https://ls1tech.com/forums/showthread.php?t=575354

 

another great read related to the same discussion...

http://ngksparkplugs.com/techinfo/sp...000&country=US

 

anyone run the 4554's?

 

there are a lot of diferent sugestions coming from that first thread. i have tried a few diferent plugs and never have noticed much diference other than the colder you go the rougher the idle is.

seems like the general rule of thumb is a tr6 for any boost or nitrous up to as much as 10-15psi. then switch over to the next step colder wich in a ngk is a br7ef. i suppose at some point maybe 25psi step up to an even colder plug in the tr8 heat range.

 

tr8s are rockin and rollin so far...no wot pulls yet and it is idleing fine so far. I will pull one in the morning Al and see how it looks

 

As I understand it, in our FI applications, it is not so much that the 4554 is a colder plug than a TR6...it is the projection of the tip being less than that of a TR6 that is desirable...I will add pics of them side by side after lunch...

 

not very clear picture, but the difference is very clear...

 

no thoughts on the projected tip?

 

I've been using the new ZEX plug for FI and seems to be real good. Smooth idle and supposed to be designed to prevent kr.

 

I agree. A TR6 can work well up to 14psi on a Lightning and even higher boost. For safety sake I wouldn't want to go past 14psi though.
Regarding insulator projection...If you want to go inbetween the TR6 and br7ef a stock Lightning plug or TR7ix would do nicely.