Cracked Piston #2..WTH?
Dec 13, 2004, 06:43 AM
#46
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Originally Posted by Bimmubishi
Looking at the first in the series of pictures, it looks like that there was some valve float and possibly some collision between the exhaust valves and the #2 piston.
Maybe the increased lift of the 272s combined with (an increased rev limit?) caused the float. If you look closely at the piston, right above the factory valve reliefs there are two very small pattermarks.
If the piston was very hot and there was a collision at the same time then that could have caused the crack.
Anyone buy into this one? Bump also for a guy that takes great care of his car and is a great mechanic.
Alex
Dent Sport Garage
Maybe the increased lift of the 272s combined with (an increased rev limit?) caused the float. If you look closely at the piston, right above the factory valve reliefs there are two very small pattermarks.
If the piston was very hot and there was a collision at the same time then that could have caused the crack.
Anyone buy into this one? Bump also for a guy that takes great care of his car and is a great mechanic.
Alex
Dent Sport Garage
Dec 13, 2004, 06:46 AM
#47
Originally Posted by DSMotorsport
I have blown up a few stock mitsu turbo DSM motors...none have ever failed like this from detonation.
Dec 13, 2004, 07:29 AM
#51
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Originally Posted by Eric Lyublinsky
I would buy that but I can't see any marks on the piston from the valves hitting.
Dec 13, 2004, 07:40 AM
#52
I bet that the marks were made after the piston cracked.
Either way, valves don't break pistons with little love taps that leave the valves unscathed. If a valve is taking out a piston, the head will at least break off and slam a hole in the piston. Also, note that the marks are colored like the surrounding piston. I bet that they were made a while ago, not with this incident.
Either way, valves don't break pistons with little love taps that leave the valves unscathed. If a valve is taking out a piston, the head will at least break off and slam a hole in the piston. Also, note that the marks are colored like the surrounding piston. I bet that they were made a while ago, not with this incident.
Dec 13, 2004, 08:11 AM
#53
Originally Posted by Bimmubishi
Looking at the first in the series of pictures, it looks like that there was some valve float and possibly some collision between the exhaust valves and the #2 piston.
Maybe the increased lift of the 272s combined with (an increased rev limit?) caused the float. If you look closely at the piston, right above the factory valve reliefs there are two very small pattermarks.
If the piston was very hot and there was a collision at the same time then that could have caused the crack.
Anyone buy into this one? Bump also for a guy that takes great care of his car and is a great mechanic.
Alex
Dent Sport Garage
Maybe the increased lift of the 272s combined with (an increased rev limit?) caused the float. If you look closely at the piston, right above the factory valve reliefs there are two very small pattermarks.
If the piston was very hot and there was a collision at the same time then that could have caused the crack.
Anyone buy into this one? Bump also for a guy that takes great care of his car and is a great mechanic.
Alex
Dent Sport Garage
But I do see those marks you're mentioning Alex...hmmm.
Dec 13, 2004, 08:39 AM
#54
Anjapower, They're 10.8 lift but I don't know what stock is. It probably didn't happen at the top of it's stroke given the location of the pattermarks. The step 2 have higher lift for sure but I don't know about the step one but it's probably moot. I've also never seen a DSM piston give up the ghost in a valve-piston fight but anything's possible.
Also noteable is that there are adjustable cam gears in the mix.
Changing the lobe profile to something as aggressive as those cams with an increased rev limit is what causes valve float. It's what happens when stock springs meet a non stock rev limit.
Also noteable is that there are adjustable cam gears in the mix.
Changing the lobe profile to something as aggressive as those cams with an increased rev limit is what causes valve float. It's what happens when stock springs meet a non stock rev limit.
Last edited by Bimmubishi; Dec 13, 2004 at 08:52 AM.
Dec 13, 2004, 08:52 AM
#55
No way is that anyone's fault, especially not the tuners.
I have NEVER seen a pistons break like that, it was not detonation. Does that crack go down or up? I mean is the pistons raised up in the cracked area or is it pushed down?
Looks like it may have gotten a hit of cold water on a hot pistons, maybe the head gasket blew a little, very very odd.
David Buschur
www.buschurracing.com
I have NEVER seen a pistons break like that, it was not detonation. Does that crack go down or up? I mean is the pistons raised up in the cracked area or is it pushed down?
Looks like it may have gotten a hit of cold water on a hot pistons, maybe the head gasket blew a little, very very odd.
David Buschur
www.buschurracing.com
Dec 13, 2004, 08:59 AM
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Originally Posted by ShapeGSX
Nate, I think you should show pictures of what happens when a machine shop balances a piston by drilling tons of tiny holes in it. Do you happen to have any pictures of what happens then?
I can't see this piston breaking being in any way tuning related. valve contant doesn't break a piston like this either...no way this is a HKS cam/valvetrain issue.
95% I think it's just a casting flaw...just a crappy piston from mitsu.
Last edited by DSMotorsport; Dec 13, 2004 at 09:01 AM.
Dec 13, 2004, 02:56 PM
#57
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Piston hitting the valve = bent valve and busted guides
Not a perfectly cracked piston. I say machine defect that just gotten worse.
Got pics of the cylinder walls yet ?
Not a perfectly cracked piston. I say machine defect that just gotten worse.
Got pics of the cylinder walls yet ?
Dec 13, 2004, 04:51 PM
#58
Good info guys keep it coming. I'd never seen anything like this ever either. The cylinder wall doesn't look too bad, a small linear mark only that should come out with the flex hone. Luckily he had the care and foresight to turn the car off and get a tow.
Last edited by Bimmubishi; Dec 13, 2004 at 05:04 PM.
Dec 13, 2004, 09:20 PM
#59
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Thanks for eveyone concern....
it is clear then..its just a factory flaw..another mitsubishi **** up...
i justed talked to AL today and hes gonna send me a rod and piston...for free...hes not even obligated to help me this much...but hes gonna, which shows how nice of a guy he is...i really appriciated it man...
i dont have picts of the sidewall right now..i will get some..
David.
the piston cracked down to the wrist pin...the 2 peices is still together...it just cracked to the pin and stop there...it didnt move up or down..just that chunk went missing..
thanks Alex for pointing this out..hopefully i'llbe at the shop on weds. and well look @ it...
like someone said this could happens to anyone..hopefully it doesnt show up as much..w. everyones help, this thing is be up and running in no time...hehe i'm only gonna run 20psi max from now on to be on the safe side...well anything can happen..i guess..
Thanks
it is clear then..its just a factory flaw..another mitsubishi **** up...
i justed talked to AL today and hes gonna send me a rod and piston...for free...hes not even obligated to help me this much...but hes gonna, which shows how nice of a guy he is...i really appriciated it man...
i dont have picts of the sidewall right now..i will get some..
David.
the piston cracked down to the wrist pin...the 2 peices is still together...it just cracked to the pin and stop there...it didnt move up or down..just that chunk went missing..
Originally Posted by Bimmubishi
Looking at the first in the series of pictures, it looks like that there was some valve float and possibly some collision between the exhaust valves and the #2 piston.
Maybe the increased lift of the 272s combined with (an increased rev limit?) caused the float. If you look closely at the piston, right above the factory valve reliefs there are two very small pattermarks.
If the piston was very hot and there was a collision at the same time then that could have caused the crack.
Anyone buy into this one? Bump also for a guy that takes great care of his car and is a great mechanic.
Alex
Dent Sport Garage
Maybe the increased lift of the 272s combined with (an increased rev limit?) caused the float. If you look closely at the piston, right above the factory valve reliefs there are two very small pattermarks.
If the piston was very hot and there was a collision at the same time then that could have caused the crack.
Anyone buy into this one? Bump also for a guy that takes great care of his car and is a great mechanic.
Alex
Dent Sport Garage
like someone said this could happens to anyone..hopefully it doesnt show up as much..w. everyones help, this thing is be up and running in no time...hehe i'm only gonna run 20psi max from now on to be on the safe side...well anything can happen..i guess..
Thanks
Dec 13, 2004, 09:25 PM
#60
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Take a look at my #2, it has a hairline crack right down the middle from top to bottom similar to this guys'. I put my nail to it and its a crack. And #3 speaks for itself 
This sucks man........Good luck, I'm on hold for a while cuz it aint gonna be cheap 
This sucks man........Good luck, I'm on hold for a while cuz it aint gonna be cheap