2 JZGTE Valve cut

Hi,

I have 2 JZGTE with STD valve head. during the drag race one valve is cut and damage the valve guide.

Boost of the car is 35 psi with pure NOS jet 62-68.

What can cut the Valve and damage valve guide?

Car is Nissan Fairlady Z 280:

Big Turbo Garrett GT45

Ice cooler

C16 Gasoline

Injector 1600 cc

Titan 280 duration 10.5 left.

car HP 950 without Nitrus

JE 86.5 mm : compression 9.5:1

G'day Abdulmohsen. Can you post up a picture of the damage? When you say one valve is 'cut', is the damage to the head of the valve, where it seals against the seat, or to the shaft where it runs inside the valve guide?

@Zac.Perston Thank your reply. Please find the photo of Engine head and block.

Ouch, that looks pretty nasty.

You've certainly had a lot of heat in there, which the melted valve seat in that cylinder shows. How long did the driver keep their foot in it after the trouble started? I wonder if there was a fuel supply problem with that cylinder, it leaned out and combustion temps skyrocketed, melting things. Was the nitrous being used at the time?

It also looks like there was some foreign material go through that cylinder, but whether that was the original cause of the damage, or happened afterwards its hard to tell after the fact.

Are there any datalogs from the EFI system at the time of failure available?

Has the head had much development time / money put into it, as far as port work goes? There are craftsmen out there that could probably repair that for you, they work wonders!