colder plugs?

[CubanCougar]

ive been reading on here about colder plugs, and i plan on chaning my plugs and probably wires soon... what exactly are colder plugs and waht do they do???? and do you guys gap your plugs?



Thanks

Chino

[ccornett]

I also had a question about cooler plugs. Does it actually make the engine run cooler? or is it just something to do with comubstion? (SP)

[KewlBird]

I have the same question, but nobody seems to know the answer. Everyone is saying you need colder plugs, but why?

[Dr. FrankenCougie]

Spark Plug Heat Range:

A spark plug's heat range has no relationship on the actual voltage transferred through the spark plug. Rather, the heat range is a measure of the spark plug's ability to remove heat from the combustion chamber. The heat range measurement is determined by several factors:

The length of the ceramic center insulator nose
The insulator nose's ability to absorb and transfer combustion heat
The material composition of the insulator
The material composition of the center electrode

The longer the insulator nose gives you a larger surface area exposed to combustion gasses and heat is dissipated slowly. This also means the firing end heats up more quickly. We are talking about exposed ceramic length, not extended tip length.

The insulator nose length is the distance from the firing tip of the insulator to the point where the insulator meets the metal shell. Since the insulator tip is the hottest part of the spark plug, the tip temperature is a primary factor in pre-ignition and fouling. No matter what the plugs are installed in, be it a lawnmower, a boat, your daily driver or your race car, the spark plug tip temperature must remain between 450°C to 850°C. If the tip temperature is lower than 450°C, the insulator area surrounding the center electrode will not be hot enough to deter fouling and carbon deposit build-ups, thus causing misfires. If the tip temperature exceeds 850°C, the spark plug will overheat which can cause the ceramic around the the center electrode to blister as well as the electrodes will begin to melt. This may lead to pre-ignition/detonation and expensive engine damage. (see the plug pictures that are part of this article)

In identical spark plugs, the differences from one heat range to the next is the ability to remove approximately 70°C to 100°C from the combustion chamber. A projected style spark plug firing temperature is increased by 10°C to 20°C.

The firing end appearance also depends on the spark plug tip temperature. There are three basic diagnostic criteria for spark plugs: good, fouled, and overheated. The borderline between the fouling and optimum operating regions (450°C) is called the spark plug self-cleaning temperature. This is the temperature point where the accumulated carbon and combustion deposits are burned off automatically.

Bearing in mind that the insulator nose length is a determining factor in the heat range of a spark plug, the longer the insulator nose, the less heat is absorbed, and the further the heat must travel into the cylinder head water journals. This means that the plug has a higher internal temperature, and is said to be a "Hot" plug. A hot spark plug maintains a higher internal operating temperature to burn off oil and carbon deposits, and has no relationship to spark quality or intensity.

Conversely, a "Cold" spark plug has a shorter insulator nose and absorbs more combustion chamber heat. This heat travels a shorter distance, and allows the plug to operate at a lower internal temperature. A colder heat range can be necessary when an engine is modified for performance, subjected to heavy loads, or it is run at high RPMs for significant periods of time. The higher cylinder pressures developed by high compression, large camshafts, blowers and nitrous oxide, not to mention the RPM ranges we run our engines at while racing, make colder plugs mandatory to eliminate plug overheating and engine damage. The colder type plug removes heat more quickly, and will reduce the chance of pre-ignition/detonation and burn-out of the firing end. (Engine temperatures can affect the spark plug's operating temperature, but not the spark plug's heat range).

Jacked from....
Plug me

[KewlBird]

Now that's much better, thanks a lot man, that really helps

[ccornett]

So for example. When it is over 100 degrees out side, if i run my AC the temp meter shows that my engine is over heating. Would cold plugs lower the engine temp? Thanks

[KewlBird]

Originally posted by ccornett
So for example. When it is over 100 degrees out side, if i run my AC the temp meter shows that my engine is over heating. Would cold plugs lower the engine temp? Thanks

Nope, as I understood it, it helps by not letting plug misfire etc., nothing to do with lowering the engine temp.