Which Spark Plugs?

[scotty nm35]

So if mine runs perfectly on 1.1mm at 40 psi running rich as fark should I drop the gap to 0.5mm just because RB owners say it should be?

XR6t owners say the same thing funny enough and they have their fair share of spark issues also. Plug gap comes down to the coil output voltage more than anything.

[Ben C34]

Ok. Here's some old school shit. From Zoom no 56.

[scotty nm35]

'On that setup' the results were better closing the plug gap, but only in the top end. Was it because the coils didn't have enough punch? Seems unlikely at such low power figures. I would want to see an AFR graph as it's obviously untuned and is probably running 9:1 afr's. It seems interesting the power dropped off around 5k at .6, maximum torque... Stock computer detecting knock perhaps?

Like I said, every setup is different, but I wouldn't go suggesting all engines should run .5, unless you are melting plugs every 1000k's and want some life out of them.

[Ben C34]

'On that setup' the results were better closing the plug gap, but only in the top end. Was it because the coils didn't have enough punch? Seems unlikely at such low power figures. I would want to see an AFR graph as it's obviously untuned and is probably running 9:1 afr's. It seems interesting the power dropped off around 5k at .6, maximum torque... Stock computer detecting knock perhaps?

Like I said, every setup is different, but I wouldn't go suggesting all engines should run .5, unless you are melting plugs every 1000k's and want some life out of them.

Cmon man. It's a dyno graph and people love that. Squiggly lines.

Don't think too much.

And yeah, I have the full article that is stock un tuned. Closing gap up too much lost power. Opening up too much lost heaps of power due to misfiring.

[r33_racer]

I wasn't saying to run 0.5mm at all for every situation, more so that you can run smaller gaps if it helps with misfiring issues. You only need to run a gap that lets you rev right out with no misfiring...

But yes with boosted/methanol too big a gap for us only made it break down. We found running 0.5mm worked the best for us with no power loss. We were running 0.9 and as we started making more and more power, it worked its way down to 0.5.

[Dose Pipe Sutututu]

In conclusion for those people who are here for a quick answer

Gap based on requirements, for all normal to mild just stick to 0.8mm for whatever fuel.. If your coil packs are shit, either replace them or gap your plugs down.

For crazy cars, safe bet if you need less than 0.8mm

Me personally, I use 6 heat range with 0.8mm gap and have no misfires on E85.

[r33_racer]

Well said and summed up