Plugs too cold?

[Weyro]

What would be the effect if any, of running plugs that were "too cold"

Ive got Heat range 8's in my V, but im only running 1bar on TD04.

Cheers

[AdamB]

You'd prob get missfires, poor fuel economy, run rich etc.

Your grade is too cold for your setup, even heat range 7's are good till like 350bhp I'd say. You could run either 6's or 7's, but 6's would need replaced more often.

[Weyro]

ok thanks, i thought that too low a heat range would have caused misfires since the tip of the plug would get too hot?

how does it work out if you have say a 400bhp setup on grade 8 plugs, but you are just cruising along off boost?

[AdamB]

If the grade is too cold, the tip wouldn't provide sufficient spark voltage to ignite the mixture, hence run rich etc.

If your running 400bhp on cold plugs, I would guess and say you've switched from the dizzy setup to atleast wasted spark where the coil has a longer dwell period providing greater spark voltage, so even at cruise there will be plenty of voltage to ignite the mixture. You need to go colder because the extra fuel injected creates more heat and increases cylinder pressures, running a grade 6 plug at 400bhp will most likely drop the tip off the plug and make a mess of your pistons and cylinders.

CDI ignition doesn't have such problems, but expect to be changing your plugs every 3000 miles as they don't last long.

[Weyro]

ah ok thanks for all that info

[AdamB]

Anytime mate