engine Code:	ECB	ECB	ECC			ECH		EDV / EDT
Displacement:	2.0 litre	2.0 litre	2.0 litre	2.0 litre	2.0 litre	2.0 litre	2.4 litre	2.4 litre
Valve Train:	SOHC	SOHC	DOHC	SOHC	SOHC	SOHC	DOHC	DOHC
HP Peak:	136 hp	132 hp @ 6000 rpm	150 hp @ 6500 rpm	132 hp @ 5600 rpm	132 hp @ 5600 rpm	150 hp @ 6500 rpm	150 HP @ 5200 rpm	215 hp @ 5400 rpm
Torque Peak:		129 ft/lb @ 5000 rpm	133 ft/lb @ 5600 rpm	130 ft/lb @ 4600 rpm	130 ft/lb @ 4600 rpm	135 ft/lb @ 4800 rpm	167 ft lb @ 4000 rpm	245 ft/lb @ 2000 rpm
Redline:	6500 rpm	6500 rpm	7000 rpm	6500 rpm	6500 rpm	6500 rpm
Rev Limiter:	6750 rpm	6750 rpm	atx: 6750 rpm mtx: 7250 rpm	6750	6750	6750
Compression:	9.8 to 1	9.8 to 1	9.6 to 1	9.8 to 1	9.3 to 1	9.8 to 1	9.4 to 1	8:1
Bore x Stroke:	3.44 in x 3.27 in	3.44 in x 3.27 in	3.44 in x 3.27 in	3.44 in x 3.27 in	3.44 in x 3.27 in	3.44 in x 3.27 in	3.44 in x 3.98 in	3.44 in x 3.98 in
Recommended Gas:	87 octane	87 octane	92 octane	87 octane	87 octane	91 octane		91 octane

3.2.7.2    What will I need to install a 2.4 engine?

Neons.org maintains a "sticky" & an entire message board related to engine swaps at forums.neons.org

3.3    Transmission

3.3.1    How can I increase performance for my automatic transmission?

There are several methods of getting more acceleration from an automatic, but all have some downside:

1. Install a high-stall torque converter, available from Howell Automotive and other sources.  The standard torque convertor will stall the engine at about 2100 rpm if the gas pedal is applied while the car is held stopped with the brakes.  This is known as "brake-torquing" or "power-standing", and may damage your transmission if done for *extended* periods (it is safe if held for a short time, 30 seconds or so).  Brake-torquing is done to allow the engine to be at higher rpm at launch, and thus closer to the power band.  A high-stall torque converter stalls the engine at about 3000 rpm, which makes for better launches.  However, it does so by allowing extra slip in the torque converter, which may affect overall performance.  This requires dropping the transmission.
2. Install a "shift kit", available from Mopar Performance and other sources.  A shift kit increases the hydraulic pressure applied during shifting, which means more positive, faster shifts with less slip.  However, shifts may become noticeably rough for normal driving.  Also, the Mopar Performance kit interferes with lockup of the torque convertor at cruise.  It can be modified to allow lockup, but there is currently not a source of detailed information on how to do so.  This requires dropping the transmission.
3. Install transfer gears with a shorter (higher number) final drive ratio.  Mopar Performance had a set (p/n P4349677) which gave 1.22 reduction, but this is no longer sold.  Units may still be available in some places.  Howell Automotive offers used sets from a different Chrysler vehicle that can be installed in the Neon, for a 1.23 reduction.  Shorter final drive ratios give stronger acceleration, at the cost of highway driveability and fuel economy.  For example, a SOHC automatic turns 3500 rpm at 80 mph.  After the gear swap, it would turn 3500 x 1.23 = 4300 rpm at 80 mph.  This work can be performed through an access panel in the left front wheel well, and does not require dropping the transmission. Note that the SOHC and DOHC have the same transfer gears, even though their final drives are different.  SOHC owners can't get a quick boost by switching to the DOHC transfer gears.

3.4    Suspension

3.4.1    What tires / wheels should I get?  I want to stay at the stock wheel size.

The stock Eagle GAs don't exactly suck, but they are definitely chosen to be smooth and quiet, with little thought for handling performance.  At replacement time, much better tires can be had for the price of the Goodyears, which aren't particularly cheap.  Tires of softer tread compound or different tread pattern can provide improved handling, sometimes at the cost of tread life or winter performance.  Tires with a higher speed rating often improve handling due to their stiffer sidewall.  Below is a chart of some recommended tire selections:

 

Recommended Replacement Tires
Manufacturer	Model	SR	Price	Remarks
Dunlop	D60A2	H	$ 55	Popular, good wet/dry grip
Pirelli	P6000 SV	H	$ 68
Yokohama	AVS-I	V	$ 88	Grippy but short-lived
Yokohama	AVS-I	Z	$ 122	205/55-ZR14 (rare size)
Goodyear	Eagle Aquatred	H	$ 84	Better than Eagle GAs
Bridgestone	Potenza RE930	H	$ 63
BF Goodrich	Comp T/A HR4-2	H	$ 56

Notes:

- SR is Speed Rating.  See question below for more information.
- Price is approximate per each cost, excluding mounting.

Also, slightly wider tires can be fitted, which improves grip, except in snow conditions.  A wider tire should be coupled with a lower profile height in order to keep the overall diameter close to stock.  See the question on tire designations below for more information.  Below is a chart (tire information and calculations courtesy of Kevin Smith) of common tire sizes for the 14" wheel:

 

Common 14" Tire Sizes
Tire Size	Total Height Whl / Tire	Sidewall Height	RPM (mile)	Error (%)	Error @  60 mph	Remarks
185/65-R14	23.47"	4.73"	859	0%	60.0	OEM size
185/60-R14	22.74"	4.37"	887	-3.2%	58.1	ACR OEM size
195/50-R14	21.68"	3.84"	930	-8.3%	55.0
195/55-R14	22.45"	4.22"	899	-4.5%	57.3
195/60-R14	23.21"	4.61"	869	-1.1%	59.3	Recommended
205/55-R14	22.88"	4.44"	882	-2.6%	58.5	Hard to find
205/60-R14	23.69"	4.84"	852	+0.9%	60.5

Some notes to remember:

- Actual sizing varies slightly by manufacturer, just like shoe sizes.
- RPM in this case is revolutions per mile (at the wheel, not the engine).
- Error is the actual speed at 60 mph indicated.

3.4.2    What wheels / tires should I get?  I want to move up in size.

Larger wheels and ultra-low profile tires look cool, but as with lowering, there will be side effects as well.  Large diameter wheels have a lot of mass at the rim, which wastes engine muscle to get rotating.  Also, a large wheel/tire combo often ends up taller than stock in total height, which changes the final drive ratio of the car.  This leads to slower acceleration, as well as speedometer error.  Lastly, big rims with low-profile tires tend to wander, rather than track straight, as they are influenced by waves and bumps in the road surface.

From the Grassroots Motorsports "Project C-ReX" article:

"... we decided to go with only 15-inch wheels (instead of something huge like 17s).  This way we got some cool looks without throwing all of our handling and street manners out the window.

Since big wheels are heavier than smaller wheels, a little common sense guided our decision.  If it takes a 400 hp Corvette to spin a heavier 17-inch wheel, what's going to happen when we put some on our CRX? Exactly - bog city."

However, stepping up to a 15-inch wheel should minimize a lot of the problems, and it increases the choice of tires substantially.  15" x 7" wheels can bit fitted without clearance problems.  Remember to find wheels with the same bolt pattern and offset as stock (see above).  The offset can be decreased to 35mm with a 7" wheel to allow wider tires to be fitted without inside clearance problems.

Numerous sport tires from Dunlop, Michelin, Pirelli, Goodrich, Yokohama, and others are available in a minimum size of 15 inches.  Below is a chart (tire information and calculations courtesy of Kevin Smith) of common tire sizes for larger wheels:

 

Common 15", 16", and 17" Tire Sizes
Tire Size	Total Height Whl / Tire	Sidewall Height	RPM (mile)	Error (%)	Error @ 60 mph	Remarks
195/55-R15	23.44"	4.22"	860	-0.1%	59.9
205/50-R15	23.07"	4.04"	874	-1.7%	59.0
205/55-R15	23.88"	4.44"	845	+1.7%	61.0
215/50-R15	23.46"	4.23"	859	0%	60.0	Front only
205/45-R16	23.26"	3.63"	867	-1.9%	59.5
205/40-R16	22.46"	3.23"	898	-4.5%	57.3
205/40-R17	23.46"	4.22"	860	-0.1%	59.9

Some notes to remember:

- Actual sizing varies slightly by manufacturer, just like shoe sizes.
- RPM in this case is revolutions per mile (at the wheel, not the engine).
- Error is the actual speed at 60 mph indicated.

3.4.3    I'm confused about all those tire designations.

Modern tires follow a standard size and duty rating system.  For instance, the common OEM tire is a 185/65-HR14.  This breaks down as follows:

185 = Width of the tire's cross section in millimeters.  Measured from sidewall to sidewall, not across the tread.
65   = Aspect ratio; the sidewall height as percentage of the section width, i.e. 185mm x 65% = 120.25mm.
H    = Speed rating (varies).  Each letter corresponds to a maximum sustained speed the tire can tolerate.
R    = Radial.
14   = Rim diameter in inches.

If you increase the tire's width, you should reduce the aspect ratio to maintain a total height that is close to stock.  Changing the overall height (diameter) of the wheel/tire combination changes the circumference.  This affects the acceleration of the car, as well as the accuracy of the speedometer, as indicated in the tire size charts above.

The speed rating indicates the maximum speed the tire can tolerate.  Sustained high speed causes tremendous heat buildup in the tire, and exceeding the speed rating can cause the tire to fail at high speed.  Not a good thing.  Heat buildup is caused by internal friction as the tire flexes while rolling.  Tires with a higher speed rating typically have a stiffer sidewall to reduce flexing; as a benefit, stiffer tires handle more crisply than tires with a softer sidewall.  The speed rating designations are as follows:

Q = 99 mph (160 km/h)
S  = 112 mph (180 km/h)
T  = 118 mph (190 km/h)
U = 124 mph (200 km/h)
H = 130 mph (210 km/h)
V = 149 mph (240 km/h)
Z = 149 mph (240 km/h and over)

One additional designation is the UTOQ rating.  This is a measure of the service life of the tire, based largely on the estimated tread life.  In general, tires with a lower UTOQ use a softer tread compound, offer more traction, and have a shorter lifespan.  For instance, the ultra high-performance Yokohama AVS-I has a UTOQ in the 100s, and an expected street life of 10,000 to 15,000 miles.  On the contrary, a consumer-oriented tire like the Goodyear Invicta has a UTOQ in the 300-400 range, and can last 50,000 miles or more.  However, handling and traction are substantially compromised in exchange for extended mileage.

3.4.4    Why should I adjust camber?

Stock alignment settings call for 0 degrees camber; i.e. the wheels theoretically sit perpendicular to the ground when the car is at curb height.  As the car corners, the load is placed most dramatically on the outside front tire.  This causes the tire to deform such that the contact patch is no longer firmly planted in the middle of the tread area, but drifts up onto the outside edge of the sidewall, and unloads the inside edge of the tread.  Compliance, or give, in the suspension components can amplify this effect.  The net result is that the cornering grip of the tire is reduced, and the tire slips.

Adding negative camber to the wheel means the loading is biased toward the inside edge of the tire.  Consequently, when the car turns, the outside front tire sits squarely on its contact patch due to the negative camber "correcting" for the cornering load.  Grip is increased, and the car will turn more precisely at higher speeds.

"Camber can be adjustable at all four wheels, but I personally recommend against adding negative camber to the rear wheels.  The Neon, like most FWD cars, understeers.  Adding negative camber to the front increases grip, thus decreasing understeer and providing more balanced handling.  Subsequently, adding negative camber to the rear will increase understeer."

Duke Wilford

Negative camber can cause wheelspin for drag racers, and is not necessary since under drag racing conditions the car is evenly loaded from side to side.  Radically negative camber (-3 degrees or more) can also lead to wheelspin on the inside tire during autocross maneuvering.

3.4.5    How can I lower my Neon?  What are the side effects?

Neons can be lowered by using shorter, progressive-rate (or higher-rate) springs.  Lowering kits are available from Eibach, Progressive, Jamex, and other aftermarket suppliers.  Eibach's kit reduces curb height by about 1 inch; others as far as 1-3/4 inches.

Lowering a Neon may look cool, but it will have repercussions in ride and handling.  Ride is a matter of personal preference.  However, handling is compromised by lowering the Neon -  they just don't have the jounce travel to waste.

The Neon has relatively short strut travel, which means the stock springs are fairly short and stiff.  This is one of the reasons that even base Neons have such crisp, enjoyable handling.  Reducing the travel even further means that the car hits the jounce snubbers (which in fact are designed to be helper springs) more frequently.  This impact reduces the grip of the tires, as the car bounces rather than absorbing the bump.  Lowered Neons tend to understeer more than usual due to this effect.  They are also more apt to make a sudden transition to oversteer at the limit.  Neither effect is a good thing.

Handling can be maintained by going to a coil-over strut setup, in which the jounce travel remains the same, but the spring perches can be adjusted to allow a lower ride height.  These kits are available from Mopar Performance, Carrera, Tokico, Koni, and others, but tend to be substantially more expensive.

3.4.6    How can I improve my Neon's handling?

Neons handle quite well straight out of the box.  However, there are a number of (relatively) easy ways that handling can be improved:

1. Put on better tires.  This is the place to start, and makes a never-ending discussion topic all by itself.  Everyone agrees that the stock Goodyear rubber is chosen strictly for its quietness, not perfomance.  Unless you are a driving enthusiast, it may not be worth replacing the OEM tires before they're worn out.  But when you do replace them, much better tires are available for the same price (or cheaper) than the Goodyears.  See the questions on wheels and tires for more information.
2. Dial in some negative camber on the front wheels.  See the question about camber adjustment for more information.
3. Install Mopar SDE (or aftermarket) swaybars.  The SDE suspension (see above for applications) comes with a 22mm front swaybar and a 16mm rear bar.  Cars other than '95-'96 Sport Coupes, R/Ts, and ACRs benefit from this installation.  See the question on swaybars below for more information.
4. Install polyurethane bushings in place of the OEM rubber units.  These are available from Mopar Performance, Energy Suspension, Eibach, and others.  Poly bushings stiffen up suspension response, and have less compliance than the softer rubber pieces.  This means more taut handling, and less dynamic change to alignment settings.  Note that at least some Neons (R/Ts and ACRs) changed to polyurethane bushings for certain suspension components in the 1998 m/y.  Below are part numbers and the blurb from the MP catalog (courtesy of Jim Waleke):

   "All Mopar Performance bushings are manufactured of a tough and durable polyurethane which gives the bushings higher durometers than the production rubber units. The added stiffness can make the part stronger but the real advantage is that the increased stiffness increases the control of the part which can improve vehicle handling in race situations. These bushings are recommended for circle track, solo, and road racing applications. They can also be used in drag racing where they apply."

Mopar Performance Suspension Components
Item	Part Number	Price
Strut Rod Bushing Kit	P4876424	36.50
Control Arm Bushing Kit	P4876425	57.50
Front Sway Bar End Link	P4876426	21.00
Rear Sway Bar End Link	P4876427	10.75
Front Sway Bar Bushing	P4876428	13.50
Rear Sway Bar Bushing	P4876429	13.50
Tie Rod End Dust Boot	P4876430	4.75
Rear Control Arm Bushing Kit	P4876557	41.75

3.4.7    What are swaybars and how do they improve handling?

A swaybar is a steel rod that goes from strut knuckle to strut knuckle across the car.  It is attached with rubber or poly bushings to each knuckle, and to the frame, where it is held in place but able to rotate slightly.  The swaybar transfers load from one side's wheel to the other, which reduces body roll as the car corners.  For instance, in a right hand turn, weight transfers to the left side of the car, and the left side suspension compresses.  The swaybar transfers some of that compression to the inside (right) wheel, distributing the load more evenly, and reducing body roll.  This stabilizes the car, and helps prevent the inside wheel from locking up under braking, or spinning under acceleration.

While a swaybar does improve balance and handling, it does not increase available traction.  Better stability is achieved at the cost of some overall traction.  Consequently, handling can be balanced from front to rear by adjusting the stiffness of the appropriate swaybar.  A stiffer bar at front or rear will cause slightly more slip at that end of the car.

There are two main swaybar setups available on the Neon (excluding the stripper '95 m/y base sedan, which has none):  20mm front/no rear bar, found on most Neons, and the 22mm front/16mm rear setup, which is found on some Sport Coupes, all ACRs, and all R/Ts.  See suspension codes SDE and SDK for more information.

The 22mm/16mm combination is more neutral in handling than the 20mm/0, as the added rear bar increases oversteer to counteract the Neon's inherent FWD understeer.  It is possible to use the 20mm bar with the 16mm rear bar.  In fact, this is the hot setup among autocrossers since it helps rotation in tight corners.  However, it increases oversteer noticeably.  For the average street driver, the car may be slightly prone to spin under emergency maneuvering with the 20/16 combination.  In fact, many top autocrossers are switching *back* to the 22/16 setup.

Swaybars are an easy and recommended upgrade for anyone with the SDC suspension, who are the majority of Neon owners (or those few SDAs).  Genuine Mopar parts can be ordered through any dealer, at a cost of around $150 total.  Also, aftermarket kits are available from Eibach and others; some include even stiffer bars than the factory parts.  See the How-To section of this site for information on installing the Mopar swaybars.

3.4.8    The Mopar Performance catalog lists a 19mm rear swaybar.  Does it really exist?

Mopar Performance has a catalog entry for both 19mm (p/n P5007026) and 22mm (p/n P5007041) rear bars.    It's a mistake in the catalog; the 19mm rear bar does not exist.  For the first year or so, the 19mm bar was on 'national backorder'.  In actuality, this is the part number for the regular 16mm rear bar.  The 19mm bar was originally to be part of the ACR's trunk kit; however, the SCCA approved the 22mm bar and the smaller item was never produced.

3.4.9    Will wheels from any other Chrysler products fit the Neon?

The forked 5-spoke alloys from the 2000 Neon ES match bolt pattern and offset and are a direct fit.  Also, the 16" split 5-spoke wheels from the Sebring convertible will fit the Neon if mounted with a 1/4" spacer to correct the offset.  However, wheels from the other Sebring/Avenger models will not since they are based on a different platform.  Below is some additional information on older Mopar products:

"All Chrysler built vehicles in the FWD era (starting in '78) have the same bolt pattern. The four lug wheels from a '78 Horizon will fit on a '94 Neon. (Although I don't see anyone trying this swap!)  The five lug pattern on the FWD cars up to '96 use the 5 x 100mm (4 inch) pattern.  Starting in '96, all the cars EXCEPT the Neon switched to the larger bolt pattern that I believe is 5 x 115mm. (4.5 inch).  So those huge 17" wheels on the new Caravan Sports that are larger versions of the Neon R/T wheels won't fit on the Neon, or other earlier K or L body vehicles.

Check out Shelby Wheel 101  for all you ever wanted to know about FWD Mopar wheels and then some.  Special thanks to Dempsey Bowling for his incredible FWD Mopar/Shelby Dodge website. It has pictures of all of them along with dimensions and other info about each wheel."

- John "Shelby Z" Fleck

3.5   Brakes

3.5.1    Should I put on cross-drilled or slotted rotors?

There is no performance advantage to be gained by installing either drilled or slotted rotors.  Drilled rotors have a tendency to warp, and the drilling creates stress points.  This can lead to cracks in a connect-the-dots pattern.  Slotted rotors are better, but still tend to warp.  Both types of rotor cause increased pad wear, as the small lip at each hole or slot erodes a bit of the pad material with each revolution.

Remember:  Porsche factory racing teams remove the stock drilled rotors and put on solid ones...

3.5.2    Can I convert my rear drum brakes to discs?

Yes.  But, as above, why?  Rear brakes handle about 20% of the braking load, which makes the conversion not worthwhile.  Grassroots Motorsports, in fact, converted their CSP autocross Neon ACR from discs to drums in back in order to save 16 precious pounds.

3.5.3    What do stainless steel brake lines do?

Braided, flexible stainless steel brake lines replace the rubber brake lines leading to each wheel cylinder.  Under heavy braking, hydraulic pressure inflates the rubber lines by a small amount.  Stainless steel lines eliminate this effect, which makes the pedal firmer and easier to modulate carefully.  Kits are available for the Neon, at around $75.

3.5.4    Should I install high-performance brake pads?

Performance-compound brake pads can increase braking power under heavy-use conditions.  However, their drawbacks can make them unsuited for street use:  they may operate worse than stock until well heated; they tend to squeal, dust, and wear out more quickly.  They can increase rotor wear as well.  In fact, many road racers use the stock pads except at high-braking tracks.

3.6    Electrical

3.6.1    Where do I connect the power to illuminate my new gauges?

For aftermarket guages which use LED's for illumination, tap into the headlight switch wire.

For gauges which use incandescent bulbs, tap into the orange wire behind the dash. That wire feeds the existing dash illumination, & the new gauges will dim with the existing ones.

3.7    Body, Chassis, & Interior

3.7.1    What does that chunk of iron under the front bumper do? Can I remove it?

It's called a mass damper. It was created & designed by Chrysler chassis engineers to reduce higher frequency vibrations at the FMM attachment point, in order to help prevent metal fatigue & fractures.

It is usually removed by drivers wishing to reduce weight to an absolute minimum, for instance in racing. Stress fractures in the chassis are considered part of the package of race-related wear, but are very undesirable as accumulated wear for car which is a daily driver.

A probably unintended but since found to be essential function of the mass damper is that it protects the Neon from the severe structural damage that occurs when the car runs up on low obstructions.

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