At what point do you need colder spark plugs?

[Andy13186]

What determines optimal spark plug heat range? At what point do you need a colder plug on e85? How about on boost + e85? Is the optimal spark plug heat range determined by anything specific like RWHP, boost pressure, or type of fuel?


How many heat ranges colder than stock spark plugs would be needed if 800 rwhp on e85 supercharged is the goal?

Thanks for any replies or comments.

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[markmurfie]

The optimal heat range is the one where your plugs don't foul out prematurely, but also don't cause preignition or detonation. Best to start cold and go from there or just replace/ clean them often.
If you are getting fouled plugs less than every 10k you probably could run a hotter plug.
E85 is very resistant to preignition and detonation, running hotter plugs, as in one heat range colder instead of two, with it will give you a longer plug life and more consistent results during its life, with out having to clean/ replace them too often.

It also depends on how you use the car. If you have 800 hp but sit in a lot of traffic, your plugs will foul out quicker. If you track you car and the engine spends as much time at WOT as it does at idle, you can run the colder plugs and they wont foul out.

 

[Mustanggt5.02011]

The only time you need a colder plug is when you go boosted. Other then that, you don't need it. This includes NOS as that increases manifold pressure and combustion.

 

[beefcake]

yep, until you boost or nitrous, your good

 

[Southview]

You Need cooler plugs when your engine starts sweating bad.

 

[qwiknotch]

best plugs for boost?

 

[3beeps]

best plugs for boost?

NGK 6510 seems to be the most often recommended. That's what I used with my D1SC and what I use with my twins now.

 

[Zelek]

I had this same question too when it came to boost. The "when" is it necessary to have them? This helps for sure. Nothing like buying a whole bunch of unnecessary parts unless there's reasoning for it. That's one thing I don't want to do with this car.

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