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I am building a lm7 5.3 twin turbo. My machine shop said they Cant find any forged pistons for the 5.3, "they have to be made" $110 a piece. I am in the dark in this so if someone can help me out I would appreciate it. I'm going for 9.5:1 compression ratio with twin garret gt3071r turbos. Ls6 cam and heads which I still need to buy so if anyone has some for sale let me know.
Stock lm7 is 9.4:1 stock. I know a sponsor on here uses forged 5.3 pistons in there motors.
So i doubt they have to be made as custom.
The stock 5.3 has been known to handle alot of hp and psi on stock bottom end.
As long as tune is correct and everything else in line.
I trust my stock bottom end 4.8 to handle up to 1000. Since its low miles and in very good condition. Stock rings gaps,rod bolts. But everything else is fortified and prepped for ho psig and hp.
I can buold an hbeam rod forged piston 6.0, but i believe this 4.8 will handle it.
Summit has KB and Sealed Power and I believe JE in cast or forged also Scoggin Dickey has a large selection
__________________ In the life of the average auto engine , the crank revolutes roughly 450,000,000 times before the engine shows significant wear .
At 6000 rpm's the pistons of an LS based engine with the stock stroke of 3.622" are only moving at 37.5 mph !
Is boring to a 3.9 inches (LS1/LS6) an option for you? That would easily solve your dilemma. The iron LM7 would safely handle that bore even under boost. A sonic check will verify what I'm telling you. If you still want extra insurance and you're looking at high boost levels, you can always use a quality block filler like Hard Blok. It's very stable even for street use.
Thanks! Do Yall really think if I bore it out that it will hold up under 25psi making 1000 HP? That is my goal for this build.. but like I said I don't know anything about lsx motors so any advice is appreciated.