Good Performance with Gas-producer Vehicles
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Ministry Tests Show Excellent Fuel Economy with Oil-engine Conversions : Excessive Wear of Bearings and Cylinder Bores RUNNING on producer gas, an A.E.C..10-tonner with a 7.7-litre oil engine and carrying a payload of 10 tons 2 cwt. covered 6,006 miles for an average cost in fuel of 3.957d. per mile, Other vehicles covered in .a report dealing with producer-gas trials issued yesterday by the Ministry of. Fuel and Power, are a Vauxhall private car and a• Bedford 5-tonner, both with petrol engines, and an A.E.C. doubledeck bus with a' 7.7-litre oil engine.
The figure of 3,957d. per mile compares with 3.75d. per mile for a similar lorry running on oil fuel, as given in The Commercial Motor' Tables of Operating Costs." The Ministry's figure is based on the consumption of 5 tons of anthracite at £8 17s. per ton1.77d. per mile-153 gal. of oil fuel at 3s. 9d. per gal.-1.147d. per mile—and the cost of eight filter cartridges for the producer plant at £3 5s, per cartridge1.04d. per mile.
Controlled Conditions The test was conducted under controlled conditions over a route embracing -Leatherhead, Dorking and Reigate, but on 15 occasions the route was increased to take in Petersfield, Brighton and Portsmouth, so that such hills as Reigate, Bolney, Handcross, Hindhead and the Portsdowns had to be negotiated.
Preliminary road tests revealed a number of expected troubles and during the early stages of the test covered by the report certain other features of the producer plant needed attention. .
The test occupied 55 days, with an average of 100 miles a day. Apart from minor air leaks in the system, the tests were practically trouble-free. Following the insertion of the lighted torch in the mouth of the tuyere, the engine was running on gas within 60 see.
Tests Covering 22,049 Miles
This vehicle in the hands of British Road Services added 14,404 miles on producer gas and 1,639 miles on liquid fuel, the total mileage thus being 22,049.
As the A.E.C. engine was reeonditinned before tbe tests, the report on its condition after the trial provided valuable data.
Cylinder-bore wear averaged 0.001 in. per 1,330 miles, which would not be tolerated with an engine running on liquid fuel. The main and big-end bearings, says the report, were in reasonable condition, although there were signs of slight scoring. The average degree of wear on the big-end bearings was 0.0057 in. No fewer than four sets of cylinder-head gaskets were fitted during the tests.
The main interest in the report is that it deals at length with producer gas as an alternative fuel to oil, whereas previous experience has, in the main, been concerned with petrol-engine conversions. Subsequent experience with oil-engine conversion showed that it was possible to obtain the same power as with liquid fuel, whereas the petrolengine figure was approximately halved.
Engine .modifications in the case of the oiler were comparatively simple and were concerned with injection-pump timing, which was advanced by approximately 32° before top dead centre. Modifications to the injection pump were also necessary and these points are dealt with at some length in the report.
The tests to which the report refers were conducted from 1953-1955, and although the gas producer used was basically similar to those brought into service during the Hitler war, the trials provided the opportunity of improving the producer-gas plant to a degree not hitherto attained.
Nevertheless, a conclusion drawn is that whilst the fuel cost of running a petrol-engined vehicle on producer gas is comparable with that for liquid fuel, the capital cost of the plant, the extra servicing necessary and the poor road performance obtained make such a conversion economically unsound.
The position as regards the oil engine is far more favourable, as is confirmed by the report on the A.E.C. bus. This vehicle carried apayload of 3,1 tonsiquivalent to a full complement of passengers.
For a continuous-run test on one hopper-full of solid fuel the route chosen was from Leatherhead to-Reigate, Guildford, Hogsback, Alton, Alresford, Winchester, Southampton, Portsmouth, Arundel, Shoreham, Worthing, Brighton, Seaford, Eastbourne, East Grinatead, Reigate, Woking and so back to Leatherhead.
A full charge for the hopper was 504 lb. of anthracite, which ran the vehicle for 244 miles, when the poor quality of the gas brought the test to an end. Operating times were carefully checked for every 10 miles and ranged from 24-1min. to 361 min., the average speed throughout the day being 20.1 m.p.h.
On this run the fuel cost, reckoning filter cartridges as a fuel cost, was Anthracite, 1.48d, per mile; oil fuel, 1.05d., and cartridges, 0.8d., making a total of 3.33d. per mile.
On a London Transport route 17.8 miles long, the vehicle maintained an average speed of 12.25 m.p.h., which included all stopping times and traffic delays. Oil fuel consumed was 4.5 pints, giving a consumption rate of 31.64 m.p.g.
Maintaining Time Schedules
This satisfactory performance was achieved with a 7.7-litre engine, as against the 9.6-litre units fitted in the buses working the route, and with a load equivalent to 56 passengers. Schedule times were maintained. On this test the fuel c.ost was 5.62d. per mile, 1.45d. of which was represented by filter-cartridge wastage.
Results of numerous tests have shown that a properly packed cartridge should have a life of at least 1,000 miles under normal conditions. Its life, however, is based on the amount of solid fuel consumed per mile, it having been established that the cost of cartridge wastage averages 0.5d. per lb. of solid fuel per mile.
Whilst the report is of only academic interest at the present time, it suggests that there is scope for the development of a basic producer-gas plant for the smaller types of high-speed oil engine.