Broken Diamond Piston. Pics why????

[turbobuick]

I've detonated my fair share of 109 motors and if I remember correctly the HG's seemed to blow WAY before knocking holes in pistons. Especially a custom forging which should be able to take considerable abuse without failing.

 

[ChrisChow]

I've detonated my fair share of 109 motors and if I remember correctly the HG's seemed to blow WAY before knocking holes in pistons. Especially a custom forging which should be able to take considerable abuse without failing.

Well in my 1 afternoon with John Wilde and a PT70, and 1 pump fail and no significant follow up tuning on the DFI

I'll see if I still have the piston. But we pretty much have the SAME result. Melted the top crown which cause significant blowby into the crankcase. I used 2 Big Bosch pumps from a Bently, bolted on a PT70 turbo (upgraded from a TE-44) and NO access to a wide band gauge. This was back in the day when dynos were few and far between.

We went WOT to 15 psi and power felt great but I noticed it backfired/broke up and let off. Limped it back home to find it barely idling. When a took the heads off, the gaskets were fine but the #5 or #6piston was shot. Quick lean spike and goodbye piston!

 

[Grumpy]

I've detonated my fair share of 109 motors and if I remember correctly the HG's seemed to blow WAY before knocking holes in pistons. Especially a custom forging which should be able to take considerable abuse without failing.

Chris remember the 87 White Limited with NO motor with 27k on it .. That had a burned piston and the headgasket was fine

 

[Grumpy]

i think this fast and alky needs to come out.

well don't start out balls to the wall !! just creep up on it. What were ya running for plugs ???? what did they look like?

 

[DailyDrifter]

well don't start out balls to the wall !! just creep up on it. What were ya running for plugs ???? what did they look like?

Good question, the plugs will tell you the story.


Also another good point made about the actual timing vs. FAST timing. Before my 1000 mile engine took a chit I forgot to verify the timing. My combo is in my sig, kinda along the same lines as you.......But my ultimate failure was a "block boring cam". My new combo however never ran "right", and was a real dog from day 1. I still kick myself in the ass for not checking the timing . When you get the new engine built, make sure you verify the timing.

 

[quickt]

And it
doesn't matter whose piston it is the ring placement is incorrect for a turbo
application.

Totally agree.

 

[87we410877]

No i never verified the timing. Plugs are autolite 103's and look fine. I'll take pics of the heads and post them up.

I will probably go with a stock ECU, MAF translator, some kinda AFR monitor and a turbo tweek chip.

 

[turbobuick]

Chris remember the 87 White Limited with NO motor with 27k on it .. That had a burned piston and the headgasket was fine

Was that a stock cast piston or a custom forging?

I agree with Dan and Lonnie above.

 

[SloGN]

I think that failure came from knock. I'm betting the knock sensor is unplugged or has a issue in the wiring. In the fast B2B i beleive that if you set the timing attack rate to zero. when knock occurs and it doesn't pull any timing it will show no knock.


Also verfing the timing is a very important thing to do on the aftermarket ecm's. I have found a few gn's that the timing was off as much as 5 degrees.


One other thing you might want to consider is have the Wideband checked.

on a another side note if ya run alky and pump gass run it a tad richer say 10.8 -11.0 any leaner than that is asking for trouble IMO










If this failure just happened for know reason it's got me bumed as i just purchased a stroker set-up from mike licht before Xmas.

 

[87we410877]

I think that failure came from knock. I'm betting the knock sensor is unplugged or has a issue in the wiring. In the fast B2B i beleive that if you set the timing attack rate to zero. when knock occurs and it doesn't pull any timing it will show no knock.


Also verfing the timing is a very important thing to do on the aftermarket ecm's. I have found a few gn's that the timing was off as much as 5 degrees.


One other thing you might want to consider is have the Wideband checked.

on a another side note if ya run alky and pump gass run it a tad richer say 10.8 -11.0 any leaner than that is asking for trouble IMO

Yea i guess everythings going to have to be checked on the new motor set up and checked again. I took alky out its for sale in the for sale section







If this failure just happened for know reason it's got me bumed as i just purchased a stroker set-up from mike licht before Xmas.

Yea i guess everythings going to have to be checked on the new motor set up and checked again. I took alky out its for sale in the for sale section

 

[Grumpy]

I took alky out its for sale in the for sale section

why ??? it's the greatest thing for a street car to run some boost sorry alky didn't do this damage.

 

[TurboBuRick]

sorry alky didn't do this damage.

X2 on that.

unless it stoped spraying.

 

[TurboDave]

Aside from the seriously high severity of the wear, the lopsided pattern looks fairly typical for an off-center motor, doesn't it?

Yup, typical for an offcenter engine, and yes, shows signs of heavy detonation.

 

[turbobuick]

These pistons are NOT from my motor that pic's coming later. This piston is very similar to the one we are discussing.

This pic is a comparison of Diamond v.s. a Ross that was HEAVILY abused and detonated but did not fail (Notice the ring placement)

Detonation or not there is a design issue with that piston IMO.

 

[BEATAV8]

And it
doesn't matter whose piston it is the ring placement is incorrect for a turbo
application.

Should the top ring be positioned lower? Thanks in advance.. looking to learn from you!

 

[Grumpy]

interesting piston pics... I def see what your sayin.. Good thing we run only "TSM" boost (24#s)


ok ... back to the original post .. maybe keep the FAST and go see Otto for tuning ??!!! He has a dyno there and has messed with Buicks and Fast for a long time .. that is whenever ya get your motor back.....
NO WAY WOULD I THROW THE ALKY OUT .. BUT it's your car

 

[turbobuick]

ok ... back to the original post ..

Is the original post about why his piston failed or how he should have Otto tune his car

 

[Grumpy]

Is the original post about why his piston failed or how he should have Otto tune his car

piston failing !! AND detonation.. I just said Ottos name because he also has a dyno. Maybe would have seen something more. I don't have a Fast or want a Fast.. Know NOTHING about them either. I am a old CHIP man

 

[quickt]

Has anyone considered the engine was just run hard and the piston failed?

1) As Dan pointed out Ring land is too close to the piston top.
2) Picture shows the relief cut left next to no material in that area Supports Dans observation
3) Bearing looks like side loading typical off set rod more wear than normal.
4) The rods look like they were not clearanced on the small end could also add to side loading if touching the pin area of the piston.
5) the Skirt on the piston in question is killed IMO could also add to abnormal bearing wear
6) The other pistons in pic look fine.



Based on the info he has provided. I see no reason to replace engine management, Throw away the alky system, put 3 fuel pumps on the car, do scientific knock sensor research or Do the hokie pokey and turn yourself around.

We are not curing cancer here guys. Its racing. Fix the engine and get back to burning some rubber.

 

[Grumpy]

Has anyone considered the engine was just run hard and the piston failed?
We are not curing cancer here guys. Its racing. Fix the engine and get back to burning some rubber.

Lonnie ya hit it right there .. Life in the big city so to speak ! They are all goin to break sooner or later! BUT...ya always a BUT.. Melissa's motor has 15k on it with Diamonds in it. We took that motor from my Buick RX7.. Had stock headgaskets on it so we took the heads off to swap in the Cometics. I looked at the pistons and commented to Russ about the "thin spots on the edge". Scatched my head for a minute and said.. Lets throw it in the car an see what it does. Melissa, Russ and I beat the living hell out of it.. DRIVE IT LIKE YA STOLE IT !! Like ya said get out and have fun with it! Blows up tomorrow ??? so what ... look at the beating it took .. Oh ya.. If ours did blow we would have been running long before this thread will end !
....I still go back to detonation for doin the damage BUT Dan knows a lot more than me:biggrin: Also have to remember how much power to most of the Buick guys run ??? Maybe 400/550?? Dan has BIG POWERED cars out there !! Nothing small like most of us run

OH... DAMMIT LEAVE THE ALKY SYSTEM IN IT It's a street car .. No fun running around with 15#s of boost!!