Spark plug heat range and it's affect on TR's...

[streetknight]

Can someone explain it to me please. I usually run AC plugs. R43TS when running low boost and R42TS when running over 22psi of boost. I do this because I was told to when I first got the TR years ago, but never really understood why. Does this help with knock, EGT's, etc?

thanks

 

[1quick6]

This might be a good read:

NGK.com

That gives a nice description of how heat ranges affect the ability of the plug to transfer heat. It's all about keeping the firing head of the plug happy given your state of tune, i.e. avoiding preignition because the plug is too hot.

 

[richkcmo]

very interesting.

thanks for the link.

 

[granatl]

My Chevy 350 TBI runs the same plugs as our Buick. When I added an E-85 kit, I noticed that the truck REALLY stumbled until it got up to operating temperature. I then put in 2 heat ranges hotter and that helped quite a bit.

So what I'm trying to say is simply is you're burning E-85 (below boost levels) you might need to go to a hotter plug to get the car to idle decently.