So im buying a '85 trans am that has a 350 tpi in it(not stock from what i understand, not sure on engine year) and im looking to drop it into my 91 firebird, which has a 305 tbi. What im thinking tho is that i dont want to leave the 350 bonestock(which for now im assuming it is, not sure) and have been trying to figure out what i want to replace/upgrade to get a nice power boost. Im trying to keep the engine mods under $500 tho. Anyone got any ideas for the best hp:money upgrades?


Also what gear do you guys like? Obviously im going to need to upgrade my 2.73 but im curious as to what you guys like. The car is to be a non daily driver, mostly for nice days (for me that means anything without rain and above 60) I thought about dropping 4.10's in the back but i think that may be **** for mileage. So im thinking something smaller....

 

The best mods for the money are going to be a cam and set of shorty headers. Most of the reason I recommend a cam is that you are going to have the motor out and it is easiest to do then. Other performance mods can be done with the motor in the car.

As for gearing, I like 3;42 with an auto and 3;73 with a manual trans.

 

Is there any shorties/cam's that are better for this? Trying to keep my upgrades as cheap as possible, but with good future upgradeability.

 

You can do alot with a cam and some time with a porting kit and die grinder. The cam itself will run $300+ so you may have to stretch your budget to get the headers which will make the cam work the way it should. A mild cam will work okay even with stock manifolds and with added lift and a little extra duration will give you a noticable midrange power boost.

If you want to go more extreme, 100hp over stock is quite acheivable with the right cam, headers and port work on stock TPI. To get it to run right at that level you will have to reprogram the fuel and spark curves and either increase fuel pressure or go to bigger injectors. Of course a high mileage stock bottom end won't live long at that level either.

 

That is kind of what ive been thinking i want to aim for. 100 over stock. Ive been reading so many articles tho ive gotten to the point where i cant decide on which one i should do. The Cam, headers and port job sounds like it would be the cheapest way, which is what im trying to accomplish. Any idea as to what cam i would want to shoot for? I dont know enough about duration and lift to know which one i need. And for headers i wont want to go with shorties will I?

 

I have LT's on my '90 RS with the LS engine and hate that they will not clear speedbumps and pretty much everything else hits them too. I have shorties on my IROC (Hedman 68470's) and love the way they clear like stock. If you will be using the car as a daily driver or even the occasional drive, I suggest shorties. Trust me, you wont miss the 5 to 7 hp difference. I would look on ebay for the headers, you would be surprised what $100.oo can get there. $300.oo sounds about right for a good Name-brand cam and do-it-yourself port/polish kit.

 

do they hang that low? If its that bad then ya shorties is what ill have to go with, i really dont want to have to worry about them 24/7. Does anyone know of a good Cam? Ive been on Jegs for a while and tbh am not sure what i can use with my stock engine, or how much hp/difference each cam will give me.

 

I looked at a thread for a torque TPI setup and i found this cam that seems similiar. Would this be something that i could put into the engine without having to mess with anything up? Like valves/springs/heads/tune.

http://www.jegs.com/i/Comp+Cams/249/08-535-8/10002/-1

 

That cam would probably work for you. It will require different valve springs, almost any cam uypgrade will require different valve springs. It will not get you 100hp over stock. For that you will need something more like comp cams 07-503-8, which will require spings, possible guide/seal work.

 

Don't forget that you will have to repin the tbi harness at the ecm to make it all work. Also at the c207 (dash harness). There are threads available for this.

 

My car has the tbi to 350 tpi conversion done and even with 273's it is a beast. With a 700r4 trans it is still hard to not spin at out of the hole. Car will spin em' in D2 also with that rear. I would just worry about getting that block in there first and repinning your harness and getting it all up and running. Then i would go after a better exhaust system. Preferably headers with matching ypipe (makes life a LOT easier) and of course a good catback system. That will keep you busy for a while.

 

410's and 373's are gonna suck in that car with tpi if you have an automatic.

 

That cam has a little too much lift for the stock,used springs. I would go more along the lines of a crane 2032 computer cam. Or check into Comps compucam line. Something with under 220 duration and under 470 lift with a LSA of 112 or higher.

 

Will i need to repin anything if i have the wiring harness and the computer from the donor car? What do i need to pull from the car to make it so i can just drop the tpi in?

 

The idea was to use the existing harness that is in the tbi car and just swap ecm's.

 

is that easier then just using the harness from the tpi?

 

https://www.thirdgen.org/forums/tpi/...d-density.html Read that thread.

 

that thread says if you cant find an existing harness to repin........ so are you saying to just use the wire harness from the donor?

 

I would. It is enough work to just get the motor in there and up and running.

 

Ok so we tore the donor car down and discovered the guy lied to my buddy about it being a 350 tpi. Its actually a 305 TPI with 350 heads. So new roadblock. Prolly just going to convert my tbi to tpi and put the 350 heads on after some work goes into them. Then just save up for a year or two and drop a LS1 in.