In the day, we used to read the plugs and go from there. Detonation, burned plugs, too hot; dark, fowled, too cold. Always looking for good color optimized for a particular driving style. Or just clone a good setup. :-)

 

Been there, done that

 

What more can you do? Sounds like you are good to go.

 

If I were the OP, that would be great.

 

The good news for the OP is that replacing with OEM G37 plugs is the same as replacing with GT-R plugs. Bottom line is that with more HP you do need to be a range cooler... that is correct, but that is not the GT-R plug as many posters have mistakenly suggested. Funny that we haven't heard from any of these guys... ROTFL

 

I'll pull my plugs at 10k boosted miles and see what they look like. I should be roughly 1/3 of the way there.

 

Denso FXE24HR11 is not the OEM GT-R plug (NGK DILKAR8A8) while they may be listed as comparable heat ranges, the tip/electrode and pre-gap is different (.045 vs .031). The Denso FXE24HR11 is actually more comparable to the NGK DILKAR7B11.

FWIW my tuner has ran the FXE24HR11 up to 500 ish whp before seeing them crack.

 

So unless you're pushing 100+hp over stock there's no real benefit in not sticking with oem sparks?

 

Good info here, and thanks to everyone's input so far!

Looking at the different part numbers posted, in addition to the gap differences, there is also a difference in "Reach". Obviously, if some of you have been running GTR plugs, then they work, but it's a difference of 7.5mm for the GTR plugs. See these links:

Stock G37 plug:
https://www.ngk.com/product.aspx?zpid=41479

"GTR Plug" (NGK DILKAR8A8)
https://www.ngk.com/product.aspx?zpid=9718

"GTR Plug" - one step colder (NGK DILKAR7B11)
https://www.ngk.com/product.aspx?zpid=9717

^ Click on the "Specs" tab.

Can anyone tell me what effect a 7.5mm deeper 'Reach' would have? The site explains that 'Reach' is measured by thread depth, so the plug tip would effectively be 7.5mm deeper in the head, while the gap is slightly smaller.

My interest is that I have a supercharger on my car, and I originally tuned the car on 93 octane, but I just moved to a state where they only have 91 octane at the pumps. I'm amazed at how much I need to pull timing in the tune, so I'm trying to cool down the spark to bring back some of the timing.

 

I keep hearing that Silver would be a lot better, but they don't last as long. I have never felt a positive change aside from factory plugs.

 

If I install the DILKAR8A8 plugs do I need to change the gap or keep it at .031?