Jake Boise

hello everyone. im new to the site but i've studied a lot,weeks and weeks of research.i have a 1987 sports coupe (berlinetta) it has the weak and small 2.8l with a 5 speed trans.i have the chance to get a cheap 5.7l tpi,pulled and complete with harness and ecm plus ship for 900 dollars.i want to throw it in the 87 but i'm not sure what year the engine is from and i was reading that the harnesses are different,something about the lights and wipers.guess my first answer is my motor mounts.do i need to move them?is it even worth getting into knowing almost everything will need to be changed?im not sure what trans i should get.i know ill have to change the rear gears since they're 4;10 or 4;11.cant remember.guess overall should i do it or just keep the measly 2.8.also my car has the drum breaks.i want disc,can i take the rear end from a 4th gen with disc breaks? thanks

five7kid

iTrader: (14)

Welcome aboard thirdgen.org.

Start by reading this:
https://www.thirdgen.org/forums/engi...swap-read.html
It covers what has to be done on any V6 to V8 swap, including your engine mount question.

I'm not a certified TPI guru, but I'm not sure how the year would affect the headlights. At most, you may have to redo something between the TPI harness and the chassis, but I'm not even sure that's true.

The earlier 3rd gen TPI years had the VSS on the cable-driven speedometer, while the later years (Firebirds before Camaros) had the VSS on the transmission and an electronic speedometer. Your car should have the cable driven speedo, but the VSS input to the ECM should not be affected (there may be a "buffer box" involved, but I'm not completely sure about that, I'm afraid).

As for transmission, the V6 T5 is a much weaker version than the V8 T5. And the bellhousings were different. So, you'd be better off finding a complete V8 T5 (or an LT1 f-body T56).

Your rear end should have 3.42 gears, unless someone has swapped them out in the past.

The 4th gen f-body rear end is wider than the 3rd gen, and is otherwise identical to the later 3rd gen rears (for 3rd gen purposes). So, your 3rd gen rims would stick out beyond the fender mounted on a 4th gen rear. You can use 4th gen rims, but in order for them to match front & back, you'll have to use spacers on the front wheels. If you want disk brakes, you'd be better off (in my opinion) getting a later 3rd gen disk brake rear. You can also convert a drum 3rd gen rear to disks (see the Brake forum).

An alternative to all the engine swap stuff is to put in a 3.4 V6. The V6 forum has a sticky that details what's required there. More power, and a much-improved engine overall.

Jake Boise

thanks five7kid,i put it in to consideration to buy a 3.4 and put in there i believe i read it would be low on the modification side.i could get the 5.7 tpi for 900 plus ship but it includes the harness and ecm, i know if i shop around more i could mostly buy a v8 car for that,as a parts car.this is michigan and a lot of people have rusted out cars.ive seen a few rotted out 3rd gens around,could probably offer 300 and leave with it,yes,my car is cable driven.as for the rear end.Im going by what the kid told me when i bought the car,he said it had 4.11 gears.not sure because i haven't played with the car since i bought it,as i said its michigan and its 19 degrees outside,lol as for the rear end i just really prefer the disc break cuz after i got the car the rear shoes and wheel cylinders were shot,it took me three days to do! i hated it,disc are easier.also as for the 3.4,would my trans bolt up? anything v6 wont bolt to v8 but v6 is v6 right? thanks again.

five7kid

iTrader: (14)

Well, 2.8 V6 bellhousing = 3.1 V6 bellhousing = 3.4 V6 bellhousing. I wouldn't say "V6 is V6" because that isn't true for 3.8 or 4.3.

As for 4.11 gears, it is true that they could have been installed. Technically, though, they would be 4.10 in a factory 7.5" 10-bolt. But, I wouldn't say they would have to be changed out if you did a TPI V8 (although some would say they are too much for a TPI engine).

I'm not disagreeing with you regarding disk vs. drum, just saying the 4th gen rear may not be the "best" way to get there.

If you're looking for a better engine with a little more power without too much cost or hassle, the 3.4 might be a good way to go.

Jake Boise

i wouldnt mind the 3.4,but i guess i also prefer to use the 3.4 top end,ive read that i would have to swap intakes? i like a show stopper engine,to say the least i could chrome it all out.lol

drdave88

iTrader: (3)

When you say 3.4 top end, the only thing different is the intake. The heads are the same between the 2.8/3.1/3.4. When I swapped a 3.4 into my car, i kept the 2.8 intake and distributor so I didnt have to go messing with wiring and swapping ECMs. There are a decent amount of upgrades out there for the 60 degree V6. You can get a cam, rockers, headers, the typical stuff. I ported the intake and heads on mine as well to open it up, since that intake is a bottle neck.

As far as the V6 trans being much weaker than the V8, I have a V6 T5 behind a 355 in mine now and its holding up. You will read a lot of different opinions on here about using a V6 T5 with a V8. Since I already had the trans, I figured I will use it until it goes, then get something else.

Jake Boise

As in the top end,sorry yes that what i meant.i believe the t5 is what i have.but now i have a guy that wants to sell me a 350 tbi out of a 1990 chevy pick up.he is not asking much for it so i think thats what im going to put in the car.if this motor go bad then id go with the 3.4.hopefully i can start i soon