Speaking of spark plugs...

[BDC]

As far as the alcohol users here, what are you guys normally doing for plug changes? I'm a Mazda rotary owner that's using Razor's kit. I'm running a fairly heavy ratio of gasoline to alcohol (about 70/30) and am starting to experience what I think might be the spark blowing out at heavier loads (23+psi boost). Do you guys normally do anything as far as running a colder plug? The ignition system I use is very stout. I didn't have this slight hesitation problem several weeks ago when the weather is warmer but I am not and am not sure if it's related to the drop in ambient temps down from 80's to the 40's outside. I've been told that one possibility is spark is blowing out and that I ought to step the heat range of the plugs I'm using down one notch. You guys experience any of that?

B

 

[Alky V6]

Run a tight gap. I run .022". If the plug color shows the need to go colder, then by all means go colder. If you run too rich an A/F ratio with the alcohol you can run into missing unless you've installed the patented mini-welder ignition setup.

 

[Pablo]

another thing to consider is that alcohol is prone to pre-ignition. This will quickly destroy your engine. If running alot of alky I would suggest running a couple heat ranges colder.

I run 2 heat ranges colder than stock to be safe and have no serious issues with a .028" gap

 

[Alky V6]

You had a fella suggest a hotter plug. I wouldn't go hotter unless the plug showed signs of being too cold. I'll assume you know how to read plugs. Only inspect your spark plug for proper heat range right after a WOT run with a shut down right at the end of the run. A cold plug can give you a lot of engine warmup deposits and then show a proper heat range at WOT. Be careful not to let the warmup deposits falsely make you install hotter plugs. In a really high HP situation, you may want to have a std heat range plug for engine warm up and then change the plugs out to the racing ones after the engine has gone through an initial warmup. That will extend the life of your racing plugs. If you choose not to use warmup plugs, racing plugs can really build up a lot of deposits during warmup because of the colder heat range, and then you WOT and burn a small amount of those deposits into the nose. This goes on time after time. The deposits buildup on top of each other. If you find that when you change a set of plugs and the missing seems to go away, change out your plugs more often. I install a new set of racing plugs at every meet. A set of warmup plugs will last longer, but since you won't really have a good chance to burn off the warmup deposits they will foul out quicker than normal. Make sure the ground electrode is as short as possible. I cut back and side gap all of my racing plugs. They are also the standard nose style. Not projected. Projected nose plugs leave you with too long of a ground electrode. Even after cutting it back.