This is the spec that is recommended from Weisco but my engine builder seems to think that it was a little tight. He said that he normally goes with more like .0035. What do you guys think?
Is anyone running .20 Wiseco pistons at .0025 piston to cylinder wall clearance
- Thread starter leftynridge
- Start date
Yeah that is what my engine builder said. It will be a street car only driven in the spring summer maybe fall and not my DD. Goal is around 550hp.
Yes, it will be a bit clacky on cold starts, fine as long as you don't push it hard until it's fully warmed up.
I found using Piston crown coatings would have thie effect as well as they reduce the expansion of the piston so clearence needed to be adjusted to suit.
I found using Piston crown coatings would have thie effect as well as they reduce the expansion of the piston so clearence needed to be adjusted to suit.
I'm new at engine building so you will have to excuse me, but what would be the benefit to going with a loose piston to cylinder wall clearance like .005 vs going a little tighter like .0035. My engine builder said that they just built a 7m drag motor with Weisco pistons and they went with .0038. Not trying to question you but just interested in learning. Thanks
In the old days forgings weren't quite the same so you had to allow a lot of clearence so it wouldn't seize in the bore as the piston expanded, in high output engines that generate a lot of cylinder temp the pistons will expand more so you leave it a touch loose.
As I mentioned earlier coatings have a huge effect on this as they reduce expansion.
As I mentioned earlier coatings have a huge effect on this as they reduce expansion.
From memory they are Coated stock, It all depends on the Alloy used and what coatings are used to how much they expand, I ran my JE's at 3 thou last build due to the added coatings.
It's a little bit of a black art given the newer alloys and coatings, worst result I had was Ross pistons Coated at their recommended specs.....
CLACK CLACK CLACK when Cold or if you were cruising using trailling throttle on a cool night..... :nono:
Good luck with your build.
CLACK CLACK CLACK when Cold or if you were cruising using trailling throttle on a cool night..... :nono:
Good luck with your build.
Black art indeed. I was going to use some used JE's and was told that .0035 was in there opinion tight according to spec. Instead I went with brand new Wiseco's and there specs are even tighter. Leaves scratching my head.
just finished my build with these pistons at 0.00375. No cold start rattle, (only 2 miles on it 
and its 95* out)
and its 95* out)
if wiesco recommends 0.0025, why not run it at that clearance? wouldn't they have tested this to make sure it wouldn't cause problems?