So a new question came up yesterday maybe you guys could shed some light. So in the rebuilding process we bore and hone our cylinders to a clean up any imperfections and true roundness. Now when we decide to bore we go with anywhere from 20-60 thousand over. Funny thing is a lot of European or Japanese motors go 20 over max then it’s time to resleeve. A lot of piston manufacturers start at 30 over and many rebuilders always start at 30. Now if you wanna save meat you need to pony up and pay the big dollars for top notch pistons that start at 10 or 15 thousand over or less with customs forged. Now with all this extra meat in the cylinders it is all good for rebuild after rebuild but the problem I see is the lowering of the combustion static pressure. Now you’ve lowered you compression ratio.
Racer except: “ The overbore penalty is a reaction from rule makers that are out of touch with reality. Most other sanctions allow a 30 thou over along with a 30 thou crank under with no penalty. When you increase the bore but do nothing to the combustion chamber volume, you decrease the static compression ratio. In talking to my machinist, they don't even do 10 thou on a street car. They go to 20 thou right out the gate on a 4 banger. Look at the after market parts guys. 20 thou is a standard. It's not like a a regular regional race you'll get a bore check anyway. You'll be lucky if tech knows the weight of the class or even has the scale calibrated. Unless you cheat the head and cam, your over bore is a performance decrease. I don't know what the agenda is for those that made the rule but it's clearly not in the best interest of the hobby racer.”
So with this info and all this over boring what are you guys doing to compensate for this? Has this question come up before?
Racer except: “ The overbore penalty is a reaction from rule makers that are out of touch with reality. Most other sanctions allow a 30 thou over along with a 30 thou crank under with no penalty. When you increase the bore but do nothing to the combustion chamber volume, you decrease the static compression ratio. In talking to my machinist, they don't even do 10 thou on a street car. They go to 20 thou right out the gate on a 4 banger. Look at the after market parts guys. 20 thou is a standard. It's not like a a regular regional race you'll get a bore check anyway. You'll be lucky if tech knows the weight of the class or even has the scale calibrated. Unless you cheat the head and cam, your over bore is a performance decrease. I don't know what the agenda is for those that made the rule but it's clearly not in the best interest of the hobby racer.”
So with this info and all this over boring what are you guys doing to compensate for this? Has this question come up before?