Originally Posted by keavze
just wondering why offroad .21engines usually use a much hotter plug than onroad .21engines?
i've seen people using os p3 for their offroad engines but when it comes to onroad engines they'll use a much colder plug like nova#7. both using 25% nitro, air temp about 77F and humidity about 70%.
also, which is more damaging? over lean HSN or over lean LSN?
the only thing i can really think of about the onroad plug thing is the way the throttle is applied , the weight of the car and the fact that they are always towards the upper revs of the engine . off road cars are definitely easier to tune with the hotter plug , our offroad engines IMO have a much higher torque load that they transfer to the engine so they like to use a hotter plug to give an advanced timing to the engine .
over lean hsn because thats where your engine is revving and needs more oil
not saying that a lean bog off the bottom is a good thing but its not just caused from a lean lsn . usually high temps or wrong pipe