Maximum torque from a straight 8

straight 8

A mechanical engineer friend of mine told me one time that peak torque and horsepower curves cross paths at a number like 5200 RPM. Since then, I've looked at dyno sheets, and that seens to hold true. When we dyno'd our Salt Flats engine, that was pretty close. 450 HP @453 Ft Lbs @ about 5200. Don't know the actual physics, but look at the dyno charts, and it appears close. Doug
 
The factory service manual for a 1940 320 inch engine says it develops 269 lbs of torque at 2000 rpm. Horsepower is 141 at 3600 rpm. A 1948 engine is basically the same as the 1940 but probably develops a bit more in each category. Just for comparison, the 248 engine puts out 203 lbs at 2000 rpm and 107 HP at 3400.
 
Maximum Torque

I'm asking because I have a rear with a ratio of 3.42. I feel if I'm going to put those gears back in after replacing the bearings. It would be most beneficial to have a ratio to give the engine it's maximum troque at highway speeds. With the 3.42 ratio it would put me in the neighorhood of 2400 RPM's at 65 MPH. When I first bought my Buick it had those gears in it, and I was getting 18 miles per gallon on my fuel mileage on the HWY. Not realizing this ratio is putting the engine right near it's maximum torque. Now I have the 4.10 ratio in the rearend, and I get 12 miles per gallon with the engine truning around 3200 RPM's at 65 MPH. Big difference! With the 3.42 ratio it cruises really nice on the HWY, now all I have to do is find bearings for it and I'll be in business again. Thank you both for the reply
 
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