Just got my block back from the machine shop and have a question about the Wiseco HD pistons. On the wiseco tech sheet with the pistons it said the P2W clearance is calculated BEFORE the friction coating was applied. They suggest a .0035 clearance, obviously it sounds tight but the coating is on an average how thick?? but if it wears away then it could be too loose if you make the p2w clearance with the coating on it.

Anybody know how thick the coating normally is? and if .0035 is safe? It's the HD pistons so it's expected to be pushed hard but anybody run a clearance like that on these pistons? I assume the wiseco engineers know what they're doing and know how much/fast the pistons expand etc.

I'll be making around 600+ hp and am a perfectionist and won't put it together if I'm not happy with it.

 

for 6-700hp wiseco told me to run .0045 ptw

 

I'm running .0055"

 

But you or your machine shop's measured the piston with the coating? So the thickness of the coating is part of your clearance right?

For example if you're running .0055 ptw and the coating wore off now your running prob over .0065

 

Well after double and triple checking measurements I found my bores werent honed big enough, I'm taking it back to get sized 2 thousandth's bigger so the ptw is around 3.5-4

Wiseco suggested 3.5 ptw clearance on the sheet it came with but I will call them tomorrow just to see if they recommend anything different for a high hp motor, altho I dont trust many tech help people cuz you can get different answers depending who you talk to (from my experience with other companies)

 

Use .0045 , Im using those pistons on a couple builts , the highest one made 765 hp on a DJ!! I dont have any problem so far!!!

 

I built my engine with .004 but wish I would have went to at least .0045 now. I'd rather take the slim chance of oil burning than the piston seizing in the cylinder walls.

 

With 2618 alloy I have expermented with .035 to .135. yes the 13.5 thou was a mistake. but it was run hard for a couple months before ring seal was lost. I ran 6.5 thou in my first 2.4 engine. That engine had 4% leak down on all four for 15k miles. I heard shep was running .007 in his 9 second car. Thats why I set it loose. .0035 is too tight from my experience. I would never go lower than .004. and at that I would put 5k on it before putting big boost to it. They do loosen up pretty quick.

4032 is whole different material. I just used .0025 for my latest build. but have been setting them at .0035-.004. no signs of being too tight at all. so I keep going smaller with this material. I think stock material might be 4032.?? they can be set at .001.

 

I called Wiseco n the guy said the pistons were made for.high Hp and.high boost etc and. 0035 "should" work fine....he had no confidence whatsoever and didn't sound very knowledgeable...pretty much just said use what the.sheet says n it should be fine because they were designed for the high Hp car purpose

 

Has anybody actually ran these at the suggested 3.5 thousandths clearance? If these were "engineered better" and dont expand as much or whatever else than the bigger clearances can just be a waste and more harmful....assuming Wiseco did R&D using these clearances on high hp motors

 

i think that Blue91 motor made by Map is .035".Blue91 has a thread in this same section about his block and excessive side wear.i forget the name of the thread,but he took his stock head off to put on a ported race head and he had some pretty major wear after 500miles.

he was asking people if it was normal or excessive and he got 50/50 answers basically,but i think the jist was that .035' was maybe too tight for the 2.4LW.half the guys said that and then the other half,including Map said it was ok/normal wear.

if i were you and i was having it opened up anyway,i would at least go to .045-.050" while i was having it done.

 

That's what I was thinking too. Is this for LR motor 2.4 2.0? I asked map and they said they run. 035 to prevent any piston slap now I'm still trying to find out if this is what they run on there 1000hp evo cuz that seems like it would be crazy. Chris also told me if I wanted to run. 045 they can accommodate me there. I want to have them build mime but blue91lx had me scared

 

Yeah I saw his thread...

Remember if you check the clearance youre checking it with the coating on in the equation so if you're at .0035 in reality it's like .004 since the coating is like .0005 thick or something

Mine is a fully forged 2.0 though