Piston Coatings

[mhopemk3]

Just a FYI.. I am finally working on the 7m build and I am getting my pistons coated. Just wanted to share this info for those who don't know!

Piston Crown
http://www.swaintech.com/store.asp?pid=10963

Piston Skirt
http://www.swaintech.com/store.asp?pid=10964

I am getting the Thermal Barrier and PC-9 on my JE's. The price was $38 per piston. Excellent price for added protection IMO..

 

[IJ.]

I use Crown and Skirt coatings and add a third Heat dispersant to the Underneath

JE's as well.

 

[mhopemk3]

From what I understand the crown coating is permanent to the piston but I wanted to find out how long the skirt coatings last..

Those look nice.. I saw a couple of JE's at the shop that had a nice hole melted threw them.. The guy at the shop said they were using a 300 shot in a racing motor though..

 

[IJ.]

Skirt coatings aren't long lived, I took a set back that I'd ran for 4000Kms as I thought they were scuffed up pretty badly my Coater was over the moon saying they were in great condition for that amount of running.

You can burn a hole in anything if it's run lean on a 300 shot

Mine leaned out and ran hot enough to close a ring end gap and kill a cylinder using triple coated Ross forgies and thanks to the coatings the pistons were immaculate when pulled (I was expecting collapsed ring lands at the very least)

One thing to keep in mind when using coatings is it affects the expansion rates of the piston and you need to allow for this when the motor is bored or you'll end up with something that sounds like a diesel at idle.....

 

[mhopemk3]

Skirt coatings aren't long lived, I took a set back that I'd ran for 4000Kms as I thought they were scuffed up pretty badly my Coater was over the moon saying they were in great condition for that amount of running.

You can burn a hole in anything if it's run lean on a 300 shot

Mine leaned out and ran hot enough to close a ring end gap and kill a cylinder using triple coated Ross forgies and thanks to the coatings the pistons were immaculate when pulled (I was expecting collapsed ring lands at the very least)

One thing to keep in mind when using coatings is it affects the expansion rates of the piston and you need to allow for this when the motor is bored or you'll end up with something that sounds like a diesel at idle.....

Thanks for that info. I read Adjusters post and remembered something about adding .001" for the coating but building it "tight" Feel free to add your comments on that or what you have experienced. You know my plan for the pistons but I will be using all ARP harware, eagle H Beams and clevites.. Not sure on the HG as of yet.

 

[IJ.]

LOL I think Greg/Adjuster means Subtract 1 thou

Clevites aren't actually Clevites for the 7M these days but reboxed NDC's unless you can find some very old stock.

Might find em cheaper in NDC boxes.

 

[mhopemk3]

LOL I think Greg/Adjuster means Subtract 1 thou

Clevites aren't actually Clevites for the 7M these days but reboxed NDC's unless you can find some very old stock.

Might find em cheaper in NDC boxes.

Ok.. I will definitely be reading through those post while my pistons are out.. I will check into the Clevites..

Thanks,

 

[IJ.]

The block needs to be bored to the NON COATED size as well
(the coatings aren't uniform enough to get a consistant sizing)

My JE's were a perfect set with no variation is size of all 6 so must have come off the same machine same day same operator same cutter.

 

[mhopemk3]

That's nice.. I hope to be that lucky.. I ordered them through suprarich (vendors section) and he was out of stock. He is having them shipped from JE to Swain..