? about spark plugs

[KCPSG]

I found a PDF document on the web decoding the spark plug #'s and what is a hotter and colder plug. But after reading here on Pelican I am a bit confused as to which is actually a colder plug. I am currently running Bosch WR7DC and after reading the PDF it would indicate that the NGK BP8ES is a colder plug... Am I correct or are Bosch rated differently than the NGK's?

[hobieboy]

Bosch & NGK uses different numbering scheme.

NGK plugs - smaller # is colder (7 is colder than 8).
Bosch is reversed.

I think a NGK BP8 range is similar to Bosch WR4 range.

[KCPSG]

Here is the chart I found...
http://www.ngksparkplugs.com/techinfo/spark_plugs/partnumberkey.pdf

So according to this chart...8's are cooler than 7's etc. But I guess this does not carry over to Bosch plugs.

Are my BP8ES cooler than WR7DC?

[Porschefile]

Originally posted by hobieboy
Bosch & NGK uses different numbering scheme.

NGK plugs - smaller # is colder (7 is colder than 8).
Bosch is reversed.

I think a NGK BP8 range is similar to Bosch WR4 range.

Actually, it's the other way around with NGK. The lower number is hotter and higher is colder. The link to NGK's chart, that KCPSG posted, confirms this. I couldn't figure out which would work best for me so I just bought a set of BP7ES and BP8ES plugs.

[JimCulp]

I called NGK and talked to customer service about their recommendation for my application and they were very helpful. The numbers on NGK's website.

[hobieboy]

Originally posted by Porschefile
Actually, it's the other way around with NGK. The lower number is hotter and higher is colder. The link to NGK's chart, that KCPSG posted, confirms this. I couldn't figure out which would work best for me so I just bought a set of BP7ES and BP8ES plugs.

duh - you are 100% right I need more coffee

[KCPSG]

For everyone's info..
I E-mailed NGK and got this response today.
Just for peoples future reference between NGK and Bosch.
Hello,

According to my notes, Bosch WR7DC crosses to a BPR6ES NGK spark plug.
The BP8ES plug you purchased is two stages cooler. These plugs should
be a good starting point on a turbocharged vehicle. Thank you.

Kristopher Zdral
Technical Support Representative
NGK Spark Plugs (U.S.A.), INC.

[gsxrken]

I'd need to dig around to back this up, but I recall guidance that said not to run the stock range plug, that it was entirely too cold for a street car. I'm running an NGK that was one step hotter, recommended for street cars to burn off the usual oil and carbon deposits. Anyone else, please feel free to bring the tech on this.