Unpopular opinion: I used to think colder spark plugs were always better for performance

Back in 2019 I ran a set of heat range 8 plugs in my daily driver during a Kentucky summer, thinking it'd prevent knock, and my cold starts turned into a cranking nightmare for months. After a buddy pointed out my plugs were fouling from never getting hot enough, I switched back to the factory heat range 7 and the car ran smooth again. Has anyone else messed up their daily by chasing a track-only mod on a street motor?

2 comments

2 Comments

miles_perez2d ago

Man, I did the exact same thing with my Civic. Threw in some cold plugs thinking I was being smart, but my car bucked and stumbled every morning until I gave up and went back to stock. Realized the thing barely left the driveway for months, just short trips to the store. Learned the hard way that street driving needs heat to burn off carbon.

reese_garcia2d ago

Cold plugs are for track days, not trips to the store.