I'd like to know this as well. Would running 91 instead of 93 affect your answers?

I'm about to buy plugs for my 408/12-15psi/10.4:1CR engine. I was planning on TR-6's again as that is what I run on both my boosted engines. This will be the first over 10psi though...

 

I have ran TR6's for 4 years, around 30k miles with no problems. they are my second set, only because i over due maintenance on my rig.

 

i had mine on 15 psi with tr6's and no problems either . but timing was low , way low like 8* at the end of the pass.

i have the br7ef going in this week . may go to an 8 but i think i will be fine these at 15 psi for the next while . going to 20+ ill go with the 8's.

 

Well I tried the 9's out and I think they are too cold too run on the street. Started out smooth but the more I drove, the rougher the truck was running and I was feeling misses just cruising. Pulled them out after about an hour of use- mostly highway cruising- they were pretty fouled. Put together a fresh set of wires with rubber boots because I noticed that some of the silicone plug boots were not too healthy, swapped in a fresh set of 9's, and it ran better again- for about another hour of use.

 

Thought I would add this link to another thread on 'Tech that has a good plug reference list: https://ls1tech.com/forums/nitrous-o...reference.html

 

If you are sure that 9 is the heat range you need for boost, try a projected tip in a 9. The center insulator sticks out like the TR6 in the pic above. It is still a 9 heat range, but because the tip sticks out, combustion is supposed to help burn carbon off the center insulator. I don't know the numbers for our plugs, but for the most common motorcycle plug, you just add a p, for projected tip, into the number. A B7ES becomes a BP7ES.

 

I have had a few recommendations to avoid projected tips in my application. I'm sure cooler plugs will be cleaner after a run down the track.

 

Sorry. I think that I can speed-read, but obviously the speed comes from only looking at half of the words.

What is the reasoning behind the anti-projected tip recommendations?

 

That the long ground strap is more likely to heat up and become a source of pre-ignition and/or just burn up.

 

I am only running 11psi and running tr6 gapped at 32 and blowing out the spark at WOT. any recommendations?