DriveWFO said:What's the range of ideal quench distances??? Just for kicks, let's assume the pistons is ".025 in hole and I'm using a ".028 compressed thickness head gasket. Is the quench decent???
I found this interesting article from Chevy Hi Perf on quench. It was a good lesson in this particular engine building principle (at least it was for me, knowing nothing about this term before reading that)DriveWFO said:What's the range of ideal quench distances??? Just for kicks, let's assume the pistons is ".025 in hole and I'm using a ".028 compressed thickness head gasket. Is the quench decent???
From CHP:69NovaSS said:isnt that possibly too much quench....I think you want around .035-040" quench you will have .053" quench if I am not mistaking.
Not sure if this will be helpful to you or not.
So, .053" would be pretty good?According to Ken Duttweiler, the tightest quench he recommends is around 0.050-inch.
NovatoriusRex said:I found this interesting article from Chevy Hi Perf on quench. It was a good lesson in this particular engine building principle (at least it was for me, knowing nothing about this term before reading that)
Kenny Duttweiler just prefers to be safer than sorrier and probably runs looser piston to bore clearances on his turbo V-6's to prevent seizing. I've been to his shop and talked to him. Piston stability, rod stretch and weird mechanical problems dog him at the stratospheric power levels he gets. I get the impression he'd rather turn up the boost than risk a physical collision of the piston to head or seizing a piston in the bore.Since piston clearance plays such a big part in piston-to-head clearance, it is possible to run a piston-to-head clearance tighter than 0.040-inch if you feel brave. Noted horsepower hero John Lingenfelter says that clearances of 0.037 to 0.040 inch are possible, but you must know what you’re doing. The late Smokey Yunick also recommended a quench clearance of 0.040 inch as a safe but critical clearance.
Paul Wright said:There is no one answer to that question. Bore size, clearance, CH, skirt design, rod material, crank material, rod clearance, and rpm all play a role on how tight you can go.
The problem is the squish effect is more pronounced the closer it gets to smacking the head. The problem is the risk or destruction goes up as well.
I've heard from other builders of engines that made the best power with the pistons just ticking the heads but they decided it wasn't worth the risk.
Since the squish dimension must be determined by repeated sessions of mocking up and using measuring tools to determine actual deck clearance of every piston and rod, the amount of piston rock, the estimated stretch tolerance, the actual compressed gasket dimension..... and then machining the deck square and true to the desired dimension is not something you can do in your garage anyway. You'll need an excellent machinist who knows what he's doing.
Over .065" is safe but it won't give you much benefit.
Less than .035" gives great squish but is too risky even for most pro's.
Your answer is somewhere in between.
Piston rock? Is that the movement of the piston about the wrist pin?68SSGrandpa said:Perfect Paul,
One of the things guys miss when they build to absolute tight squish is piston rock in the bore. All of a sudden you have the piston kissing the head, and or valves, yet, your perfect math, says no way that can happen.
Had my rotating assembly together 4 times before I was happy with quench, and other clearences, and the only way you can make sure, is to screw things together, the math can lie, the micrometer does not.
DriveWFO said:Piston rock? Is that the movement of the piston about the wrist pin?
Could you please post some part #s of pistons with good shapes for creating swirl?stock z/28 said:The only technical thing I would add to this discussion on quench is, the effect of the shape of the outer edge of the piston. I have seen a lot of engineerig about the best design of this part of the piston. I have seen several different types and Im not sure sure what the best one is for the best swirl generation.
Good luck guys