2.8 rebuild questions

[Buck89RS]

I am going to rebuild my 2.8 into a 3.1, (I want to keep the car looking stock so a motor swap is out) meaning that the bore is going to be 3.5 (also bored 0.030 over) and the stroke is going to be 3.31. I am going to use 3.1 pistons and a 3.1 crank. My question is do any of you foresee any problems in the future? Will the crank fit? I have heard that the 2.8 and 3.1 were the same block. Will the computer for the 2.8 work on the 3.1? Any advice or suggestions? What is going to happen if I use the same computer and any advantages to getting a 3.1 computer because I know the 3.1 had a knock sensor and they are speed density and not Mass air flow ( from what I have read ) Also the compression of a 2.8 is 8.9:1 and a 3.1 is 8.5:1. What would the compression be for this motor using the same heads? Thanks

-William

[jc Kyle]

y didn't anyone answer this guy?

[Jerriko]

The 2.8 and 3.1 are the same block. Actually, the only differences between the two is the crank and heads. A 3.1 is a stroked 2.8. As for the computer, I would stick with the 2.8. It will be easier and not too much of the program between the two motors is different. Just to make sure, I would try to find out the following items:
-Throttle body size of the 2.8 and 3.1
-Fuel pressure of the 2.8 and 3.1
-Injector size of the 2.8 and 3.1
Get that information and compare and that should give you a ball park idea of which way you need to go. Which heads are you going to be using? The 3.1L heads flow so much better. Also, if you don't have the injectors for the 3.1 and there is a noticeable difference in fuel pressure and injector flow rates, you can buy a fuel pressure regulator cap for a 5.0/5.7. They also fit our V6s.
Jim

[Buck89RS]

Alright thanks for the info, but I do have a couple of questions ( imagine that )!!! If the compression of the 2.8 heads gives 8.9:1 and the 3.1 heads gives 8.5:1, even if the 3.1 heads do flow better, why would i want to give up the compression of the 2.8 heads. This car is just going to be a daliy driver and all i want is a stoplight racer. I dont really care about going over 100 mph, the 0-60 is what i am wanting, and I think this little motor will be all i need. Thanks

-William

[Buck89RS]

UPDATE:::::!!!!!!!!!!!!!!!!

I got a 91 bretta this weekend and before i got this car i was planning on rebuiling my 2.8 into a 3.1. So my question is what can i use from this 3.1 FWD car in my 2.8. ( crank, pistions, heads, injectors, PCM or ECM, etc....). If i put this post in the wrong area, would a mod please move. Thanks

-William

[black98V6]

umm, you might want to check out a fiero board or 2 and see what is there, I'm willing to bet you might find a little more info on 2.8's.. also you might want to try to find some s-10 boards as those motors were in s-series pickups and the jimmy and blazer.. unfortunately I think our 2.8 knowledge is limited here.. just a suggestion..

[Buck89RS]

I am having trouble finding anyone to help. I may have to go to a speed shop and kick some rocks over and see whats underneath there. Thanks for your post!!

-William

[3.4 slow to go]

read up on teh 3400 swap someone did. I think it ws Russel

anyway. Do an engie swap. Keep teh 2.8 timing cover & accesories & ssssssssssssssslide in a 3.4 block. ask me how I know ;) :D . 2.8 & 3.1 heads are actually the same. The 3.4 heads, keep them, are newer, along w/the springs on them. Make the 3.4 look exactly like the 2.8. This has beendone, as the insperation for my swap did this & has passed nazi Cali nazi e-chack many a time, including the dredded "pop the hood" check.

edit: Here's the link

edit 2: interesting, & good that you're also using teh thirdgen.org boards ;) [img]graemlins/thumbsup.gif[/img]

[ September 23, 2003: Message edited by: 3.4 slow to go ]</p>

[black98V6]

there used to be a company that sold 2.8 stroker kits, I think they were more aimed at the s-series.. do some searching through google or something on "2.8 stroker" or "3.1 stroker" or some variation on that you might find the company... I found them through a link to an S-10 board that was posted on here but for the life of me I can't find it now..