RB26DETT , RB26 Spark Plugs, VR38DETT Spark Plug

 Lots of guys like to run the cheap copper plugs. I never had much luck with them. Electricity takes the path of least resistance.  You can see one owners fix for leaking spark, that was causing misfires on his Nissan Skyline GT-R. Watch the video if you have an RB26. Sometimes just a little work/cleanup is required to fix an issue, rather than just parts replacement. However a lot of people would just rather replace a part than fix something they already have. Too many people get new “aftermarket” coils, which may fix the issue, but really don’t address the issue. The combustion chamber is a very harsh environment. Lots of heat, lots of pressure. Heat = resistance. High resistance means the spark will not arc across the spark plug gap.  This is why I like the Iridium plugs. Fine wire on the center electrode makes it easier for the arc to jump. The really expensive, and good plugs, are double fine wire.

“One of the most contentious areas of disagreements surrounds fine-wire spark plugs. It seems that everyone has an opinion about platinum and iridium plugs compared to the standard copper-core version. We’ll just start by saying that there’s a good chance that whatever you’ve read or been told about fine-wire plugs is probably incorrect.” Read more



Reading the Plugs: Spark Plug Tuning with Different Fuels

A lot of people also run the “K” or ISO length plugs. These are 2.5 mm shorter than the JIS plugs.  If you are trying to get the most out of your ignition system, don’t short anything.

JIS length or “C” – 53 mm from seat to plug tip. STD GT-R plugs are JIS length. BCPR

ISO length or ‘K” – 50.5 mm from seat to plug tip BKR

Racing NGK plugs. Recommended by Nismo

Double fine wire Iridium plug. If you are serious, run these.

* R7238-7, 8,9,10.
o Replaced by R7436-7,8,9,10
+ Hand made fine wire racing plug
+ 14mm, 3/4 reach, 5/8 hex, JIS length , fine wire iridium center electrode
R7436-10 part number 4900 $ 38.81 each JIS – I like
R7116-10 part number 3179 $22.34 each ISO – I have used
R7119-10 $33.12 each ISO – Not used – should work
BKR8EIX $7.60 each ISO – Not used – should work

IFR8H-11 $11.71 each ISO – Not used – should work
NGK Racing plug 4898 R7436-8 $41.52
NGK Racing plug 4899 R7436-9 $41.52
NGK Racing plug 4900 R7436-10 $41.52
 

7436-10 on the left, BCPR7EIX on the right.

NGK IRI (WAY)(TOP)(MAC) plugs have a 0.6mm iridium tipped Center Electrode with a tapered cut ground and are sold under the name Iriway, Iritop and Irimac throughout Japan and other select countries.  In the US and Europe these same plugs have been released under the IX Iridium Series and can be identified by their alphanumeric part numbers. The list below shows appropriate interchanges.  The IRI Series and IX Series are produced in the same NGK factory.  They are identical in construction, with packaging and marketing being the only difference.

IRI Series	=	Alphanumeric Part#
IRIMAC8	=	DCPR8EIX
IRIMAC9	=	DCPR9EIX
IRITOP7	=	BCPR7EIX
IRITOP8	=	BCPR8EIX
		(Not available in the US.  Can use BKR8EIX, which is identical but is ISO length instead of JIS)
IRITOP9	=	BCPR9EIX
		(Not available in the US.  Can use BKR9EIX, which is identical but is ISO length instead of JIS)
IRIWAY7	=	BKR7EIX
IRIWAY8	=	BKR8EIX
IRIWAY9	=	BKR9EIX

Stock R35 GT-R Spark Plug

VR38DETT GT-R plugs. DILKAR8A8

R35 GT-R Spark Plug. DILKAR8A8