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Author Topic: Spark Plug Heat Range?
Teamfour Verified Driver Made Donation to Website
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Region: WDCR
Car #: 04
Year : 1993
Posts: 519
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NGK Plugs - I know the stock plugs are -6 heat range. Most info on this forum calls for one step colder or -7. I just pulled the plugs in my car and they are -5 or one step hotter. Why would someone use a hotter plug? The plugs look real good.

FWIW, I just had my AFM tuned and the tuner said the previous tuner had done some "strange" adjusting to the point that he was surprised the car ran. The car idles much better with the new tune and has noticeable better power. Could the old tune have necessitated the hotter plug?

Going to the dyno Saturday so I want to have the right plugs installed.

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Lee Tilton
1993 Meowta #04
Brimtek Motorsports/ Team Four Racing
Team Four Racing

Teamfour Verified Driver Made Donation to Website
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Region: WDCR
Car #: 04
Year : 1993
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Well not much response here other than a PM that led me to the following questions:

Now to really confuse things (at least for a newbie for me). NGK plugs have an opposite numbering system for heat range then say Bosch. NGK 5 equals Bosch 8. A colder NGK plug goes up in number while a Bosch goes down.

So my new question is: If running a tuned AFM results in a slightly leaner mixture, can a hotter plug cause issues? Is a colder plug needed because of less fuel and less fouling?

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Lee Tilton
1993 Meowta #04
Brimtek Motorsports/ Team Four Racing
Team Four Racing

ChrisA
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Year : 1999
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I use a Denso 20, which is one step colder than the stock range which is 16.

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Chris

"Nothing can be simple. Everything's got to be a pain in the ass." - C. Adams

SAE113 Verified Driver
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Region: Central Florida
Car #: 01 & 99
Year : '92 & '94
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I run a cooler plug. Since the car doesn't sit in traffic idling or coasting around like a street driven car.

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Steven Elicati
'92 Protege ITA#01
'94 Miata ITA#99

Muda Verified Driver Made Donation to Website
ComingToAMirrorNearYou

Region: WDC
Car #: #23
Year : 1991
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+1 for Denso K20

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Muda Motorsports
"We're all here 'cause we're not all there."

   

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