would like to go hotter ...The plugs I have now are, TR6NGK...After two years, they are turning black...My LS1 is making 493 HP...So i want to go to a better or hotter plug..?John.

 

You need to tell us about your setup.

Also, who tuned your setup? What do they recommend?

 

Typically a TR6 is used on boosted applications and not needed on a N/A engine
The TR55 or TR5 is a better choice
There may be other reasons for the black plugs--usually means a over rich condition---
Without knowing your combination it can be many things that are the cause
1 too little timing
2 fuel trims way off during P/T
3 injector flow rate not properly scaled (if you installed larger ones)
4 dirty air filer OR fouled MAF sensor
5 incorrect fuel pressure
6 LT headers----( LT headers require special tuning as they always make your engine run RICH)
Lowering the 02 switching points helps--try to get your front 02 averages to be around .400 to .500 millivolts The larger the average reading the richer the P/T fueling becomes-- the re location of the front 02's as much as 3' back makes them not read correctly and gives your ECM false readings--That is why they are illegal in most states--

 

Here are the NGK plugs from hottest to coolest (more hp you would want to run cooler)

TR5 – 2238 (.040)
TR55 – 3951(not colder just larger gap - .050)
TR6 – 4177 (.040)
BR7EF – 3346 (.030 gap)
RS5724-8 – 7317 (.030 gap)
RS5724-9 – 7891 (.030 gap)
RS5724-10 – 7993 (.030 gap)

From stock LS1 to LS3 the NGK website shows the TR55 as a standard replacement

The LS7 and LS9 they have the TR6 listed - so you already have a plug they feel is correct for 505 - 640 hp

As stated above tuning issues may have more to do with your spark plug color than plug selection

 

493, HP, 639 LIFT CAM..what gap on my TR6 plugs...? thanks John.

 

.040 gap

 

You guys are all way to concerned about plug gaps-- Gm originally suggested a .060 gap on their stock LS engines then later they changed it to a .040
Plug gaps are not that important---however with a .040 there is less of a chance with old wires for the spark to not fire and go to ground instead
From a racing background with over 25 years of racing experience the most important choice is not the gap but the "heat range" There is no HP advantage by going to a colder/hotter plug unless when reading your plugs they show abnormalities--
The smaller gaps now recc by GM are strictly to avoid misfires from poor wires--or poor ignition voltage------
Old school reading of plugs still applies even in today's computer controller cars
Ideally with new plugs-----you would want the color change on the strap to be exactly on the bend---Closer to the threads would mean you have too much timing--closer to the tip means you need more timing As far as AFR goes on new plugs you want the color to be about 1/8 to 1/4 " above the bottom of the center porcelain
An in correct heat range would be indicated by both of these factors not being even close------A car driven on the street mostly at P/T needs a hotter plug to clean them out----A racing plug or a colder plug is only needed with a boosted engine or a highly modded N/A engine that rarely sees RPM's below 3500---