Induction choices for the N/A EFI
Without a doubt the FWD Mopar TBI intake and throttle body is poop! It's all squished to fit under the hood of cars with low hoodlines. Ugh!
From Chrysler Engineer Dave Zelkowski-
"The TBI engine was looked at years ago and as I recall no matter what was tried (camshaft, exhaust, etc.) power was still in the 110-120hp range. The intake manifold was certainly a limiting factor but nothing was done beyond this initial look."
So that's where we are starting from. What are your options? Well here are a few suggestions...
1) Retain the stock intake and do nothing, look for other ways to free up some hp.
2) Modify the stock intake so it flows better. I have heard of people taking a carburated intake and welding a TBI flange on, the carb unit is *supposed* to flow a little better but I don't have any hard information on that.
3) Boring out the throttle body and installing a larger throttle blade perhaps? The stocker looks to only be 40 mm across, perhaps a 46 mm Turbo blade could be fitted? I'd raise the throttle body up off the intake as much as I could, it's wickedly close to the floor of the intake manifold!
4) Replace the stock intake with a 87 Turbo II unit. Without a doubt a good flowing intake but would require extensive rewiring of the car to run the turbo electronics to fire the four injectors. If your going to go to that trouble you might as well add a turbo while your at it! Still I understand that this is attractive to some people and their racing class may not permit turbocharging. A custom calibration would be required (or a stand alone fuel injection system) and I don't know anyone I would feel comfortable recommending to do the job.
Anthony Huczek went this route- check out his cool Daytona!
Other things to do and don't
1) Classic hot-rod trick- Some sort of hood scoop sealed to the air cleaner housing to force cool air into the motor while driving down the road. Could be mounted to the hood or even drawn in through under the radiator support area.
What not to do- Yes the air cleaner housing maybe restrictive but drawing in hot air from under the hood is worse! Cool, dense air makes power, hot expanded air doesn't! Removing the baffles and flapper door inside of the air cleaner housing so you improve the airflow is a much better idea.
2) K&N air filter elements almost always flow better then paper units.
3) Try slipping an extra gasket between the throttle body and intake manifold to raise the TBI unit or slip extra gaskets between the air cleaner and TBI unit.
Use to work with the carb cars, don't see why it wouldn't work here. Check your hood clearance before slamming the hood of course!
4) Another tip from the past- The intake manifold on the 2.2/2.5 TBI are heated by engine coolant for better low speed atomization of fuel. I'd disconnect the cooling lines so that the intake manifold ran cooler for a more dense air charge. On a 440 Mopar blocking the intake heat passage was good for 11-14 hp! One thing I always wanted to try on a TBI car is disconnecting these lines and running cool water through it. All you would need would be a small electric pump and a small radiator or heater core and you would have a liquid cooled intake manifold! It gets pretty hot sitting over the exhaust manifold.
5) Consider Nitrous Oxide- Easy to make big power that way and these motors could take a 50-75 shot without blinking an eye. Hardest part would be to come up with a nozzle or plate to work with the TBI unit and consult with NOS to determine what jets you needed based on desired hp and fuel pressure. You could run more N.O. then that of course but I would consider upgrading the connecting rods to Turbo II units if taking that path.