Well, we all know (or should know) about trailing and leading plugs

I've heard from a couple people with rotary knowledge that running 9's will be 'safer' and last a little longer than running with 7's in the leading holes

what benifits can be seen from running all 9's?
Basically what are the pro's and con's?

thanks for the insight

-Markus

 

Bump.. i am talking about spark plugs here guys, it's not rocket science, i'm just confused. is running all NGK 9's better?

 

I was told by a mechanic who specializes in these cars that the 9 and 7 is the heat rating of the plug so he runs all 9s which is a colder plug. So I don't see any con's to this, pro's would probably be less detonation prone. Next change I'm going to try it out.

 

I thought the 9s were a hotter plug? If they are a colder plug, then read above^.

 

9's are colder than 7's

 

so would running all 9's be 'safe' in an N/A Rx-7 running intake / exhaust?

Thanks - Markus

 

Colder plugs are more prone to fouling if you're running too rich. If you're running stock or near stock power levels, you should just stick with the stock configuration.

 

I don't think you'll need to run 9's unless you're making serious power... ~400hp up. For the N/A that's pretty much impossible so the 7's will be fine for just about any application

 

anytime you're mixture is leaned from stock such as with an AFC you should run 9's all around to be more detonation resistant. just like with a piston engine if you're making hotter more violent combustion (running leaner) colder plugs give you a safety margin.

 

dude DONT do it there was the same # plugs in my car when i got it, it ran like sh*t!! go with the NGK 9s on top and NGK 7s on bottom trust me it will run alot better!! they r both the same price so u mys well do it the right way!! PEACE!!