Running 3000 rpm will not use any more fuel to produce "X" horsepower than at 2000 rpm to produce the same "X" horsepower!!! Maybe in neutral, but not when trying to push against the 70 mph headwind.
The throttle setting required to produce the required horsepower against the 70 mph headwind will be greater at 2000 rpm than at 3000 rpm--that is part of the horsepower forumla PLAN.
P is pressure produced by the explosions; L and A is the length of stroke and the area of the bore ( or together the Size of the engine); and N is the NUMBER of times these explosions happen per mimute or RPM!!
Increase ANY of these letters and you increase horsepower, decrease Any of the letters and you decrease horsepower.
The throttle setting is determinimg the PRESSURE portion of the formula in the opening sentence. How about this-- 3000 rpm will not use more fuel when in neutral than 2000 rpm will use when in any driven gear! RPM aint got hardly anything to do with fuel consumpton. Its the load or demand placed on the engine that determines fuel consumption.
This is why all F.I systems must have manifold vacumm inputs to tell the computer the load on the motor-to determine the correct a/f mixture for that load at the amount of air flow being let in by the particular throttle setting.
If you would or could find a dyno chart that also graphed the mean brake specific (whatever the engineering term) curve along with the hp and torque curves, this would be easily shown. On a dyno chart, all the numbers are achieved with wide open throttle settings, because the whole reason for the dyno run is to see what the MAXIMUM HP/TORQUE is for the test engine, many times this fuel consumption graph is included. If I remember correctly there are some shown on a few of Tom Lowe's tests.
The total amount of hp needed to maintain 70 mph IS PRODUCED only at that the particular throttle opening needed to keep the vehicle at 70 mph, no more, no less. And unless said vehicle is powered by Cushman Eagle, then it will never be a full throttle setting.
Since nobody stated that excessive rpm is wearing out the bearings and somebody did state that excessive rpm IS wearing out the bores & rings, let me state that the before mentioned 83,000 mile 235 engine went back together with STANDARD rings and original pistons- they were also oiled by the same unfiltered non detergent oil. Since the cylinder bores are primarily oiled by the oil slung off of the rod bearings, they recieve better oiling at the higher rpms.
