[Flick]

I've been running 300zx pistons for about 25k now. The plugs were brand new after the rebuild and were stock nkg's. I was taking my engine apart for a head swap and the #3 spark plug was missing part of the insulation and part of the spark arm. Well when i finally got the head off, the cylinder was scored pretty badly. First off is the damage done repairable? The grooves arent that deep but i don't have a bore scope to check it. Secondly what would have caused this? The copper on the spark plug looked like it had suffered from electrolisis. I had the timing set between 15 and 17 with a jwt ecu program. Thanks,
Jason

 

[nizzan4u2nv]

Never any signs of detonation?

 

[Flick]

Never any signs of detonation?

I never heard anything out of the ordinary

 

[SR20DEe]

what heat range plugs were used initially.. ?

 

[eric96ser]

Sounds like detonation to me. Did you have the JWT program for the 11:1 pistons? What grade of gas were you using?

 

[cnynracer1]

11:1 is high compression. A bad tank of gas on a really hot day can cause some nasty things to happen.

 

[Flick]

Sounds like detonation to me. Did you have the JWT program for the 11:1 pistons? What grade of gas were you using?

Yes I have the ecu program, and i run 93 octane constantly. Btw it has been in the 50's and 60's when I think it broke. The only thing i can think of is that the timing was over advanced for the ecu. I had it set between 15 and 17 degrees. Wouldn't the engine make some kind of noise if it was detonating? No check engine lights or anything.

 

[Flick]

Sorry to post twice but I got a new block to have the bore job done again and rebuild it over. It was out of a 91 G20. I brought it to the same shop that machined my NX block and they said it couldn't be done because of some kind of nickel.... coating on the cylinder walls and soft aluminum under it. Now why on earth would Nissan use two different materials on their blocks for the same year? Has anyone else ran into this?