Tony K

Someone once told me that the heat ranges on Bosch spark plugs get hotter when the number goes down. Is this correct? Or the other way around?

Or, in other words, which is hotter: WR7DS, or WR8DS?

Thanks,

Mike1982

I THINK the wr8ds is hotter, but I am not 100% sure because one of the companies goes the other way, meaning higher number hotter lower colder. I know when I put colder plugs in mine I had to do some research on this. By the way, why you putting in a colder plug??

Techno Duck

Typically the heat rating number goes down on plugs with a lower number. Im pretty Bosch uses the same type of standard rating...tough i cant seem to load their webpage at the moment, i know the information you are seeking is on there.

Dilberto

The coolest Bosch plug is the copper-core one WR7DC. They work excellent in the NAs and turbos too. However, their half life is literally half of the Platinum's. Use them to achieve lower NoX levels to pass smog.

MHT

bosch plugs, lower number lower heat range. Does not mean lower combustion chamber temp or any other such thing, it is a measure of how fast the plug can move heat away from the electrode to the cyl head. Unless there is a good reason to change stick with the heat range the manufacturer recommends for the application. If you are running more boost and its a track car then maybe run a cooler plug, if the car spends all it's time in stop and go traffic and you are having a problem fouling plugs, then run a hotter plug.