The lower the ambient temperature, the lower the resultant bottle pressure leading to a potential fuel rich condition. Although usually not harmful to the engine, loss of optimal power can occur. On the other hand, very high ambient temperatures can lead to leaner burning conditions and loss of optimal performance as well as possible damage to engine components. Gauges are an excellent way to monitor problems before they can occur.




Nitrous / Fuel Ratios - Never Run LEAN


The difficult part of using nitrous is tuning the flow of nitrous and fuel so the engine maintains the proper air / fuel ratio. That's very important for running your engine without damaging it.

The chemically correct nitrous to petrol ratio is 9.649:1. If you run lean, you can destroy your engine in a matter of seconds. There must be enough fuel to maintain the correct ratio, if there isn't, temperatures rise rapidly. The oxygen that was left over from burning the limited amount of fuel will result in a lean burn situation raising cylinder temperatures and melting components. So don`t run lean.




Heat ranges - Which spark plug should I use?


Part of a spark plug's responsibilities, in addition to firing a spark, is to remove heat from the combustion chamber. This is accomplished by channeling the heat through the insulator material and metal housing. From there, the heat is transferred to the cylinder head where the engine cooling system can go to work.


A spark plug's heat range is its ability to dissipate heat. The "colder" the plug, the more heat it can channel out of the combustion chamber. In a performance application, colder heat ranges may be necessary to handle the extreme temperatures brought on by higher compression ratios, forced induction, and high RPM`s. While "Colder" plugs may seem to be the way to go, please remember that the spark plug must achieve its "self-cleaning" temperature where it can burn off fuel and carbon deposits. Otherwise, the plug could "foul out" where it is prone to misfiring and poor acceleration. A plug that is too "hot" can overheat, also causing power loss, detonation, pre-ignition, and possible engine damage.


A good, general rule of thumb is to start with the factory recommended heat range. For every 75 to 100 hp you add to your engine, you may go to the next colder step. the difference from one full heat range to the next is the ability to remove 70 degrees C to 100 degrees C from the combustion chamber.




Hot & Cold Spark Plugs - A Closer Look on Heat Range


The heat range of a spark plug is its ability to dissipate heat from the combustion chamber to the cylinder head. The heat range, or dissipation capability, of a spark plug depends primarily on the length of the insulator nose. The heat from the combustion is transferred from the insulator nose through the center electrode to the plug housing, and from there it goes to the cylinder head.

Hot Plug

A "hot plug" has a long insulator nose which exposes more surface area to the combustion gases. This keeps the plug temperature higher overall which is ideal for stop-start city driving conditions.

Cold Plug

A "cold plug" has a shorter insulator nose, which minimizes the amount of surface area exposed to the combustion gases. Cold plugs are... (continued)

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