What caused this piston damage?

nycstev said:
I agree . Fatigue failure. This guy is telling me its detonation and I don't buy that explanation. If you had that much detonation in all 8 cylinders you would be noticibly down on power. This Chally had only 700 miles on it! Obviously it didn't have time to reach fatigue failure in a conventional sense . I think it was WAY WAY over boosted so it just blew up.
This is the same person who is telling me my pistons failed from detonation.
I find it hard to buy. My AFRS were right on and the engine ran smooth as glass and pulled very strong with no signs of detonation.
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The factory engines are steup to last many miles (tight clearences) a race engine needs much more clearence on most all of the components due to the heat, block/crank flex ect. Pistons/ rings need more, cranks need more also as do the side clearence of the rods. Full floating wrist pins are a must also.

There has to be enough clearance for things to expand and move around without binding or siezing. Example :in a Harley the piston clearance is/ was .001 , in the hot rod engines Yettie uses Venolia Forged pistons at .006
S&S uses (made by) TRW( or how ever they are now) pistons at .002 for the street. Parts must be adjusted for the application .........period.
 
Marc T said:
You guys sure know how to ruin a persons day!!:mad: :eek:
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Marc, My truck has had a supercharger longer than anyone..... Maybe not with respect to mileage, but in years.....

My opinion is that the level of boost and heat are the two culprits....

To the best of my knowledge Django2 hasn't become a member of the "Kablooey Club" yet.....

As Mike Brady once so sagely advised me, "Keep it at or under 600hp and you should be fine"...... I was at 595rwhp.........

D
 
Wifey said:
The factory engines are steup to last many miles (tight clearences) a race engine needs much more clearence on most all of the components due to the heat, block/crank flex ect. Pistons/ rings need more, cranks need more also as do the side clearence of the rods. Full floating wrist pins are a must also.

There has to be enough clearance for things to expand and move around without binding or siezing. Example :in a Harley the piston clearance is/ was .001 , in the hot rod engines Yettie uses Venolia Forged pistons at .006
S&S uses (made by) TRW( or how ever they are now) pistons at .002 for the street. Parts must be adjusted for the application .........period.
Click to expand...

Hmm.. this seems to be in total contradiction with the Lorentz Contraction as I once knew it.:confused:
 
rottenronnie said:
I'll offer one explanation:

I can no longer hear an engine ping.
Does the guy operating the dyno play in a rock band? ;)

Audible ping starts at approx. 1750 degrees F. After that point, detonation can set in if the condition(s) causing it aren't corrected.

Good A/F doesn't guarantee an engine won't ping; but leaning toward rich is a safety measure however.
It is just that lean mixtures burn hotter and end up being closer to the 1750 degrees above. When cylinder pressures build due to f.i., the engine getting
"up on the cam", gear selection or what have you, the A/F AND TIMING better be close to optimum because a rise in pressure is also a rise in temperature. Throw in a few variables like fuel that is too low in octane, too high a static compression ratio, incorrect timing, INCORRECT TIMING COINCIDING WITH THE BOOST BEING APPLIED, vehicle weight, etc; problems can surface. Heat PLUS the shock produced by an erratic flame front can quite easily shatter a cast piston ring land and compress a forged one, killing any ring movement. The shock caused by detonation can also hammer rod bearings and even loosen bolts on harmonic balancers and flywheels.
Click to expand...

Ditto.
 
Django said:
Marc, My truck has had a supercharger longer than anyone..... Maybe not with respect to mileage, but in years.....

My opinion is that the level of boost and heat are the two culprits....

To the best of my knowledge Django2 hasn't become a member of the "Kablooey Club" yet.....

As Mike Brady once so sagely advised me, "Keep it at or under 600hp and you should be fine"...... I was at 595rwhp.........

D
Click to expand...
Just saw her put down 628 and running real rich. It really needs a tune.
 
Django said:
Marc, My truck has had a supercharger longer than anyone..... Maybe not with respect to mileage, but in years.....

My opinion is that the level of boost and heat are the two culprits....

To the best of my knowledge Django2 hasn't become a member of the "Kablooey Club" yet.....

D
Click to expand...

Tim, Even the addition of billet main caps ( seems to be popular in these parts) won't really help when a lot of boost is applied ( they are only as strong as the treads in the block:eek:I believe what is needed on the bottom end is a full (one piece) girdle ,with incorperated main caps to help stop the block flex that seems to be apperent in this mile long block ( it would cost about 5-7 grand to make one though:D
 
Django said:
Marc, My truck has had a supercharger longer than anyone..... Maybe not with respect to mileage, but in years.....

My opinion is that the level of boost and heat are the two culprits....

To the best of my knowledge Django2 hasn't become a member of the "Kablooey Club" yet.....

As Mike Brady once so sagely advised me, "Keep it at or under 600hp and you should be fine"...... I was at 595rwhp.........

D
Click to expand...


I am only putting down about 565 so I will sleep a little better!!

Thanks for the lift!!:D ;)
 
Detonation is the cause of that failure from the picture.............

You can detonate a motor with a rich mixture......

Too much ignition timing is the likely cause of this failure.

Some folks can hear detonation and some can't.

At increased cyl pressures such as under boost, this type of failure can happen in 1 or 3 milliseconds.

Sorry about your friends motor.
 
Jack is right. The A/F ratio does not mean shit.

To much boost, or to much timing and you will have detonation regardless of how much fuel you are dumping in it.

For some reason I cannot see the pictures, but listen to the old man. I sure as hell wouldn't bet against him.
 
there wasnt any detonation, look at the piston you can not run boost with rings that close to the top of the piston, the upper ring expanded and broke the crown off. cylinder temps, and pressures took that piston out
 
Wifey said:
Tim, Even the addition of billet main caps ( seems to be popular in these parts) won't really help when a lot of boost is applied ( they are only as strong as the treads in the block:eek:I believe what is needed on the bottom end is a full (one piece) girdle ,with incorperated main caps to help stop the block flex that seems to be apperent in this mile long block ( it would cost about 5-7 grand to make one though:D
Click to expand...

Jerry,

If you don't stop posting as Wifey .... It's startin' to creep me out....

D
 
Django said:
Jerry,

If you don't stop posting as Wifey .... It's startin' to creep me out....

D
Click to expand...
It creeps me out, too :eek:

Some of the tech stuff I do know, but some of it I don't. :D

Maybe he will start wearing a dress next - POSER ;) ;) ;)
 
Overheated piston / detonation IMHO...cylinder temps too hot, even with an overly rich mixture can still cause detonation.

Junk Piston doesnt help either :D
 
curious

I had a snowmobile do the same thing . the ring broke off and bounced around in there. beat the crap out of the head and top of the piston. looked exactly like that. I am curious as to why the top ring broke off up when all the pressures are down. cylinder pressure is down on top the the piston pushing it down in the bore. not up from underneath. Ring must have seized to the cylinder wall ,:dontknow: :confused: near the top of the stroke?
 
Plus most dyno operators use ear phones cause it's soooo loud in the dyno room and if he wasn't wearing ear protection it would be almost impossible to hear it running the car through the gears from the driver's seat
 
Fine tuning often comes from the passenger seat, on the road. Sean was riding back from hours of tuning my truck on Saturday...and in a burst in third gear he heard a ping in an rpm range that I never would have heard...and adjusted my hot rod program card on the spot, by adding a little more water/meth in that rpm range.

Nothing like having a guru ride and listen...
 
Prof said:
Fine tuning often comes from the passenger seat, on the road. Sean was riding back from hours of tuning my truck on Saturday...and in a burst in third gear he heard a ping in an rpm range that I never would have heard...and adjusted my hot rod program card on the spot, by adding a little more water/meth in that rpm range.

Nothing like having a guru ride and listen...
Click to expand...


That may be a solution to my problem but not an answer to my question. What does the average person do
who does not have Sean next to them to tune their truck? Are these "canned " tunes really safe? I mean if you can have engine detonation and not know WTF is going on it even with perfect AFR's then what good is this meth enjection.?

This meth system was supposed to have taken the place of an intercooler but falls short IMO . What I learning of late is the Roe intake system does not flow evenly causing subsequent localized lean out conditions that do not show up on " perfect or OK AFR's" and the meth system does nothing to correct this. The lack of underhood geometry is the real reason that there is no intercooler yet for these trucks AND this is what really is needed.
 
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Sean is working on the intercooler. It should hopefully be available by the end of the year.
 
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