Supra
Spark Plugs Facts

 

To begin with, our cars call for a
resistor plug that: contains a projected ISO tip with a 19mm thread reach,
14mm thread diameter, and a 5/8″ hex size. To fit this description,
Toyota used the BKR6EP-11 (2978).
This plug is defined as the following:

B = 14mm
thread diameter
K = Projected ISO tip w/ 5/8 Hex size
R = Resistor plug
6 = Heat range # 6
E = 19mm (3/4″) thread reach
P = Platinum tipped
-11 = x/10 which is 1.1mm pregap
(0.044″)

This plug fits the exact description of
what the 2JZ-GTE motor calls for at stock levels. But as we modify the
motor and increase boost, we generate more heat, which is why it is
necessary we drop the heat range at least one step colder to prevent
preignition and detonation…and the platinum plugs do a horrible job at
it. So the plug that best fits this description would be the BKR7E/BKR7E-11
(6097/1283)

B = 14mm
thread diameter
K = Projected ISO tip w/ 5/8 Hex size
R = Resistor plug
7 = Heat range # 7
E = 19mm (3/4″) thread reach, V-grooved
center electrode with 1.5mm insulator
-11 = x/10 which is 1.1mm pregap
(0.044″) (1283 only)

Keeping these facts in mind, now let’s
look at the BCPR7ES/BCPR7ES-11 (3330/1095):

B = 14mm
thread diameter
C = 5/8 Hex size
P = Projected Insulator (Not good)
R = Resistor plug
7 = Heat range # 7
E = 19mm (3/4″) thread reach
S = Standard electrode, 2.5mm diameter
-11 = x/10 which is 1.1mm pregap
(0.044″) (1095 only)

The 3330/1095
plugs use what is called a “projected insulator,” which is found
in many NA cars, including many Hondas. Projected insulators have higher
chances or ‘blow outs’ associated with its design and shape. And if you
would compare a stock plug along side a projected insulator plug (3330),
you’ll notice it’s a tad big longer than usual.

The 6097/1283
plugs integrate the projected tip design the 2JZ calls for. These
projected tips will run about 10-20°C hotter than regular plugs (which is
why people are complaining)… but this is perfectly normal, and what is
required by the motor for the most efficient combustion. You want the
combustion chamber temps as high as possible, without preignition and
detonation. Having too low of a combustion temp will even in fact make the
engine lose HP. The ‘tan’ and ‘greyish’ color people see when using 6097’s
are telling them they are running a bit hotter, not as a result of the
‘wrong’ plug, but as a result of inadequate A/F tuning (lean).
“Hot” doesnt mean bad… “hot” is only ‘bad’ when your
preigniting. Some people dont understand that.

The 6097‘s,
unlike the 3330 also has a smaller center
electrode as well as a V-Groove. Having a smaller diameter electrode will
help the spark flow more efficiently with less chances of blow-outs and
missfires. Think of the spark as water flowing in a narrow steady stream,
as opposed to a wide stream with wild and uncontrolled rapids. The
V-Groove also helps combustions by directing the spark towards the edge of
the electrodes, bringing it closer to the A/F mixture for a more efficient
burn. (If you’re a sparkplug guru like me, you will notice a difference
with these plugs as a result when you try to J-gap and index them w/ the
V-Groove).

All these reasons make the 6097/1283
a better plug overall. Perhaps the only negative effect of the 6097’s is
that they dont last at all…especially if your A/F isnt properly tuned.
Running too rich (like most BPU’s do) will quickly foul these plugs in a
few thousand miles. A plug with a standard and wider diameter electrode (3330)
will withstand this a little better, but the “right” plug with a
standard electrode would perhaps be the BKR7ES
(and not BCPR7ES)… unfortunately, NGK does
not manufacture this plug here in the US, and the 3330
would be the closest match. The guys who originally discovered the 3330‘s
in our cars probably took this into account, and also the fact that unless
you order directly thry NGK (Monarch)…
you’ll never even have heard of the 6097/1283‘s.

I hope this “clears up” all
the confusion and misconceptions.

-Jeff L.
SupraTurbo527@aol.com