hey guys, i was looking in my manual and spark plug gapping for b series motors and noticed that the gapping for a GSR motor and Type R were different, surely there gapped different for a reason.. is this because of compression difference? I have a jdm b18c (10.6:1 same as USDM ITR) in my 95 gsr, should i be getting my plugs gapped to type r specs?

 

you mine as well gap to type r plug specs man. ill bet its gapped like that because of the change in compression

 

yea but i don't know if the bottom of my head is just like a p73 or not... i have a p72.. so i don't know if compression would be the same.

 

if it's the same compression as the us itr i would probably use the itr gap. also i believe the itr plugs are 1 step colder than the gsr.

 

yes the jdm b18c and usdm ITR b18c5 are both 10.6:1

 

yeah i'd go for it. i believe the usdm itr plugs are heat range 7 while usdm gsr's are 6

 

As long as it isn't breaking up in the higher RPMs you're fine. I would think that something in the .40-.45 range should work for you

 

ok thanks guys!

 

Who says that the spark plug gap is because of the difference of compression? If the compression is the same in JDM GSR and USDM ITR, than why is there a differences in gapping specs?

Its because the difference is not based on compression, but on camshaft lobe height and duration. The valves in the ITR engine stay open for longer (than gsr) due to the taller cam lobe. So in the VTEC range, there is more air going in and out of the engine, and therefore a more fuel delivered. Thats why the spark plug gaps are different between GSR and ITR

But I'm sure the ITR spark plug gap specs will work.

 

It is always best to follow the factory recommended plug gap. Unless you find ignition breakdown at high RPM's. If you do have ignition breaking up at High revs, it can be helpfull to make the plug gap smaller. The smaller the gap is, the easier it is to fire. I have found that when i ad a turbo or supercharger to many vehicles, especially those with coil on plug ignitions, I have to make the gap smaller whenever exceeding 8psi of boost. This makes the run really clean on top.

 

yea but i don't have any factory spark plug gaps, my motor is a JDM b18c, so i either gotta choose between gsr or type r plugs.. I mean there is a factory spark plug for that motor, but i don't know what the gapping on it is.

 

I spoke with some engineers at Autolite, they say you should start with a gap of .050 or 1.3mm. Bring it down to .040 if you experience any mis fires at high rpms. Use Autolite Iridium XP3923 plugs. Want a set to try for free? Email me your address
Motorking

 

go for the itr spec

 

There's a new shop in Detroit?
I want some free spark plugs. I need a step 7 for boost.