juice12ufo

This may be my setup, but I have some concerns about my dynamic compression ratio. 93 octane is very available in my neck of the woods. I will for sure be using Patriot stage 2 LS6 style heads with 59cc combustion chambers. I cc'd them tonight and it looks like the real number in 59.5cc per chamber. I would like to go with the TR224/224 .563 112 LSA cam. This setup nets an 8.83:1 dynamic compression ratio and an 11.29:1 static compression ratio. To get these numbers I have to run the stock gasket at .055", so unfortunately, assuming I will be .007" out of the hole... I will have a quench of .048". Not terribly desireable, but seemingly it is necessary.

The ultimate question is, can I run this DCR SAFELY? All I have seen is 8.5 is safe, but is 8.83 on the ragged edge, or am I still okay.

mr2guru

iTrader: (16)

what's the .006 numbers and icl on that cam?

juice12ufo

66.7 ABDC @ .006
108.9 icl

Slowhawk

iTrader: (12)

That works perfect.Have a few setup's like that.Made 435hp/425tq with incredable midrange power---pump gas.

juice12ufo

That's exactly what I'm looking for. Great power throughout the powerband. What realistically is the safe limit for DCR?

Patrick G

iTrader: (14)

With a tight quench and a good chamber, you can safely run into the upper 8s with DCR and 93 octane. Cool incoming air and a 160 thermostat also help. My car has 8.73:1 DCR and it runs knock free even up to 30 degrees timing at higher rpm.

voda1

iTrader: (4)

Are those figures from the cam card. If so could you post the .006 valve event/duration numbers.

If the cam is installed at ICL 112(straight up) your DCR goes to ~ 8.6

juice12ufo

Yes it is from the cam card. By straight up, do you mean dot-to-dot? The .006 is as follows:

Duration 275.1
Open 28.4 BTDC
Close 66.4 ABDC

juice12ufo

It was my understanding that those 4 degrees of advance are ground in. PLEASE correct me if that is not the case, as I will then go with an adjustable timing chain and degree it in.

EDIT:
Just spoke to a tech at thunder racing and the 4 degrees of advance is in fact ground in. If the cam is installed straight up (dot-to-dot) it will be on a 108-109 degree ICL. If it is installed straigh up, it will be the 8.83:1 DCR like I said and not 8.6:1. To retard the cam, I will need to degree it with an adjustable timing chain.

Patrick G

iTrader: (14)

Just for clarification, straight up does not mean dot to dot. Straight up means the intake centerline of the cam matches the LSA, or in other words, there's no advance or retard...it's straight up.

A 224/224 112LSA +4 cam installed straight up would be in at 112 intake centerline. To do this would require you to retard the 4 degrees of advance ground into the cam. If you installed the cam dot to dot, it should be in at 108 intake centerline.