bullet proof bottom end ????????

[carsan57]

I got a 01 GP I'm im replaceing the 3100 for a 3400. I wanted to put together a strong lower end, one that can handle some boost 12-15psi, the pistons i can special order but i didn't know about the rods and crank. The turbo will be coming at a latter time but i will be using the 3500 heads and intake system. Will pistons alone take it up to a 9:1 or will i need to take other things into consideration to keep this motor from coming apart under boost. This is my first attempt at a turbo motor!!!!!!

[silvergtjrad]

Not to piss anyone off here, but wouldnt it be easier to just swap in an
L67??? They run a 14.7ish stock.

[El_Diablo]

I got a 01 GP I'm im replaceing the 3100 for a 3400. I wanted to put together a strong lower end, one that can handle some boost 12-15psi, the pistons i can special order but i didn't know about the rods and crank. The turbo will be coming at a latter time but i will be using the 3500 heads and intake system. Will pistons alone take it up to a 9:1 or will i need to take other things into consideration to keep this motor from coming apart under boost. This is my first attempt at a turbo motor!!!!!!

9:1 might have you running higher octane than you want but will be fine if you can get enough fuel (large injectors will be needed) to it and get the timing right (you'll obviously have to tune)

crank will be fine and so should the rods, just debur and shot peen them (the rods), maybe cryo aswell and of course upgrade the rod bolts, you could also use 5.7" small journal SBC rods with slight modifacation (you have to narrow them on the big end and the pistons will need to be spec'ed with the larger pin)


oh, BTW, if your going with ported heads and intakes you might want to consider the 3400 heads and LIM with a 3500 UIM from ben, turns out that the 3400 heads modified by him can currently outflow anything that can thus far be done on the 3500 heads

[carsan57]

Whats the stock compresion on a 3400? will a stock short block hold up to a turbo 15psi

[El_Diablo]

some have pushed it that far but it'll be far from safe, if you get any detonation you can kiss your engine goodbye... stock compression is 9.5:1

if it were me i would rebuild the engine to make sure its in spec, debur and shot peen the rods and swap to arp rod bolts from the store, then get some custom pistons at around 8.7:1 or 8.8:1 and a felpro severe duty head gasket, top it off with atleast ls6 springs to help get rid of valve float and your good to go

that would be a decent budget build....

[ForcedFirebird]

3500 heads will give you about 9:1 with 3400 pistons.

[blackbombshell95]

A stock 3400 bottom is pretty strong in stock form. Just make sure you have a good tune plus some nice pistons/rings would help.