In our last edition of Project Neon (Feb, '02), we applied the basic bolt-ons to our Neon's SOHC engine in hopes of eliminating the cheap rental car power output blues.
Our carefully chosen bolt-ons were, in our opinion, a great success, but it took a lot of parts. Adding a CNNP exhaust, AEM intake, Unorthodox pulley, Mopar Performance ECU, Kirk Racing header, Random Technology cat, RC engineering throttle body, and advancing the cam two degrees with an AEM cam gear provided up to 16 hp and 18 lb-ft of torque.
Now, we're going deeper into our Neon's engine in hopes of getting more than just acceptable performance.
When reviewing the specs of the stock Neon camshaft, it became apparent our engine needed help. For whatever reasons, probably emissions compliance and fuel economy, Chrysler has put an amazingly small cam into the SOHC engine. This conservative tuning is probably why our engine's power drastically falls off above 5000 rpm. The conservative valve events also mean a very unsatisfying powerband that encourages short shifting and explains our engine's reluctance to make power with bolt-on mods.
Our stock cams had a ridiculously low intake valve lift of 0.283 inches with a very small duration of 207 degrees. The exhaust valve lift was an even smaller 0.277 inches with 229 degrees of duration. This is the least lift we've ever seen on any automotive engine. The cam's lobe centers are spread so far apart there's no overlap at all. As a comparison, the intake cam in a stock Nissan SR20DE has 41 degrees more intake duration, and 0.112 inches more lift. The SR20 also has 17 degrees of valve overlap.
The tech wizards at Crane recommended we run the second of their three available cam grinds, P/N CHR-250-2SR-8. This cam, which is supposed to make gains from 1500 to 6800 rpm, has considerably better lift and duration numbers than stock. The intake lift was a much higher 0.355 inches with a duration of 250 degrees. On the exhaust side, the lift was 0.315 inches with a duration of 250 degrees. The Crane cam has a tighter lobe separation angle of 108 degrees. Although these numbers are much bigger than stock, they pale in comparison to your typical high-performance grind.
We noted that the SR20 and the Neon engine are both 2000cc with similar bore and stroke. However, the Neon cylinder head has much smaller ports, especially on the exhaust side. The angle of the Neon's exhaust ports is also rather flat, with the port turning a tight radius inside the head. Usually ports of this nature do not flow well at high lift, the flow tending to stall as maximum lift is approached. In this case, opening the valve higher than the stall point usually does not help power and is much harder on the valvetrain. A big cam on a stock head would simply narrow the powerband and make the idle rough without giving much of a peak power gain.
The SOHC Neon also has a rather poorly conceived rocker arm/cam follower design. The heavy hydraulic lash adjuster is built into the valve end of the rocker arm where it cycles at the valve's maximum stroke with each revolution. This is the worst possible place such a device could be installed. On most typical overhead cam engines, the hydraulic lash adjuster is stationary. The Neon's design probably necessitates overly heavy valve springs and increased friction that robs both power and fuel economy. Why the engineers chose to place the adjuster where they did is beyond us.
To help control the gyrations of the valvetrain at high rpm, we replaced the stock valve springs and retainers with Crane's recommended valve springs and lightweight titanium retainers. Though not mandatory for use with this cam, the heavy rocker arms of this engine make the choice an obvious one.
The Neon uses shaft-mounted rocker arms. Note that the hydraulic lash adjuster (HLA) is in
The Crane cam, titanium retainers and higher tension valve springs are at the top of the p
Looking at the cam lobes closely, it's easy to see that the lobe profile on the Crane cam
Doing a cam install on a Neon is a huge pain. Where virtually every modern engine has spli
The results from the installation of the Crane cam were impressive. No loss in power was created anywhere in the rpm range, even at low rpm. The idle smoothness stayed nearly stock, with only the slightest lope. Even the cheap rental car sound was replaced with a deep, throaty roar. This camshaft and spring combination is worth every penny and is probably the best addition to Project Neon we've added to date.
We recorded a peak gain of 15.1 hp at 6300 rpm and 12.6 lb-ft of torque at 6300 rpm. These peak gains were accompanied by impressive gains in both power and torque throughout the powerband. Peak power jumped impressively from our previous 125 hp at 5700 rpm to 135 hp at 5900 rpm. We like this cam so much we think it should come with the Neon as standard equipment from the factory.
The car is really a changed beast. Previously, the car did not have the beans to spin the tires under any dry-weather conditions. Now it needs a limited-slip differential. In fact, we plan to install Phantom Grip's economical limited-slip differential in the next edition of Project Neon.
Crane HI-6D12 Fire Ball Ignition
At this power level, it's unlikely the Neon's stock ignition is in over its head. But we figure it will need help later as we make modifications that are more taxing on the ignition system.
The Crane HI-6 ignition has some superior features. Fifty percent more current at the plug gap than the stock ignition helps fire the plugs with no misfire, even with the higher cylinder pressures caused by nitrous, turbo boost or high compression. The HI-6 features an adjustable sequential rev limiter, surface mount technology, urethane potting for moisture and vibration, as well as a self-diagnosis system with fault codes. In addition, its plug-and-play installation with adapter module made especially for the Neon prevents the tachometer and fuel pump problems commonly associated with high-powered ignitions on sensitive, OBDII cars.
One problem we had with the ignition was finding a place to mount it in the Neon's cluttered engine bay. We fabricated an aluminum heatshield/ ignition box mount and bolted it to the bracket used to hold the stock air filter box over the headers. It's not the ideal place, but it's the only one we could find short of moving the battery to the trunk.
As expected, the HI-6 ignition did not show any conclusive power gains. Typically, modern engines have such excellent stock ignition systems that they're perfectly adequate until you dramatically increase cylinder pressures with nitrous oxide or boost.
|Cam Specs |
|STOCK CAM |
| ||Valve lift (in.) ||Duration (crank degrees) |
|Intake ||0.283 ||207 |
|Exhaust ||0.277 ||229 |
|CRANE CHR-250-2SR-8 |
| ||Valve lift (in.) ||Duration (crank degrees) |
|Intake ||0.355 ||250 |
|Exhaust ||0.315 ||250 |
At The Drags
We decided it was time to take Project Neon to the drag strip for the first time. Before these modifications, we made the long haul to Central California's Famoso Raceway, recent home to the Battle of the Imports. Project Neon whipped out a rather weak 16.8 seconds at 83 mph with the stock engine, our Ground Control suspension and 17-inch wheels and tires.
We attribute much of this poor showing to the very dusty track, which offered awful traction (we were generating pathetic 2.6 second, 60 ft times). The power-robbing 17-inch wheels and Famoso's high altitude probably robbed the car of two to three tenths.
To remove the spring retainer keepers, we used a special spring compressor tool that we bo
The Crane Hi-6 ignition system and the plug and play adaptor box for the Neon bolts to thi
An accurate tire pressure gauge is a must. This is our homemade unit. When our old pressur
After installing our bolt-ons and cams, we returned to Famoso. This time we went home with a far more respectable 15.8 seconds at 88 mph. The 60 ft time was once again an abysmal 2.6 seconds. This is a full second and five mph quicker than the stock engine under the same circumstances.
We were somewhat disappointed in the overall speed of the car, however. Some Neon SOHCs with similar mods have pulled low 15s and high 14s. We attribute our somewhat poor second showing to a very slippery track, high altitude and 17-inch street tires. The very stiff, track-tuned suspension is also far from ideal for drag launches.
The drags showed us we desperately need a limited-slip differential and new clutch. Our planned addition of a Phantom Grip limited slip in a future installment should greatly help the car's 60-ft performance. We feel Project Neon has the potential to run 2.2 seconds or better with a little work, especially if we can run on a prepped track at sea level.
Trial By Autocross
Since Project Neon is built to be an all-around, kick-ass, jack-of-all-trades machine, we had to prove its cornering prowess at a local autocross.
A good autocross car does not understeer. On a tight autocross course, understeer means slow times. The car also has to rotate well. Rotating means the car has to be good at pivoting around the front end. These characteristics are often difficult, or even impossible, to obtain in a front-wheel-drive car. Fortunately, the multiple national championship-winning Neon platform has good autocrossing DNA.
Taking advantage of Project Neon's full suspension adjustability, we set the front camber at negative two degrees. More camber means less contact patch on the inner tire, so we stayed conservative. We also dialed in 3.5 degrees of positive caster to get some negative camber gain when the wheels were turned, and added 1/8-inch toe out to also help turn in. In the rear, we ran 1.5 degrees negative camber and zero rear toe. Our initial inflation pressure was set to 37 psi front and 35 psi rear.
At our local autocross test-and-tune practice race run, we were surprised and pleased to find our baseline settings perfect right out of the box. Our pyrometer readings showed we were making full use of the rubber. This speaks highly of the Neon's basic platform and the excellent Ground Control/Koni suspension system. We only had to bleed the tires to maintain the pressure as they heated up and do some minor tweaks to the rear rebound damping to better deal with the rough parking lot surface.
The car exhibited no understeer and rotated like a top when the throttle was lifted, making us look like seasoned autocrossers. Amazingly, we ended up second in Street Touring Class with a time only a few tenths off of the local hero national class winner. We can only imagine how well the car would do in the hands of a real driver. The only area of major weakness was the lack of a limited-slip differential, allowing us to smoke the inside tire at the exit of almost every corner. Can't wait for that LSD.
At-the-track camber changes were made using a Smart Camber digital camber gauge from Truec
Longacre toe plates make toe adjustments quick and easy. You can approximate this measurem
A Truechoice digital pyrometer confirms that the car is working well and using the full tr
Auto Meter Products, Inc.
413 Elm St.
Koni North America
1961 International Way
20807 Higgins Ct.
Kirk Racing Products
1131 Via Callejon
2700 California St.
CNNP Racing, Inc.
Advanced Engine Management, Inc.
Ground Control Inc.
Crane Cams, Inc.
530 Fentress Blvd.