Turbo on test
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A VOLKSWAGEN LT31 panel van equipped with a prototype turbocharged version of the six-cylinder 2.4-litre VW petrol engine has begun evaluation trials in the UK with VAG.
The turbocharged engine is intended for ambulances and emergency vehicles and features a Ho!set H1-series turbocharger with a pressurised Solex carburettor system.
All engine conversion work on the 3.36-tonne gvw van has been carried out by PAO Preparations of Aldbourne in conjunction with VAG, using existing exhaust manifold parts normally used on the turbocharged LT diesel engine. All petrol and diesel-engined LT models share the same basic six-cylinder engine block.
According to Volkswagen, the aim of the conversion is to increase mid-range torque rather than add to outright power, although the normal 6 7kW (90bhp) maximum output on the naturally-aspirated petrol engine is raised significantly to 82kW (110bhp) at , 4,250rpm. Peak torque has also increased from 1 3 4Nm (99 lbft) at 3,300rpm to 192Nm (142 lbft).
Engine modifications have been kept to a minimum although the prototype unit has required a new air cleaner system for increased air flow (the original trunking remains) and a revised distributor advance curve compatible with the turbocharged engine.
An extra water/oil heat exchanger has also been fitted to the lubrication system, although PAO claims the LT31's cooling system is "more than sufficient" to cope with the conversion.
Zero to 60mph acceleration time for the fully laden turbocharged LT31 has been improved from 31.5 secs to 21.8 seconds according to PAO. This is within the frontline ambulance 0-60mph requirement of 23 seconds.
Left: Volkswagen will shortly be fitting a PAO turbocharged 2.4 litre petrol engine to its LT31 front line ambulance demonstrator. VAG has sold two LT ambulances to Powys Area Health Authority.
Above: The prototype engine is fitted in an LT37 van and will undergo evaluation trials of up to 50,000 road miles. PAO has used exhaust manifold parts used on the LT turbocharged diesel engine.
Maximum boost pressure is relatively low at 13.79kN/sqm (2psi), with the turbocharger becoming effective above 800rpm. The overall conversion adds 11kg (24.3 lbs) to the overall weight of the 2.4-litre engine, which in turbocharged form runs on four-star fuel compared with two-star on the naturally aspirated version.
Volkswagen is hoping the turbocharged 2.4-litre will further improve sales prospects of LT31 vehicles as frontline ambulances. The Pilcher-Green LT31 ambulance demonstration unit seen on VW's Motor Show stand will shortly receive a PAO turbocharger conversion.