Basically it helps dissipate heat from the combustion chamber. This is from the NGK site which may give you a better idea.

Heat range

The term spark plug heat range refers to the speed with which the plug can transfer heat from the combustion chamber to the engine head. Whether the plug is to be installed in a boat, lawnmower or racecar, it has been found the optimum combustion chamber temperature for gasoline engines is between 500°C–850°C. When it is within that range it is cool enough to avoid pre-ignition and plug tip overheating (which can cause engine damage), while still hot enough to burn off combustion deposits which cause fouling.

The spark plug can help maintain the optimum combustion chamber temperature. The primary method used to do this is by altering the internal length of the core nose, in addition, the alloy compositions in the electrodes can be changed. This means you may not be able to visually tell a difference between heat ranges. When a spark plug is referred to as a “cold plug”, it is one that transfers heat rapidly from the firing tip into the engine head, which keeps the firing tip cooler. A “hot plug” has a much slower rate of heat transfer, which keeps the firing tip hotter.

An unaltered engine will run within the optimum operating range straight from the manufacturer, but if you make modifications such as a turbo, supercharger, increase compression, timing changes, use of alternate racing fuels, or sustained use of nitrous oxide, these can alter the plug tip temperature and may necessitate a colder plug. A rule of thumb is, one heat range colder per modification or one heat range colder for every 75–100hp you increase. In identical spark plug types, the difference from one full heat range to the next is the ability to remove 70°C to 100°C from the combustion chamber.

The heat range numbers used by spark plug manufacturers are not universal, by that we mean, a 10 heat range in Champion is not the same as a 10 heat range in NGK nor the same in Autolite. Some manufacturers numbering systems are opposite the other, for domestic manufacturers (Champion, Autolite, Splitfire), the higher the number, the hotter the plug. For Japanese manufacturers (NGK, Denso), the higher the number, the colder the plug.

Do not make spark plug changes at the same time as another engine modification such as injection, carburetion or timing changes as in the event of poor results, it can lead to misleading and inaccurate conclusions (an exception would be when the alternate plugs came as part of a single precalibrated upgrade kit). When making spark plug heat range changes, it is better to err on the side of too cold a plug. The worst thing that can happen from too cold a plug is a fouled spark plug, too hot a spark plug can cause severe engine damage

 

very interesting!

Ok, let me see if i got the science lesson correct .

From reading i have found that our engines run Rich (Fact).
And from reading an earlier post, i recall rflow saying that the stock plugs are hot.
and form reading brains link..
Hot plug means the spark plug tip is hooter for longer and heat transfer is slow, which makes sense, as our engines run rich (which means more fuel), which means the spark has to insure it can ignite it.

if that is correct then i am a happy camper, if not need to read more

but... if i am correct then how does cold plugs help if we run rich?

 

[QUOTE=SleeperX;2459444]http://www.superchargersonline.com/content.asp?ID=104
FEATURES :: ENGINE TUNING & MAINTENANCE
Detonation, Knock, and Pre-Ignition 101
8/4/2003 1:59:00 PM







Higher octane fuel burns more controllably and is not as likely to combust before the flame front. This is why racing engines use 100+ octane gasoline. The ONLY benefit of racing gasoline is that it moves you away from the detonation threshhold, which allows you to be more aggressive with power producing factors - i.e. raise compression, advance timing, etc. This is why you'll be disappointed if you put racing gasoline in your mom's bone-stock '82 Toyota Cressida thinking you'll turn it into a race car. If you don't have detonation, the increased octane will do you no good. For cars designed for daily street driving, you obviously won't want to fill up with 100+ octane fuel every week at the tune of 5 bucks a gallon. This is why supercharger manufactuers tune their supercharger systems to run properly without detonation on 91 octane fuel - aka "premium" at your local gas station (in some states premium gasoline is around 93 octane).

GREAT post SleeperX:

I always get weary about posting a long one, but very ensiteful!

One point that was left out about HIGHER octane fuel is that you will actually LOOSE performance if you use TOO high of an octane. As you pointed out, higher octane fuels actually burn SLOWER, so if you engine is designed for say 87 octane, and you use 100, your engine would actually put out LESS horepower with the 100 octane. This is because the flame front woulod not porpegate fast enough through the combustion cahmber. Oh well, I don't want to write a book here, its suffiecient to say that you only need to use the amount of octane that keeps you from spark ratteling/pre-ignition, NO more, NO less.

See yeah

PS: Octane booster's actually help as well and are cheaper than race gas. Just don't buy the ones at Pep Boys for $2.00 that claim a 10 point gain. Stick to 104 octane booster, Amsoil, or other WELL known brands for best results

 

Is this any good as an octane booster - will it foul up the cats ?

https://www.ragingspeed.co.uk/catalo...roducts_id=670

 

Nah, but won't help as much as ya think.

Great Hotrod article "Octane Shootout" here.

 

They need to test the torco accelerator, that is the only one I would use.

 

is the 100 octane that I use. Pretty happy with it.

 

+1 I have used this several times

 

actually (most) octane boosters are extremely inefficient at increasing octane ratings (although some may help in preventing minor detonation which under some conditions could increase power) and they can end up being more expensive than mixing a couple of gallons or race gas if raising octane is the primary goal. under no circumstances should fuel additives be a substitute for quality fuel in our cars!

http://www.************/car-videos/10...-additives.htm

 

Hey chiromikey:

That video is EXACTLY what I was talking about. If an engine does NOT need more octane, ie slower burning/slower flame propagation, it WILL LOOSE POWER.

On a side note, they did not say what THAT engine required, ie octane rating from the manufacturer. Oh well, I agree NOT to use additives for a replacement for poor fuel.

Buyt they CAN and DO work on supercharged/high compression engines, I know first hand with my stang with its whipplecharger.

See yeah

AND THANKS!!