HarrisSpeedWorks

The TR6 will go out a little faster then a plug from the stock heat range, like the TR55s, but it shouldn't happen overnight or anything.

Matt

Jim D

I noticed that the heat range for the stock LT1 is 5 but goes to a 9 with AFR heads...why does it jump that far? I have read elsewhere on this board people recommending the TR6...
Just trying to figure out the reasoning behind this so I can get a set of plugs for my new motor
Thanks for the well organized chart and the effort here!

quickmedic1

I have been using tr6 plugs and wanted to know if I should keep that plug with my new 383 and 10-12 psi?

Injuneer

Let's "sticky" this one....

HarrisSpeedWorks

The '9' is for the 210cc up heads, direct from AFR. The smaller heads do start out at a heat range of 5. Remember these are just starting guidelines...compression, power adders, etc are all going to have an effect on what plug to run.

Nick

HarrisSpeedWorks

Thanks.

matt65

Great Info!

Thanks for the work.

Jeremy95TA

So would the NGK TR6 be the correct plug for running a 75-125 shot, yet still maintain NA power and longevity?

HarrisSpeedWorks

It should. A colder plug might need to be replaced a little sooner then a factory heat range plug.

Matt

jsetzer

So what about stock lt1 heads and 12.0:1? And @ 400rwhp

I am running the tr6 right now, but that may not be cold enough even NA. What about when I start spraying a 200 shot?

SABLT194

I just bought a set of TR6's and a set of BR7EF's. The TR6's actually look to have a lot more exposed than my stock AC Delco 906's. It actually looks hotter than the stockers. The BR7EF's Look way colder than the TR6's and slightly colder than the 906's. I'm on LT1 Heads at 12:1. I'm gonna try the BR7EF's and open the gaps up to about .040 since I have LS1 coils and plenty of firepower. We'll see if cleans anything up.

Steve

staleyracing

Do I run the same 2 step cooler plugs on my L98 that are on the LT1?

flusz28

well i will be switching to autolite 104's now since my 103's tend to foul out and need cleaned since i rarely drive the car and when i do its just for short slow drives. this is a good post!!

Bandit 1

great info

JustNO

I just get Autolite 3923 for my 210cc AFRs and 11:1 Compression. I don't use nitrous, could that be a problem?? I think they are 3 steps colder.