Engine autopsy
- Thread starter TrentNell
- Start date
I guess the jury is still out on whether the Mahle Forged pistons are plenty adequate though. I mean, we've seen Pat's set that got really hot and failed, we've seen Matt's that failed due to heat via nitrous, I'm sure there are others that have failed but have they been failing because of inadequacy or because of unneeded abuse? Sure, they are more brittle than the Arias, that much I've learned, but if the Arias eats rings up and possibly bores too, why go through the hassle? Some have called the Mahle a "compromise piston" but until I see a situation where they failed or caused a different failure without extenuating circumstances I don't think that's a valid claim against them.
drugs :baby:
bad tuning, bad injectors, holding it wide open for 120 seconds or something rediculous, you know.....unneccessary
bad tuning, bad injectors, holding it wide open for 120 seconds or something rediculous, you know.....unneccessary
Man I know I will never be at a power level you guys are at that are cracking these psitons but boy does it worry me non the less. Dustin to bad you can't have a dd and a race truck.
ok heres a thought.
what is bore diameter?
what is piston diameter cold?
what temp does the piston itself see at sustained wot under load?
how much does piston expand? ie piston hot diameter?
again i do not have a degree in chemistry or physics but just like thinking outside the box. i wonder if a slight overbore could help a little?
what is bore diameter?
what is piston diameter cold?
what temp does the piston itself see at sustained wot under load?
how much does piston expand? ie piston hot diameter?
again i do not have a degree in chemistry or physics but just like thinking outside the box. i wonder if a slight overbore could help a little?
Hmm I was hearing from someone doing forged pistons that there trying to tighten up the clearances maybe we'll see I will probably just run delipped stock pistons cussed think ill be happy with 700-800 HP but how many times have we herd that story
drugs :baby:
bad tuning, bad injectors, holding it wide open for 120 seconds or something rediculous, you know.....unneccessary
Abby has used drugs had my bad tuning, kennedys crappy injectors!
It's been WOT for well over 120 seconds (you sure make a distance that way too
)I really dont see any of that as unnecessary,Perhaps thats just me though
Abby has used drugs had my bad tuning, kennedys crappy injectors!
It's been WOT for well over 120 seconds (you sure make a distance that way too
I really dont see any of that as unnecessary,Perhaps thats just me though
haha, I agree, kennedy's injectors leave a lot to be desired I've heard; I can't say anything about your tuning but you haven't ran a 9 even after we all thought you would:joker:
the WOT comment was kinda tied into the bad tuning comment.
I just think that there is a way to make the Mahle's live...maybe i am wrong...but I'll let you guys know
since I'm using them
x2 - to get the type of power where you are even thinking about forged pistons I would say you are going to need some "unneeded abuse". Matt has had stock pistons last much longer than the Mahle forged pistons, he still hasn't sent them back to Guy to be inspected for cause of failure but 6 passes on $2600 pistons...... They'll live if you don't abuse them, but then again so will stock pistons.
I would rather replace rings than pistons - cast or forged. And like I said at 900+ rwhp you are never going to get everything to last forever - you have to decide what you would rather replace. You could make steel bearings that would last forever but they would tear the sh*t out of your crank. My vote goes to replacing the cheaper "wear items" like bearings and rings rather than replacing hard parts. Monotherm or monosteel pistons would be nice - you could have a steel keystone ring in them and not beat the ring lands up, but at the cost of a considerably heavier piston and about double the cost of forged pistons.
drugs :baby:
bad tuning, bad injectors, holding it wide open for 120 seconds or something rediculous, you know.....unneccessary
Nitrous is just a turbo in a bottle :baby: So are you gonna send your injectors in for testing every couple thousand miles? Get your truck set up to where stock tuning will do 900+ rwhp so that you can run "good, safe" tuning?
I wish I could afford to and talk my wife into it.
The different expansion rates of stock cast vs forged pistons is taken into consideration buy the piston builders. The Mahle forged pistons need .006" clearance, compared to stock that needs .0025", and Arias that needs .008". For a standard Duramax bore (4.055") the stock pistons are 4.050", Mahles should be 4.043", and the Arias should be 4.039". And the pistons are also tapered. You could have the engine slightly over bored to allow more piston to wall clearance but I don't think that the cracked pistons are a failing due to clearance issues.
The weight of the piston also makes high RPM a lot harder on the wrist pin holes, as do the extreme cylinder pressures you need to get 900+ rwhp; and every crack I've seen is parallel to the wrist pin.
Here is a good read: http://www.enginebuildermag.com/Article/1788/diesel_pistons.aspx
Forgive me if this is dumb but would bore diameter change cold to hot following or receding from the piston ?
haha, I agree, kennedy's injectors leave a lot to be desired I've heard; I can't say anything about your tuning but you haven't ran a 9 even after we all thought you would:joker:
the WOT comment was kinda tied into the bad tuning comment.
I just think that there is a way to make the Mahle's live...maybe i am wrong...but I'll let you guys know
do you tune your own truck?
Simon, it wasn't a dig at you buddy, sorry if it came across that way. I was rooting for you and abby to hit it this year. Ive followed your threads from the first day I knew what a diesel forum was. I was actually not referring to abby or anything having to do with you when I first posted in this thread. It was more directed at caspers unfortunate failure as well as mats...which caused me to research the piston choices and pros and cons again (after buying the ones I have)
and to answer your question, absolutely not. I would probably have a set of melted pistons or worse if I tried to tune my truck myself right now, lol
Man i hear that every day from one of my coworkers
It get old hearing everyday about how i shuda bought a 12valve. I just told him i would rather blow my stuff then use old tractor technology nothing against a 12valve
You would have to be an idiot to trade a smarty/mp-8 for EFI. That's the best stack ever. Nothing compares. :rofl:
Pistons
I'm not sure some of you guy's are being real with your want's! You are NOT going to have a 1k motor and drive it like escort! You are NOT going to run 10's and NOT have to work on it! The Mahle piston will work for a daily driver/racer/puller and hold up FAIRLY well. Pat was doing something hard on a motor and nobody had really done until he did it with a duramax so it was a steep learning curve. It's hard that's why nobody had done it. He learned a lot and will benifit from it. Matt's truck (with stock pistons) had stock injectors. You can only get so much fuel from stock injector's! You add a bunch of nitrous with a limited amount of fuel it will live for a little bit. Now he is running stock pistons with big injectors so we will get a better idea of how long that will last. I hope it holds up well then all we need to do is put rods in these motors and let them eat. It would be a lot cheaper for everyone. If he gets a season out of it it would be stupid to build a motor! Get a stocker, put rods in it and have at it. Nothing will last forever no matter how much money you have or what supertuner you have or who you know! It's still mechanical and it will still break! Jeff
I'm not sure some of you guy's are being real with your want's! You are NOT going to have a 1k motor and drive it like escort! You are NOT going to run 10's and NOT have to work on it! The Mahle piston will work for a daily driver/racer/puller and hold up FAIRLY well. Pat was doing something hard on a motor and nobody had really done until he did it with a duramax so it was a steep learning curve. It's hard that's why nobody had done it. He learned a lot and will benifit from it. Matt's truck (with stock pistons) had stock injectors. You can only get so much fuel from stock injector's! You add a bunch of nitrous with a limited amount of fuel it will live for a little bit. Now he is running stock pistons with big injectors so we will get a better idea of how long that will last. I hope it holds up well then all we need to do is put rods in these motors and let them eat. It would be a lot cheaper for everyone. If he gets a season out of it it would be stupid to build a motor! Get a stocker, put rods in it and have at it. Nothing will last forever no matter how much money you have or what supertuner you have or who you know! It's still mechanical and it will still break! Jeff
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