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Ford Model A 01.jpg

The Ford Model A with wood gas generator (FIVA 079460)


In 2016 - 10 years after the conversion of the Opel Kadett - it was time for a “proper” wood gas car, i.e. historically correct, FIVA-certified and up to date in terms of performance. This Ford Model A, type Fordor Leatherback, was built in 1929. The vehicle and its successor, the Model B, as well as countless tractors with the same engine were ideal conversion objects. With the large-volume, throttled engine (3.3 liters, 40 hp), it is possible to achieve the same performance with wood gas or lignite as with petrol.

Kaiser wood gasifiers


The Swiss car dealer Alois Kaiser is still known today for his wood gas generators. These usually consist of a cylindrical gas generator and a cylindrical filter of the same size with an integrated tube cooler.

Kaiser wood gasifiers

This special type of gasifier was intended for large cars and small buses. However, it was not the success that was hoped for. It was too heavy for most cars and not powerful enough for a truck.

Kaiser gas generator mounted on car

The system was a very good visual match for a large passenger car. The heavy monobloc construction was mounted at the rear of the vehicle (gas generator, filter and radiator).

The rear suspension was reinforced. A light car was lifted out of the front springs by the leverage effect, causing the front brakes to fail.

Installation possibilities

Because of the problems with the springs and brakes, the additional weight was usually distributed at the front and rear.


This Kaiser generator was fitted with a Sulzer cyclone filter, as well as a cooler and fine filter of unknown origin.

Hearth conversion 1

The gasification technology of the 1940s is still considered very advanced today. However, there were many patent disputes. This is why the Kaiser brand generators had a patented, central air supply. The hearth was lined with fireclay.


The central nozzle pipe was fed through the middle of the 1400°C hot hearth. Only the incoming air cools the steel pipe; the system was correspondingly vulnerable. 

Hearth conversion 2


I decided to completely redesign the hearth and combine all the advantages of the various systems.


To do this, the fireclay was removed from the hearth.


I wanted to use the hole in the generator base to be able to shake the cast iron grate from the outside.


The cavity between the hoppers is used for the air supply. This preheats the intake air and cools the inner hearth.

Output on wood gas operation

Gas temperature at intake manifold: 40 °C

Displacement: 3.3 liters 

Speed: 2200 'min

Filling level: 75%

Gas volume: 187.3 m³/h

Wood gas content: 89.2 m³/h (L = 2.1)

Wood gas calorific value: 4800 kJ/m³

Thermal output: 118.9 kW

mech. efficiency: 25%

mech. output: 29.7 kW or 40.4 HP

Hardwood consumption

35.7 kg per hour under constant full load

or 35.7 kg per 100 km at Ø 50 km/h and Ø 50% load

US conversion units

Approximately 1.20 to 1.35 lb of hardwood is consumed per mile.

Comparison to gasoline 

1 liter gasoline = approx. 3 kg hardwood

35.7 kg hardwood : 3 = 11.9 liters gasoline / 100 km

(corresponds to the factory specifications)

See also Blueprints / Links

Fitting the wood gasifier


In addition to the Imbert intake flap, a cast iron grate from Imbert is now also installed instead of the welded originals.

The cast iron grate can now be shaken from the cockpit. The solution is similar to the WISCO generator, instead of the unpopular Imbert solution with the infamous “Rütteldorn”.

Depending on the vacuum gauge reading, it may be necessary to remove the ash from the reduction zone so that the vacuum does not increase too much. This would lead to a loss of performance.

In the past, the ash was mainly removed by the potholes in the roads and because most of the roads were not tarred but graveled. Because of the better quality of the roads today, you have to shake more often.

View of the rear body structure


This view shows why a Kaiser brand gas generator was chosen; its design simply fits the design of the Ford Model A. The low construction makes refueling easier and there is no obstruction to the rear window.

After the cyclone filter, a pipe leads the gas to the front to the separator and from there to the gas cooler. The pipe under the car requires a drain tap to empty the condensation water. But it doesn't disfigure the car like the pipe routing above the roof, which was previously recommended. And of course the conversion was easier than with hidden piping under the car.

The lowering of the rear end and the dynamic behavior of the additional sprung mass was initially compensated for with a hollow rubber spring. In 2019, the stronger leaf spring from the delivery van and a Panhard rod were installed instead.

Completing the rear attachment


Galvanizing is a nice thing, but the heat deformed the components. I had to learn this painfully... I thought I could quickly fit the galvanized and painted parts. In the end, it took hours until everything was straightened and fitted again. 



The Kaiser wood gasifier is designed as a so-called monorator. This means that it can also cope with damp wood, which it can pre-dry. The monorator was invented by chance, due to the desire for a low gas generator for a better view to the rear. It was discovered that this form of storage container can separate far more moisture than the standard generator.

Monorator design

Heating / vaporization only takes place in the middle. Only the middle part of the fuel is dried and carbonized. The hot, moist gases in the middle rise to the top. In the outer zone, the fuel supply is cooler. This cools the gases so that moisture condenses on the generator wall and is discharged to a container via a drainage channel.
Part of the fuel thus works as a surface condenser with a very large surface area. The gases freed from the moisture are then drawn in towards the center and fed through the stove into the reduction zone.

Fuel reserve


Wood weighs three times as much and has six times the volume for the same amount of energy as petrol. Bag holders for 2 x 12 kg of wood are fitted to the left and right of the wood gas generator. 

Together with the 40-45 kg (88-99 lbs) in the gas generator (must not be completely emptied), this results in a range of approx. 150 km (93 mls) in pure wood gas operation. 

With two additional bags in the back seat, the range increases to approx. 200 km (124 mls). Not bad compared to today's electric cars. 

With lignite instead of wood, the range increases by approx. 1/3 (higher bulk weight and higher calorific value). 

Filter and gas cooler


Separator, cooler and fine filter are integrated into a very wide construction in the Imbert system.

This design, which was actually developed for trucks, had to be installed in front of the front wheels, as can be seen in the picture on the left. 

A more attractive solution with the same technical function is achieved by accommodating the two filters and the cooler in a so-called detached design. This means that the fine filter is housed separately from the separator and the gas cooler.

Ford Model A Holzvergaser Kühler
Ford Model A Gaskühler und Filter

Separator and gas cooler


The outlet pipe of the gas cooler runs along the right-hand fender to the fine filter, without modifications to the vehicle or concessions to the turning circle. The bumper is still the end of the vehicle.

I wanted to use original components from WW2 wherever possible. So I used a matching, albeit heavily dented and rusted, separator. After three evenings of work with a cutting disk, hammer and welding tool, it was in a reasonable condition again and had exactly the right dimensions. The side cover is even made of cast iron.

Fitting the fine filter


I installed the fine filter under the right front fender. This required a fairly complex construction. However, the perfect functioning of this filter is very important, so that the effort pays off with trouble-free operation.

Galvanized and painted, the filter blends seamlessly into the vehicle. The two aluminum caps come from original components.

With the exception of this filter housing, original components were used for the complete conversion.

Conversion of intake manifold


In Germany, an auxiliary carburetor was often fitted, or the wood gas mixer was available with an integrated auxiliary carburetor. This meant that the vehicle could be run on gasoline if necessary. If the gas was poor, the vehicle was often started with gasoline and then switched to wood gas operation.

In order to be able to run on either petrol or wood gas at full power, this vehicle retained the original petrol carburetor. This was common practice in Switzerland and France at the time, as liquid fuels were sometimes available in these countries despite the war.

The engine compression was increased. In this way, the power loss of approx. 30% is compensated. This means that the engine has the same 40 hp output with wood gas as it did originally with gasoline.

Motor test run after overhaul



A fan is required to fire up the gas generator. The Ford Model A is positively grounded. This makes the installation of additional electrical equipment difficult.

The solution: an original fan from the 1940s, with the electric motor insulated from the housing. This can be operated in a positively earthed vehicle without having to insulate the housing from the vehicle.
The pipe leads under the front left fender to the outside. In this way, it is possible to check on the driver's side whether the gas is flammable and therefore whether the engine can be started.

6-12 volt serial parallel switch

When starting the engine with wood gas, it is important that it turns quickly to prevent a gas hole developing in the wood gas generator. The old operating instructions therefore strongly recommend converting from 6V to 12V or installing a 6-12 volt serial parallel switch, as shown here. However, this requires two 6V batteries.

The vehicle electrical system remains at 6 volts, only the engine starter is started with the 6V batteries temporarily connected in series. Instead of the original mechanical switch, with which the starter was operated directly by foot, an electric pushbutton switch is installed in the same place (the bright shiny button by the brake pedal). 


The Ford Model A is not really blessed with storage space. A toolbox is mounted under the rear floor to make room for tools and a jack.

Ford offered a toolbox (still available today). But it is is mounted in front of the radiator - where the separator of the wood gas generator is now attached.

Ryan Overdrive

In 2020 I installed a 1991 Ryan Overdrive. The Ford now has a total of 6 gears and can be driven much better and more gently.

Ryan Overdrive Model A

Maiden voyage on wood gas, June 26, 2016

The engine was fired up at 10:45 and I was able to drive off after 10 minutes. The performance is enormous, the vehicle accelerates with reserve to 80 km/h (50 mls). The starting behavior on inclines and at traffic lights is excellent.

The filling capacity of the gas generator is 40 kg with hardwood chips and approx. 45 kg with ash wood cubes.  

The coarse hardwood chips are proving to be very effective. This provides a fuel that does not have to be processed at great expense.

The wood pile in the photo is therefore not in danger of going to waste...

240 kilometers in pure wood gas operation

April 2017: We drove 240 km to the Tannenmühle and back in a fully occupied car using only wood gas. The power of the wood gasifier is amazing, a detour to Küssaburg was no problem. 

Around 90 kg of hardwood was used for the 240 km route.

In 2017, I drove around 1200 km in wood gas mode. This consumed around 450 kg of hardwood. 

To this day, I drive the Ford regularly and with great pleasure in wood gas mode. For example, I drove to the Schwägalp and over the Brünig several times.

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