What's Quench?
- Thread starter SmokeShow
- Start date
That flat area on the piston that gets really close to the head.
I call it Squish Band from old 2-stroke drag bike days.
I call it Squish Band from old 2-stroke drag bike days.
so it's what's remaining of the top of the piston outside the bowl. Is it better for that surface area to be bigger or smaller? Lets say on delipped pistons, does that help or hurt as far as quench goes?
In a perfect world, the combustion area would be a sphere with the flame front starting in the center. Obviously that is not practical.
Certainly for emissions purposes, the squish area should be large as possible, as that is where much of the slow combustion occurs at.
But... I'm not absolutely sure it makes a huge difference with a turbo diesel for racing. I've run .080" headspace and got about the same performance as .020". I run it about .005-.010 more than stock to allow for extra insurance when the piston gets really hot.
Certainly for emissions purposes, the squish area should be large as possible, as that is where much of the slow combustion occurs at.
But... I'm not absolutely sure it makes a huge difference with a turbo diesel for racing. I've run .080" headspace and got about the same performance as .020". I run it about .005-.010 more than stock to allow for extra insurance when the piston gets really hot.
how is this area adjusted? not as far as area but on the clearance you are talking about . Im guessing you assemble the motor and measure what the specs are then take it apart and shave the piston tops to what you want ??
Pat is excactly right , the only other theroy behind quench also is if you have fuel splashing outside the bowl a tight qeunch will force it back into the bowl and help a more complete combustion .
here is some discusion on it also
http://www.dieselplace.com/forum/showthread.php?t=272131
here is some discusion on it also
http://www.dieselplace.com/forum/showthread.php?t=272131
GM makes 3 (A,B,C) gaskets. You can deck the block, or flycut pistons to adjust as well. Aim at B gasket for the machining, then use gaskets for fine adjustment.
BTW, this area is critical in gas engines because the tighter you get it, the more compression you can run before detonation. That's the biggest power gain. But we don't detonate.