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Old 12-07-2018, 02:01 PM   #51
dl242gt
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Doesn't detonation create burnt snickerdoodles? Give that monster a cookie!
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Old 12-07-2018, 02:59 PM   #52
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There's an obvious solution here. See if the marks on the head line up with the marks on the piston. If so, FOD! If not, det!
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Old 12-07-2018, 03:03 PM   #53
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My detonated pistons looked pitted and grainy, but maybe forged pistons damage differently?
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Old 12-07-2018, 03:28 PM   #54
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Quote:
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My detonated pistons looked pitted and grainy, but maybe forged pistons damage differently?
Same. The pictures I posted are all forged pistons. One CP, the others JE.
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Old 12-07-2018, 08:37 PM   #55
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I know nothing about this but curious as to whether or not that spark plug hole had a helicoil repair to it.
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Old 12-07-2018, 08:52 PM   #56
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Has not been helicoiled. Going to check spark gap tomorrow (working late tonight). Think these we're ngk 6s?
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Old 12-07-2018, 09:13 PM   #57
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Has not been helicoiled. Going to check spark gap tomorrow (working late tonight). Think these we're ngk 6s?
Any of the ceramic insulator missing?
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Old 12-07-2018, 09:24 PM   #58
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Originally Posted by LeedomtoFreedom View Post
Has not been helicoiled. Going to check spark gap tomorrow (working late tonight). Think these we're ngk 6s?
Isnít that kind of warm to be running elevated boost and an hx35? I was always under the impression that at least 1 step colder was probably safe.
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Old 12-07-2018, 10:12 PM   #59
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There will be aluminum transferred to the plug as well
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Old 12-07-2018, 10:25 PM   #60
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I'll post some pics of the plug tomorrow.

I noticed some of the gouging had buildup on the end. Kind of like a plow with snow. Whether it was bits of aluminum from det or FOD it looks kind of like an object got knocked around (no pun intended)
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Old 12-07-2018, 11:06 PM   #61
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Sniff... Sniff... Snifffff... I think this thread still smells of PNW Troll, but maybe I'm mistaken.

The piston that goes with this cylinder head


is


And those solid chunks in it are a needle bearing. See this link.

The piston that goes with this cylinder head


is


And you'll notice the missing piece of top ring. See this link.

(Gee, aren't 2-strokes grand? Any debris in the crankcase can make it into the combustion chamber via the intake/exhaust/transfer ports.)

For factory references on piston damage, I found some good links (if you have lots of spare time):
Kolbenschmidt Pistons (painfully long) - link
Mahle Components (eDoc only) - link
Echo Shindaiwa 2-strokes - link
Or a shorter doc from a bike shop - link

For the OP, I'm curious what boost you're running, how many miles on the engine, and if you know the piston protrusion&head gasket thickness. Your comment of
Quote:
Originally Posted by LeedomtoFreedom View Post
I also remember when this engine was in my other car, it once or twice 'kicked back' when under boost. Pretty aggressive kick, kinda like if you were to sidestep the gas then get back on it.
makes me wonder if piston rock was allowing the piston to hit the head, but only on one side. Maybe the experts here know which side will hit first if there is excessive rock? (And this could explain why damage is nearest spark plug, instead of classic detonation starting furthest from the plug.)

There's also the chicken&egg question of did knock cause broken chunks that gouged the piston, or did debris cause damage which could then cause follow-on detonation?

Last edited by bobxyz; 12-07-2018 at 11:50 PM.. Reason: fixed bad link
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Old 12-08-2018, 02:27 AM   #62
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Quote:
For the OP, I'm curious what boost you're running, how many miles on the engine, and if you know the piston protrusion&head gasket thickness.
so for the entire time I've had the turbo I've kept it at stock (wastegate) boost (22lbs). The engine has 120-130kish miles using the original head gasket. I was going to check for any weird stuff loose upstream (turbo fins) and the throttle butterfly. I remember someone started a thread a while back titled like (Engine blew up, I don't know why) and it turned out to be one of the screws for the butterfly backing out.

I've also put the head back on with a new headgasket so I can't get any more pictures other than the ones I've posted. I didn't expect this much feedback but it's all pretty interesting. Regardless of what it was, it's not right and the pistons and head are going to be junk after I get the 16v in.

Last edited by LeedomtoFreedom; 12-08-2018 at 09:25 AM..
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Old 12-08-2018, 03:38 AM   #63
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22lbs stock boost.
ok
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Old 12-08-2018, 09:33 AM   #64
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I meant off the wastegate. It was nearly 3am cut me some slack. It's been adjusted (sold to me by a Dodge guy) from the original 12lbs or whatever they're at out the box
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Old 12-08-2018, 10:57 AM   #65
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Quote:
Originally Posted by LeedomtoFreedom View Post
I meant off the wastegate. It was nearly 3am cut me some slack. It's been adjusted (sold to me by a Dodge guy) from the original 12lbs or whatever they're at out the box
WAT
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Old 12-08-2018, 12:37 PM   #66
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Quote:
Originally Posted by apachechef View Post
WAT
Havenít had your coffee yet this morning??
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Old 12-08-2018, 05:33 PM   #67
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Quote:
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Haven’t had your coffee yet this morning??
I had some Christmas coffee. Really woke me up

Starting work on the car today. Please hold for plug information. Have to do the ujoints on driveshaft and get the car going again.
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Old 12-08-2018, 06:48 PM   #68
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So the lite blistering in the center of the piston that gets heavier towards the crown is nothing?
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Old 12-08-2018, 07:48 PM   #69
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[IMG][/IMG]

[IMG][/IMG]

[IMG][/IMG]

here you go. Measured .7-.75mm They are brp6s which are probably a step too hot than most would use.
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Old 12-08-2018, 08:42 PM   #70
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Plugs perfectly fine to me.
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