Is there any flat top 3.1 pistons? Do they have to be specially made? I've got an '89 Firebird 2.8 block and heads , 3.1 #981 crank and dished .030 pistons. I'd like to use a flat top pistons for more compression, do they exist?


Thanks

I haven't seen any flat-top pistons that are commercially available. Sealed Power sells the deep dish (26cc) and shallow dish (12cc) pistons for the 3.1 V6. And that's basically it.

I have flat top 3.1l pistons. I was told they were made for low compression (Turbo), and the dished pistons (Which I also have) were made for higher compression. I've been told the flat tops are not easy to find and haven't been made for a while.

Aren't 2.8l and 3.1l pistons the same?

Ive got a lot of 2.8l/3.1l stuff, including a new block, balanced crank, and more.

[This message has been edited by MadDanceSkillz (edited 01-16-2011).]

will a 2.8 from a" Front Wheel Drive "Car work in a fiero ?? bolt pattern the same ?

quote Originally posted by MadDanceSkillz: I have flat top 3.1l pistons. I was told they were made for low compression (Turbo), and the dished pistons (Which I also have) were made for higher compression. I've been told the flat tops are not easy to find and haven't been made for a while.

I think you have things backwards. The flat-top pistons will yield higher compression than dished pistons (assuming everything else is the same). The aluminum-head 3.1 V6 uses deep-dish pistons, because the combustion chambers in the heads are smaller than the iron heads. The iron head 3.1 V6 uses the shallow dish pistons.

No, 2.8 and 3.1 pistons are not the same. Since the 3.1 V6 has a longer crankshaft throw (and the same rod length), the piston tops are shorter, to compensate. If you put 2.8 pistons in a 3.1, serious carnage will ensue.

Unfortunately, that's what I thought. The 3.1 pistons have the pin in a different place and you use the 2.8 rods. The 2.8 pistons with the 3.1 crank will come out of the block. So, what would the compression ratio be with the shallow dish iron head pistons .030 oversize? I know that a 3.4 would be the hot set-up but I already have all this other stuff. Although the 3.1 crank could be used in a 3.4.

Thanks for the replies.

Mad, check one of your suspected 3.1 pistons(flat top) against a known 2.8, if your flat top 3.1's have the pin in a different place they may be some "custom made" one's. They also have the same bore as the 2.8, 89mm. The compression height of the 3.1 pistons I have is 1.450 in. so if your 3.1's are 1.450in. from the top to the pin center they must be custom 3.1's.

[This message has been edited by raysr11 (edited 01-17-2011).]