In reference to a few suggestions made to me earlier regarding my "missing" HP/TQ with my configuration, a few members suggested that my plugs were too cold (NGK TR8IX) and may be fouling out. As far as I can tell, my vehicle is running fine, no stumbling, etc. I understand the concept - I've been racing dirt bikes since I was 8, and 2 cycle motors will easily foul a plug if the mixture's off or they're too cold, however oil is involved, and in that situation, the plug's insulator must get to a heat range as to vaporize oil or reject oil sludging. With our motors, oil's obviously not a problem, (unless you have mechanical issues) unless the mixture is very, very rich.

I'm running these plugs as a safeguard to detonation. I don't think they're fouling, because I haven't seen any ill behavior or rough running. Is there a need for the insulators in our 4 cycle engine operation to be at a certain tempature range to assist in the combustion process?

 

Too cold will result in inneficient combustion, higher emissions, lower mileage and suboptimal power in addition to possible carbon build up.

Really is the same as a 2 cylcle engine but not as obvious because there is no oil in the mixture.

TB

 

When going to one step colder plugs I would see a drop of 1- 1.5 mph at the track.

With that being said, as the boost goes up you have to eventually step down in heat range. The trick is to run the hottest plug you can get away with. I was able to run TR5's with a 4# and a 5# pulley. I felt that I was pushing it with the 5#er so I switched to TR6 plugs.

I experimented quite a bit with different plugs and heat ranges. That drop off in mph seem to be consistant.

The one thing I found with NGK plugs is the Iridiums burn a little colder than their copper equivalent. It wasn't just the color of the plugs either as the mph confirmed this too. In other words the TR5IX burned closer to the copper TR6 and ran very close to the same mph (slower than the TR5). The TR6IX is the same way on the color compared to the TR6. I would say the TR6IX burns closer to the BR7 even though I have never ran the BR7. I have seen past pics of the BR7 and the burn looks very close.

P.S. I run a WBC so the A/F was right at cruise and WOT (no quess work).

TR6IX pics running 5# lower, 2.8 upper and ported blower:

 

So, the TR8IX's are about 4 ranges colder than stock, (or TR5), eh?

I'm running the MP with the stock 2.7 MP upper and 9.75 (6#) lower. I would like to run a elevated timing curve on 93 octane - will the TR6 fill the bill? If not, what plug, at what suggested gap for this application?

 

I run the TR6ix with a KB at 18psi, and 16 degreees of timing, no issues, .035".

 

https://www.f150online.com/galleries...003-115389.jpg

(pre-ported eaton)

 

Chart doesn't go above 17lbs

 

That chart is so far on the conservative side it's not funny. It also assumes the NGK iridiums burn just like their copper equivaliant.

MOP,

I would put in some TR6IX plugs gapped at .032" (because of high boost) and see how it runs.

I gap mine at .034" running a KB @ 15.5 - 16#'s in the heat. This is on a stock motor.

 

Or BR7's... right?

 

I ran (and still have) the TR8IX's in my truck for a year now. Never any fouling, rough idle or missing. I am changing plugs this week because last Friday my truck dropped 1.5 MPH in the quarter mile while my friends' trucks out there remained the same. We all had the exact same amount of cool-off time, so I believe it's something specific to my truck.

I am replacing the TR8IX's with TR6IX's for no real reason other than I did not get the desired result of reduced detonation tendency that everybody swears you get by going to a colder plug. By the same token, you will get plenty of people that will claim that you will load up, foul, miss at idle, get worse gas mileage, dilute your oil, and God know what else. I am here to say that all of that is bunk.

I would probably go back to TR8IX's if I go with an aftermarket blower with higher boost levels. I do believe that a non-iridium design in the "8" heat range might be more prone to fouling than the thin tipped iridium plugs. I like the iridiums because they are supposed to be easier for the coil packs to jump the spark under increased boost pressure compared to conventional design.

Good luck.

 

I would say the TR6IX is very close to the BR7 but you don't have to put up with the idling roughness because of it being a cold plug.

 

BR7's here and no idle issues. They're gapped at .034 and I'm running a ported eaton/4lb lower.

Steve