Melted Wossner Piston

[Daniel306]

This is the mark so they are fitted the correct way

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This is what it should look like


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The crown edge

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[silverzx]

Is this a random car you've found on the internet or...?

[cully]

Is this a random car you've found on the internet or...?

LMAO

[silverzx]

Is this a random car you've found on the internet or...?

LMAO

I fail to see what's so funny. Am I supposed to know what he drives!? The 205!?

[Ruan]

Looks like it's gotten hot for sure - what injection system is it running?

I'm talking ECU/Injectors/Fuel pump...

[Daniel306]

Its from my 205 turbo thats on here, looks like i now need new pistons. im just waiting for the company that built it to tell me if there was a reason they used 16v pistons in a 8v engine, i have no idea what happened to it and why its only one cylinder, the engine has only done 10k miles

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its emerald K3 ecu, 440cc Bosch injectors and the pump and regulator are not standard but i dont know what they are

[cully]

detonation?!

[Daniel306]

I dont know much about petrols but dose that mean i nees to install a knock sensor and a egt sensor plugged into the ecu for good measure?

[cully]

copy n paste from here http://www.contactmagazine.com/Issue54/E...asics.html

Detonation causes three types of failure:

1. Mechanical damage (broken ring lands)

2. Abrasion (pitting of the piston crown)

3. Overheating (scuffed piston skirts due to excess heat input or high coolant
temperatures)


Detonation is influenced by chamber design (shape, size, geometry, plug location), compression ratio, engine timing, mixture temperature, cylinder pressure and fuel octane rating. Too much spark advance ignites the burn too soon so that it increases the pressure too greatly and the end gas spontaneously combusts. Backing off the spark timing will stop the detonation

[Ruan]

Hadn't noticed they were 16v pistons...

That won't have helped at a guess...

The piston near the perimeter will typically have that kind of look if detonation occurs. It is a swiss-cheesy look on a microscopic basis. The detonation, the mechanical pounding, actually mechanically erodes or fatigues material out of the piston. You can typically expect to see that sanded look in the part of the chamber most distant from the spark plug

[Rippthrough]

Yeah, looks like slight det/pinking damage.
Could be the wrong timing, too lean, or poor chamber shape due to the wrong pistons perhaps, amongst others.

[Daniel306]

Turns out when this was built in 2007 there was no forged pistons for the 406 available, i can buy a set of pistons but they wont fit as the rods are different lengths so i need to buy a kit

Anyone want to buy a full set of Gti6 turbo forged pistons and rods?

[Niall]

Turns out when this was built in 2007 there was no forged pistons for the 406 available, i can buy a set of pistons but they wont fit as the rods are different lengths so i need to buy a kit

Anyone want to buy a full set of Gti6 turbo forged pistons and rods?

Price?

[Daniel306]

Offers? 3 are good and that one would be ok with a file and sandpaper? there 87mm so thats +1 oversized giving 2044cc i think

[Niall]

Offers? 3 are good and that one would be ok with a file and sandpaper? there 87mm so thats +1 oversized giving 2044cc i think

Tbh, if i was to make an offer, it would only be a silly one seeing as one piston isnt known good now. PM me with the figure you have in mind!

[Daniel306]

Il find out if i need to replace them with 8v pistons but the only difference is the cutouts, the 406 dose not have any. if i do end up buying more il let you know. should be within the new day or two

[Ruan]

Hmm, tbf, I really wouldn't expect it to be an issue with chamber design - they're both dished pistons and from looks, they aren't vastly enough different to cause issues IMO.

I'd expect since it's only light, that's possibly signs of a failing fuel pump or it briefly running lean - get an EGT gauge on there and make sure you have wideband o2 readings, that way you might pick up if it does it with new pistons, I don't think a change to 2.0 8vT pistons will save it detting again...

EDIT: Just realised - you're running a 1.9 head on the 2.0 8v bottom end - the bore on the 1.9 is 83mm, you've got an 87mm oversize 2.0 bottom end - that could be combined with the slightly odd 16v pistons to cause det... The combustion chamber in the head of the 1.9 is going to be a good bit different than the 2.0 head... Who built this engine out of interest?

[Daniel306]

I believe it is a 2.0 head. Just the inlet mainfold is from a 1.9. I was told when I bought it that it was all 1.9


It was built by pug1off. I cant see this being a fault with the map or such like, it could be the pump or injectors or something that has worn as it has done 10k miles since it was built in 2007. And its only in one cylinder

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I also have no idea how long it was driven with a blown head gasket,