Miata Mailing List: November 1993, Message #171
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   From: Stan Whitney <71763.644@CompuServe.COM>
Subject: NGK Plugs
   Date: Mon, 22 Nov 1993 11:02:54 -0500


Regarding the post from
Mike Rother 

> Shop manual notes that NGK  BKR6E-11  plugs are standard equipment for
> the manual transmission car.  However, the shop manual also lists the 
> BKR5E-11 and BKR7E-11 as options.  What is the difference?  Colder &
> hotter?  Which is which?  Which is better?

The BKR5's are the hottest, and the BKR7's are the coldest.  
The hotter plugs come up to working temp. faster, but remain hotter
(at the electrode/insulator), which makes them more prone to detonation/pinging.
With the timing advanced, you'd be better off with the BKR7's, the only trade off
is perhaps slightly more cold blooded starting (5-10sec. more idle before driving 
off would eliminate it)

Sparkplug heat range schemes are not at all uniform, NGK and ND have the low numbers]
hottest.  Champion is just the opposite.

The V-power plugs are not standard NGK's they have a small groove in the electrode, and cost 
more, but supposedly burn cleaner.


Stan Whitney
Black '94 C -just picked it up!  ;>