Quote:
Originally Posted by Jim Huseby
Does anyone have figures or calculations indicating the HP required to push say a '30 model A coupe at 35 mph to 70mph in mph increments of 5? Assume conditions at sea level, 70 deg F., 70% RH with 35 psi in 475-500x19's and 600 wt gear lube at operating temp, no drag in brakes, etc.
|
By doing a search for Cd and frontal area I found data for many cars but nothing for old cars. By doing some seat of the pants interpolation it looks like it takes about 450 hp at the rear wheels to go 150 mph in a model A sedan.
We know from talking to many people that a model A with a slightly modified engine (so called touring) will go approx. 75 mph. These engines usually develop around 60 to 70 hp. With a couple of data points you can guestimate a curve.
I can tell you that the 450 for 150 is fairly close because the SBC in one of my A's (stock body 2 door) pushed a 38 Chev coupe 154 at Bonneville and it will go 140 by GPS on the stretch of road I have to test on.(still accelerating)
The wind noise and buffeting at 140 is quite loud even through a helmet and ear plugs.
I think the easiest way to get the data you want is to get one of your cars on a chassis dyno and get hp at a given mph. Then you can figure in the frontal area/Cd. This will get you practical data but a wind tunnel would be the last word.