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Originally posted by camaroman1181:
i too have a little engineering degree and i understand all the math being thrown around...i'm just saying that i believe we are not taking all things into consideration with simply the math being used thus far.
i too have a little engineering degree and i understand all the math being thrown around...i'm just saying that i believe we are not taking all things into consideration with simply the math being used thus far.
Every little tweak that we make to our engines does something to its power curve, its torque curve, and its efficiency curve. (There's actually a lot of stuff going on in even an mildly modded engine.) It is entirely possible that the result of a series of engine, intake, and exhaust mods could be the sliding of the peak efficiency point down the RPM range. This actually makes sense because most of our engine mods are actually focused around minimizing energy losses, thus boosting engine efficiency as opposed to just burning more fuel.
That all being said, remember that the engine accessory belt does take more energy to drive at higher rpms. (This is why so many guys use underdrive pullies to slow down the belt and yeild more usable engine power at a givn rpm.) So, in order to be more efficient at 3,000 rpm than 2,000, the engine would have to overcome all the additional accessory belt drag (and any other internal drag forces) seen at the higher rpm and still be able to get more power to the ground for a given amount of fuel.
The very definition of efficiency is the ability to get more power to the ground for a given amount of fuel. Our emmisions controlled engines ALWAYS burn the fuel to create the maximum amount of power for a given amount of injested air, so this debate all comes down to how much energy is lost before the power makes it to the wheels.
In my car with a basically stock engine (and automatic transmission), the higher my revs, the worse my economy. My 202,000+ miles of data shows that my best mileage occurs somewhere between 60-70 mph and cruising at higher speeds (75-80 mph) costs me ~1-2 mpg. Maybe once I finally install a CAI, or if I bolt up a cat-back, install headers, and reprogram the computer, that all will change.
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