LB7: Cracked Piston

[S Phinney]

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Looks like I have cracked another piston. This time it is a Mahle Cast Race from SoCal. I drive it occasionally not every day. How is forged holding up under this application? How many guys are putting some miles on them and not having leak down or blow buy issues? I can't keep working on this thing so I need better options. Any input is appreciated.

 

[blk smoke lb7]

Sorry to here that Shane.

 

[matt78]

Sorry man

 

[MAXX IT OUT]

What happened? That sucks. Are you going to use fingers pistols?

 

[Stingpuller]

Pistons

Shane I have to ask a real question. Why would you think that a forged piston would have more or less blowby than a cast? The extra clearance has nothing to do with the ring seal. Sorry to hear about another setback.

 

[blk smoke lb7]

I'm rather surprised you would try and run tripples on lb7 slugs anyways their live expectancy at 900 horse is like dancing with the devil 1000+ your doomed IMO.

 

[arneson]

Sounds like a good candidate for fingers oval pistons.

 

[bullfrogjohnson]

How much boost are you seeing and what size injectors?

 

[Fingers]

Durability of the Forged is a fraction of Cast, but your mileage will vary.

Tuning and lowering the compression go a long way to keeping the pistons alive, especially in big builds. (> 700 HP)

Were you running a Mahle ring set?

 

[S Phinney]

Shane I have to ask a real question. Why would you think that a forged piston would have more or less blowby than a cast? The extra clearance has nothing to do with the ring seal. Sorry to hear about another setback.

I understand clearances and motor building. I ask about that specifically because people say the rings do not hold up. I do not have experience with forged pistons on diesels. I want to be able to enjoy the build more than 5-10k miles. You have been using them so you may have good information for me.

I'm rather surprised you would try and run tripples on lb7 slugs anyways their live expectancy at 900 horse is like dancing with the devil 1000+ your doomed IMO.

They were Mahle Race cast from SoCal. I have broken a stock cut and coated while running the 66 mm turbo.

How much boost are you seeing and what size injectors?[/QUOTE
I have seen 85 psi of boost. I am running 100 overs from Exergy. The weird thing is that I have been experiencing unusual egts and boost since I dynoed the truck. Almost like a boost leak would do but have not been able to find anything out if the ordinary. I know that I have had some blow by and the rings not completely seating but not enough to loose any oil.

Durability of the Forged is a fraction of Cast, but your mileage will vary.

Tuning and lowering the compression go a long way to keeping the pistons alive, especially in big builds. (> 700 HP)

Were you running a Mahle ring set?

The rings were what Guy at SoCal sent in the set. They had a stainless top ring. I have not pulled it apart yet but highly suspect it is piston or ring related. Please explain the durability being a fraction of cast. Will I have to rering or replace the pistons if I go that direction? I am planning to buy from you but want to make a better decision that before with the ones from Guy.


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[adeso]

I see in your sig that you do your own turning, not trying to be a dick but maybe have someone look at it?

 

[S Phinney]

I can do a pretty good job at it myself. Bob Olson use to tune it for me years ago. I am influenced a good deal by his philosophies. I do not think that he is extreme in his thinking. I tune several trucks as it is and have zero problems with how they run or how durable they have been. I have a truck that I drive everyday with 375k on it still using the original stock trans. It has been very durable. It has had tuning most of its life. I think the problem comes from too much power for the parts. Pistons are the weak link in my build. I want to remedy that problem.

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[x MadMAX DIESEL]

Durability of the Forged is a fraction of Cast, but your mileage will vary.

Im confused by this post?

 

[BigDMax05]

what about the new monotherm's? i am behind the curve on the latest and greatest pistons and would like to know myself. sorry to hear bout your trouble.

 

[1slowmax]

Damn! That sucks man. You will get it figured out. Ill be going with Fingers Forged oval bowls real soon to try and avoid this issue.

 

[S Phinney]

Well it us official. Zero compression on number 8. I am not certain which way to go right now. I need input from guys that are running forged pistons. Have you had them apart and what did they look like? Have you been able to rering and use again or was the top land ruined from being beat out? Any help or advice from experienced perons is open and welcome.

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[1slowmax]

Your only choice is forged IMO several guys drive on them daily and i will drive mine on the street with forged. ill be dipping 9s real soon so i really have no choice but to go forged which is fine. I have six good 20 over Mahle cast fly cut if you need one. Good luck:thumb:

 

[770JOHNNYW]

Shit!!!

 

[sweetdiesel]

Running Arias pistons was the best decision I ever made.

Sorry to hear that Shane....really suxs

 

[dbev24]

What about diamond pistons? Never heard much about them?