Ok i am trying to figure out where i should set my gap at on the plugs and what plugs to get? I was looking at the tr6 4177. My car is a stock motor with a s-trim 6-8 #s of boost non intercooled, 42# injectors long tube headers, ory pipe. What do you guys think? thanks

 

Gap at 35. I have run the TR6's with nitrous for the last few years with great results. I'm trying a new NGK for my boost setup. Ed Wright wants me to bring the car for tuning with Auto Lite 104's. Once he's tuned it, I'm going to swap plugs and re-dyno to see the results. Ed claims a lot of misfires with NGK's, so I'm not going to take a chance when I trailer the car to OK for a day of tuning.

 

A ran the TR6 for a few years; really didn't like that the end cap screws on (and off). I've been running Autolite 104's for the last 5 years with no issues. My car has 10# boost with an intercooler. Plugs gapped at 0.035" with a Crane multispark ignition system.

 

You may find .035" is too large for the stock ignition system and 8psi. I was down to like .022" before I Got a MSD 6a ignition.

 

I am running about twice as much boost (15#'s). My original gap was at .035, and was too big. (I found this out because while on the dyno the boost was blowing out the spark).

I had to tighten the gap down to .028, and then it ran like a champ (no spark blow out).

 

Just curious - what was your ignition? I run a .035 gap or larger and don't have any issues but have the Crane hi-6 and their best coil LX-92, I think. Like you I have about 15# when it gets going.

 

MSD Digital 6+ ignition box, MSD Blaster coil

It also might depend on what RPM you are running yours up to. Mine didn't have any issues until we passed the 6100 RPM mark on the dyno. But my setup goes to 7,000 RPM.

 

Sorry to thje OP to take this thread off topic...


I think the blaster coil is a little better than stock and I bet that is part of the limitation there. The one I use is quite a bit different - it's an E core coil which is hard to fire, but it makes a powerful spark that can jump a bigger gap. But, you are right, I don't go to 7000 normally, although I have and can. I just don't have a lot of cam and shift sooner than that - usually around 6400 or so.



Back on topic - OP - I think NGK 5 or 6 heat range would work fine for your application. With a stock ignition, you may have to try the smaller gaps, but if I were you, I would upgrade the ignition, then you can run a bigger gap again, especially if you are around 8# or so. One thing I like about NGK is that they have good heat ranges which are a little more forgiving than some other plugs and they have good quality porcelain - this is because their parent company manufactures ceramic insulators and chips, etc. Autolite is a favorite of engine guys because they just seem to work well in performance cars. I have used them in the past when I was having problems with other plugs and they seemed to solve my problems. The only thing is that there are some chinese plugs in the mix and you really don't want to get the ones made by Torch for Autolite. They are inferior and on close inspection side-by-side, you can tell the difference.