I'm wondering about what horsepower difference would it make if I run 2 heat range lower plugs on an N/A car. (Right now I have Autolite 103 gapped 0.045") Would it be better to go to NGK TR6s? My car should be making about 400 RWHP N/A and I plan to spray a 100 shot sometimes. (not very often though)

Thanks.

 

There will be abslutley no difference in hp unless the plugs foul and it misfires, which it should not.

Rich Krause

 

I saw 2 tenths and 2 mph difference....same day test at track. Iam running high compression (11.2) so thts why the colder plug helped me. I stick with autolite 103's

 

Thats interesting. How did the plugs look when they came out? Thats a huge gain.

 

I agree. I have Autolite 103's and my car runs great on and off the bottle.

 

Me and 2 buddies were running nitrous a few years back. We all went to the track to get some track times before running the nitrous. We were all using the stock heat range without the nitrous on. Once we went back to run the juice, we switched to 2 heat range colder plugs. All the cars ran 2 tenths slower with the cold plugs and smaller gap. Once we kicked in the nitrous, we really didnt care though!

 

I made my test runs without nitrous. The plugs looked normal. But I am sure my high compression is what made my times better with the colder plugs

 

I could see a difference if the hotter plugs were causing KR but if you are not getting KR, the colder plugs "should" make the same power but take longer to foul in my opinion.

If you can not check for KR or if you are getting KR, that might eliminate it and help you out some.

Maybe some of the dyno tuners could shed some more light on this and answer the question better.

NighTTrain66