JZ'sTA

iTrader: (23)

A friend has a 2003 Z06 with Heads and Cam.
He is runing stock C/R with the Z06 heads.
He has been considering making the car a 12.0:1 Compression motor by doing the heads. Is this possible with LS6 heads, and if so what is the process to get that much more compression? Would you have to mill them like 60 thousands? The cam in the car is a 232 230 595 602 114LSA, where would he run into P/V clearence problems when milling?
Also with the maxium amount of extra compression(11.0. 11.5.12.0????) with this cam about how much power increase would be seen just by adding compression???
He is currently making 430HP on a fairly low dyno (probally closer to 440 on most dyno's) and has every bolt on with LT's and LS1edit.

My suggestion was to buy the new fast 90mm Intake and TB which would be about the same price as a shop would charge to repull his heads, and mill them for the extra Compression.

I believe the results of the fast setup would be better.
Thanks for the help.

JZ'sTA

iTrader: (23)

Guys I really need some info here.
Someone has to beable to give me some rough ideas.

CHRISPY

I wouldn't mill them that much if he wants to run on pump gas. Also if you are pulling the heads may as well put in a set of ported ones!

I would do the FAST intake if anything.

Cheers,
Chris

Just Floor It

Cant really answer your question....But I can give you some information on compression, I wouldnt really wanna go with 11.5 or 12:1 compression, unless you plan to use race gas...I have heard others say that theyve gone with 11.5:1 on 9x octane, but I beleive that is pushing it...For maximum street performance, Id say 11:1 MAXIMUM...Personally, Id stay with 10.5:1... But since your making good power, I would say use 11:1 if you plan on using 9x octane....

Hope this helps

Oh BTW when i say you I mean your friend...Good Luck!

JZ'sTA

iTrader: (23)

Well the heads are already done as far as the porting goes.
Heads wern't milled at all or at least not much when they were off the first time.
Pump gas isn't a concern, just trying to figure out what is the highest CR you can go with a similar cam and Z06 heads before running into P/V clearence problems.
And also how much power gain would you see?

JZ'sTA

iTrader: (23)

Thanks fir the reply just floor it. There are quite a few cars down this way running 11.0-11.8 C/R with 93 Octane, and a very good tune.
Sometimes you have to pull a bit of timing, but there are about 15 cars I have seen runing just fine like this, and making good power.
The highest C/R I have seen with just heads is 11.35 using 5.3 heads milled like 45 thousands or something.
I haven't seen anything over 11.0 with Z06 heads.
Just trying to figure out how this works so my bud dosen't **** a bunch of money away from little gain. (we all know how some Z06 guys can be, and just dont want him to end up this way)

DaleMX

iTrader: (4)

Read this post (at the top of this forum). Hope this helps, looks like you need to mill the snot out of the heads and notch the pistons.

https://ls1tech.com/forums/advanced-engineering-tech/111207-ls1-head-combustion-chamber-cc-volume-vs-cr.html

Just Floor It

No Problem!

Yeah, I forgot to mention a good tune, that would help

Also, I forgot to talk about "pulling the timing." But I dont thank thats really worth it...But thats just my opinion....(To each his own)

Well maybe with a good tune you could probably get away with a tad more than 11:1.....

Good Luck

Just Floor It

Also FYI, you gain about 3%-4% for horsepower by raising the compression one-full point...(This is what I read, dont quote me on this....)

GueSS Who

We have 11.5:1/12.0:1 compression on alot the cars that leave our shop. We angle cut the heads alot more then .06. On the dyno we set them to 12.8:1 afr and 30 degrees timing. We never see any knock and the car loves it. We run 93 octane gas in all these cars (premium down here in Texas). We then run the car on the street with the tech2 to check for knock. We also did this in the summer time and had to pull 2 degrees of timing out of the car because of the high intake temps.

JZ'sTA

iTrader: (23)

What does this do for PV clearence, and how much HP should we expect with the added compression.