F6

How far can I go with DCR

My CR is 11.3 and I don’t want to go any lower. With the new cam I’m using I’ll be at about 8.6-8.7 DCR. The question is, how high can I go with DCR using 93 octane gas and having a quench of .037"??

Bersaglieri

Don't forget to factor in altitude. Also you'll probably find that different calculators across the net will give you different answers for DCR. 9.0 seems to be were things can get hairy, but I've read folks getting away with 9.1 and 9.2 with cool intake air, good coolant system, tuning and good fuel. Problem is I wonder if their calculated number was correct.

-Dustin-

Injuneer

What is the octane rating system used for that "93 octane" fuel? European rating system (Research octane) is not the same as US system ([Research + Motor]/2).

Bersaglieri

Good eye Injuneer, didn't see that location.

-Dustin-

Revolutionary

How good is the tank of gas that is in the car at the time? How efficient is the chamber? How much ignition timing do you have? How much piston dwell do you have at the top?
There are way more factors than just DCR to figuring out a magical number that you can run with pump gas. I don't ever consider DCR but look at the whole package and apply a little common sense.

F6

Fred, the 93 octane is using your method. We have 98 ROZ and this would equal 88 MOZ. I could even go somewhat higher but that would mean paying even more than I'm paying at the moment for one liter gas.

Using the Pat Kelley calculator I'm pretty high, just under 9.0. My engine analyzer says 8.7. Really don't know which one is correct. Since Bullet doesn't even think of writing back when I asked them for the seat timing events, it's hard for me to calculate the exact seat timing from .050".

BTW, I wouldn't buy a cam from Bullet again, if they were the last place on earth to get a cam!!!! But this is a different story.