Phil99vette

iTrader: (11)

We need to increase the compression alittle and instead of ordering new pistons we're going to mill the heads. Does anyone know how many thousands you need to mill to get 1cc off of the ETP LS7 heads?

Haans249

iTrader: (24)

Its really small, around .005-.008, but I can't remember exactly how much, and I don't have my spreadsheet with me right now.

Check out my thread about, "Is this normal" and see what you think....cause I have no idea, its in this section..

Thanks!

WKMCD

iTrader: (2)

No help on those particular heads but the compression being too low would explain why you weren't making any power....

I do know it's .006 on smaller bore heads like LS1/6/3, etc.

Kingsize

iTrader: (13)

I can't tell you how many thou. to mill to remove 1cc from you heads, but you can determine how much to mill to get to a desired compression ratio if you are shooting for a target CR. I believe the Formula goes like this. Anyone correct me if I am wrong on anything.

Compression Ratio = Displacement Ratio + 1

Displacement = Cylinder Volume/Chamber Volume

Amount to mill = New Displacement Ratio - Old Displacement Ratio/New Displacement Ratio X Old Displacement Ratio X Stroke

Haans249

iTrader: (24)

What size bore is the heads?

Cary@Perf-Induction

iTrader: (1)

phil,


It is .006/cc

cary

Phil99vette

iTrader: (11)

The heads are ETP LS7 heads setup for 4.100 bore.

Phil99vette

iTrader: (11)

I never thought I'd be saying this but I think I need more compression in my turbo motor. After talking to a couple of well respected turbo engine builders I may have missed the boat when it comes to power/compression. And this ain't your normal Ls1 motor. We've made 1100hp @ 13# of boost. We're looking to raise the compression just alittle....

veee8

iTrader: (40)

What is your current CR?

Phil99vette

iTrader: (11)

Its in the 8s.

Haans249

iTrader: (24)

You must be bumping that baby up to 9.0:1

Phil99vette

iTrader: (11)

More than that.

veee8

iTrader: (40)

I debated over this a lot when selecting components for my engine. I feel confident with my choice of the 9.5-9.7:1 range. Especially with a race fuel/e85 setup.

Phil99vette

iTrader: (11)

Yeah thats a good number for a combination of street/strip with a mix of fuel.

Haans249

iTrader: (24)

Oooooh, how many CC's are you taking out?

Phil99vette

iTrader: (11)

More than a handful.

gnx7

iTrader: (28)

Contact TEA. They will know.

veee8

iTrader: (40)

ETP answered it for him.

edcmat-l1

iTrader: (10)

If you're trying to get a full point from milling the heads, you will most likely take off enough that you will have intake fitment problems. The heads should have a thick enough deck, but you will most likely have some other issues.