Mahle Motorsport cast piston VS Fingers Oval

[Chilly]

So been doing a little research on some replacement pistons as I cracked a de-lipped Mahle factory replacement piston around 800-900HP.

I love the fact that Fingers oval pistons are that little bit stronger, but hate the fact that they smoke at idle. I almost ordered a set but after talking to someone who has a set they hate them. He is embarrassed sitting at traffic lights.

How big of a difference is there between the Mahle factory replacement pistons and the motorsports version? I understand the physical difference’s looking side by side, but I’m talking real world HP numbers.
How much "reliable" horse power are guys putting down with the motorsport pistons? Wish there was a safe piston for street trucks around the 800-900HP mark. Scared I’m going to do the same with the Motorsports replacement piston, but I don’t have to many choices.

How many guys are still cracking the motorsport pistons and at what HP level? What CR are most guys running around with 80lbs of boost? Safe to stay around 16.0-16.5?

 

[Bdsankey]

IMO go forged from CP or Mahle. The days where a forged piston was only good for one to two seasons is long gone. SoCal, according to Guy's commentary on one of the diesel podcasts, was that they did a lifecycle test and the outcome was 75k-100k was achievable. Any built motor will be coming apart long before that happens.

I'm running 16.5:1 on my built truck with CP forged pistons. The issue with forged pistons years ago was the alloy chosen had such a large expansion rate that the piston would require a large piston to wall clearance and rock in the cylinder eating up the rings. For sure the CP and Mahle run almost the same PTW as cast pistons. Another option would be D&J's FSR pistons which are a forged piston with a steel ring land.

 

[Chilly]

I made a quick call to D&J, they do NOT make any Duramax pistons. So that rules those pistons out.

How many guys are driving the forged pistons on the street? I will be starting the truck twice a day from cold and live in Canada where weather gets down to -22 Fahrenheit. I feel that running forged pistons in my climate is different to southern California. Your operating temperature comes up MUCH faster than where I live.

 

[M.A.M.]

I’ve got a set of the oval bowl pistons in my LML, with 200 over injectors. It’s easier to tune out the fuel at idle on an LML, but I have barely any smoke at idle. Smokes a bit until everything gets up to operating temp, only a slight haze after that.


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[Chilly]

I talked with Larry at Danville. He said Mark tried everything to tune the smoke out at idle and couldn't.

 

[JoshH]

The Mahle Motorsports pistons will be significantly stronger than the delipped stock pistons.

 

[Bdsankey]

I made a quick call to D&J, they do NOT make any Duramax pistons. So that rules those pistons out.

How many guys are driving the forged pistons on the street? I will be starting the truck twice a day from cold and live in Canada where weather gets down to -22 Fahrenheit. I feel that running forged pistons in my climate is different to southern California. Your operating temperature comes up MUCH faster than where I live.

They used to, or at least advertised them. In that climate I would run the mahle motorsports if its a 12mo a year truck that sees cold climates since you cannot guarantee it will be plugged in every time it is going to sit (at work or overnight at home etc).

 

[Chevy1925]

Interesting, I’ll bet he has other contributing issues that is not directly a piston issues. I’ve put a few engines together with fingers pistons and all of them were able to have the smoke tuned out. Honestly they smoked no more than any other big injector truck before tuning was done and they cleaned up.

Any forged piston will require much more piston to wall and piston to head clearance than cast which can eat some oil till hot and be a bit noisy till hot. I believe diamond is the only ones with a steel ring land in a forged piston so you can run a stainless steel top ring like stock.

It’s a give and take either way but I’d go fingers in a heart beat

 

[Chevy1925]

They used to, or at least advertised them. In that climate I would run the mahle motorsports if its a 12mo a year truck that sees cold climates since you cannot guarantee it will be plugged in every time it is going to sit (at work or overnight at home etc).

Drew and the crew have been um...... interesting the last year or so. I wouldn’t buy anything from them right now

 

[JoshH]

Diamond is the company that makes the forged pistons with steel ring lands, but a steel ring land isn't going to keep a forged piston from eating rings. The problem is like you stated earlier, the piston, with a traditional forged piston, rocks in the bore when cold because of excessive PTW clearance.

 

[Chilly]

The Mahle Motorsports pistons will be significantly stronger than the delipped stock pistons.

Can you define "stronger"? 20%, 40%?

 

[JoshH]

I really like Fingers pistons, but if I were building an engine that needed pistons that strong, I would be using a forged piston. Anything up to 1000 HP, I feel pretty confident in the Mahle Motorsport piston.

 

[Chevy1925]

I would say 20%. They still break/crack which keeps me away from them

 

[JoshH]

Can you define "stronger"? 20%, 40%?

I can't put a number on it, but I ran a set of Mahle Motorsports pistons for 2 years at 800-900 HP and never had a problem. Unless there is something else going on with your setup, I see no reason why they wouldn't work for you.

 

[Bdsankey]

Diamond is the company that makes the forged pistons with steel ring lands, but a steel ring land isn't going to keep a forged piston from eating rings. The problem is like you stated earlier, the piston, with a traditional forged piston, rocks in the bore when cold because of excessive PTW clearance.

I know about Diamond's steel ring land pistons but D&J used to list the FSR piston for a duramax application on their website ~18mo ago when I was building my engine.

 

[Chilly]

I can't put a number on it, but I ran a set of Mahle Motorsports pistons for 2 years at 800-900 HP and never had a problem. Unless there is something else going on with your setup, I see no reason why they wouldn't work for you.

Thanks, that gives me some confidence. What were you using the truck for? Did you do any sled pulling or drag racing with the Motorsport pistons? Or were you just driving around town and occasionally fooling around on the highway with your largest tune?


Who is cracking Mahle Motorsport pistons?

 

[Bdsankey]

Thanks, that gives me some confidence. What were you using the truck for? Did you do any sled pulling or drag racing with the Motorsport pistons? Or were you just driving around town and occasionally fooling around on the highway with your largest tune?


Who is cracking Mahle Motorsport pistons?

A cast piston has limitations purely from the material, there is absolutely no way around it. It seems like anything over 1000hp is playing with fire. Some guys have pistons that live and some can't keep them together. Fingers pistons have shown positive improvements but also haven't shown to be the solution. The only solution is forged pistons when attempting to make that power level and keep it together on a regular basis. I'm not saying cast pistons are not capable of holding together, just the repeated trips to Mexico, drag strip passes, sled pulls etc all will take their toll.





Josh beats his truck like it owes him money, if he didn't break them then I'd venture to guess you'll be fine.

 

[Chevy1925]

A cast piston has limitations purely from the material, there is absolutely no way around it. It seems like anything over 1000hp is playing with fire. Some guys have pistons that live and some can't keep them together. Fingers pistons have shown positive improvements but also haven't shown to be the solution. The only solution is forged pistons when attempting to make that power level and keep it together on a regular basis. I'm not saying cast pistons are not capable of holding together, just the repeated trips to Mexico, drag strip passes, sled pulls etc all will take their toll.





Josh beats his truck like it owes him money, if he didn't break them then I'd venture to guess you'll be fine.

Johns pistons have pretty well proven themselves. its the only cast piston that had not cracked as most do and those that showed failure were from other mechanical problems (easy to see). they have seen 2k hp, been beat to death in 1200+ hp trucks, and even with the few mechanical failures that took the pistons with them, in the 8+ years they have been out i would damn well say they have proven them selves

 

[Ne-max]

LBZs haze at idle stock. Lol. Tuning plays a huge roal in haze at idle. My race truck with 200s, 9100 cam and 14.5:1 always hazes with ppei and ridgerunner tuning. Both said there was nothing they could do. When I switches to Rob haze was gone. Now with 400 over injectors and 16.5:1 fingers Mark has it pretty clean for what it is. Yes they cost more but cast fingers are the only pistons good from stock to over 1600hp.

 

[Ne-max]

A cast piston has limitations purely from the material, there is absolutely no way around it. It seems like anything over 1000hp is playing with fire. Some guys have pistons that live and some can't keep them together. Fingers pistons have shown positive improvements but also haven't shown to be the solution. The only solution is forged pistons when attempting to make that power level and keep it together on a regular basis. I'm not saying cast pistons are not capable of holding together, just the repeated trips to Mexico, drag strip passes, sled pulls etc all will take their toll.





Josh beats his truck like it owes him money, if he didn't break them then I'd venture to guess you'll be fine.

Fingers will hold well past 1000hp. Nate Bandstra did over 1700hp at ucc with cast fingers that have 3 hard seasons on them.
I had 3 seasons on my old ones. Last year almost 1400hp. Cracked block and crank but pistons still looked new.