My VR6 track car had a new head gasket as it mixed oil and water on number1 cylinder. The head was skimmed checked an fitted with new gasket.
We then done brands hatch track day and I noticed a pinking that was quite loud and only at full throttle. Bring off 1/4 throttle and it was quiet.
At the end of the day I was black flagged for blue smoke.
Came in and noticed a missfire.

Compression test showed 150-160 through all cylinders apart from number 1 which was 50
Took the head off and found this???




You can see the mark on number 1

 

Anyone any ideas on cause?

 

Sign of early detonation?
Sure others will have a better guess.

 

What causes that on one cylinder? If pre ignition would all 6 have signs?

 

not really no, there is a few things that can cause it and can happen on only 1 cylinder.

Its the first think i could think of especially if you hearing pinking.

 

There looks to be a small chp out of the piston where the damage is? Maybe a crack causing oil to be combust?
Need to get the engine out now and have a look.
I am looking for another engine and I can rebuild this one.

 

Would a weaker flow on an injector not potentially cause pot no.1 to run lean, and make it more likely to det??

Tom

 

That was definately a thought I had??

 

Its certainly worth a look, not sure if its just the pic but it looks like its ran hot on on cylinder 1 & 6 due to the discoloration on the pistons.

Dont think its much to get the injectors flow tested plus you have piece of mind when you know there all ok or at least you know what to replace.

 

Iv taken the injectors and rail off and the injector nozzle and seal are wet with fuel on number 1. Like fuel has been blowing back out rather than down the inlet??