I don't think you've been lucky Kidnova. You always had a good tune, good cooling and good maintenance. That is why you never needed the insurance of extra clearances.
BT :cool:
I'd like to think that too, BT. But who knows..... Soon the engine is getting a complete tear down in preparation for some upgrades. The lower end will get a thorough check up, including piston to wall clearances. Will be interesting to see 1st, what the actual clearances are, and 2nd what the condition of the cyls and walls are given the existing clearances. It has been run hard i.e. extended WOT. So the ZZ check up might give some more insight into this subject.
Reed Jensen
12-11-2006 01:55 AM
Re: What should piston to wall clearance be
Originally Posted by HPJunkie
Would ceramic coated piston tops add or subtract from the clearance? My builder said run 006 and another said run 0065. JE max is 0075. Out of 2 meltdowns none were from skuffing of the pistons to the cylinder. Both were detonation. This time I ceramic coated the pistons, chambers and Exhaust ports. I wonder if that was a mistake. Keeping the heat in the chamber might increase the detonation possibility. No teflon on the skirts though.
Ceramic coated piston crowns keep the heat from transfering into the piston crown. If the heat is kept in the combustion gases while they are burning, there is more force pushing on the piston. Heat equals energy. If you can keep the heat in the burning gases there is more pressure in the cylinder. More pressure means more hp on the crank. The energy that isn't utilized by the crankshaft flows out the exhaust pipe. My thinking is you can run slightly closer clearances with the coated piston crown because the piston won't see as much heat. But.... most pistons are measured at the skirt for clearance, not the crown. So I wouldn't close up the clearances any more than about .001 across the diameter. The most critical time during a life of an engine is during the first few hours of running. That is the time that the cylinders and pistons 'break-in". Don't hold the throttles wide open for more than a few seconds. If you open the throttles for a while, close them in an attempt to create a high vacuum in the cylinder. This will aid in sucking some oil from the cylinder walls up into the upper cylinder area and onto the piston skirts.
EYEBURN
02-20-2007 07:16 PM
So what did we end up with for end gap ideas here?
260Velocity
07-21-2015 12:10 AM
This is a great Thread, It is dated but was wondering if anyone had any modern info to add to this thread? Or is all this on Par for the modern day Builds?
