Curbside Tech: Dual Supercharged Twin-H Hudson Six

All engine photos are from the Owner’s Build post located in the Hudson Essex Terraplane Open Forum.


Paul recently (re)expressed his love for straight sixes in a post with a nicely warmed up six mounted in a ’37 Chevy. This reminded me of a very special Supercharged Hudson six I ran across several weeks ago.

The car showed up at the weekly car South Orange county car show, and rather than using modern components, it pressurized the intake passage using two pre-war superchargers. I didn’t have a camera, but I found some excellent information online (source sites linked at the end of this post).

This image shows the completed project, and Hudson fans will recognize the big Hudson 308 Cubic Inch Flathead six. The dual carbs identify this as a “Twin H Power” engine, but the piping running across the head and the pair of superchargers on the driver’s side of the motor are definitely NOT Hudson parts.

This ad shows the source of the supercharger- Pre-war Grahams used this centrifugal style supercharger to good result. It’s assumed Graham drew their inspiration from Duesenberg, mounting a smaller, but near identical unit.

The Graham engine used a draw through design, with the carburetors mounted on top of the superchargers. The Hudson uses a blow through design, perhaps because the superchargers are mounted further away for the block, increasing the length of the intake plumbing. Whatever the reason, the plumbing takes on the form of classic sculpture.

The build page includes many images of the project over time, starting with this image of the initial mock up (in wood). The owner states the project took him about 18 months, which seem unimaginable.

This image shows the initial test fit of superchargers in their fabricated brackets. Keep in mind these superchargers were NOT designed to be used in pairs, so the back plate on the first supercharger and all the driveshaft parts between the units are unique and fabricated for this build.

To wrap it all up, here’s the complete system. Note the oil lines under the superchargers, the opening in the mounting plate to clear the Hudson distributor, and the tight clearance between the rear supercharger and the starter motor. I just love these details- the builder had a vision, and worked tirelessly to form it into three dimensions.

This article is just a brief overview of the entire project- To see the complete build, click on this link:

Build Link

The car also appears in a car show video. Click here and move the timer bar to 14:50

Car Show Video

Finally, for more information here at Curbside classic, check out these two links:

Supercharged Graham

Hudson Twin H Power