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1:11JALL VANS
Page 54
Page 55
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Until now all the activity in the world of dual-fuel has been on heavy trucks, with suitably heavy conversion costs. But now Bracknellbased van Aaken Developments has produced a system that's equally suitable for the van world.
The system's full name is the van Aaken SmartKit Liquid LPG injection system, and the name reveals what differentiates this one from other LPG conversions, usually on petrol engines.
Liquid fuel
Unlike systems which effectively release gas into the induction tract at around atmospheric pressure,the van Aaken system maintains the fuel in a liquid form up to the point of injection. Its first demonstrator is van-based but the system is also being developed for larger vehicles. So far it has been fitted to a Volvo FM12 and a Cummins-powered ERF ECT, with a Daf conversion currently in progress.
The van Aaken demonstrator is a Nissan Primastar with the 100hp 1.9-litre DCi engine. Physical differences outside the engine
in a Iqule orm up to
bay are minor — you could almost believe the van's designers had alternative-fuel technology in mind when designing the fuel filler.
The standard van's filler flap reveals a space for a second filler; van Aaken has used this to produce a filler that neither pokes through a makeshift hole nor dangles from a bracket.
The van we drove had an 80-litre LPG tank mounted in the spare wheel well. necessitating the relocation of the spare. The ground clearance of this tank is marginal, although future examples will feature a slightly smaller tank.
The original diesel tank stays in place so the van's range has been considerably extended. Unlike conventional LPG installations this one has a pump incorporated into the tank to provide the five bar pressure that keeps the fuel liquid.
Busy under the bonnet
A dash switch incorporates a live-level LPG 'tank contents' light.but the system will run as well as ever on diesel if the gas runs out.
Under the bonnet there are rather more extra components. Van Aaken's standard SmartBox ECU module inter rupts the signal between the standard ECU and the fuel delivery system, superimposing an extra threedimensional fuelling map over the standard one.This is usually done to increase fuelling and hence power. but with the dual-fuel conversion it actually reduces the diesel fuelling, making up the shortfall with LPG.
Each application is individually mapped with the help of van Aaken's chassis dynamometer. • The filler neither pokes nor dangles The LPG is metered by the distributor assembly. which also contains a pressure sensor and solenoid to act as a safety device.
The electronic injectors, developed by Siemens. comprise a central solenoid surrounded by a fuel-filled housing. In this case the injector is mounted in a housing fitted to the air intake tract, but on larger truck engines up to four injectors are fitted to holes drilled in the inlet manifold.
As few people operate vans for fun, or even to save the planet, the all-important issue in any alternative fuel vehicle is the bottom line. Here the facts are not yet fully clear, largely due to the state of limbo surrounding the govert ment's Energy Savings Trust grant scheme.
The long-term futur( LPG as a road fuel is al: in question in the light the Chancellor's plan ti reduce the duty benefit The final pre-grant cost of the conversion is st being cakulated,but 1 van similar to the Nissan we tested it woul somewhere between £3,000 and £5,000.
Van Aaken's figures suggest that with( the government grant, for a hard workin doing 60,000 miles a year, the conversior have a pay-back time of around two yea] This period will fall, of course, if the expe grant aid is forthcoming.
The system will be available through distributors, initially Future Fuel Technr of Blackpool and Bristol-based Altemat Fuel Technology. •