I think its time to just let it go, Flyinwrenches.
DK pistons, junk or good?
- Thread starter flyinwrenches
- Start date
Agreed, I apologize guys. Consider it let go
Now that we're past that rabbit trail, I'll go back to the original topic. I say give them a shot. I've seen enough Mahle Motorsports pistons break to that I don't even use them in builds anymore. At this point, I would guess these DK pistons couldn't be any worse. At least this gamble is a little easier on the pocket book. I'm somewhat curious about the speed of air pistons. They seem like a gimmick, but maybe they really do work. I'd like to test them, but they're very expensive. As of now, I believe Fingers pistons are the best option for a street driven Duramax, but that's just my opinion.
Isn't part of the problem with forged is the expansion ratio is a little higher then cast so additional clearance is needed to allow for this? Once up to temperature the clearance is pretty much the same. If you coated them, wouldn't they them be too tight when hot? Or I'm I mixing this up with something else?
There isn't much that hasn't been discussed here many times in the past. Search is your friend. post #5 here is a start: https://www.duramaxdiesels.com/forum/threads/street-build-cast-or-forged-pistons.90375/
The line 2 line coating wears out where clearance is needed. It’s used in racing applications so not sure how it would hold up for a daily driver.
Speed of Air has an interesting product but for $4000 it's a hard pill to swallow when I can simply buy Fingers (for almost half price) and never need another set of pistons.
Fingers I 100000% agree is the "be all end all" cast piston option out there at this time in terms of strength.
The Speed of Air design is manufactured by UEM for Speed Of Air. They seem to be working in other platforms.
But as mentioned... the price at least for this market, seems excessive....
But as mentioned... the price at least for this market, seems excessive....
Maybe I misunderstood, but was thinking Mahle quit putting a steel top ring land on their cast pistons
I've never seen a cast Duramax piston from any manufacturer that doesn't use a steel top ring land and a keystone shaped top ring.
You still have to have clearance clarence lol. If you run a .004 ptw clearance for a forged, it will grow to the .002 or less clearance as it heats up or pushed hard so you are back to cast clearances when hot. That will wear the coating and piston slap will be back and we didnt gain any sealing.
The theory is you’re able to run a tighter clearance, even with a cast piston. The coating will only wear out where clearance is needed.
.0015 for a cast
I guess i dont see the gain because its going to wear off lol. Like you were saying, maybe an engine strictly raced and refeshed often
I’m curious to try it on my next build. If I end up with piston slap ??
can’t be any worse than my hone job I did at home and slapped pistons back in after cracking some ?
I’m curious to try it on my next build. If I end up with piston slapcan’t be any worse than my hone job I did at home and slapped pistons back in after cracking some
can’t be any worse than my hone job I did at home and slapped pistons back in after cracking some 
It wont be worse than without it!
My Mahle Cast pistons said PTW .002 Measured 0.500 up.
After all the info fingers and others have shared over the years, i like the .0015-.002 range. Ill vary it depending on power but the limo had .0017 ptw iirc. Ill have to look back at my notes. Pth was .025-.027 as well
I ran .002-.003 on my stuff, service limit is .010
Fleece guys set me up with .006 one time and I expressed my disappointment and they got me another block
Fleece guys set me up with .006 one time and I expressed my disappointment and they got me another block