spark plug question again......


Staff member
On the GNTTYPE website it says..Cars running 12.99-13.50 seconds or faster should use R43TS or CR43TS plugs (one heat range colder) and 12.00 and faster cars should use AC R42TS or CR42TS....

But if i'm in between the two I assume I use the 42's? Whats so different between the 42's and the 43's?
Just bringin' this back to the top, as I had the same question, and did a search for an answer. I was gonna "freshen up" the car this spring, and new Spark Plugs were on the agenda. I have a Chiltons manual, so finding the stock replacement would be no problem, but my question was the same as TurboV6's.
My car will probably (almost definitely) be getting new injectors and an alky kit, hopefully putting her in the low 12s (if I can remember how to launch right) What spark plug (Model and Brand) would you guys suggest for this? Thanks a lot!! :cool:
The 42s are one heat range colder and may work better if you are running higher boost. In normal driving, the 43s might last longer but in practice I never left a set in long enuf to find out.

I run Autolite 23s which are equivalent the AC43s because I run over 22# of boost all the time with alky.

I don't believe that you will go wrong with either the 42s or 43s so you use whatever you find. If you are running in the 11s every week, I would go to the 42s.
I have tried them all. IMO, the Autolite 23's offer the best performance.
Awesome, thanks a lot for the quick responses. Looks like I'll be makin' a trip to the local parts DEPOT tomorrow (in the GN, if this damn SNOW holds off). I'll go with the 43s, my car doesn't live at the dragstrip for sure. :cool: