Duesenberg
Model SJ

Why it matters

The SJ was the factory-supercharged Model J, and only about three dozen engines received the centrifugal blower. Raising output from 265 to 320 hp, it made the fastest American luxury cars of its era even quicker.

How rare is it?

Six separate kinds of rarity – never combined into one number.

Each kind of rarity is rated separately and never combined.

Photos

Exterior, interior and detail photos with their licences.

• Duesenberg Model SJ (Wikimedia Commons: Duesenberg SJ)
  Photo: Steve Ginn from Western Washington, United States · CC0 1.0
• Duesenberg Model SJ (Wikimedia Commons: Duesenberg SJ)
  Photo: Daderot · CC0 1.0
• Duesenberg Model SJ (Wikimedia Commons: Duesenberg SJ)
  Photo: Dennis Elzinga · CC BY 2.0

Production

Every figure says what it counts.

Independent counts (e.g. engine and colour) are never combined into a calculated figure. Surviving examples are never presented as original production.

History

Duesenberg offered a centrifugal supercharger for the 420 cu in twin-cam straight-eight of the Model J, lifting rated output to 320 hp. On the SJ the blower was permanently engaged, and RM Sotheby's notes it brought the cars closer to 140 mph, about 20 mph more than an unblown J. Supercharged engines were fitted to a range of coachbuilt bodies, such as the Brunn Riviera phaetons commissioned for the 1933 New York Auto Show, one of which (J-525) was supercharged.

Technical specifications

Engine

Transmission & drivetrain

Chassis, body & dimensions

Performance

“Not yet verified” means no source has been checked for that value yet. Nothing is estimated to fill a gap.

Identification guide

How to tell an original from a replica or later conversion.

The SJ is the supercharged Model J: it has a centrifugal supercharger and external chromed flexible exhaust manifolds, the dramatic tubes that became its signature. The engine needed complete disassembly to take tubular connecting rods when converting a standard J.

Sources

Each number links to the exact facts it supports.

1. 1
   Old Cars Weekly – Beautiful beast: a supercharged Duesenberg Model SJ Level C

   • 36 Model J engines fitted with the factory centrifugal supercharger

   Accessed 2026-11-11
2. 2
   1935 Duesenberg Model SJ Convertible Coupe by Walker-LaGrande – Amelia Island 2013, lot 137 Level B RM Sotheby's · 2013

   • DOHC inline eight-cylinder engine with centrifugal supercharger
   • three-speed manual transmission

   Accessed 2026-11-11
3. 3
   Supercharged Duesenberg Model SJ Level C Angelo Van Bogart · Old Cars Weekly · 2010-08-10

   • 420-cid straight-eight engine
   • centrifugal supercharger
   • boosting output to an incredible 320 hp

   Accessed 2026-11-11
4. 4
   1930 Duesenberg Model SJ Convertible Victoria by Rollston (St. John's 2012, lot 158) Level C RM Sotheby's · 2012-01-01

   • 420 cu. in. 32-valve, DOHC straight eight-cylinder engine
   • 142.5 inches for the "short" chassis and 153.5 inches for the long one

   Accessed 2026-11-12
5. 5
   1934 Duesenberg Model SJ Speedster in the style of Walton (St. John's 2011, lot 143) Level C RM Sotheby's · 2011-01-01

   • 320 hp at 4,200 rpm

   Accessed 2026-11-12