20/06/2026
📣 The Judson supercharger is one of the most iconic aftermarket kits ever produced for the air-cooled Volkswagen Beetle. It was marketed in the 1950s and 1960s by Judson Research & Manufacturing Co. of Conshohocken, Pennsylvania, and allowed a significant increase in performance without opening up the engine.
🛠️ How it work
The Judson is a sliding-vane positive-displacement supercharger. It is driven by a belt connected to the crankshaft and compresses the air-fuel mixture before it enters the cylinders. 🌪️⛽️
📖 Typical features:
* Boost pressure: around 4–6 psi (0.3–0.4 bar).
* Power increase of 30–40%.
* Use of the original carburetor, modified, or a dedicated carburetor.
* Lubrication via a small oiler (“Marvel Mystery Oiler”) that meters oil droplets into the intake to lubricate the vanes.
Beetle versions
Kit were produced for:
* 1200 (36 hp)
* 1300
* 1500
The kit included:
* Judson supercharger.
* Specific intake manifold.
* Pulleys and brackets.
* Modified carburetor.
* Marvel Mystery oiler.
* Cylindrical air filter with “JUDSON” lettering, now a highly sought-after piece.
🏁 Performance
On a 1200 with 36 hp, it was possible to achieve approximately:
* 45–50 hp.
* More low-end torque.
* Better acceleration and higher top speed.
👍🏻 Advantages
✔ Vintage look and period-correct for a 1950s–60s-style modification.
✔ Installation without internal engine modifications.
✔ Very smooth power delivery.
👎🏻 Disadvantages
✘ The vanes wear out and require maintenance.
✘ Produces more heat.
✘ Requires carefully tuned fuel mixture and ignition timing.
✘ Original spare parts are rare and expensive.
