mods for TBI cars!

hey i used to be into the TBI cars a lot when i first started driving so i compiled all the mods and stuff i used to do.

-you can port the intake manifold out but i really reccomend you just port match it to the head unless you are really good at porting things. the TB sits way to close to the floor of the intake so porting the bottom out a little helps a lot. but porting to much in one place can screw up the air flow through the manifold and maybe cause a lean condition in one cylinder so if you do this know what you are doing or get a professionally ported buy someone who does.
-putting a 1 inch spacer underneath the TB will help it breathe easier. the TB sits wicked close to the floor of the manifold and air has a problem getting through there quickly. you can make these your self or summit sells spacers for a 2 barrel carb ive adapted to work.
-as far as exhaust, a cheap way to performance is grabbing a stock turbo exhaust from a turbo car with the same body since they are 2.25" in the early cars and even the later ones had 2.5" but thats not good for a NA car so id stick with the 2.25" setup from lets say an 85-88 turbo car. i think they started 2.5" in 1989 but dont quote me on it. add to that a NEW 2.25" replacement catalytic converter from same car or a good one from same car or another one as long as its not plugged with gunk. and slap a 2.25" glasspack on the back and it wont be real loud but should give you a nice mellow sound and give you a decent gain. or you can have a shop bend you a setup for about $150.
-also mopar used to make a full length header for the NA cars but these are really hard to find. if you can find one they are great! i had one back a long time ago on a TBI horizon and it sounded a lot throatier and had a lot more balls when it came time to get going quickly. but be fair warned they love to crack at the flange on the head due to hard launching and the motor rocking back and the header can hit the bottom of the car and put stress on the flange. i recommend stiffer motor mounts if you get one of these. also putting some more welding around the flange that bolts to the head. this will help prevent it from cracking.
-you can have the head shaved like say maybe 20 thousands and that should bring your compression up a bit. but be careful you can shave it to much and can possibly cause the pistons to hit the valves if the cam timing is bumped to far.
-also you can get an adjustable cam gear to adjust your cam timing. i believe advancing it helps your top end power and retarding it helps the bottom end. but be careful as advancing to far can cause pistons to hit valves. or actually loosening the tensioner on the belt and advancing the cam a notch or retarding it is 8 degrees for every notch. but this is not as accurate as an adjustbale cam gear.
-bumping your ignition timing helps to. i believe most people bump theirs to 18 degrees before top dead center. and this was what i always bumped my NA cars to and it seemed to give it a few more ponies. this also will help with your gas milage. you will pick up a few mpg's!
-mopar performance used to make some nice cams for the normally aspirated cars. they no longer make them though and they are hard to get anymore. but you can find them on ebay or on here sometimes for sale. you can convince some company's such as crane to make you a nice cam as long as you have the specs you want. you can look up the specs you want and they should be able to make you a cam to the same specs. i dunno if they would still do it but im sure that one of the cam companies would if you had the specs for the cam for them to go buy. should cost you about $150 though.
- also i dont know what it may benefit but you can bolt in a newer model head with the roller rockers into a TBI car that didnt originally come with one. i have done this but dont know what kind of benefit it gave. did seem like the engine was a tad bit quieter though.
-on 2.5 engines you can pull the balance shafts and plug the oil feed hole and this gives you around 5 or 6 more horsepower. MAKE sure you plug the feed though as you will lose all oil pressure and ruin your engine and wont be very happy at all about it. you will lose some engine smootheness by doing this but its not really that much of a bother you wont miss it. but the engine will rev a little quicker due to less drag of the rotating mass.
-porting your head and having the passages polished will help with flow. but as in the intake id leave this up to a professional as you can really screw up the flow pattern of your head if your not careful. but port matching your intake and exhaust manifolds to the gasket is good for flow and is easily done. just dont go any bigger then the gasket as it will back up behind it if you do.
-fwd performance also sells an underdrive crank pulley and has apps to fit most every 2.2 and 2.5 engine chrysler made. i have not tried this route but im sure that it would free up a few ponies. should also help motor to rev quicker and be a bit smoother. it works by slowing down the accessories on your car to make them use less horsepower to turn. it may cause your alternator output to drop a bit, cause your power steering to be a little stiffer and your ac output may be compromised a bit but you wont really notice the difference. it would be worth it in my opinion. someone on the board may be able to go further on this with their experience. but i would recommend it if you had the extra money to spend for it.

thats about as far as ive gone in my quest for NA power! i dont have any TBI cars anymore so i aint messed with one in a while. but a fair warning if you get to far into mods you may have to raise the fuel pressure to keep up. i think anything above 140 horsepower and you need to raise the fuel pressure a few psi or may eventually have to get a bigger injector.

if anyone has anything that they would like to add to this list feel free to post it! this will help all those in need of more power from their TBI cars!

also most of these things listed should also apply to carb cars as well except for the parts about the tb and such. i havent messed with the carb cars much but may do so one day if i get a HO carb car.

hope this helps everyone out!

Will