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Old 11-15-2010, 01:09 PM   #1
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Default J-gap Spark Plugs

So I was watching Omniman's B18C rebuild video and there was a short segment on something I believe that was referred as J-gapping.

You take a plug and cut the ground electrode so it just covers half of the center electrode. Then you cut a V groove into the ground electrode. It appeared like he cut a V into the center electrode as well.

Anyway, on the dynoplot Mx24 (???) showed he picked up 4whp. Omni man said he probably picked up 1 whp, but the better throttle response was significant. This was on n/a motors. Downside was that plugs wore faster.

Anyone try this or know more about it on FI motors? Sound like splitfires.
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Old 11-18-2010, 07:51 AM   #2
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Sounds like it would grind material that would other wise aid in that tiny bit of heat transfer, creating hot spots on the end of the electrode, and would lead to possible detonation...

Much like any flashing in the combustion chamber would do, except on the plug itself
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Old 11-18-2010, 07:55 AM   #3
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Is it enough of a gain for you to A) do all that work, B) risk any potential side effects it could have on your motor if something goes wrong/flies apart?

If so, give it a shot and let us know what you think of the results.
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Old 11-18-2010, 08:56 AM   #4
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Quote:
Originally Posted by Dlaitini View Post
Sounds like it would grind material that would other wise aid in that tiny bit of heat transfer, creating hot spots on the end of the electrode, and would lead to possible detonation...

Much like any flashing in the combustion chamber would do, except on the plug itself
I'll agree with this.

I'll also say that unshrouding the kernel yields a tiny benefit, but so does indexing the plugs, and who among us cares to be that ---- about it? The only reason that they are going to so much trouble for such small gains is that they are N/A and can't add .5lbs more boost and get four times as much benefit as that. N/A guys often screw with silly little **** because they have to.
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Old 11-18-2010, 09:44 AM   #5
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I believe Audi does this in the R15 and Peugeot does this in the 908.
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