They should if you coat them with Ceramic on top and put a dry film lube on the skirts. Mahle now offers high performance forged and steel pistons for our applications. If I had money to burn I'd go with Steel pistons.

 

Show me where to get the steel mahles...

They have denied, denied, denied anything to do with steel 7.3 pistons however many times and whomever I have asked thus far.

If you know where they're hiding them tell me.

 

Stockers will hold 900 RWHP according to some. Should be fine for what you are doing.

 

If you've got the engine torn down... you will surely be doing a bore on the cylinders. That would require an oversized piston. Either way, while something is apart, do what you can to help it out. You wouldn't pull a clutch and replace the disk while leaving the same pressure plate, unsurfaced flywheel, worn out pilot and thowout bearings. While you're in there, swap em out.

But if you are running an engine in a truck and have no plans of taking it apart and no plans of driving it for a DD that would preclude you from possibly having it skatter across a pulling track, then 900 should be doable on the stock rods ... The pistons should hold much more than that if done right.

This would require things that Brian can't understand, much less accomplish though. So file his SA comment under the frustrated fat kid tab.

 

I have cut Mahle's, no coatings.

 

Hey swamps wanna be reject-

If I remember, I actually have experience with these things that you theorize about, and I love the fat kid comments-that will make our next meeting fun for me......you blew your POS at a "durated" 300 RWHP.

The stock Mahles with some prep will support "durated" (its not a word) 700+ RWHP without failure for thousands of miles. Check with BIGR.......

 

You are a member of the "Fat Kid Pulling Team" no? Did you quit then?

I've done every last thing I said I would. And it all worked as I said it would. One thing left to test out.

My pistons had heat induced cracks in all of them from the 5 or so years running egt in the 1600 to 1800 degree range. The ones on #7 lined up with the wristpin and popped down to the top of the pin.

Give me a break.

 

How would anyone know if the stockers can hold up to 900 RWHP if no one has ever made that kind of power with a PSD............With the exception of D.O.T. :shrug:.........

IMHO Id listen to Charles, why waste the time and out stock pistons back in with XXXXXX amount of miles and stress put on them.........
Buck up and get a set of Mahles theyre only 900 or so, which is alot cheaper than another rebuild when your stocker makes an exit out the block.

 

I would be putting new ones in no mater what and if i recall mahles makes alot of the O.E.M. stuff for the psd

 

I'd cut and coat the Mahle replacement pistons. For examples check the link in my sig to my engine pics (click on the picture of the engine). There are some cut and coated pistons hiding in that album along with a few other ideas that might help someone looking to start a build.

 

cut and coated Mahle's here

 

Cut, Coated, and Cryoed here

 

Uncut, uncoated, uncryoed, and standard size here.

 

Mahles here- standard deck height with some bowl work done to drop the compresion and no coatings.

 

Cut, coated, .10 over and dryfilm lubed skirts.

 

what kind of temp differences will you see if coated as apposed to uncoated??

 

Not really any temp differences, it's just the main thing you worry about with EGT's at the 1250 level is the fact of the aluminum pistons melting, as pure aluminum melts at 1228*. Not sure what a piston would melt at, somewhere north of 1350 i would assume as it has other metals too. With ceramic coating you're virtually eliminating the worry about EGT's.

 

With ceramic coating you're virtually eliminating the worry about EGT's.

Ceramic coating does little to nothing to insulate the pistons. The ceramic coated pistons crack the same as the uncoated ones. One of mine currently runs standard height with enlarged bowls ceramic coated.

 

1350??? mine should be blobs of aluminum by now.

 

I know mine get HOT. Thats why I coated them. Watch the front fenderwell in most of my videos if you want proof that coatings work.

Jason

 

Everyone should bare in mind that the pistons don't get anywhere near the temperature of the exhaust gas.

If they did, the years of 1700 -1800 degrees I gave them wouldn't have taken more than 30 seconds, nowhere near the 3 years I gave them before the thermal cycling finally got the better of #7, and it split where two thermal cracks out of the bowl had weakened the piston.

I turned out the bowls on mine and dropped the CR down to something in the 14.5 - 15.0 range. They are .20 over Mahles, and are sitting at the coaters right now getting the tops and skirts done. When I cut the bowls I put a healthy radius on the bowl exit so it wouldn't be such a heat sink and start the cracking.... hopefully.

I did a couple and then had a machine shop do the rest after the lathe got pissed and threw a piston at me going 400rpm. :hehe:

I would love to be able to talk to someone at Mahle about offering some reduced CR steel pistons. And I plan to. I've ran into about 4 dead ends with them so far, but I have one more number to call in the performance division at Mahle.

Sure would be nice to pick up a Mahle piston with an enlarged chamber right off the shelf. Especially being made from steel.

 

yeah Kenny, the actual piston probably doesn't get much over 800* in extreme cases, due to the fact that oil is constantly being squirted on the bottoms, the incoming air charge is much cooler than the temperature of the piston, and this cycle happens so fast, it takes a LONG time for the piston to soak in the heat that is on top of it for just a small amount of time.

 

If that is the case then why install a pyro in the exhaust manifold:shrug:

Go look at HotRod's video. Now, can you tell me the top of the piston is 800*.

Charles is right the whole piston will not get that hot BUT the top will. That is what you have to worry about.

If you think that oil squiter is doing much at 3000 Rpm's and a pegged pyro gauge, please go tear into a diesel and figure it out for yourself.

Part of my job as being a Diesel Mechanic is changing melted pistons or melted holes through pistons.

 

Even then, the heat is only on the very top. If the rest of the piston ever got anywhere near that hot it would seize in its bore.

 

its called thermal growth

 

Oh, so that's what i can say next time she.... uh... Oh never mind :blah:

 

The cermaic coating does insulate the top of the piston, but its just insulation. Insulation in the real world only SLOWS the heat transfer to/or from an object. Ceramic coatings help, but pistons can definately still crack when running high EGTs. When I rebuild my motor I plan on changing to a steel piston just to try an avoid this very problem. I thought Mahle was working on just that, a steel piston with a keystone ring land that would work for a DD. If they are not getting ready to make one, or just aren't available at the time, then I will probably just put in Arias pistons since mine doesn't see any street use. Plus the ring lands are lower allowing for more radical valve reliefs and more wild combustion chamber designs than just "opening it up".

-Note: I do not feel that we need more valve releifs than what can be currently had. I just wanted to clarify that because someone will jump my case since the intake runner is the limiting factor in flow.....

 

The cermaic coating does insulate the top of the piston, but its just insulation. Insulation in the real world only SLOWS the heat transfer to/or from an object. Ceramic coatings help, but pistons can definately still crack when running high EGTs. When I rebuild my motor I plan on changing to a steel piston just to try an avoid this very problem. I thought Mahle was working on just that, a steel piston with a keystone ring land that would work for a DD. If they are not getting ready to make one, or just aren't available at the time, then I will probably just put in Arias pistons since mine doesn't see any street use. Plus the ring lands are lower allowing for more radical valve reliefs and more wild combustion chamber designs than just "opening it up".

-Note: I do not feel that we need more valve releifs than what can be currently had. I just wanted to clarify that because someone will jump my case since the intake runner is the limiting factor in flow.....

Do more research before spending the time and money ... that's all I'm saying.

 

I have some info in my inbox to support the Mahle steel pistons will be coming out in the future. There was even a blurb in Dec DP about there plans @ sema.