Spark plugs

ProjectClubCar

I'm wanting to get an understanding of how the spark plugs work, pertaining the heat range of a spark plug?
Say if I wanted to go to a hotter plug than what I have, would that create better combustion, or a more complete burn, by adding this spark plug with a higher range, do you increase engine temperature?

So by using a colder spark plug, you get less combustion, but cooler engine temps...

Right now, my spark plugs show a beautiful light tan around the spark plug, but I am thinking a hotter plug will help me out with better combustion, and more power, but with that comes the price of heat?

And say that your spark plug is at normal heat range, how many times can you bump up the heat range till it becomes dangerous for the motor?

I have never ever messed with spark plug heat ranges as far as hotter or colder plugs. I have always just gone by what the manufacturer recommends....

Are there any benefits by bumping up in heat range?

BGW

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saddlertime

It has been a while since I have done my research on this (had to for my 18' jet boat with a big block olds running 100 octane fuel with nothing left stock) but if I recall correctly, it has to do with the spark plug's ability to remove heat from the combustion chamber. The hotter temperature will keep combustion chamber temperatures hotter and colder visa versa. Now generally speaking when you add power goodies, you go with a colder plug to help remove some of the heat from that added power and prevent burning things up. I think I recall something like drop one heat range for xxhp added, and I think that number was like 50 or 100 hp.

Keep in mind this was at least how it worked on a big block olds and 100 octane leaded fuel, so I'm not sure that it is exactly a 1:1 swap into these small engines. However, I would be awfully surprised if that were the case.

Also typically the reason for changing heat ranges is to prevent fouling. When your plug is too cold, it doesn't let the combustion chamber temps get hot enough to burn off the residue from the combustion and you'll get carbon buildup and foul your plug. If your plugs aren't fouled, I probably wouldn't mess with it for risk of burning things up.

I'm sure someone here has played with the heat ranges on the small engines, and will have better input.

E36Racer

Basically with modded motors you typically mess with plug temps to fine tune the jetting at a very granular level. And typically as you add power (increase compression and timing, add boost, etc.) you normally run a colder plug to help reduce cylinder temps. Even in a heavily modified cart motor I don’t think that much of a granular level of tuning adjustment would yield any kind of noticeable difference. Plus with cart motors it’s not easy to adjust the timing for changes in jetting and plug temps (all 3 impact each other). I’m willing to bet your current plug (if stock spec) is probably on the upper half of the temp range available anyway. If you go too hot it runs the risk of pinging and worst case burning a piston.

Regardless, it seems like your jetting is spot on based on checking your current plug, so I wouldn’t touch it. Just make sure your using a good plug, I only buy NGK-R plugs regardless of manufacture’s recommendation. I’d seek out other ways to get the power you’re looking for.


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Rooster59

Beyond the rudimentary spark plug reading to adjust mixture that many experienced members have explained, reading a spark plug is best left to experts. For the rest of the world, changing spark plug heat range is one of the last things you do to tune an engine. Changing spark plugs heat ranges is done to finely tune an engine already being pushed to the upper limits, not find more horsepower in a low tech engine like those in carts, mowers, etc. Back in the 70's Champion employed Bobby Strahlmann to visit race events and read spark plugs for the participants. For free. He used a jeweler's loupe to read conditions. He was so good it was said he could tell what the rider/driver had for breakfast by reading their spark plugs. But few people have that level of skill to garner an outlandish reputation like that.

Take a gander at this tech article if you want to learn more. Written by an engineer from Champion.
https://www.vdlfuelsystems.com/anyth...t-spark-plugs/

Shepard

As was said earlier a plug needs only be hot enough to clean itself. This is what gives the insulator that caramel color - to hot it's white - to cold it's black and fouled. To hot burns holes in pistons. That being said --------------
I would recommend trying the Autolite AR3910X. It's a surface fire plug that puts the fire where its needed, not hidden. This plug can increase your hp according to the cart racers, I noticed the difference. Several others have posted the same. Give it a try -- only you can judge if it helps.

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ProjectClubCar

That looks like a wicked plug, is that the correct number on the plug that I need for my V-Twin? Or do I cross reference the champion spark plug that's in there now with this Autolite plug?

raydhd

I second that statement. You can feel the increased power and throttle response. It make the engine sound different. My guess is much more complete combustion.P.S. I have have A-B tested this several times and the results are very obvious.

Shepard

It's a racing plug and the number fits everything -- it's normally a cold plug so it's safe.

ProjectClubCar

Sweet, when I make it into town today I will pick up a couple of those plugs and see how they work for my own self....

Thanks for the input guys, y'all know I love knowledge, and with all that empty space in my head there is definitely
Room for knowledge!!!

Rooster59

One comment of note that I have seen more than once on the racing plugs in general and specifically the AR3910X (0 equals the coldest heat range offered) is idling. This is a RACING plug and as such runs cold. Some folks have experienced wet fouling and similar issues when idling or running very slow for extended periods. Racing engines are usually run wide open or shut off. But it does seem most of our members who have used it like it.