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:
The car also appears in a car show video. Click here and move the timer bar to 14:50
Finally, for more information here at Curbside classic, check out these two links:
Wow, Twin H plus Twin S – as in HHoly SShit! That would be a fascinating car to try out on the track somewhere. The next question is how well it would hold together under load. I recall reading that the Hudson 308 tended to be hard on head gaskets, but I could be wrong. Studebaker’s supercharged engines did so well because almost everything about that Stude V8 was so ungodly overbuilt. I know the Hudson 6 was stout, but there is the kind of stout that holds up with normally aspirated twin carbs and the kind of stout that would stand up do dual superchargers.
I am not schooled in fluid dynamics, and wonder if doubling the supercharger volume actually provides double the boost as opposed to, say, a single supercharger with a Y in the plumbing to feed the two carbs.
This will probably be the coolest thing I see this week. Thanks, Dave!
I think there’s a lot of factors in how much boost and power would actually be made here. I’d guess that pre war centrifugal superchargers aren’t particularly efficient for starts. In the build thread it’s said to be getting 5psi boost.
At any rate the primary goal here is probably the wow factor and the visuals.
Given that there’s no pressure box to contain the inherently (air)leaky carbs, I doubt this one generates a whole lot of actual pressure. Blow through supercharging requires either special air-tight carbs or air boxes around the carbs, like the ones used on the Studebaker (below)
I believe this type of supercharger is essentially a centrifugal fan, while the more commonly-seen twin screw compressors are essentially a positive displacement air pump. The centrifugal fan design is more forgiving since the volume of air delivered will drop off as the resistance (aka back pressure) rises instead of over pressurizing things as an actual compressor can. The trade off is they can’t create as much pressure in the first place.
As far as how much air they move, that’s as much a function of pulley sizes as anything. I suspect the idea here is beauty as much as function, but there may also be some efficiency gained by turning two fans slower instead of a single fan fast.
That is just awesome! And I love what he used for shaft couplers. A job very well done!
Wow. Thoughtful engineering…this is a work of art AND science.
Wow. Would this car have had power steering originally? It’s beyond-professional work all around.
” Would this car have had power steering originally?”
Never say never, but the only cars using power steering in the early fifties were very high end (Starting with the Imperial in 1951). If the car came with power steering, it has been upgraded using more modern parts-
The power steering pump used in this build is a Saginaw unit (GM), which came out in the sixties and is as common as dirt. Because of this, it’s the go to unit for retrofit projects. The build also uses a modern air conditioner compressor, indicating the owner upgraded all the mechanical systems on the car.
Chrysler and Imperial were first with power steering in 1951 and the big GM cars like Cadillac, Buick and Olds had it available for 1952. A quick peek at the 54 Hudson brochure says nary a word about power steering (though they tout the needle bearings in the steering gear that make for “fingertip” steering). I don’t think they got power until the AMC models.
That’s kind of what I was thinking. Thanks for doing the research though.
Maybe it was a mid year introduction?
Consumers’ Research Bulletin tested a Hornet in their May, 1954 issue, and commented: “Steering was precise, and the power steering required enough initial steering wheel effort to give the driver a satisfactory sense of control over the car; steering ratio, high (slow response requiring a large number of turns of steering wheel). With the engine stalled, the steering effort required was no greater than that of the same car without power steering.”
Astonishing. He’s created the same type of mechanical beauty found in the original Duesy or an E-Jag.
+1.
Whether its truly affective at raising the performance or not so much, that is absolutely a work of design engineering art! Kudos to the builder for the vision and perseverance to make it a reality!
In the video they owner estimates “200hp plus”. Hemmings shows the stock Twin H-Power 308 at “160hp at 3,800 rpm, with 260-lbs.ft. of torque at 1,800 rpm.” My guess is that those two superchargers turn that inline six into a torque monster.
I like it, twin turbos would probably be an easier build but this is a very cool idea.
Some amazing work there. It’s a shame it has to hide under a hood. It’s the sort of build that would be right at home in some kind of hotrod with an exposed engine to show off the artistry.
If you open the video link, you’ll see the owner drives it sans hood to better display his work. Not real practical for most regions, but that’s just one more reason that SoCal is Hot Rod Heaven™.
Very nice find! This car is fantastic. It still appears to be of the era, but actually has a host of subtle modern upgrades to make the car more enjoyable. It looks like he has the added P/S, A/C, upgraded engine fan, headers, an alternator and also a modern starter. I am sure there is more hidden beneath. While originality is great, subtle modernizing and improving a car without destroying the vintage feel is right up my alley.
FWIW, according to the owner of this car, he sealed up the carbs and he claims that it has 4 PSI of boost at about 4000 RPM.
Along the same note, locally there is a ’36 Ford that has a turbo-charged Flathead V8. The owner appeared to be in his 70’s and did all the custom fabrication himself. He claims it moves out very well.
carbs should be mounted on intake of blower not into carbs ,I installed a graham
supercharger on a 1933 Essex terraplane 8. in. 1957 with a similar drive system but mounted. carb on top as it should be