By Darren Chandler
fig. 1. The Commodore
after it’s first Hydrogen road test.
While I have an interest in cars,
it is not an all-encompassing interest, just one of many
interests. I am
actually very narrow minded with cars- I am really only interested
in one brand, Holden!
I suppose it is because I grew up with Holdens. They were always big,
comfortable, reliable and uniquely Australian. Another interest I have is
alternative fuels. I
believe that one day we will either run out or not be able to
afford petroleum fuels, meaning that hundreds of millions of
petrol driven cars could be rendered useless to their owners
unless we can convert them to operate on a new, sustainable
Converting a car to run on
Hydrogen is a passion that I have had since I was quite
young. The idea of
being self-reliant and creating my own hydrogen fuel from water
through electrolysis and then powering my car on it, no longer
relying on petrol companies has always been a dream. I also like the fact that
a vehicle running on hydrogen emits mainly steam from the
exhaust. Assuming the
power used to obtain the hydrogen is produced in an
environmentally friendly manner, cars powered by hydrogen actually
improve the surrounding air quality, because pollutants in the air
are burnt inside the engine and no new pollutants are
produced. This is why
hydrogen powered internal combustion cars are sometimes called
“minus emission vehicles”.
exhaust is mainly harmless steam
In 2003 my father handed over the
keys to his 1980 Holden VC commodore, the goal was to “do it up”.
I decided that the VC would become my first attempt at a hydrogen
While the VC was 26 years old,
the aim was that the conversion could be applied to almost any
petrol driven car, including modern fuel-injected types. The conversion also needed
to be as safe as possible and with minimal tendency to ‘ping’
(pre-ignite the hydrogen fuel). The car was also to be a
‘dual fuel’ conversion, meaning it could switch between hydrogen
While cars have previously been
converted by introducing hydrogen into the air intake, this method
is flawed as it creates a large volume of mixed hydrogen and air
inside the intake manifold.
Due to the extremely high flame speed of hydrogen, this is
dangerous for the engine, as any pre-ignition event could cause a
very large “backfire” inside the manifold, frightening everyone
nearby and damaging the engine. Pre-ignition is one of the
main problems with hydrogen, as the flame speed is faster than
that of any hydrocarbon fuel, if the ignition timing is not set at
top dead centre right through the rev range, the flame front
inside the cylinder will burn back through the still partially
open intake valves and ignite any fuel/air mix inside the
manifold. This is not
the only thing that can cause backfiring, even before it is
ignited the hydrogen can self-ignite when entering the cylinders,
just from contact with a “hot spot” inside the cylinder. This is one reason why it
was decided to use a sequentially injected system on the car. This would involve using
specially made “gas” fuel injectors, one for each cylinder, and
each “firing” just before it’s corresponding intake valve
opens. In addition,
the ignition timing would need to be able to be altered from
inside the cabin both when tuning the car, and when changing
between hydrogen and petrol fuel. Compressed hydrogen would
be used, initially obtained from a local gas supplier.. Two “E” size cylinders fit
in the boot easily and these are filled to just over 2000 psi
giving a range of around 30km just enough for testing
The first part of the conversion
involved extensive modification of the ignition system. The existing ignition
system on a VC is a conventional one for 1980; a distributor,
reluctor system, using a single coil and a rotor button to
distribute the high tension to each of the six spark plugs. Timing is controlled by
weights inside the distributor that, by centrifugal force, rotate
the reluctor assembly, advancing the timing as rpm increases. This
works well when running on petrol, however to run on hydrogen,
there needs to be no ignition advance. Additionally, the
sequential fuel injection system needs to know the position of the
engine at all times to enable the correct injector to fire at the
right time, and this engine, being a carburetor engine, has no
sensors to determine engine position. This meant removing most of
the existing ignition system, retaining the distributor and
reluctor only as an engine position sensor. The centrifugal weights
were clamped so they could not move, and an optical sensor was
fitted to the distributor case. The only function of the
rotor button now is to trigger the optical sensor.
Modified distributor. Arrow indicates optical sensor.
This optical sensor now gives a
reference signal, and the existing reluctor provides the six
“firing points” needed to determine the position of the
engine. These signals
are fed into a “sequencer box”, which drives six separate ignition
coils. This consists
of a PCB containing logic circuitry, which drives two, 3 channel
coil driver devices, pictured in fig.4. This also provides the
signals used to drive the fuel injection system.
fig. 4. sequencer box which drives the six coils
fig. 5. the six ignition coils can be seen here.
The ignition advance is
controlled by a PIC based controller inside the cabin, which has
two pre-set programs- one firing at T.D.C across the rev range for
hydrogen fuel, and one giving the advance curve needed for petrol
programs can be changed with the push of a button.
fig. 6. the PIC based device used for ignition timing
Next, the fuel injection system
was constructed. The
fuel injectors were ordered from a company in the U.S.A. They are specially
designed for gaseous fuels, and can be used with hydrogen,
compressed natural gas (C.N.G) and propane. They are rated at 80 psi
input pressure for hydrogen, and are “peak and hold” type
injectors, meaning they need a special type of driver which
delivers full (6 amps) current initially to open the injector,
then reduces the current to 1 amp to hold the injector open for
the rest of it’s
A special mounting bracket was fabricated to accommodate
the fuel injectors, along with the fuel rail, which was salvaged
from a later model Commodore that featured fuel
fig. 7. two of the fuel injectors and fuel rail.
Ports for the fuel injectors were machined from brass
plumbing fittings and ¼” copper tubes carry the hydrogen from the
fuel injectors, through the intake manifold and to within 2 cm of
the intake valves.
What this means is that, because the injector will only
fire when it’s intake valve opens, there is minimal mixing of
hydrogen and air within the intake manifold, which minimizes the
extent of any pre-ignition event.
fig. 8. here the ¼”tubes carrying hydrogen fuel can be
The injection system is
controlled by a potentiometer which is connected to the throttle
cable; when the throttle is depressed, the potentiometer reduces
the voltage supplied to a voltage controlled oscillator (V.C.O),
and this reduces the frequency of the square wave output of the
V.C.O. The cable is an additional throttle cable which works in
parallel with the original throttle cable.
fig. 9. potentiometer attached to throttle cable.
Mounted to firewall.
This V.C.O signal is fed to the
injection control box, which consists of flip-flops and
counters. When an
injector is fired, a flip-flop is set and stays set until it’s
counter has received 128 pulses from the V.C.O, when the flip-flop
is reset and the injector is turned off. If the V.C.O frequency is
reduced (throttle pedal depressed), those 128 pulses take longer
to occur and so the injector stays open longer. This is how throttling is
tuning of the V.C.O is possible using the controls inside the car
and this allows for idle speed and throttle range adjustment.
fig. 10. peak and hold injector driver and control
fig. 11. injection control box with cover removed.
Solenoid valves are used to turn the petrol and
hydrogen supplies on and off when necessary.. These are operated from
the fuel selection switch in the cabin.
fig. 12. V.C.O box in centre console.
The hydrogen fuel cylinders are
mounted laterally in the boot in special brackets, which hold the
The regulators mount directly to the cylinders and are two
stage regulators, set at 80 psi. 10 mm I.D hose carries the
hydrogen up to the fuel rail under the bonnet.
fig. 12. cylinders mounted in boot.
13. dual stage regulator.
The VC was test driven on
hydrogen and after some adjustment of fuel injection timing it
performed well. As
expected the power was approx 80% of that when running on
petrol. The VC was
driven at over 110 km/h and on flat roads achieved 13-15 km per
cylinder of Hydrogen.
When the engine is hot and under heavy acceleration, some
pre-ignition is still occasionally apparent, however it is not
severe and the future planned is to add a water injection system
which should solve this entirely. A further plan is to test
the car on C.N.G as this is currently the most feasible
alternative fuel in this country, and the idea of filling the car
with C.N.G at home is appealing.
fig. 14. first test run on hydrogen fuel.
This project took almost three years to complete due mainly
to other commitments and projects happening along the way. It was
a learning process and it has paved the way to creating a fairly
economical conversion system which, in the future, can be utilised
to convert other, newer vehicles. On the subject of cost, here are
some figures for the higher cost items in Australian
6x gas injectors: $1200
peak and hold
2x ignition coil drivers:
6x ignition coils:
2x dual stage hydrogen regulators:
All other major parts for the conversion were designed
and constructed by the author, so the main cost here was time,
however the remaining parts / materials cost would be no more than
another $1000, so the total cost of the project was approx
As mentioned earlier, while the conversion was
primarily designed for use with hydrogen fuel, it is equally
suited to operation on C.N.G, a fuel which is plentiful in
Unfortunately, it seems Australia is a country of
governments whom are reluctant to embrace change, presenting a big
challenge to any new or developing technology. While other countries
encourage the use of C.N.G in cars, it is an unknown fuel in this
country, and while there are hydrogen refueling stations in the
U.S to encourage research and improvement of these types of cars,
the Australian government has just decided to offer a $2000 rebate
to anyone converting their car to liquid propane gas just because
petrol prices have gone up!… An abhorrent waste of money, which
could be spent with a view beyond the next election. For these reasons, some
specialized parts (i.e. the injectors) were impossible to obtain
locally, as there is no automotive hydrogen or C.N.G industry
However, when we do finally move away from petroleum
fuels and hydrogen does become readily available, this type of
conversion will mean motorists will be able to continue driving
their internal combustion vehicles, and all of the energy and
materials put into their manufacture will not be wasted.