99Z28LS1

iTrader: (4)

I just ordered a 370 from speedinc and the pistons they put me down for were -15cc and I told them specifically that the car was a turbo car and a highway car

Should I have gone with a different piston?

otherwhitemeat

iTrader: (3)

The dish on the piston is relative to the head chamber size...so figure on what you working with before you jump to conclusions.

99Z28LS1

iTrader: (4)

stock 6.0 heads so far.

jumping to conclusions? I've seen people run anywhere from -8cc to -28cc and I just wanted to know the reason

otherwhitemeat

iTrader: (3)

It's because there are different size chambers in the heads...also head gasket sizes are different too...just call them and asked what compression ratio the motor is......thats all. My new motor will have -36 pistons.

cablebandit

iTrader: (37)

i think i got -15cc wisecos to give me 10.3/4 cr for my turbo setup

ss1

iTrader: (32)

-20cc Wiseco, 403ci, 9.6:1 to 10.0:1 depending on chamber size (62-65cc).

Shawn @ VA Speed

iTrader: (3)

the -15cc piston will give you around 8.6-1 compression with the 72cc heads,alot of people run this on turbo setups,i personally dont like to run anything below 9.5-1 compression and would probably have run a flattop piston with a 4cc valve relief

99Z28LS1

iTrader: (4)

why would you not want to run that low?

Is it beacause of motors that run that low of CR are usually "laggy" without boost?

It is my understanding that low compression will help fight deteonation is it not?

ls1290

iTrader: (20)

Ding, ding, ding

Josh@KY-Turbo

iTrader: (120)

That (8.6:1) is right on the money with a -15cc dish and 72cc heads.


Lower compression will help ward off detonation. Dont worry about the 370 being laggy. I drove my old shop car around for 2500 miles with a 8.6:1 370 and 6.0L LQ9 heads. It was not a turd by anymeans. It also started spooling a TC76 at 2400 rpm by what my FAST XFI logs showed. I was up aginst the WG by 3400rpms.

Dont worry about your choice. You will be fine.

fenix999

iTrader: (17)

like stated above, you will be absolutely fine my car is at about 8.0:1. If anything you can always have the advantage with lower compression to turn up the boost to get your setup exactly where you want it (relative to dyno #'s and track times etc) The real good thing about low compression is that it will help you in the sense that it will allow you to run pump gas with practically anything you do. Some guys dont like too high compression because at a certain boost level you will need methanol injection or race fuel or BOTH. Good luck and dont worry about it.

rx_treme

iTrader: (9)

I'm running -16cc Mahle with 72ish cc heads (347ci) and that puts me around 8.7 or 8.9:1 Its good for cranking the boost with pump gas with a bit of a margin for error.

veee8

iTrader: (40)

That is what I am running, flattops with 4 cc reliefs, and 75cc heads.

ss1

iTrader: (32)

If you don't already have a bunch of money into your heads, you could always go with a set of 65cc 243's to up the compression a bit. It looks like with MLS gaskets you'd be around 9.3-9.5:1 depending on how much the block is decked.

B18CYA

iTrader: (17)

4.005 bore -20 wiesco's 72cc head= 9.0:1

99Z28LS1

iTrader: (4)

i've read and read on here that low compression = less detonation, I want less detonation to keep the shortblock alive as long as possible obviously.

Im not too worried if the motor feels "laggy" of boost, this is gonna be a highway monster "trying" to do 40-180 rolls against anything thats worth racing. But im mainly doing this build to go after liter bikes and busas

Thanx for all the input fellas, I will use this knowledge to expand whatever little knowledge I have of my LSX

tim99ws6

iTrader: (31)

I am going to run Mahle flat tops with valve reliefs from my nitrous setup. Just changing heads and gonna see what it holds on boost....

I'm only going to be running race gas though.

AmericanMuscle33

-34cc Diamonds, 56cc heads, 9:1 cr (LT1)

Shawn @ VA Speed

iTrader: (3)

there is alot more to reducing detonation than just removing compression.We have made over 1000whp with 9.2-1 and pump gas.We have also made over 600whp on stock ls6's with 10lbs boost,i believe they are 10.7-1.