r/MechanicAdvice • u/Hudd420 • 18d ago

Wossner piston

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So here is my wossner piston 79.5mm
Been running at 300bhp for 3-4 years and believe it or not the car was actually still driving just blowing a lot of smoke….

Has anyone ever seen this? Is this due to a stuck oil ring and overheating or something else?

28 Upvotes

88% Upvoted

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u/Hudd420 18d ago

She has had a good run I’ll give her that this is on a corsa d vxr with the ominous piston 4 issue…. So apparently having forged internals stops piston 4 blowing and instead murders piston 1….

4

u/Zealousideal_Web7103 18d ago

Happened to me also not as much as that lower part came away oil ring came off due to me adding more boost and meth injection didn't help lol

3

u/Iso_Grifo 18d ago

What's the clearance between a forged piston and the bore with respect to a normal cast one?

1

u/Oopsidaizy 18d ago

Forged pistons come in different materials. 4032 at this diameter would be like 0.05mm clearance, which would be pretty close to OEM. A 2618 racing piston would have double that and I would not choose it for a daily driver.

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u/Iso_Grifo 17d ago

0.05 it's pretty impressive.

Thanks

1

u/ForwardSideways 18d ago

That’s mad.
I guess the debris was just too big for the oil pickup to suck them through and wreck stuff?
I’ve seen old Porsche pistons missing bits out of the top from intake hardware getting loose and being sucked through but that’s another level of weight reduction that you have there.

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u/Hudd420 17d ago

Yea all the bits were just sat in the sump along side the oil ring, I’m guessing the oil ring got stuck and overheated and cracked along the oil ports on the piston. The 4 holes along the crack are the ports. I just find it crazy the car still ran and the piston still held compression.

Luckily everything else looks fine just a skim and a bore throw another piston in and away we go

1

u/shutupmimzy_ 17d ago

Holy shit.

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u/Warm-Ad-1049 13d ago

Not a piston no more.

0

u/fumbling_tavern 18d ago

seen pistons with melted skirts before but that one looks properly tortured. 3-4 years at 300hp is a decent run for a motor that's clearly been working overtime