We've heard all the blah about Different Heat ranges, but what does that really mean..

When does a Heat range really come into play.. How compression can you run, and why does "range" on a spark plug effect Pinging.


Discuss.

 

off the top of my head...
a cooler plugs center electrode is longer to be 'colder'
and it is a balance of not to hot to cause pinging/detonation and not so cold as to cause carbon build up.

 

The term "heat range" refers to the relative temperature of the core nose of a spark plug. The words "hot" or "cold", when used in referencing spark plugs, are often a source of confusion and misunderstanding, since normally a hot spark plug is used in a cold engine (low horsepower) and a cold plug in a hot engine (high horsepower). The terms actually refer to the heat rating or thermal characteristics of the plug; more specifically, the plugs ability to dissipate heat from its firing end into the engine cooling system. A cold plug, by definition, transfers heat rapidly from its firing end into the cooling system and is used to avoid core nose heat saturation where combustion chamber or cylinder head temperature are relatively high. A hot spark plug has a much slower rate of heat transfer and is used to avoid fouling where combustion chamber or cylinder head temperatures are relatively low. The primary means of adjusting heat range are by varying the length of the core nose and the alloy material used in the electrodes. Hot plugs have a relatively long insulator nose with a long heat transfer path. Cold plugs have a much shorter insulator nose and thus transfer heat much more rapidly.

The preceding paragraph was taken word-for-word from from literature I received from Champion racing plugs.

A plug that is "too hot" can cause "detonation" because its tip will not dissipate heat quickly enough and the temperature of the tip will rise to the point that the air and fuel surrounding it will ignite by temperature alone before the spark plug is fired. This has the same effect as over-advancing the ignition timing and is referred to as "pre-ignition" since the air/fuel mixture ignites before spark plug is fired.

Basically, you want a plug that is "hot" enough so it will burn off raw fuel, carbon, and chemical additives so they do not coat the electrodes and block the path of the electrical spark. You also want a plug that is "cold" enough that it does not promote detonation. You need to find that happy medium.

However, there is far more to spark plug design than simply heat range. Gap distance, reach (how far into the combustion chamber the tip of the plug projects), gap design (surface gap, retracted gap, projected nose gap, etc), electrode diameter and material, etc. to name just a few. You do not have to stick with with the stock design and many other design are available which suit specific builds better than the stock design (such as using a retracted gap on a turbo-charged engine). Consult plug manufacturers for recommendations if you are serious about getting the right plugs. They are the experts, not internet forums.

 

well scott pretty much summed it up. the "heat range" in other words is the plugs ability to absorb and transfer heat that is generated in the combustion chamber to the engines cooling system. so picking a spark plug comes down to things like; what type of engine it is (race or street), weather force inducted, naturally aspirated or used with nitrous also what conditions it will be used in and what type of fuel is being utilized. i know thats not all the things to take into consideration but thats all i can think of right now.

 

Thanks for contributing info

here are some useful links I've found on this forum

http://www.strappe.com/plugs.html
http://www.dragstuff.com/techarticle...ead-plugs.html

 

well ****, i coulda copy pasted twice that. but i was under the impression this was about what *you* know.

 

Well, first of all, only the first paragraph was copied and it was not copy and pasted. It was information that I don't think is currently available on the internet because its from older reading material. Second, I do know what heat range is but I don't think I could have worded it better myself.

No one person can memorize everything there is to know about high performance engines. If they say they can and don't need reference material they are full of ****. Credibility is hard to find on an internet forum and if I had to choose information sourced from some 20 year old kid with no relevant education (I am NOT saying that is you) or information sourced from the people who actually make the products, I will take the information sourced from the people who make the products every time.

 

Amen....

This is the problem with many forums and especially this one lately. The people that really know what they're talking about tend to rarely speak but when they do, the infomation they give is amazing. For some others, it's more important to be "A big deal" than it is to actually contribute anything useful, and it's the ignorant that continue to let them get away with it.

 

ya but.. i guess since oil is less concrete on what is better and more experience based, that thread was having decent discussion.
this thread was kinda pointless.

 

When it comes to heat ranges NGK goes specifically by numbers on their plug (ex. 6,7,8). I currently run cheap Autolite plugs and their heat range seems more broad. Should I switch to NKG?

 

Only if those plugs aren't working out for you or you want to try/experiment with something different.

 

Actually there is concrete information on what properties are required in an oil for a certain application, as there is for most parts of a high performance engine. However, most people who are vocal on this site have no idea what they are talking about. People on this site are so easily swayed by marketing and the *opinions* of other 'hobbyists' that they don't listen to concrete engineering principals. Just because 1 product worked well in 1 engine does not mean it will work well in another.

 

I agree with this. If they are working for you there is no need to switch just because they are cheap. On the contrary, stay with them because they are cheap! I see too many posts that say you *have* to run platinum or iridium plugs since they are expensive they must work better. In reality, plugs that use exotic materials for their electrodes were originally developed to increase the service life of the plug for emissions reason, not performance.

It you are having a problem that you believe is related to the plugs you should post the details of that problem, such as "my plugs foul after a few thousand miles to the point that the engine misfires". Not paying enough for spark plugs is not a problem or a symptom.

 

Nah, I switched from NGK to Autolites. To me, they are cheaper and easier to "read" than the NGKs. Car runs perfectly fine with these "cheap" plugs. I got into an argument with some local dude saying I should stick with NGK cause that is what Honda/Acura put in as stock and it's the best spark plug evvvaaaarrrr!!!LOL. I know Rocket uses autolite for his "modified" spark plugs.

 

my boss swear by autolites instead of champion for gm's. says they dont foul as easy.

the only thing i would absolutely not put in a honda is the damn bosch plats autozone loves to sell everyone.

 

Ahh, the old 'some dude' argument. Unfortunately, 'some dude' seems to "win" a lot of arguments simply by repeatedly voicing his 'opinion' as loudly and forcefully as possibly without ever backing his 'opinion' with any scientific principles. He hammers home his opinion by telling you that you are stupid for not listening to him. The secret to getting good information on the internet is to completely ignore those who make the 'trust me blindly, I am an expert' statements and listening carefully with an air of caution to those who back their arguments with science. Use your own education and knowledge to determine if you trust what those people say. Hell, don't trust *me* unless I back up a statement with strong engineering principles!

 

I do not use platinum spark plugs in anything that did not originally come equipped with platinum spark plugs. I had a ton of problems with them when they originally became popular in the early 90's and I still occasionally see driveability problems caused by them. Stock ignition systems do not have enough energy to fire them when they get fouled, and they have a tendency to foul more than standard plugs. Their only advantage is that their electrodes last longer than standard plugs. But people who have high performance cars tend to replace their plugs more often than needed so what the point?

 

The only time I would use Platinum plugs is in a car that doesn't have easy access to the plugs. Honda 4cyl cars take 5 minutes tops to change plugs so no advantage. My wrx on the other hand is a PITA so it gets platinum's.

 

I was just about to say this. Certain transverse v6 cars with the rear cylinder bank right up against the firewall would be a perfect example.
.

 

Great job.

 

 

Great information. Very search worthy.
scott great response i was hoping someone else would get it..

 

What part was easier to read? The fuel ring? The electrode color? The detonation signs? Which heat range seemed to transfer combustion heat away the the head better after continued hard use? Street plugs really do not have alot to do with race plugs as there operating enviroments are different.

 

i sadly will admit that i dont know how to read plugs ,, as in when the car is leanin our runing rich or detonating .. can we inclue that in this thread?

 

http://www.dansmc.com/spark_plugs/sp...s_catalog.html