29 replies to this topic

[Hemituner]

Well This goes to show you that it dosen't matter how much real estate you put above the ring land if you leave like .020 at the eye brow to burn off and waste your engine.

18 lbs on C-16 20 deg timing 11.8 Afr PHAIL.

[HemiSam]

HemiSam

[Williams RT]

Dam AJ, Do you not think having flat tops would help with that? More meat? I never liked a dish piston and would always have higher CR dome pistons cut down to flat tops to get the CR I wanted. Is that possible on these newer hemi pistons?

[Hemituner]

Dam AJ, Do you not think having flat tops would help with that? More meat? I never liked a dish piston and would always have higher CR dome pistons cut down to flat tops to get the CR I wanted. Is that possible on these newer hemi pistons?

Well if you look at where the failure occured making it a flat top really won't help it. You really need the bore to be bigger to add enough material if your cutting a large relief. Search the web for pics of these engines you won't believe how many pistons are thin like that. We can get thick flat-tops pretty much for any application and get creative with compression. Flat top pistons are so good in so many ways I try to run them whenever possible.

[Williams RT]

Ok, I was just thinking if it had some more material on the other side of the valve notch. The eye brow might not have lifted off as easy? Like these older Hemi pistons. I had over sized valves on a 426 one time and actually had to have that eye brow shaved off the pistons.

[Tout]

AJ
Add a little more information
How long in use
What kind of use race only or daily driver also
CR of engine
type of blower
Nitrous if so how much
Piston material

We have been ceramic coating the pistons to help with heat issues on highly boosted/nitrous applications.
Tout

[srt5939]

Well This goes to show you that it dosen't matter how much real estate you put above the ring land if you leave like .020 at the eye brow to burn off and waste your engine.

18 lbs on C-16 20 deg timing 11.8 Afr PHAIL.

Who's piston is it?

[J-Z]

I know its hard to see here but I was worried also when I first saw my eyebrow, Not alot of meat there.At least there coated I guess.

[MoparManiac]

Who's piston is it?

It was tagged as a Weisco failure.

[srt5939]

Who's Weisco piston is it?
Is that better?

[Tout]

I thought there was a discussion on Wesco pistons a while back, could have brands mixed up????
Tout

[Speedy]

So shaving that area is the solution?

[rdrdr90]

I thought there was a discussion on Wesco pistons a while back, could have brands mixed up????
Tout

There was a Buckwheat rant on them that involved Andy if I recall correctly...it had more to do with the block than the pistons...again, if I recall correctly.

And I might add, none of the blame was on Andy.

[Andy@PWR]

Thats the old Wiseco piston design. That thin spot became an issue when high heat was present. Wiseco has since changed their design to eliminate the thin spot as has Manley.

A flat-top isnt going to help as your still going to have a thin spot right there at the valve relief. The solution is a smaller valve relief or the angle mill at the surface to eliminate the thin spot.

If this is the motor I think it is, it made 1100rwhp and was built by ERL with a Twin Turbo Creations turbo kit on it.


This is the old style Wiseco piston with the thin spot at the relief.


Here is their newer design. They actually angle mill the face to eliminate the thin spot.

[Speedy]

I've been trying to find a picture of the 2618 Mahles in my motor. I think they had that angled relief as well. I'll have to check my pics when I get home.

[Andy@PWR]

Im 99% sure the Mahle's do have the angle mill as well.

Will update in a little while with video and sheet. Time for a leakdown and 3 bar mapsensor.

[Speedy]

^^ That yours Andy?

[lakersfan7272]

Was there detonation of some sort / tune off?

[Andy@PWR]

^^ That yours Andy?

Nope, ERL built this, but the builder couldnt have prevented it. It could have just as easily been me but it wasnt.

[Williams RT]

Thats the old Wiseco piston design. That thin spot became an issue when high heat was present. Wiseco has since changed their design to eliminate the thin spot as has Manley.

A flat-top isnt going to help as your still going to have a thin spot right there at the valve relief. The solution is a smaller valve relief or the angle mill at the surface to eliminate the thin spot.

If this is the motor I think it is, it made 1100rwhp and was built by ERL with a Twin Turbo Creations turbo kit on it.


This is the old style Wiseco piston with the thin spot at the relief.


Here is their newer design. They actually angle mill the face to eliminate the thin spot.

That is how the older Hemi pistons are machined on the edge also.But I also machined the whole lip off of my 426 pistons there was enough meat there to do it. It also seems the pressure getting down inside the dish puts more strain on the valve notch than a flat top also? But the piston you show does not have much of a dish like the first one AJ posted either. Forged pistons are much better than cast ones with out a doubt. But with forged ones just being pressed into shape, bends and edges are weak like any other pressed metal. I have never checked and I am sure it would be very expenseive compared to forged pistons, but a set of cnc machined billet pistons would fix all our piston problems I would think?