Ive done many searches and couldnt find an answer to my problem. My car is a evoIX thats always run on race gas either 110oct or q16. my problem is that i have gone through about 6 sets of plugs since august and since then i have put on about 1000miles on the car. Im also running a sparktech ignition system. The plugs that i have been using on the car are ngk iridium (7 heat range). The car is making around 675 whp on q16, but lately whenever i switch from 110 and q16 the plugs keep fouling out, so when i do a pull in the car it starts breaking up bad around 6500 rpm. I change the plugs then its fine till they decide to foul out again. I was going to try the ngk two step colder plugs but i cant see spending 140.00 on plugs when they are just going to go bad right away. Has anyone else had an issue like this on an evo IX? do you think its maybe the q16, or switching back and fourth between the two different gases? any help would be greatly appreciated, $60.00 plugs start to get really expensive having to switch them out every 100-200 miles.
the 110 is also leaded.

 

oh great thanks

 

what is the length of the threads on the plugs?

 

first off, you have to run colder plugs at your power level. secondly, running high boost with a lot of hp and high octane fuel will wear your plugs faster than usual, that's the way it is.

Why don't you just give AMS, Buschur racing a call, they will know what's the best bet for you.

 

try br8es plugs, stock # 5422. they r another step colder

 

I'm pretty sure those are Evo 8 plugs. He has a Evo 9. Their thread length is longer. Evo 8 thread length is 19mm, Evo 9 is 26.5mm. This could be why he is going through so many plugs.

 

Good response, they are longer. I have been having the same issue.

If you tap rev limiter once, or anti-lag (which you could almost expect it to happen) immediately makes your car sound like a subaru wrx.

I am on my 4th set since august also. But, i am only running plugs and not a COP

 

thanks for some of your help, i think i might buy a set of the colder plugs and see what happens. i do drive around on 110 and the q16 every so often for a long period of time.