3.1 from grand prix to '88 s10 blazer

[sbc350]

I'm planning to swap a 3.1 v6 from grand prix to my 2.8L s10 blazer.
Is the 3.1 internal or external balanced? I have a manual trans and I want to keep it and the grand prix is auto so I need to use the old 2.8 flywheel, if it even bolts on?
Another thing is the engine mounts, does the FWD engine have same mounting positions in the block? Does the 3.1 accept the same rollertip 1.6 ratio rocker arms than the 2.8?
Is there a intake for the 3.1 to accept tbi throttlebody ?
Anything else to think about?
Thanks!

pesty-joulu2014.jpg

[caffeine]

I have a thread on here about swapping a Sunbird 3.1 into an S10. Reading through that should answer most of your questions.

[sbc350]

I have a thread on here about swapping a Sunbird 3.1 into an S10. Reading through that should answer most of your questions.

Url? tried to search it but couldn't find it..

[caffeine]

http://60degreev6.com/forum/showthread.php/51025-Supercharged-3-1-in-a-Sonoma

[sbc350]

thx, 2 bad the pix don't work

[caffeine]

Fixed! And to answer your question about TBI, no there is no TBI intake available for the aluminum heads. Re-pinning for a '7165 and tuning with $12p is probably the easiest option (IIRC only about 6 wires are different). Or you could use the grand prix ECM.

[sbc350]

Nice project! You flipped the FWD intake 180 degrees? I wish I could use the 3.1 heads and ecu, but the regulations here in Finland are strict with these low emission cars. Need to do expensive smog test if I change the engine(I have to double check this). I just might use the iron heads and intake from the old 2.8.

[caffeine]

You'll have to change pistons to iron head pistons as well otherwise you'll end up with ridiculously low compression.

[sbc350]

You'll have to change pistons to iron head pistons as well otherwise you'll end up with ridiculously low compression.

3.1 heads have smaller chambers then? I guess I cant use 2.8 pistons because the 3.1 has lower pistons due to the longer stroke?

[caffeine]

You could use 3.1 Camaro pistons. They would work with the 2.8 heads.

[sbc350]

Does anyone know the difference of the the combustion chamber sizes? I'd rather have high compression since I'm running with e85.

Trying to keep the costs down, wish I could use the whole engine from the grand prix but dunno if I get it legal..

[geoffinbc]

Considering the whole project I would put your 3.1L crank into your current 2.8L block. This will net you a 3.1L but the engine mounts will work, the starter will be on the correct side and you can use the stock flywheel with the stock starter. Using the iron heads with the FWD pistons will net you a very low compression ratio so you will want to buy new 3.1L iron head pistons. If your going to the machine shop then get some .040" over pistons and you will have yourself a 3.2L. Getting the compression up can be achieved by taking a cut off the heads and block. Or if you want to get crazy you can investigate custom pistons or milling the tops of the stock 2.8L pistons. But this will require re balancing and more machine work.

[sbc350]

The fwd block has different engine mount places in the block? My goal was to make it cheap, boring the 2.8 block and balancing the crank will cost a lot more than the complete 3.1 engine I get from the junk yard.
But thanks for the info, have to see how it goes.

[geoffinbc]

Yea they are different. You would have to make mounts in order to fit the engine. Stock replacement pistons for an Iron head 3.1L should work fine with a backyard ball hone to clean up the cylinder walls. Put them in your 2.8L with the 3.1L crank and some new bearing inserts and you should be in business.