Simanaitis Says
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DUESENBERG HORSEPOWER—BUT WHICH ONE?
CLASSIC DUESENBERGS were powerful automobiles, but how powerful? How does horsepower circa 1930 compare with today’s measurement of automotive power? Yesterday’s tale at this website continues.
A selection of Duesenbergs; the SSJ was a Short Supercharged version. This and other images from “The Duesenberg J & SJ,” by T.R. Nicholson, Classic Car Profiles 1-24, Profile Publications Ltd., 1966.
When E.L. Cord bought the Duesenberg Motor Corporation in 1926, he gave Fred Duesenberg a carte blanche to build the best car in the world. The Model J, launched at the 1928 New York Salon, fit the bill. All bodies were custom-built by bespoke coachbuilders selected by the purchasers. Model J chassis were available in two wheelbases, an imposing 142 1/2 in. and even longer 153 1/2 in.
To put these in perspective, even at the height of U.S. car exuberance in the late 1960s, a wheelbase of 127 in. was considered lengthy. Today’s S-Class Mercedes-Benz sedan has a Long Wheelbase version at 124.6 in.
Duesenberg built an extended chassis, at 178.0 in., for a Bohman and Schwartz-bodied sedan, specially commissioned as Throne Car for black evangelist Father Divine. But his is another tale, for another day.
Duesenberg Model J powerplant. Image by Larry Stevens.
The Model J’s inline-eight displaced 419.7 cu. in., 6878 cc, and had double overhead camshafts actuating four valves per cylinder with hemispherical combustion chambers and dual coil ignition. This engine wasn’t the first with any of these particular features, but its combination of size and sophistication gave it real panache—and an advertised 265 hp. With centrifugal supercharging added as a 1932 option, the Model SJ Duesenberg claimed 320 hp.
The Model SJ’s centrifugal supercharger, best seen in the right photo, produced a maximum boost of 5 psi.
Duesenberg performance was superlative as well: The supercharged Model SJ claimed 0 – 100 mph acceleration in 17 seconds; 104 mph maximum in second gear; 129 mph in top. This was 17 years before the Jaguar XK-120 sports car made news with The Motor magazine’s recorded top speed of 124.6 mph.
Were these Duesenberg J and SJ horsepower figures legit? Here’s some chat that has me thinking they were somewhere between SAE gross and “horsepower at the brochure.”
In the Model J’s defense, the engine evolved from Duesenberg’s racing engines of the 1920s, one of which powered the 1921 French Grand Prix winner. On the other hand, gasoline of the era supported only a modest 5.7:1 compression ratio. The Model J’s specific output, a standard measure of engine performance, is calculated at 38.5 hp/liter. The SJ’s, supercharged to a modest 5 psi, works out to 46.5 hp/liter.
Today, these are nothing to write home about. High-performance engines produce well over 100 hp/liter. Even a Honda Accord sedan’s 3.5-liter V6 produces 278 (SAE net) hp, 79.4 hp/liter. Yet the Duesenberg far outshone its competitors of the early 1930s. Cadillac’s 7.4-liter V-16, built between 1930 and 1937, was rated at 165 hp, 22.3 hp/liter.
Chris Summers, the Auburn Cord Duesenberg Club’s Duesenberg historian, wrote of the Model J engine as delivered from corporate sibling Lycoming: “Dyno-tested, they only produced around 200 hp. The result was that, once every engine reached Indianapolis [Duesenberg’s home facility], it had to be rebuilt from the ground up, tuned and tested again to produce the power claimed of it before it could be installed in a car.”
Wrote James C., in an Amazon.com review, “The stock J engine never developed 265 hp, more like 165 – 183 hp on observed dyno tests of four engines. The SJ never put out anything like 320 hp, even with the dual carburetor setup; 215 hp on a personally observed dyno test of a perfectly restored engine.”
I recall that car enthusiast extraordinaire Jay Leno has a Superflow dyno and several Duesenbergs. Maybe he might pull out one of the powerplants and dyno it. Or maybe he already has. ds
© Dennis Simanaitis, SimanaitisSays.com, 2015
Simanaitis Says 
If Jay is unwilling to remove an engine from one of his Dueseys, perhaps he could take advantage of his apparent good relations with the Petersen Museum and its esteemed Curator, Leslie Kendall, to borrow their free-standing J engine. What I wouldn’t give to be present for such an experiment!
I recently had a correspondent ask about the Father Divine “Throne Car” and reopened my Duesenberg blog:
https://carmacarcounselor.wordpress.com/2015/05/25/duesenberg-pinacle-of-the-classic-era/.
I have since learned that the story of the two “400 hp” dual carburetor engines that did not belong to Ab Jenkins were actually in the SSJs loaned to Clark Gable and Gary Cooper. I was at Gooding & Co. when Charley Ross dropped the gavel on the Cooper car for a US car auction record $20 million. ($22 million with fees)
You and I have discussed the advertised v. actual v. taxable horsepower issue before and somehow I missed this blog. Well done!
BTW, James C. should have dyno’ed the Mormon Meteor’s engine. You don’t lap the salt flats at 150 in a big boat like that with 215 hp.