Citroën A-type LPG/GPL conversion

© Copyright: J.Cats.


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Disclaimer:
This page only provides information based on the personal opinion of the author. The author can't be held responsible for damage in any way that could result from modifications mentioned here.


LPG / GPL Basics
LPG stands for Liquefied Propane Gas. A gas is kept under high pressure in a container (tank) so that it is a liquid. When the output valve is opened, the fuel comes out of the tank. When the fuel depressurizes (and turns into a gas again), heat is taken from the surrounding area. As soon as you start depressurizing larger amounts of fuel a device is needed to add additional heat to the fuel. This is where the vaporizer comes in. The gas is then fed into the engine. On carburetted cars this is done by feeding the gas into the top of the carburetor through a pipe / jet. On fuel injected cars, the gas is fed into the fuel rail and then distributed as usual.

LPG / GPL Requirements
So what does your car need in order to run on LPG / GPL? LPG is leadfree so your car has to be able to run on leadfree. Most Citroëns can use leadfree petrol. Check out Cats Citroën Net Unleaded Fuel for more info on this.

Original Citroën LPG/GPL Acadiane
From July/August 1980 onwards Citroën commercially sold an Acadiane and LN with LPG system in various countries (France, Belgium and Holland at least). In France these cars only had a LPG fuel system, the normal fuel system had been removed. The engine used for the Acadiane is a modified Acadiane, engine type AM2A GPL. Technical data:

  • Compression ratio: 8.5:1
  • Power: 25 DIN bhp @ 5000 rpm
  • Torque: 36 Nm @ 2500 rpm
The fuel is heated by a special fitting located in the right exhaust manifold pipe just after exiting the cylinderhead. On all modern A-types a strange rod shaped extension can be found here without any apparent use. On the french cars the fuel was heated by water being heated at this spot and the water being pumped around by the no longer needed fuelpump.

The trick with LPG is to store the liquid under high pressure in the tank, then let it flow out and heat it so it turns into a gas again. This heating can be done in several ways. "Normal" cars use the water in the cooling system to heat up the gas in the vaporizer. However, on aircooled engines there is no water to heat up anything. So here are the most commonly used options:

Water heated vaporizer
A water circuit is introduced. With or without (electric or mechanical) waterpump the water is heated in a steel or copper tube wrapped around the exhaust and fed to the vaporizer. This means you can use all standard bits but pay attention that all tubes and pipes have E markings on them. This solution has proved itself in recent years and works very well. If anything in the water system would go worng, the vaporizer freezes and you'll stop. Nothing will break and no damage is done. This is by far the most practical solution to problem.

Exhaust heated vaporizer
Here the fuel is led through a special connection on the exhaust to heat it up. This is by far the most efficient method because the exhaust is hot immediately after starting your engine. Through EU law this is now no longer allowed, specific regulations vary for each country though.

Oil heated vaporizer
The oil heated vaporizer has 1 big advantage: no need for a water system which keeps things simple. However, there are some big diasadvantages: The vaporizer is fed with pressurized oil from the engine oil pump. If a hose would break, tear or dislodge itself, the engine would die of oil starvation before the oil pressure light comes on. Another disadvantage is that there are no or very few vaporizers which can be fed with oil that are EU approved and/or that can stand the enormous oil pressure variations in the citroën engines.

Tuning for LPG / GPL
When using LPG you lose some power because of the lower caloric value (amount of energy released when burning one liter) of LPG compared to regular fuels. But LPG has a higher octane rating then regular fuels. So one way to overcome the power loss would be to raise the compression ratio. You have to be careful though, LPG fueled cars tend to run a little warmer.

Available systems today
As far as I know, these specialists currently supply systems especially for A-types:

  • Operation 2cv
  • This belgian/dutch specialist has converted quite a few 2cv and other A-types (and a few GS) using the water circuit solution. He has found an electrical waterpump which is used in diesel cars and which is very reliable. His solution has proven itself in many cars and is compliant has pass all Benelux technical tests. His cars can be seen in the pictures on this site.
    WWW: www.operation2cv.com
    Email: info@operation2cv
    Telephone: +32476652273

  • Duckservice
    This Dutch / German specialist sells a kit in which oil is used to heat up the gas. The system is sold as a kit for DIY installment or you can have it installed by Duckservice. The system works very well and has been fitted to a number of cars succesfully. Contact Duckservice on www.duckservice.nl

Example installations

2cv6, tank in place of the spare wheel, filler behind the licenseplate, water circuit for evaporator. Water is heated by a stainless steel tube running through the exhaust crossbox.
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1960 AZU, tank behind the front seats, filler on the fuel tank cover, water circuit for evaporator. Water is heated by copper tube wound around the exhaust inside one of the original heat exchangers. Click for full screen Click for full screen Click for full screen Click for full screen Click for full screen Click for full screen Click for full screen Click for full screen

2cv6 (Operation 2cv / P.Franck), tank diagonal in the spare wheel well, spare wheel under the bonnet, water circuit for evaporator. Water is heated by copper tube wound around the exhaust below the heat exchangers.
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2cv6 (Operation 2cv / P.Franck), tank in the spare wheel well, spare wheel under the bonnet, water circuit for evaporator. Water is heated by copper tube wound around the exhaust inside the heat exchangers.
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Dyane 6 1969 (Operation 2cv / P.Franck), tank in the spare wheel well, spare wheel under the bonnet, water circuit for evaporator. Water is heated by copper tube wound around the exhaust below the heat exchangers.
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Acadiane (Operation 2cv / P.Franck), tank in the cargo bay, spare wheel under the bonnet, water circuit for evaporator. Water is heated by copper tube wound around the exhaust below the heat exchangers.
Pictures will follow soon.

Ami 8 Service 1973, tank in the cargo bay on modified frame, spare wheel under the bonnet, water circuit for evaporator. Water is heated by copper tube wound around the exhaust inside the heat exchangers.
More info and pictures can be found here


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