Well, I lost my mind and plopped down the $$$ for a D-1SC Kit and install by Dragon Race Engineering. They are going to pull my heads and open the chambers to 72cc to drop the CR to 9.5 to 1. They're also adding a thicker head gasket and installing arp head studs. I also got almost a day of Dyno-tuning to get the baby dialed in... 12# is going to be pushing it, but with the lower CR and our thin air up here (5000+ ft altitude...), we thinks we can baby it til next winter when my 355 will be ready...

 

Very nice

But one question, what heads do you have though? I am pretty sure that stock ones cant be opened up that large...

 

Well, I've got stock heads, so I hope you're wrong...

 

You can't hog your stock heads out to 72 cc.

 

I lost my links to CR calculators but I don't think it will take 72cc to drop it that low anyway. Maybe a 60cc with a thicker head gasket will do (lt4 heads are 58 I think). But, you don't want to use a thick head gasket when your running that much boost.

Hal

 

FWIW my head porter was only able to open the chambers on my stock heads to a max of 62cc's.

Throwing a few #s real quick on my lunch break into my calc i come up with 10.04:1 c/r as around lowest your going to get with a stock gasket and 62cc chambers. I agree with Hal that you dont want to use a thicker gasket with boost, and then your quench will suffer also. Id say to drop your c/r that much you either need dished pistons or aftermarket heads that can be opened up more... Sorry this stuff aint cheap I think if it was possible we would have many people with huge chambered stock heads running tons of boost...

 

>I was under the impression that the stock heads were 56cc .But I have abosolutely idea what the stock heads can get ported out too ... give a reputable LT1 machine shop a call (or e-mail) . This seems like a good question instead of everyone guessing .

 

After reading these posts, I gave a call to Peter at DRE and talked about it again. He's got a flow bench and is a former Callaway engine builder and he says he's gotten 70.5cc before and thought there was more there to be had. I certainly value you guys and your experience, so I've got a very uneasy feeling...

If we can just get it to 10 to 1 CR we'll have to look at other solutions. Has anyone had any luck programming the shift points earlier to stay further from max boost? What about underspinning the blower with a different pulley? I know these have probably been asked before, but I'm new to this... Time to use the search some more...

Thanks, guys.