3.4 pistons?

[Alxsmt]

so im finally puttin together my 3400, today i noticed on the side of my piston box it said "91-96 3.4 lumina/monte" these pistons were suposed to be for my 01 impalla 3400 and have 10.7:1 compression

does any1 see a problem with that? they are also sposed to be Hypereutectic, which the box doesnt say. the box also says "sealed power" the the guy at the maching shop told me they were "MTI"

my freind that is helping me build this is going to look into it by giving a maching shop he goes through the part # and stuff.

i pretty much just dont know what to think at the moment.

ether there just labled that way because they were modified 3.4 pistons to work correctly in the 3400, or im gonna be F@#$*&% pissed and... and.. and i dont know lol

[sharkey]

iirc, 3.4l tdc pistons (wich it sounds like you have) were a flat top with valve releifs cut into them. i beleive by running them you will end up with very high (12:1 range) compression.

[Ortie666]

yeah I second that... flat top pistons with the aluminum heads= Mad compression.. be prepaird to be using race mix to go get grocerys

[geoffinbc]

More than likely it was a box he had that he put the pistons into. Maybe you should call him before you ask us since we don't know the whole story.

[Alxsmt]

here is a pic

and yes i do plan on talking to the shop, but its sunday and there closed...

[bszopi]

Yeah, those would be DOHC pistons, not 3400 pistons.

[geldartb]

i got one tip for you, dont let these guys ever touch anything you own again.
i hope your not paying for this.

[ForcedFirebird]

Yeah, those would be DOHC pistons, not 3400 pistons.

I have never seen a GM DOHC piston until now, but wow that is an obvious mistake with the four reliefs.

[Alxsmt]

well yeah they asked them about the valve releases and they said so it will work with different engines with out completly redesigning them, so i figured that was true... but after noticing what the side of the box said im having 2nd thoughts...

and yeah im not planning on going back to spend my paychecks, that shop got about 1600 from me total..

[Superdave]

according to the CR calculator on this site those pistons will give a 3400 13.73:1 compression. That's a little more than you wanted.. LOL


I don't know how you'd get 10.7:1

3.4 camaro pistons will give you 12.9:1 with a .060 headgasket and 13.9:1 with the .040 camaro gasket.

[SappySE107]

Those are 96 DOHC pistons, that have a .040 dome and larger reliefs than the 91-95 pistons. I cced .040 pistons and with the 3500 heads im using, it is 12.4:1. That is with .060 head gasket. Race gas? Nah, im thinking premium and a tune. I know the camaro pistons will run on 87 or 89 with tuning.

I have a set of .030 over DOHC pistons that I started to modify to bring the compression down some. You could probably cut the dome off those and maybe even dish the middle I guess if you wanted. If the skirts are coated, those pistons will be just fine for you with some work.

[Alxsmt]

so the shop knew what they sold me.... dohc pistons, they said those are the performance pistons for my engine... i hate liars!

they were all tryin to tell me it wouldnt be THAT high of compression, and it would be fine to run... yeah maby on race gas! i let them know what i wanted and what my car was being built for (daily driver)...

what would you guys do?? i cant take the pistons back in till wendsday


BTW i personally dont want any higher than 10.5:1 (give or take .3)

and then there is the fact that i could get those same pistons for $190... they changed me $395!

EDIT: also when i bought them i had 3 choices of compression ratios, dont rember what they were but i went with the hightest ones he could get (which would have put me at 9.8:1 if he was right about what they would have been with the 3400 heads)

what would you guys do?

[SappySE107]

400...wow. Id take them back. I can modify a set of DOHC pistons to give you close to the compression ratio you want, but I wouldn't modify a $400 set of pistons. What size pistons are you using?

There are 3.4 camaro pistons, 3400 pistons, and 3.4 DOHC pistons. I haven't cced a camaro piston yet to know its exact compression.

[ForcedFirebird]

400...wow. Id take them back. I can modify a set of DOHC pistons to give you close to the compression ratio you want, but I wouldn't modify a $400 set of pistons. What size pistons are you using?

There are 3.4 camaro pistons, 3400 pistons, and 3.4 DOHC pistons. I haven't cced a camaro piston yet to know its exact compression.

IIRC, 8cc dish on the Camaro pistons (3.4).

[geldartb]

with the camaro pistons you have to remove a good amount of the cc chamber to get the combust ration down. as ive learned from my own research and the pics that someone posted comparing the iron head vs alum head.
8cc's vs 27cc for the 3400