spark plug suggestions...
NGK TR55 for 50k miles, TR55-IX (iridium) for 100k miles
for your naturally aspirated engine I would run the above (your choice) and gap them at 0.055 I believe
with forced induction if you are boosted, you usually start off with a NGK TR6 plug, again it is your choice to go with a standard TR6 (lower mileage durability) or a NGK TR6-IX (iridium) (higher mileage durability)
call NGK if you are interested.
FYI, the cadillac CTS-V uses NGK TR7 plugs (sure they are branded AC Delco...but AC Delco doesn't make the plug.)
the way it goes is
TR55 - standard heat range
TR6 - one stage colder plug
TR7 - two stages colder plug
also, ngk has a nice FAQ - info page on their website
I'm using the TR-7IX and have yet to have any problems with my spark plugs. running ~11.0 AFR 9.8:1 compression 18 degrees timing, LS6 heads
Last edited by ZL1Killa; Jan 1, 2012 at 08:35 PM.


