Turby

I know alot of you have expressed the BPR7ES as the best, but why? I did some reasearch on NGK's website and came up with the R4304A as a good plug, although they are a "RACE" plug.... They also go to say on the site, for every 75-100 HP increase, 1 step colder heat cycle is needed...... so if my motor is making 5XX hp this just seems like a better choice. I would love to dyno both, but dont have the time or $$ to waste myself. Special Tool? Anyone???

Turby

Oh, and the BPR7ES are OEM to a Polaris snowmobile! Sorry, thought that was funny......

special tool

Turby - if Beantown means Boston, YOU cannot go more than 1 size colder, or you will foul plugs in the cold.

The Polaris probably takes a BR7ES - that is the famous 2 stroke plug, very similar number.

jimbo1111

Yep. My polaris is a four stroke and it has a BR7ES. Just changed it 3 days ago.

Turby

ST ......I never even considered that..... "DUH" yes I am in Boston. She is a spring-fall car anyway, but knowing I shouldnt drive her in the winter kinda sux.

Skunk Workz

Only difference in the BPR7ES and the BR7ES is that the "P" has a protuding electrode. Try the "P" in a Polaris and you'll see the difference when the piston gets torpedoed by the plug.

special tool

That's right!

Turby

What about the BPR9ES or BPR8ES...... 8 is one colder han the 7, and 9 is one colder than the 8 right?

special tool

Yes.
Are you having high EGT on the 3 liter?

Skunk Workz

8's might work in the summertime if it's really hot...9's are generally too cold. Tool said it,there's NO advantage in the colder plugs if they foul. The higher number,the colder.

Turby

Yeah, I think its time for some better management.......... Was hoping plugs would help. Skunk, thanks for the clarification on what the #'s mean........ And I'd be lying if I told you I didnt foul a plug here and there already.