Connect with us


Autolite Introduces XP Xtreme Performance Iridium Plugs


For engine builder who have made modifications to an engine, they should refer to their component manufacturer’s specifications and/or contact the experts at Fram Group at

Click Here to Read More

Company: FRAM Group

Autolite XP Xtreme Performance Iridium enhanced spark plugs are one of Autolite’s most technologically advanced spark plugs ever.

With an iridium-enhanced 0.6 mm finewire design and proprietary V-trimmed platinum sidewire technology, these spark plugs provide better durability* and a more focused ignition for better overall ignitability** and optimal performance.


Importance of Heat Range with Performance Engines
Racing Modified Engines – Generally, any engine modification that alters the overall compression ratio of the engine will involve spark plug selection issues. One thing to consider is heat range.

The heat range of the spark plug determines how much heat the spark plug is capable of removing from the combustion chamber. The heat range of the spark plug does not increase or decrease horsepower. It changes the temperature of the tip of the spark plug. If the heat range is too cold, the deposits will not burn off the tip and the spark plug will foul. If the spark plug heat range is too hot, pre-ignition can occur.

A switch in heat range of the spark plug will change the temperature of the spark plug tip by 70-120 degrees. If you are unsure of the correct heat range to use, always start with a colder spark plug. If the plug is too cold, the plug will eventually foul and a misfire will occur. This will not hurt the engine. Unfortunately, though, if a spark plug that is too hot is inadvertently chosen, pre-ignition and detonation can severely damage your engine. Don’t go to a hotter heat range unless you’ve consulted your engine experts.


As there are many different ways to modify your engine for racing applications, we can’t tell you here which specific spark plug to use. If you have made modifications to your engine, you should refer to your component manufacturer’s specifications and/or contact the experts at Fram Group at

*Compared to 0.8 mm finewire, multi-electrode design and standard plugs.

**Compared to average of other premium brands.



Tech Center

Service Issues on Ford 4.6L SOHC & DOHC Engines

Carburetor Tuning: A/F Mixture, Air/Fuel Equation

Cleaning Engine Blocks & Engine Cylinder Heads

Ticking, Knocking Noise Complaints: Ford 4.6L / 5.4L 3V Engines