Greater Power and Economy by Turbocharging
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QTRIK1NG results have been obtained P., by fitting a Simms-Eberspacher exhaust turbocharger to the 11.3-litre sixcylindercd oil engine of an A.E.C. Mammoth Major Mark II vehicle operated by Bowater Transport and Services, Ltd. The lorry is used on long-distance timber haulage.
The output has been raised from 155 b.h.p. to 200 b.h.p. at 1,800 r.p.m., and the maximum b.m.e.p. from 110 p.s.i. to 145.6 p.s.i. Conversely, the specific fuel consumption of the turbocharged engine over the entire speed range at maximum load varies from 0.34-0.39 lb.-b.h.p.-hr.. compared with 0.35-0.41 lb.-b.h.p.-hr. with the normally aspirated version.
Turbocharging is stated to have improved acceleration, flexibility and quiet running. Even when the engine is operating under , maximum load, the turbocharger is not audible above the engine. Gear-changing can be delayed and the fully laden vehicle will negotiate certain hills on a test route in a higher gear than the normally aspirated version, and with power in reserve.
The conversion was a joint project between Bowaters' engineering department and Simms Motor Units, Ltd. A completely reconditioned engine was fitted with a specially fabricated twin-branch exhaust manifold, each branch serving, in the sequence of the firing order, three cylinders and leading to the twin inlet port of the exhaust turbine.
The turbocharger is a standard unit, 'laving a water-cooled bearing housing with self-contained splash lubrication, which is joined by fin, copper pipes to the cooling system of the engine. The outlet of the exhaust turbine is connected by a 3-in.-diameter metallic flexible hose to the exhaust system without altering the existing Burgess straight-through absorption-type silencer.
Fresh air is obtained through a scaled ducted Purolator air cleaner connected by a 3f-in.-diameter corrugated-wire reinforced rubberized hose to the air intake of the compressor volute. Pressurized air from the compressor is fed to the engine by a 3-in.-diameter swan-necked light-alloy duct to the air-intake orifice of the pressure-sealed rocker cover.
The original fuel-injection pump, fitted with 8-mm.-diameter plunger elements, was changed to one with 9-mm. plunger elements and the original 0.35-mm.diameter injector nozzles were replaced by nozzles with a diameter of 0.4 mm. Fuel-injection timing is unchanged.
The initallation is accommodated within the original engine cowling, the only alteration required being a small " blister" in the side cover.