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                               LS1 - LS2 - L76 - L98 
Text Box: LPG 


Riverstone LP Gas Centre a Sydney based LPG conversion company established for 29 years  and specialises in converting Gen111 & 1V to LPG and recently converted a Cross 8 to operate on duel fuel petrol and LPG using the new Italian OMVL sequential vapour injection kit. I have been involved in the tuning development of several Riverstone LPG powered vehicles all with positive feed back. The Cross 8 customer was impressed with the standard LPG conversion result with the comment he felt it performed better on LPG than petrol. I offered to load a developed custom LPG upgraded tune into his vehicle and he could evaluate, he came back from the test drive and was amazed with the increase in performance, consequently purchased the upgrade.  The customer rang back the following day and again confirmed he felt it performed better on LPG than on petrol. It was clear that there was no loss of power on LPG with this vapour injection system which responded positively to custom tuning in the same manner as petrol custom tuning. 

There are three LPG conversion categories :

The conventional Vapour Mixer Type comparable to the efficiency of petrol carburetor cars and proned to backfires.

Liquid Injection which has been demonstrated to deliver higher performance than petrol, however has been under development for the past 10 years or so and still is, when the technical issues are resolved this will be a more than viable hi-performance automotive fuel particularly with forced induction with the benefit of what I call chemical intercooling as the liquid LPG is released from the injector as a liquid and absorbs enormous amount of heat as it changes to a vapour state .

Vapour injection which is the approved LPG kit available for LS1 LS2 & L76 the main difference between vapour injection and the mixer type which has been used for the past 30 plus years  is the elimination of backfires and the introduced induction restriction with the ability to achieve fine control over the fuel delivery. The LPG vapour injection system has an operating pressure of 22psig at the LPG injectors.

LPG is stored in a conventional LPG tank. Propane at 24 degrees C has a vapour pressure of 119psig, liquid LPG then travels from the LPG tank to the converter mounted in the engine bay by means of pressure differential. Radiator water is piped to the converter to supply latent heat which is required to convert LPG from a liquid state to a vapour state. LPG vapour is then piped to the injector distribution block at 22psi, the solenoids 4 LH bank &  4 RH bank on two injector blocks are driven by the GM engine management computer via the petrol injector pulse width through the LPG computer, tracking sequentially and performing close loop and open loop operation as petrol would.

The LPG management computer controls start up on petrol and until rpm is above 1600rpm and 25 seconds pass it will then automatically switch seamlessly to LPG and it is seamless. Under wide open throttle the LPG computer is monitoring the LPG vapour pressure and at WOT if this falls below a pre-set level it will change to petrol automatically, again seamlessly. While data logging on the standard program it did not change from LPG to petrol at WOT throughout the rpm range in first gear however on the custom program it was switching to petrol because the gas converter could not meet demand this can be overcome if required with dual converters and can also be configured to utilised forced induction. The automatic switching to petrol is a design feature of this system which meets emission standards and keeps petrol injectors operating optimally. The operation can be switched manually by a dash mounted switch to operate on either fuel.

Automotive LPG can be a mixture propane and butane with an unofficial standard of a maximum blend of 60/40 respectively. Propane has the highest octane rating at 104 plus(depending on where the information is sourced) and Butane at around 90 octane. LPG has a lower calorific content than petrol and requires approximately 15% more LPG (on vapour injection systems) than petrol for the vehicle to travel the same distance, however LPG as a vapour blends homogenously with air and does achieve better combustion efficiency than petrol, another benefit of LPG is there is no carbon particles as a byproduct of combustion consequently the engine oil remains clean and wear is reduced.  

The major Sydney LPG storage facility is the Elgas Cavern and underground storage facility  at Port Botany , Elgas and Kleanheat operate at a retail level as Unigas, Unigas has predominantly supplied propane only. 

A good way to determine a retailer has propane only in his bulk automotive storage tank is to ask if the same delivery tanker filled the bulk tank and the BBQ 190kg refiller bottle as the 190kg cylinder must contain propane only as a statutory requirement.	 

Traditional custom tuning procedures apply noting the characteristics of the LPG ignition curve is different to petrol and stoichiometric for LPG is also different. Dual ignition maps can be configured to accommodate low octane unleaded and high octane LPG for optimum dual fuel operation.

Vapour injection set up correctly will as a minimum achieve performance equal to 98 octane petrol and will respond positively to custom tuning again with performance equal to petrol.

                                 LPG CONVERTER AND LOCKOFF

                           LPG FUEL MANAGEMENT COMPUTER


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Component installed

Injector Block

Converter Location

LPG Computer Location





Engine LPG Components

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