Broken Diamond Piston. Pics why????

[87we410877]

Pulled the rods and pistons out last night to find piece of #6 piston missing. Is this common with these pistons? The car has never run right at higher boost levels and im thinking this has been the problem for a while. I pulled the motor because it leaks alot from the gurdle and started pushing compression into the coolant system.

What would cause this? Just detonation? You can see tons of detonation marks on the piston. I polished #1 piston and it had none at all. Im thinking this has been the problem for a while. What do you think and what should i do? i was thinking of calling diamond and just ordering one piston. Can you do that? Enjoy

 

[turbobuick]

Been there done that. Throw them in the garbage and call a vendor to order CP's or J&E's. Diamond doesn't put enough material between the dish and the top ring land. I blew apart two sets of them last year costing me thousands. Put a set of CP's in from DLS and leaned on them WAY harder than I ever did the diamond's and they lasted all season and looked mint when I tore the motor down this winter. Granted I am doing stuff to a piston most would cringe at, but I have seen this in other motors more similar to yours.

 

[turbobuick]

FYI the ring lands on the other pistons are probably starting to lift and are junk anyway. Look at the upper shell of the rod bearing for detonation. The nicks in the piston are from piston material dinging it and it could've migrated to other cylinders doing the same. That piston broke it didn't melt, if you leaned on it to hard you would've torched it and melted through. The piston is to weak and the ring land lifts eventually smacking the head before it breaks. They also typically break on the intake side from heat and detonation as that is the side of the piston with the most heat from combustion. Also look at the bottom side of the piston for burnt oil, if you where getting hot you will see it there also. Check you turbine wheel.

 

[turbobitt]

My guess would be a design flaw as stated in previous post. There doesn't appear to be much section thickness between the ring groove and valve relief. The marks on the piston are probably made from the piece of piston and not detonation.
My question is, why such a large valve relief ? I don't have anything near that and I'm using a stage 2 head with big valves and over .600 lift.

Allan G.

 

[turbobitt]

My guess would be a design flaw as stated in previous post. There doesn't appear to be much section thickness between the ring groove and valve relief. The marks on the piston are probably made from the piece of piston and not detonation.
My question is, why such a large valve relief ? I don't have anything near that and I'm using a stage 2 head with big valves and over .600 lift.

Allan G.

After looking at the picture, I'm going to answer my own post. It looks like the piston was made from a "shelf" piston blank and not really a custom buick piston.

Allan G.

 

[Grumpy]

big time detonation ... I also didn't care the way they are cut so close to the edge BUT we have been pounding the hell out of them for $15k+ with NO DETONATION Oh IF ya detonate the crap out of it you are goin to get the same results . Oh what does the top rod bearing look like ??

 

[Mike Licht]

I have broke plenty of JE's and Wiescos the same way. No matter what you put in if you detonate it hard, it is going to break. Hundreds of sets of Diamond pistons out there working fine.
Mike

 

[JayC]

Id be more concerned about where the piece of the piston went. Better check your turbine wheel. I think youre going to be sad.

 

[DailyDrifter]

Id be more concerned about where the piece of the piston went. Better check your turbine wheel. I think youre going to be sad.

Way to be a buzzkill Jay

 

[Robert Wilson]

Isn't it unusual that the piston would still have such a "slick" finish after being detonated? I would think you would see more of the "sandblast" finish on the top of the piston from the tiny balls of molten aluminum being released. Maybe the sharp edges created a hot spot that concentrated the detonation to one particular area??

 

[thadeal4real]

ring were all outta wack

that was creating detention pistin broke cause top ring butted gap too tight i would check all cyl ring combo in that/next motor

 

[slimtastic]

when my motor detonated and took a S$%T the piston had a sandblasted look and the edges of the "dish" were rounded out hard. like detionation had been taking bites out of the piston crown.... my guess is a flaw in diamond's piston outta the box


that or rings being too tight.... whats the crosshatch looking like?

 

[Grumpy]

.. my guess is a flaw in diamond's piston outta the box

well everything is goin to break sooner or later .. Detonation is a killer !!! I have used weisco's, J&E's, TRW's, Stocker's, and Diamond's. I have seen them all fail over the years.. For years I have watched Buicks poop and fart goin down the track and smoking like a mofo !! Guys would just keep it to the floor waiting for it to "clean out" Sooo I put 99.9% of the blame on the "TUNA's"

 

[ThatOrangeGT]

I am a friend of his and have watched every aspect of the car built from the start. After this engine was completed it has always had issues of breaking up under high boost. The builder has definitely invested in what he though to be quality parts and superior tuning and the results have always left questioning.

For those of you who have broken ring lands in the past was it noticable immediately? We are trying to figure out how long the car has been like this because it should have been performing better in the past. We have broken ring lands on non-buick engines and it was immediate failure.

 

[Kip]

Just a question, what was the owner using to tune with?

Thanks, Kip

 

[87we410877]

Just a question, what was the owner using to tune with?

Thanks, Kip

Ok to answer all questions, I polished the top of the piston to get that look and see everything more clear.

The cyl. walls look fine as do the heads and the turbo.

Rod bearing top looks ok the botton not so ok (some coper) more copper some rods than others. It was pushing coolant through the head gasket so this may have added to the problem with the bearings.

The tunning is by FAST bank to bank tuned by Jack Cotton. Something always seemed off with the way the car ran though. Always trouble idleing, starting and running high boost (more than 24). We couldnt never figure it out.

I will take pics of before and after polishing of the other pistons probably tonight if i dont get too drunk in depression over building a $15k motor twice. RPE will be doing it next.

More to come on pics, other cylinders, and whats next. Thanks.

 

[nickdiesel]

15 G's

 

[Grumpy]

hmmm.. who built the motor 2 times ??? What were the ring gaps ??? Ya sure do have some "cool guy" parts .. Do you see knock on a Fast system ??? (just wondering.. we r still on a chip)

 

[chasmat2316]

I am a friend of his and have watched every aspect of the car built from the start. After this engine was completed it has always had issues of breaking up under high boost. The builder has definitely invested in what he though to be quality parts and superior tuning and the results have always left questioning.

For those of you who have broken ring lands in the past was it noticable immediately? We are trying to figure out how long the car has been like this because it should have been performing better in the past. We have broken ring lands on non-buick engines and it was immediate failure.

breaking up under high boost will do it!!!

 

[bison]

Do you see knock on a Fast system ??? (just wondering.. we r still on a chip)

Yes, and you will typically have a nice data log showing the exact instant your engine turned into a pile of chit:biggrin: Ive been on the current set of JE's 3.820 1/16 comp rings for 12 years. Probably have hours of WOT time on them.