ryanewing88

I have a 347 with either a cracked piston or a bad ringlet (don't know, haven't pulled the motor yet). Either way, I need a new motor. I've pretty much decided against getting a used SB and to continue with my goal to supercharge. Obviously the blown motor sets me back.

My question is, do I go with a forged rebuild (done locally for around $3k) or go "off the shelf" with someone like TSP for $4000 plus shipping?

Are there alot of problems with rebuilt motors with around 14-15 #s of boost?

I'm looking for alittle more than "its personal preference". Any knowledge from similar experiences would be helpful. thanks.

got-a-ls1

iTrader: (12)

347 is the usual term for a forged motor... do you have stock ls1 rods and pistons or a forged motor right now? if you broke a forged motor i would wait before i installed a new motor and see exactly why you already broke a forged piston. if you dont make a change to your tune or whatever caused it, it will probably happen again.

ryanewing88

Its a stock LS6, so, 346. Sorry about that. And it was tuned for the Z06 it came out of so it most likely ran lean. but why the piston cracked isn't really what Im concerned with. The new motor with a new cam will be tuned before It ever sees the road.

Bob@BruteSpeed

iTrader: (16)

I see several potential problems here. First is if a ringland cracked and the piece got wedged in there it can put a hairline crack in the cylinder. I have seen this happen twice, and you might as well scrap the blower if it happens. Second is whether your local machine shop is well versed in machining LS engines and whether they use torque plates. If they don't have LS torque plates, don't use this machine shop.

The stock crank has proven itself to handle 1000 hp, so better rods, pistons and rings are all that are really needed. When properly built and with a good tune and fuel system, you should be able to run this engine for years at 16 psi of boost. Bob

JoeMama's GTO

iTrader: (3)

Do mean to say that? Why would the blower be screwed if one of the cylinders is cracked? On another note, I am willing to bet that TSP block includes forged everything for $4k. However I would highly recommend calling Automotive Engine Specialties (AES) for your needs.

Bob@BruteSpeed

iTrader: (16)

Sorry, meant engine block. Bob

lmt0705

iTrader: (7)

I would go new engine route, get good pistons and rods! Not eagle and mahle garbage. Compstar rods and diamond pistons is a great well proven package that doesent break the bank

blue00ZZleeper

iTrader: (5)

I would suggest disassembling your engine and see what your working with. This will either confirm Bob's possibility or confirm that it's ok for a rebuild. An off the shelf engine from one of the sponsors would be great but my favorite thing about building motors is that you know 100% whats going into it and can set the specs to your taste. Or in this case, you can have a shop build it to your specs. Like Bob said if they don't have the equipment or knowledge on LS engines I would keep looking. Like LMT said you should go with decent parts, callies compstar rods, diamond or weisco pistons. A rebuilt engine would be fine but until you know the damage, it might just need a quick rebuild.