Pekka_Perkeles

Well, my tuner almost blew my LS7-based engine and unfortunately one of the cylinders was damaged. So I need to overbore the block and use new forged pistons. I read somewhere that GM limits the overbore to 0.020, but I don't know if there are any forged blower pistons available at that size. I was able to find out Diamond pistons from Texas-speed, but they are only .005 over at 4.130 and if you look the pic below, that might not be enough.

Forum vendors, feel free to propose new pistons. And other comments are also welcome.

I guess new Darton sleeves would be the ideal way to go, but it's bit pricey to send the block from Europe to U.S.



Here's the rest of the story:

https://ls1tech.com/forums/forced-induction/932152-melted-6-spark-plugs-what-would-you-do.html

davidws6

iTrader: (36)

Yes, it would be expensive. However if you do decide to go that route, Steve @ Race Engine Development does great work. He has worked with Darton on the development of the sleeves for the LS series blocks.

There are also other shops who are doing good sleeve work now.

Good Luck.

Stang's Bane

iTrader: (22)

I wold contact Diamond or Wiseco directly and ask about a custom piston.

First I would find out if the overbore will fix the problem though....

Sucks for you man, I feel for you....

Robin L

Those scratches are not that big a deal. Before you spend a lot of money I would put the heads back on and run it. Get the tune figured out and put a few miles on the car. Then if you have issues you can change pistons.

We see a lot worse on some of our race engines and they run just fine.

Listen to Harlen over in your other post.

Good luck!


Robin

pirre

I was just same problem year ago there Finland. I measure bore and appraise that scratch deep and then order oversize pistons from Lingenfelter (made by mahle). Next i carry block and all moving parts to Lahden Kansityö, Lahti, Finland, Europe and they drill pistons made instruction (looseness) and balance all parts.

Luck to project ...

Jake@EPP

The best thing to do would be to take it to a machine shop and see what it takes to bring the scratches out. It could be .005 or it could be .020, hard to tell from pictures.

sdbrown84

iTrader: (22)

Don't waste your time with using the stock sleeves on a blower assembly. It's best to take the time to prepare, because the $ you spend now on even an overbore will make those sleeves razor thin, and if you scratched them now, think about what will happen if your tuner goes too lean, or your sleeves just cant hold up to the boost.

Get a good re-sleeve and call it save measures. Think about ordering the sleeves and having a shop do it for you there. Might be a better deal for you.

L337HomerSimpson

I wonder how expensive it is to re-sleeve one of these blocks?

I also wonder if a .010 overbore would stress stock sleeves for a forced induction set-up?

99blancoSS

iTrader: (115)

+1 , do some reasearch on LS7's and their sleeves.