Print

Please login or register.
1 Hour 1 Day 1 Week 1 Month Forever
Login with username, password and session length

[J.S.H.]

This attached article from Thunder Press discusses the use of Iridium spark plugs and their ability to reduce heat generated in motors.  Basically near the end of the article is says that you can reduce the heat range of the plugs by 2 heat ranges and that will decrease the combustion chamber temp by 70 to 100 degrees C or 212 degrees Fahrenheit.  I did this in my 09 Ultra classic and had no problems at all.  I know that the first year that I had that bike it was very hot and after I changed the plugs to 2 heat ranges lower and Iridium, I never felt the heat like I did before.  I didn't actually take any temp measurements, just by the seat of my pants I could tell a difference. 

Just wondering if anyone else tried this with their 110 and saw any difference with the heat issue. 

[MY2NDCVO]

No, but what part number, brand, heat range, do you use?

[dlaws01]

I really believe that the heat is created by the combustion of fuel/air mixture and not by the source of ignition.  If anyone can explain this differently I would love to hear it.

[Beak Boater]

Ok....I am confused. Wouldnt the temp. of the combustion be the same no matter what the heat range of the plug may be. Unless you changed the air/fuel mixture.

[1sharprdkg]

I really believe that the heat is created by the combustion of fuel/air mixture and not by the source of ignition.  If anyone can explain this differently I would love to hear it.

I agree with you dlaws01. I have to scream BS that lowering the heat range of the sparkplugs will reduce HEAT. Anyone?

[LC110]

The heat range of a spark plug has only a minute effect on combustion chamber and overall engine temperature. A cold plug will not materially cool down an engine's running temperature.
With today's computer controlled engines w/ knock sensors to adjust timing and avoid detonation, IMO running a colder heat range plug probably won't make much difference unless you're really beating on the motor.

[grc]

That Thunder Press article reminds me of some of the supposedly "technical" articles found in various other rags these days, usually written by some editor with zero real education in things mechanical who is trying to promote a product without making you think it's an advertisement.

The temperature of combustion is not affected by the heat range of the spark plug.  What is affected by the heat range of the plug is the rate at which heat is transferred away from the firing tip through the shell and into the cylinder head.  The entire reason for different heat ranges is the need to keep the firing tip of the plug within a certain temperature range.  Too hot, and the plug can cause preignition and suffer rapid erosion of the electrodes.  Too cold, and the plug can foul.  If you were to use the logic of the author of that blurb in Thunder Press, I would guess that the extra "heat" transferred to the head would just make the head hotter, which is not a good thing.  The entire idea of an internal combustion engine isn't to tranfer heat to the heads, it's to use as much of the heat as possible to force the piston down and create torque.  

Believe whatever you like, but running a two or more step colder plug isn't doing wonderful things for your engine.  If you want to cool the engine, replace the EPA cams and tune the engine to run richer, utilize a good oil cooler, and increase the air flow across the cooler and the engine.  And never forget, without heat you wouldn't create torque and you would have a large heavy paperweight.

BTW, while I think this person's logic is faulty, I do agree that the fine wire electrode plugs do have advantages.  Unfortunately, making your Harley run "cooler" isn't one of them.


Jerry

[tennisman]

I've heard some ridiculous chit on forums and more ridiculous chit on improving auto gas mileage.  But to think that changing the heat range of a spark plug is going to markedly reduce the operating temperature of an I.C. engine is TOTAL BS!!!  LOL!  P.T. Barnum was sooo right!

[tompen]

The heat range of the spark plug is how long it retains heat after firing. Controlled primarly by the center electrode insulater. A hotter plug is used to help keep the plug from fouling with oil or fuel from a rich mixture. The plug ignites the air-fuel mixture and it is all done with it's job. It has nothing to do with engine temperature.
Thats the way I remember Auto Mech. 101.
If Harley could cool these engines by changing spark plugs they certainly would.

[sadunbar]

The heat range of the spark plug is how long it retains heat after firing. Controlled primarly by the center electrode insulater. A hotter plug is used to help keep the plug from fouling with oil or fuel from a rich mixture. The plug ignites the air-fuel mixture and it is all done with it's job. It has nothing to do with engine temperature.
Thats the way I remember Auto Mech. 101.
If Harley could cool these engines by changing spark plugs they certainly would.

hehehehe.....   

Nope, not gonna say it.....

[UFO_HOG]

From NGK's website:

"The spark plug firing end temperature must be kept low enough to prevent pre-ignition, but high enough to prevent fouling. This is called “Thermal Performance”, and is determined by the heat range selected."

More Info:

Heat from the combustion chamber escapes through the exhaust gases, the side walls of the cylinder and the spark plug itself. The heat range of a spark plug has only a minute effect on combustion chamber and overall engine temperature. A cold plug will not materially cool down an engine's running temperature. (Too hot of a plug may, however, indirectly lead to a runaway pre-ignition condition that can increase engine temperature.) Rather, the main effect of a "hot" or "cold" plug is to affect the temperature of the tip of the spark plug.

[kraut]

seems to be a matter of belief with those iridium plugs. Topic arises every couple of month since years. Never seen any real proof of it's advances. But some do believe in them ...

[Gecko]

There are advantages to iridium plugs, being a very durable metal they don't erode like copper or steel plugs so will last much longer (lifetime or a hundred thousand miles in cars) if the insulator holds up.  With computer contolled fuel injection plug fouling isn't much of a problem anymore if you haven't messed the mapping up completely.  But heat removal?  Nope.  If it worked drilling a hole and threading a bolt into the cumbustion chamber would do it too.

[Twolanerider]

Just read this on the Internet (or at least will have read it as soon as I write it) so it must be true:

Iridium spark plugs when installed properly will deliver superior heat propagation to atmosphere while supporting higher exoatmospheric coefficient delivery of torque for better fuel economies and superior tire wear.  The capacitive discharge parameters of the insulators encapsulating the iridium ignitors are far superior for enhanced battery live.  Also, chicks dig the word "Iridium" if said with a Latin accent so using these plugs will get you laid."


So it's true, these plugs really are great.

[txhawg]

Do they make a split fire version of iridium plugs? 

That could get you laid by twins