I will run the numbers when I get home (I am at work).

Rich Krause

 

I hate it that the small town I live in has 91 as the best gas I can get. I went with a KB piston with an18cc dish , my afrs started with 53cc chambers and were cleaned up a bit, they were just above 51cc after. I used the fel-pro gasket. The cam I started with was the XE 224/230 on 112, it ran fine on 91, but power was not what I wanted. I switched to the cam youre going with(230/236 XE on 112) it still has none to very little knock and runs much better. I got a real deal on an GM 12370847 cam and will be popping it in this winter , along with a thinner head gasket. We'll see what happens.

 

hey viperkiller (brad) didnt you forget to metion you want to spray. ehy try to find your spec card. so we can look at all the valve timing events.

 

Mine WILL end up right at 11.1:1 most likely. Im running SRP blower/nitrous pistons, so theyre dished 16cc, so it would be almost impossible to go much above that without having too short a quench height.

Ill end up with 52cc chambers, according to Lloyd, thats about as far as you can go without having to mill down the intake as well.

.039 felpro head gaskets
.005 deck height

This puts me at .044 quench height and 11.1:1 Static comp ratio

Wont have any problems here with detonation

I was speaking above after hours upon hours of research and reading on the subject, and a few buddies in town running that high no problems.

 

ttt for ya

 

I think your CR is too high for that cam. With a flat top and a 57cc combustion chamber I calculate a DCR of 9.2:1 with a 4.030" bore, 3.75" stroke, and a 0.045" gasket+deck height.

Rich Krause

 

I run 12.5:1 in my 383 camaro with sunoco ultra 94, with a hotcam !

I have no problems with this combo at all

 

What would be the problem with running a quench of say .030 or so.....I know .035-.045 is optimal range but why?

 

Parts tolerances.

Ideally it would be great to have the piston just touch the head when it hits TDC, but we all know that cant happen

So for parts that stretch/expand/piston rocking you have to leave yourself some room in there so they dont touch, even more room with aluminum rods.

.035-.045 is recommended range, but over .040 is even more recommended on a not so high budget motor with awesome parts and machining.

 

My motor has high buck parts and I still use 0,045". As John says, too close and the piston can "touch" the head, which is NOT a good thing.

Rich Krause

 

Wouldnt a race type motor with say titanium rods be able to run a closer quench than that though? I thought I had heard somewhere it WAS possible, just not recommended.

 

yea maybe in a year or so,i'll deal with that at the time. i will prob. just give it a little shot and pull the timming?? i just want this compresion to be right now.

thanks alot rich, if you have time could you tell me what i should shoot for to keep it on pump gas, i'm guessing around 11.5 from what i've been reading.


wssick what is your deck hight, compression ect

 

My deck height was untouched since the block was flat so its as it comes from the factory, I calculate my compression ratio to be right around 11:1 with the standard deck height, with a 0 deck and this set-up it calculated to be 11.6 I do beleive.

 

Okay, my engine shop is putting together a 383 for me with a 306 cam, what's the highest static compression I can run and still use pump gas?

And what about if down the road I want to run a supercharger?

-Sean

 

I wonder how many times this question can be asked on this board before people realize there is no set number?