When I got my car it had bur6eq plugs in it. Leading and trailing. It also has an hpi ignition box. The turbine is a t88-33d, 6x1000cc injectors, and boost is set at 1.4 bar. Is that safe with the 6 heat range plugs? There was also 3 other sets of dead plugs on the passenger floorboard, 9's, 10's, and 11's. Thanks.

-Destin

 

6L and 8T is stock for the 20B. Mine had 7L and 9T and was all carboned-up inside.

Try a set of 7s in leading... maybe. I bet RETed would know for sure.

 

Noticed your location is Japan. The land of the traffic jam.

The BUR6EQ plugs are a necessary evil to combate the low speed your 20B powered JC Cosmo is forced into. Although I am surprised it had the 6's in the trailing aswell.

These hotter plugs wont foul as quickly & will give better burning, thus fuel consumption.

The different heat range plugs in the glovebox of the car may have been for the previous owner to use when the occassion suited him. EG, highway driving

Personally, I run BUR6EQ + BUR8EQ for my 20B powered Cosmo as the lower RPM from the big block rotor requires hotter plugs. Gives me better running compared to the 7+9 combo seen in the manual gearboxed FD RX-7

 

I noticed while @ Gotham Racing this week end that Steve also had 6's in his motor

 

How would having 6's affect high boost, well 20 psi?

-Destin

 

Depends, if you have 6's in the trailing then at 20PSI, its "ping time"

6 + 9 may be a different story.

With that type of boost, I would be using a 7+9 combo, maybe even colder depending if its street or race driven

 

What about 9's all the way around and 1 Bar boost? Too cold?

 

9's in the leading are way too cold if your running on the street. Leading plugs will foul after just a thousand km or so, Because of improper burning, trailing plugs wont be far behind.

1-bar boost on the street. Use the 7+9 combo. Mazda didn't spend millions getting that combo sussed out for nothing mate...............REgards

 

I find running all 9's is perfectly fine for most people.
Only if you do the most heineous stop-and-go traffic jam driving will the 9's foul.
We run all 9's in our 13B's.

BTW, most 20B's I've seen are running the SD29 / 31(?) spark plugs when shipped.


-Ted

 

Japanese guy told me to run all 11's for the dyno tomorrow. I think all 9's would be okay for normal driving and the occasional high boost. I'll post the dyno sheet tomorrow.

-Destin

 

i usually run all 9's, but for tuning mine i went with 7's and 9's. they are still in it, and working fine