Spark Plugs for 800+rwhp Supras

**Kirk** · 11-09-2007, 10:31 AM

The plugs to use if you make 800-1200 rwhp are:

Track/Drag: NGK # 6239 / R5671A-10
Daily Driving: NGK # 3030

Plug gapping should be used as follows:

DLI/DIS-4 or Tec3R highly recommended/required if you go big boost:

(** C16 and/or Methanol - use the lower number)

up to 25psi: .26 - .28
25.1-30psi: .24 - .26
30.1-35psi: .22 - .24
35.1-43.5psi: .18 - .22

I've tested this with 3330's as well, and those work ok, but the main difference it that the 3330's are better for daily driving and the 6239's are better for track/drag/big hp primarily due to the design. 3330's and most other plugs have the electrode and the white ceramic higher than the end of the plug - this I'm told is good for low/medium rpms, but doesn't burn as well at higher psi and higher temps. These 6239's have just the electrode protruding from the "top" of the plug (i.e. you look at the plug from the side, you'll see only the electrode not the white ceramic sleeve)

I've tested different plug gaps on the dyno now for several days, and this setup seems to work the best - I'm running 36-43psi, and I have problems if my plugs are gapped less than .22 (i.e. I don't burn all the fuel).