jkrouset

please help out

Jameslt1TA

Several on here are doing it.

jkrouset

are they pulling lot of timing

96capricemgr

Depends on the cam and quench, good quench and enough overlap and it will be fine, .060+ quench like stock and a small cam and it will rattle itself to death.

jkrouset

please explain alittle better its my first engine im doing they are 56cc heads on a 383 zero decked with -5cc pistons

94Z396_0621

on my 398 LT4 i'll be running 12.1 compression, with custom .45 over JE racing pistons. Real Big cam, and still will be running on pump gas. I'll probably buy a set of good O'2's were i can run either Racing gas or Pump. Anybody know who makes O'2's for 112 or 114?

jsetzer

I am running 11.7 with .041 quench -5cc pistons on a 357. Cam is the cc306 and my dynamic should be in the 8.7ish area.

I am seeing some knock retard, but don't know yet if its my forged pistons or pump gas. Just got it running a few days ago and havent messed with it too much yet.

jkrouset

explain quench a little and what gasket to use

CCCCCYA

nope, it's not too high. Justhave to tune it correctly(and no, you don't have to pull all the timing out). You need to do a search on here and in advanced tech for dynamic compression. Your static compression ratio is only part of the story; cam selection and how it's installed determine the compression the motor actually runs on.

I'm running 12.5:1 static with an 847 cam installed straight up. Although I'm about to put new slugs in it for a pending turbo build-up, I've had no issues with knock to date (with 94 octane sunoco).

Call the cam manufacturer. They can point you in the right direction.

Good luck,
Dave C.

jkrouset

cam is 242/250 .544 on a 110

jkrouset

anyone help figure dcr and what i need to get it

bdc95ta

what's your ivc? For a cam that size I would go w/ a 12.5-13.0 static comp ratio to get the dcr up. Running evans NPG coolent, increasing the reverse cooling lines, 160 stat, ewp, will keep it from detonation. You have to run premium gas at this level its a most. You might even need to knock back the timeing a few degrees in the summer. Just depends how much you want to push the limits.
-b

96capricemgr

Evans is junk science it has lesser cooling ability than water.
As far as pulling timing in summer why not just setup the time to account for tempatures, pcm scales a lot of things off tempatures so it can accomodate seasonal changes.

With just a quick calculation off those number I came up around 12.2-3 using the Felpro .039 gasket which would mean .039 quench, I DO NOT KNOW IF THAT IS APPROPRIATE WITH A STROKER you will need more experianced guidance there.

Mindgame

Free DCR Calculator:
http://members.uia.net/pkelley2/DynamicCR.html

Keep in mind that DCR is only a part of the story. Generally you'd shoot for 8.5-9.0:1 but IMO there are reasons why you might want to be closer to 8.5 than 9.0. If you believe that inlet temps and volumetric efficiency don't play a part then you're missing the boat.

Some reasons I might shoot closer to 8.5:1...

Lower elevations
Better cylinder heads/intakes (higher potential VE)
Higher temperatures
Heavier cars
Automatics

-Mindgame

jkrouset

i will find out ivc and figure the dcr out