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Opel Kadett Holzvergaser wood gasifier

The Opel Kadett City with wood gas generator


I restored the first wood gas generator at the beginning of the eighties. Since then, I have heard all kinds of stories about this technology. During the 1973 gasoline crisis, a Cadillac with a wood carburetor was on the road. There was nothing more to learn about it. But the dream of one day driving a car with a wood carburetor never left me.

Shortly before the petrol price explosion in 2005, I said to my employees that I would drive to work with wood instead of petrol if the price of unleaded fuel was more than CHF 1.60 per liter. When the prices actually exploded a few months later, I was somewhat forced into action. 

In spring 2006, I bought a nearly new 1200 Opel Kadett City automatic with 75,000 kilometers on the clock. I fitted a Wisco gas generator to this vehicle, which I had already had in my collection for a few years.

Walter Isendahl & Co. gasifier

Walter Isendahl & Co. gasifier


The 1947 WISCO gas generator for lignite and wood has a total weight of 80 kg, making it ideal for mounting on the 850 kg lightweight Opel. 


Originally, this gas generator was intended to be mounted at the front of the vehicle. However, for optimum weight distribution and road safety, I wanted to mount it at the rear.

Wood gasifier Holzvergaser Schema WISCO

The state of the art

As with the combustion engine, there is a point at which gas generators can no longer be developed further. This was the case with the gasoline engine at the end of the 1930s. With the exception of direct injection, everything was already in place, and no further fundamental improvements have been made to date - the optimizations have been achieved through modern materials and engine management. The development of the gas generator was completed around 1947. Thanks to its highly integrated and minimalist design, the WISCO is considered one of the most compact, efficient and lightweight gas generators.

Modernization of the system

The gas generator from Walter Isendahl & Co. is a welded construction practically in one piece. It is designed for the gasification of lignite and wood.

It is an absolutely minimalist design and is still state of the art today. However, I separated the construction into several parts and fitted the gas cooler with flanges. This made it possible to galvanize the gas generator.

The asbestos was removed. Various modifications were made to improve the ease of maintenance.

Opel Kadett Holzvergaser wood gasifier
Opel Kadett Holzvergaser wood gasifier

Support structure

The entire construction rests on a chassis which is connected to the Opel. The gas pipe is routed under the car into the engine compartment.



The fan is located on the right in the direction of travel. The gas outlet of the fan is at the front through the radiator grille.


The Opel has hardly been modified, with the exception of the hole in the radiator grille. But I only made this hole after I had obtained a replacement grille. This means that the Kadett can be restored to its original condition at any time.

Opel Kadett Holzvergaser wood gasifier
Opel Kadett Holzvergaser wood gasifier

Gas mixer and hybrid installation

The carburetor has been moved to the left. The Solex wood gas mixer can be seen on the right in the direction of travel. The gas is sucked in from the rear, mixed with fresh air and fed to the engine.

The ignition distributor can be adjusted by 15° from the cockpit to take account of the slow combustion of wood gas.


Instead of the radio, this car has two vacuum pressure gauges on the dashboard, from which the status of the generator can be read.


If required, the generator's grate shaker can be operated electrically via a toggle switch. Two additional Bowden cables for the fan and for adjusting the gas mixture during gas mode have also been installed.

Left: Underpressure after generator (is improved by grate shaking)
Right: Underpressure after fine filter (replace filter material if necessary)

Opel Kadett Holzvergaser wood gasifier
Opel Kadett Holzvergaser wood gasifier

Bet redeemed with a slight delay

The crazy idea became reality: the promise to drive to work on wood gas at a petrol price of over CHF 1.60 per liter was kept.

The car struck a chord with the times: due to the now astronomical rise in petrol prices, the car attracted a lot of attention from the public and the media. Even if this drive system is neither contemporary nor suitable for everyday use - it works.

Opel Kadett Holzvergaser wood gasifier
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