I have doing some standard maintenance on my truck to get ready for the winter and am considering changing my spark plugs out. In the installation instructions for my supercharger, the say "if your vehicle see prolonged high speed use, we recommend going with a spark plug one range colder". Is there really any benefit and why?

The plugs I have in there are okay but should I go one range colder?

Do you run one stage colder in your Speed?

Since a SC is rpm dependent, I guess I could see the benefit if you were always on the highway or something.

Even tho a supercharger makes boost in a more linear fashion, when the engine is off load a bypass valve should be open so you're still not making boost.

Are your current plugs fouled at all? That's a sign you're running a plug that's too "cold". If not, you can stay where you are at.

If you have experienced any pre-ignition then you're plug maybe too "hot". A colder plug provides a greater safety buffer for pre-ignition but a hotter plug can increase fuel mileage (marginally at beast) and start up times. With a colder plug you will notice it will take an extra second or two for the engine to turn over.

Here is a great read-up on hot/cold plugs by NGK: http://www.ngksparkplugs.com/tech_support/spark_plugs/index.asp

I just installed some NGK step colder in my ms6 and the car runs wayyy smoother. My stockers were pretty fouled tho. The only reason i changed is because im running 15-16psi.

Ron I remember looking into this a while back. Seems to me that a colder spark might help prevent detonation, and may also help keep AFRs on the rich side by not fully burning all of the fuel. In a FI vehicle, fuel is often used as a charge coolant, so you don't want all of it to burn. Just what I remember, haven't looked into it in a while.