Estimated 1933 Plymouth De Luxe Performance
While the my car was disassembled I became curious as to how fast it should be when it was back together. I have not seen contemporary performance numbers based on actual road tests published by American magazines. Apparently that type of new car coverage came later.
There some numbers from British magazines but they are only valid for the car equipped with the small bore export motor and quite a different final drive ratio. [Motor 1933] states that the Chrysler Kew Six (basically a Plymouth) with a rear axle ratio of 4.875:1 was capable of achieving 56 MPH from a stand still in 21.4 seconds. It also lists a top speed of 70.87 MPH. But that engine was also about 13% smaller than the US version.
The AllPar - Chrysler, Plymouth, and Dodge car information web site has an article [AllPar 2001] that includes more British performance information from the era. As noted above, the United Kingdom version of the Plymouth differed mechanically from the US version, so it is not clear if this information is applicable. [AllPar 2001] cites Auto Guide as the original source of data. The values for Plymouth differ significantly from those reported by [Motor 1933]. In any case, there comparison of the 1933 Plymouth, Chevrolet and Ford shows:
|Ford V-8 Tudor||Chevrolet||Plymouth Six Coupe|
|0 to 40 (seconds)||12.4||17||11.9|
|0 to 60 (seconds)||29.7||39||29.0|
|Top Speed||83 MPH||65 MPH||85 MPH|
Hewes 1942 pg93] lists the assumed acceleration values for passing maneuvers. Reformatting the numbers into a form more suited for this topic and doing some simple arithemtic we have:
|Estimated time to
|Estimated time to
So the highway engineer of 1942 assumed that the average car would take nearly 1⁄2 minute to accelerate from 10 MPH to 60 MPH. If the 1933 Plymouth could accelerate from 0 to 60 MPH in 29 seconds as reported by [AllPar 2001] then it was a very good performer in its day.
A Computer ModelThe above information I found long after becoming curious about this item. And being a programmer by trade and a mechanical engineer by education, I set up a simple numerical integration model and fed it some basic data regarding the vehicle characteristics. Naturally, as with all computer output, this is subject to the GIGO (Garbage In, Garbage Out) situation. A lot of simplifying assumptions were made.
|0 to 60 Time:||>18 seconds|
|1/4 Mile Time:||>20 seconds|
|Top Speed:||<77 mph|
Now that the car is back together, I have not tried to push it yet and find out how accurate my estimates were. But based on casual about town driving and a couple of trips where I ventured on to the freeways at speeds of up to 60, I think the model was reasonably good. The top speed is probably about right. The acceleration numbers are probably optimistic.
Maybe some day I will get out with a stop watch and check the model for accuracy.
|Max Power||70 hp @3600 rpm||Automotive Industries, November 12, 1932|
|Final Drive Ratios:||High:||4.375:1||Owner's Manual|
|Weight:||2,700 pounds||Automotive Industries, November 12 ,1932|
|Wind Resistance (typical)||40 hp @ 70mph||Automobile Digest, February, 1935|
|Rolling Resistance (typical)||0.2 hp /mph||Automobile Digest, February, 1935|
|Gas consumption (typical)||>1 GPH per 10 hp||Automobile Digest, February, 1935|
Assuming a late 20's and early 30's L head motor design have similarly shaped horsepower curves, then using a curve for the Model A (from How to Restore Your Model A) and scaling it for the difference in peak power and the RPM at which the peak occurs:
|Model A||'33 Plymouth|
Further assumptions: Weight of driver, fuel, etc of 300 pounds.
Shift time of about two seconds (no synchromesh). No "red line"
limit, shifting based only on horsepower. Acceleration run
continued until no substantial increase in speed possible, that is
until maximum vehicle speed is reached. Since a gasoline motor puts
out no power at zero RPM, it is assumed that for road speeds that
would require RPMs below 500 (idle) that the engine is running at
500 RPM and the clutch is acting as a 100% efficient torque
|Time (sec)||Speed (MPH)||Distance (feet)||Gear||RPM||HP|