OK.... I've got to get this off my chest...

7-8 months ago an NGK Tech Rep via telephone told me that the NGK TR-6 was actually the same heat range as the lightnings stock plugs... I recall very distinctly him saying this and even questioned him. Stating to him that many many lighting owners are writing in several different forums that the TR-6 is a heat range colder than the stock plugs... His response was that the tr-6 was infact the stock plug for the base 5.4 liter but that the lightning had a stock plug which was one step colder than non lightnings and that there for the tr-7 was actually one range colder than the stock lighting plug.....

Any body else heard of this....??

 

I've always been told that the Ngk Tr-5s were the same heat range as our stock plugs and the Tr-6s were on step colder! I use the Tr-6s and have had good luck with them!!! Jim

 

Yep what he said

 

If you go to NGK web site it says tr-6 are stock for the Lightning
Mike

 

I guess it's like our Government
Without any notice, and after years of saying one thing
WAM they just change their minds and say something else

 

Here ya go

 

i've checked on every cross refererence i could find and tr6's have always been the stock replacement plug. (this was done a year or more ago when i was going to install cooler plugs, on this site i found many an arguement about what tr6's are )

Some people " felt " since they were copper they were colder, atleast that's what i've heard.

Alot of engines have run well on tr6's but how many engines have blown up on tr6's?

I run tr7ix if it matters and yes they are 1 step cooler than a cross referenced ford (lightning) plug and 1 step cooler then a cross referenced tr6 plug.

 

They've always been saying that. The only reason people are confused is because JDM has been saying for a long time that tr6's are two steps colder than stock.

TR6=STOCK HEATRANGE

 

TR6=The only plug most people will ever need.

 

I plan on cleaning out my intercooler in the next few weeks so I figured that would be a good time to change my plugs. My truck is stock except for a JLP air intake, but I plan to add a 4# pulley. Should I go ahead and switch to a plug that is 1 heat range colder? And can I go ahead and make the switch before I actually put on the new pulley?

 

yup. I would only go colder when using lots of spray.

 

So what if yer runnin TR55's on a stock L? I gapped mine to .37 per the chart. Runs really well.....no problems.

 

TR-55 is the stock replacement plug for a standard F-150. V-6 Explorer's use that plug also.

A TR-5 would be one range colder and a TR-6 would be 2 ranges colder vs. a n/a F-150.

The best way to tell if your plugs are the correct heat range would be to pull them right after a pass. If they are orange/brownish they are too hot and you need to step down a heat range. Don't forget to play with the gap either.

As far as NGK's website & reference chart is concerned just look up a '03 Cobra and then a '04 Cobra. They list a tr-55 for the '03 and a tr-6 for the '04. Same car and same engine. I think their data base might need some tuning up.