Sorry to start a similar thread, but this one will grab attention to the issue at hand.

Anyways, I'm running the Scat 9000 crank w/ 6" rods, and SRP pistons. Cyl Head combustion chamber is ~54cc. Pistons have a 5cc valve relief. The heads will be milled slightly, since they were glass beaded. I'm going to have him take the minimal amount off possible.

My question is what pistons are you using? CC on the dish/valve relief?
What's your compression ratio?
Got detonation?
What octane are you running?
What head gasket?

Anything else pertinent you can think of...I can't seem to get this CR down.

Especially if I want to be .005 out of the hole with a .041" gasket, or a .039".

Thanks! This crap is driving me nuts!

 

I had mine built with the same crank and rods.

I installed Keith Black Hypers with a 19 cc dish. 52 cc chambers with impalla gaskets. Block decked with the piston .006 in the hole. I am planning on about 10.9:1.

Can't tell you how it runs yet. Should be getting my heads back from AI this week and hope to have it running by next week.

 

you need a dish when running a 383 I feel, some people differ but with a -12cc and a slight head surface it is almost 11:1

 

Ooooh, well a dish would certainly make things much easier! Do you know if SRP makes dished pistons? I paid for SRP with the kit, I'd like to keep it that way...

At least he eats shipping charges on this We'll see what he says tomorrow about it

 

they are 184.00

 

Forged?!?

 

hypertectnic

 

yea, unless you wanna open the chambers, you need to run dishes pistons
my old 383 was 11.5:1 with 52cc chambers, 16cc dish, .035 quench

 

Ooooh, I want to stay away from hyperpuketic, thanks for the idea though!

I think I'm going to go this route instead:

I checked out SRP's site, they make a Forged dished piston out of 4032, with a 16cc dish weighing 403g. It says it will be 10.4:1 CR @ 58CC, vs 11.8:1 @ 58CC with the pistons I believe he has right now.

So what that means is that even with milling the heads a little bit, and decking the block, and 54cc heads, I should still be able to retain a decent compression ratio. I'll run this by him tomorrow.

The selling point on me getting the kit through him instead of Brian Adams or somewhere else was that if the wrong parts came, HE eats the shipping and gets me the right stuff. We shall see! :joy:

http://www.jepistons.com/pdf/2002-srp-chevy.pdf

At zero deck w/ the 54cc heads and a .041" gasket, it's putting me at 10.9:1.

At -.005, it comes up 11.028:1, and at +.005, it comes up 10.767:1.

Is -.005 above or below the deck? I would think BELOW, but wouldn't then the CR be LOWER not HIGHER? Unless the sign's mean backwards...

I think this is the best option, what do you think?

 

How did that setup run? Any times/ HP figures? I know it's a lot to do with the cam, heads and traction etc.

I am getting the heads ported though, but I'd rather not have to do 'fixes' when I can build it right from the get-go...screw opening the chambers and milling the piston and all that crap. He should have checked this **** first. I guess he didn't take account the small chambers on these LT1's. Do regular chevy SB's have 'bigger' heads?

 

Got 2 pages full of pistons in the Jegs catalog. I don't know what ratio your shooting for but I used 170817 from JE to get 9.4:1 since I will use a blower (when I can afford it). I think these are -23cc inverted dish. They are forged and I am using 6" rods. My heads have a 56cc chamber. Right now without the blower, I do not have detonation. Obviously it will have to be reconfigured for the blower when I get it. Anything else you want to know email me at jamianddave@juno.com

 

what compression are you aiming for?

keep in mind you can run a ton of compression in the LT1 without detonation issues...

 

I run 12.3:1 and know some guys running almost 12:1. None have detonation issues...compression is free power

 

badass383,
Thanks for the info...I'd check Jegs but I'm sourcing them from the builder as part of a package...but I did find a Part # for one with a 16cc dish...

Trey,
I was aiming for AROUND 10.5ish:1, maybe a little more. But with these flat tops, In order to run the piston-head clearance I want, I'm looking at 12.5+:1. I feel that I can get better results with the dished piston, lower compression, and tighter quench...and it would be the RIGHT way...

I was looking at Advanced Tech and there's some running fairly high compression do to the Alum. Heads I'm assuming. But then again, ask 100 people how high compression one can run on pump gas and you're likely to get 125 different answers....

What do YOU define as "a ton of compression" ?

 

i thought you wanted to keep your compression down

I *think* i heard rich krause say Je will custom make pistons for you at off the shelf prices.

12:1 is as far as i'd really want to push it- but then again depends on your cam and octane available.

I also suggest coating your pistons and heads. Check advanced tech for more info on that.