How much Spark Plug Gap for Forced Induction? - Honda Prelude Forum

prepreludesh · 02-08-2010, 05:57 AM

I am trying to recite this from memory, but want to make sure I'm right.

What is the gapping I should be going with on a Forced Induction H22? I think stock gap is .40 and I swear I've heard forced induction means you should gap your plugs to .32.

Can somebody confirm or deny this? Thank you.

For those that do not know, I am running a built H22A4 with 9.2:1 CR with a Jackson Racing Supercharger with a 9psi pulley and it has the ability to run up to 8,000rpms based on headwork it has done to it.

prepreludesh · 02-08-2010, 11:41 AM

bumping my thread because I posted it so damn late at night.

Artifex · 02-09-2010, 12:57 AM

Ideally you can experiment and find the best gap on the dyno. Technically, it's the highest gap in which you don't get misfires under high load. I think .30 is probably good for most FI builds, unless you get over 20psi.

jimbo24 · 02-09-2010, 02:25 AM

i'm not sure about a jrsc but i believe the stock gap is 0.044

prepreludesh · 02-09-2010, 03:29 AM

Quote:

Originally Posted by jimbo24

i'm not sure about a jrsc but i believe the stock gap is 0.044

Yes, you're right. I always threw in my NGK Coppers at their stock rating which was .044. My bad that I wrote the numbers wrong, I'll go change that on my first post now!

ismael-robert · 02-11-2010, 03:11 PM

My research has shown to start with .032 but MSD ignitions can affec this. I have a MSD 6al and I've been told I can start at .035 and possibly go wider with proper tuning

willybv · 02-28-2010, 01:01 PM

Most tuners will start at .030" for a reasonable boosted setup. The closer the gap, the less energy is required, of course, and the dynamic compression of a boosted engine will increase resistance in the combustion chamber considerably. The larger the gap, however, the more energy is exposed to the fuel/air mixture, increasing the efficiency of the light-off. As ismael-robert said, a high-power ignition system, such as a comprehensive MSD setup, will allow a larger gap, but of course only the dyno tuner will be able to show power gains reliably. I run NGK 7 series plugs at .030", with an MSD 6AL-2, Blaster 2, wires, cap and rotor on 9psi, and was told by my tuner that there is little gain in opening the gap, but there are gains to be had. Also, remember to use a prong-style gauge, and not a ramp style gauge if you're very serious about a very good gap. Good luck!

ismael-robert · 02-28-2010, 04:26 PM

prong style gaper? Any pics of this? Are those the long slivers like feeler gauges?

AllMotorBB6 · 02-28-2010, 11:29 PM

i always start with .030

willybv · 03-01-2010, 09:29 PM

Here's a link for a picture:

http://www.sears.com/shc/s/p_10153_1...0070921x00003a

Lisle and AC make good gauges.

jonbar87 · 03-02-2010, 11:11 PM

between .026 (minimum) and .032 (good up to about 15psi.) .028 is a good happy medium.