I got a 2 mil over bore with spears thinner head gasket. Thinking of taking .010 off and redoing the cam timing. What is the most any of you have taken off?
Depends on Piston Volume and how much work has been done to the Combustion Chamber. We ended up with .015” off the heads on the stock bore bike with a +5cc dome volume and .040” piston to head. That put us at 13.5/1...
I've had heads come in the shop with 0.040" or more removed. As stated here, depends on the rest of the configuration. The squish is more important, IMHO, because those engines like to detonate.
678 CP pistons 2 mil over bore. Stock cyclinder as far as milling and thinner spears head gasket. St 12.5 to 1 right now.
What’s the practical limit on compression with the Sunoco APEX fuel? I want to run an MA round or two but am worried my current engine has too much compression for the APEX fuel. I have run either U4 or Sunoco 110/112 leaded.
Thats a pretty loaded question..... It all depends on your combination really. I’ve not done a tear down yet on our current configuration but it was 13.5 like I previously said and I saw no signs of detonation on the plugs. I would be careful getting much over that especially if it is big bored. JMO
Yeah, I know there’s tons of variables but my dynamic pressure measurement was something like 210 psi (can’t recall exactly but I recall it was up there) and I don’t know what the static CR is but I think it’s pretty freaking high (kawi 650). I’m going to have the engine refreshed and mostly curious if my engine guy is going to tell me I need different pistons or if he can adjust CR down to match the fuel in other ways. I’m mostly looking to just qualify for a race or two and not get lapped by KT38 lol....
210 cranking really isnt that high to me... That is as much a function of when the Intake closes as it is compression.
Bigger bore doesnt matter, other things that are a result of the bigger bore do. I don’t think 13.5/1 will be a issue with a 2 mil honestly. I’m still holding out hope they just set the limit at 700 though.. Are those flat top pistons or a small dome? The Busa dome’s wont clear without a little work. We had a catastrauphic engine failure at Miller and the current engine hasnt been apart since then.