Quote:
Originally Posted by Boss330
I know that the brakes generates more heat/energy braking the car down from higher speeds. But it wasn't the brakes I was asking about, it was the engine (as that was one of your concerns).
To reiterate my question, do you still believe that the engine in a ///M car isn't suited for track use? And if so, why?
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Like I said, it's all the moving parts, particularly the pistons and flywheel that would be affected in the engine. More work is being done by the engine in the acceleration phases than if it was just at a constant speed. Getting the energy of the car up to the requirement for a given velocity requires work to accelerate the mass of the car. After it has gained speed, it only requires additional energy to counteract friction and air resistance. The cornering requires the car slow down and speed up, repeatedly. This stresses the moving components much more than if they were just moving at a constant fixed rate.
Of course you know that city driving you get less mileage than highway and this is the same principle. More work is done by the engine in stop start or speed up and slow down than just running at constant speed. It is this additional work that dissipates the greater power and also subjects the components to dynamic stress.
Higher RPM in the lower gears are required to accelerate the car to a given velocity. You don't run the car at the top of the power band in the stretches nor would you on the highway even at 120mph. In order to get the car to the high speed, the engine must rev higher in the powerband and it must do it repeatedly when tracking the car. This puts more stress on the engine than if you were just running it up to say 120mph and leaving it at 3500 RPM in 7th gear for 30 minutes or an hour.
So yes, the engine is subject to much greater stress due to tracking because I am sure the average RPM is much higher. That is reflected in the lower gas mileage due to the greater amount of power dissipation/consumption.