View Single Post
Old 04-08-2019, 02:01 AM   #2
Registered User
Join Date: Feb 2005
Location: It's a kind of magic.....
Posts: 6,277
Originally Posted by KRAM36 View Post
I've always used Bosch FGR-6-KQE spark plugs. I decided to try some NGK 94279 FR6AHX-S Ruthenium HX plugs because of people always commenting on the Bosch plugs having a prong break off on them, although I have not had that issue, but I thought I would ease my mind on it and go with the NKG plugs.

Plus with the mods done to my car and not knowing if the engine is running lean or rich (she eats a lot of gas though) along with NGK's claims on this plug, I figured why not try them out. I also only run Ethanol-free gas in my car.

With the Bosch plugs my cars temp gauge was always around 185° to 186°, even during the winter time. Last week I changed to the NGK plugs. I have gone for many drives since installing them, some pretty spirited and just normal driving and my temp gauge just barley cracks past the 180° mark now.

Is it possible that the type of plug you use can affect the engine temp like this?
Heat range of spark plugs refers to the rate at which the firing tip of the plug transfers heat to the cooling jacket of the cylinder head. "Cooler" plugs transfer it faster, "hot" plugs transfer it slower. This keeps the spark plug temperature high, which allows the plug to self clean and prevent fouling.

The heat range of a given plug should have little to no impact on the car's stead state coolant temperature, that is controlled by the thermostat.
Anything really new is invented only in one’s youth. Later, one becomes more experienced, more famous – and more stupid.” - Albert Einstein
JFP in PA is offline   Reply With Quote