Piston to bore on coated pistons

General engine tech -- Drag Racing to Circle Track

Moderator: Team

Post Reply
AC sports
Member
Member
Posts: 194
Joined: Mon Jun 03, 2013 6:25 am

Piston to bore on coated pistons

Post by AC sports » Mon Apr 15, 2019 12:30 pm

I recently send some forged JE'S away for a dry film skirt coating by Tech line coatings, they call TLML.
It was done to aid in anti scuff. Pistons went away at 84.42mm and came back around 84.46mm. Given my nominal bore size is 84.5mm that only leaves a piston to bore clearance of 0.04mm or exactly half the JE recommended amount.
Do I run them this way and assume they bed into the bore? Or should I scotchbrite the coating down a little?
I'm concerned they may scuff the bores even more now when they get up to temperature.
Who's used this particular coating before? Thoughts please.

bentvalves
Member
Member
Posts: 130
Joined: Mon Dec 12, 2016 3:37 pm

Re: Piston to bore on coated pistons

Post by bentvalves » Mon Apr 15, 2019 5:53 pm

I guess it would depend on if JE called that coating an abradable coating like line2line or something else entirely.

GARY C
Guru
Guru
Posts: 5049
Joined: Tue May 14, 2013 10:58 pm

Re: Piston to bore on coated pistons

Post by GARY C » Mon Apr 15, 2019 6:18 pm

AC sports wrote:
Mon Apr 15, 2019 12:30 pm
I recently send some forged JE'S away for a dry film skirt coating by Tech line coatings, they call TLML.
It was done to aid in anti scuff. Pistons went away at 84.42mm and came back around 84.46mm. Given my nominal bore size is 84.5mm that only leaves a piston to bore clearance of 0.04mm or exactly half the JE recommended amount.
Do I run them this way and assume they bed into the bore? Or should I scotchbrite the coating down a little?
I'm concerned they may scuff the bores even more now when they get up to temperature.
Who's used this particular coating before? Thoughts please.
What did Tech line say?
Please Note!
THE ABOVE POST IN NO WAY REFLECTS THE VIEWS OF SPEED TALK OR IT'S MEMBER AND SHOULD BE VIEWED AS ENTERTAINMENT ONLY...Thanks, The Management!

Newold1
Guru
Guru
Posts: 1844
Joined: Fri Apr 08, 2016 9:50 am

Re: Piston to bore on coated pistons

Post by Newold1 » Mon Apr 15, 2019 6:34 pm

That's only about .0015" in our crazy measuring system. On your small 3.30" (84mm bore) I would say on a short stroke that even a forged piston that size might need only a .0055" to .006". So depending on what JE might say they want .007" you will probably be fine depending on what your clearance is set up for now especially as some of that coating will wear off in critical areas pretty quickly. What ifs your measured clearance now with the coating?
The Older I Get, The Dumber I Get :wink:

Post Reply