RennBod

I know that spark plug temps are the number within the plug part number, such as the "7" in WR7DC. But, what way do the numbers go?

Is a cooler plug an 8 or a 6??

shortyboy

6 would be stock for the 951.i think the higher # is colder,not too sure.but im using NGK BPR7ES and its the choice by most for the 951.

lart951

NGK BPR7ES

Driftomagnifico

For NGK the higher the number the colder the plug.

Ie.

BKR7E is 1 step colder than BKR6E

RennBod

Is it the same with a Bosch or Beru plug? a higher number being a colder plug?

reno808

dumb question but why would you colder? i have on the stock bosch plugs and my car runns awsome.

shortyboy

rule of thumb when modding is:when you start modding your car,ie:chips wastegate,boost control.its a good idea to go one range colder to prevent detonation.

95ONE

The higher the number the "colder" the plug. The ceramic is recessed a little more with each successive number. on the smaller or "hotter" plug, It will hold heat longer and therefore be more prone to detonation under larger loads like a heavily modded car. The downside for the colder plug is, if you don't use that power much or putt putt around, it doesn't get enough heat, they start to foul.

reno808

ic thanks

baldheadracing

With Bosch, the higher the number, the hotter the plug.

Using your example, WR7DC means:

W=Thread, 14mm in this case
R=Type, Suppression resistor
7=Heat range (2=coldest, 11=hottest)
D=Thread Reach, 3/4" (.708" with tapered seal) and extended tip electrode
C=Electrode, Copper core.

http://www.boschusa.com/images/designationcodes.jpg
http://www.boschusa.com/images/PlugHeatRange.jpg

Every manufacturer uses a different scheme, however.

95ONE

And so they do! here are some that use larger numbers for colder, but also use different sets of numbers.

http://www.sparkplugs.com/sparkplug4...ampion)&mfid=0