Do Colder Plugs Affect Driveability?

[habitatguy187]

I've never thought about it until a buddy brought it up yesterday. We get colder plugs when we're running more boost, but wouldn't that be harmful to the cylinders during normal driving conditions? He was suggesting irridium plugs for this, which everyone says not to use, but it has me wondering.

And to be truthful I haven't done any other research on this, thought it'd be a good topic to discuss.

 

[PieEyedPiper]

I've got no science to back it up but I would imagine that the "colder plugs" are still plenty hot enough to operate as intended under normal driving conditions. I might even suggest the difference in output from one heat range difference would have to be minuscule to have the only difference in operation noticed in high boost applications.

If you're running too cold of a plug it will just simply foul out sooner. I wouldn't waste a worry.

 

[toofast82]

I've ran 7es plugs for years in real daily driving with no issues. It is going to lower your combustion temps some which may result in a not/barely noticable fuel economy loss and slightly richer a/f ratio.
But like I said, it will not cause any type of drivability "problems", but really wouldn't bother unless you're running 17-18psi+
I also began to run the non-projected br7es, which seemed to be a tad less knock prone on 93oct.

 

[AjWit]

A hot plug does not make an engine run hot, nor a cold plug make an engine run cold. A hot plug merely means that the insulator nose will run hotter and keep itself clean by burning off deposits.

A plug which is too cold collects carbon and fuel deposits on its insulator, which leaks energy from the ignition, causing loss of power, if allowed to continue it will foul (not spark at all).

The length of the insulator determines the heat range of a plug. Use the hottest plug that doesn't burn the tip of the center electrode.

If your plug is too cold, you will see deposits on the nose of your plug.
(not my wording, got it from an automotive book)
but i hope it helps.

 

[toofast82]

A hot plug does not make an engine run hot, nor a cold plug make an engine run cold. A hot plug merely means that the insulator nose will run hotter and keep itself clean by burning off deposits.

It has no real effect on the engine's coolant temps, but they can have an effect on cylinder temperature
Bottom line is though, that the 7es plug is harmless for daily driving and can take you pretty far power wise before needing an even colder plug.
I have no personal experience with 8es and above for daily driving so will not comment if there is any issues. I'm sure you could tune out any potential problems though very easily
A hotter plug as you said, will help keep the plug freer of depostis from the hotter burn. But if you want to clean the deposits and carbon, going WOT usually helps do that

 

[TRBOBLU]

I have noticed no difference in driveability using colder vs. hotter plugs on gasoline. I did however switch to hotter plugs when running E85 because of cold start issues. If you are on gasoline and running higher boost colder plugs are fine and I recommend them.