will forged 2.8 pistons work in a 3100

[Rushman04]

Pm bashmanx

[bashmanx]

I have a set of forged 3100 pistons with stock forged rods. They have 150 miles on them, so very close to new. Nothing wrong with them. Are you interested?

[no_doz]

I have no clue how my crank trigger post ended up in here, sorry about that.

[Superdave]

Gen 2 heads have a 26.4cc combustion chamber, 3100/3400 has a 28.6cc


Just an FYI.

[SappySE107]

We sell forged pistons for the 2.8, 3.1, 3.4, 3100, and 3400 engines, for stock or .927" SBC pin that work with our forged rods. Heavy duty pins, extra milling to lighten the pistons, and skirt/top and hard anodizing options are also available. We use Total Seal rings for these piston sets.

http://wot-tech.com/shop/gm-60v6/for.../prod_262.html

You can use the 2.8 pistons in a 3100, but you also have to change the crank, which will give you a displacement of 2.8L ("2800"?), and will if the forged pistons produce the same SCR as the stock counter part reduce the SCR to 8.9:1 from 9.5:1. The good thing here is that the gen2 pistons do not come proud of the block and so thinner head gaskets could be used to raise the SCR slightly, IIRC it would be around 9.2:1 at that point.

If you are referring to the stock TGP pistons, they are not forged, they are cast. This would give you an SCR of 8.8:1, just like the stock TGP had, since the combustion chambers are the same between gen2 and 3. Again, a thinner head gasket could be used but only raises the SCR to about 9.0:1 or so.

Why are you wanting to run forged pistons? I have found that very few people actually need or benefit from using forged pistons where cast is usually a better choice.

no_doz; what problem with the crank trigger?

[no_doz]

Will a set of forged pistons from a turbo 3.1 work with this combination? and if so what would the compression ratio be?

Also, will him using a Gen 2 crank eliminate the problem with the crank sensor? if not what is needed to make the 7x crank trigger work with the OBD2 system?

[TREsab]

where can i find these forged 3.1L pistons

[sharkey]

i thought the 2.8l trw pistons were discontinued anyways. but no, they wont work.

there are forged pistons for the 3.1l, and will work with the 3100

[Doubt_Incarnate]

no. the connecting rods are the same also, so in order to make up for the added stroke of the 3.1/3100, the pistons have a shorter compresion height (center of pin to top of piston), so the 2.8 pistons is way to tall.

[TREsab]

will a set of forged 2.8 TRW pistons work in a 3100 engine? i know they have the same bore but is everything else the same?