The primary objective of this project has involved a demonstration of the low oil consumption characteristics of the stepped piston engine. The support enabled the design and build of a single cylinder 150 cm3 SP engine and this is shown above as a modification to an existing motorcycle crankcase and gearbox assembly. The original 125 cm3 crankcase scavenged "base" engine can be seen below.
Results from the project are very encouraging even at this early stage of development. Many conventional crankcase scavenged engines operate at an equivalent fuel:oil ratio of 50:1 at full throttle. Operation below this level often causes catastrophic engine failure. The stepped piston engine operates on neat fuel with lubricant supplied from the sump as per four stroke engine practise. If we consider the total fuel consumption as a ratio against the total measured oil consumption then data for comparison with conventional crankcase scavenged two stroke engines can be generated. The stepped piston engine has so far been demonstrated to run at levels approaching 200:1 at full load or in other words a 75% reduction in oil consumption against typical precision oil feed pump metered two stroke engines. The following bar charts show some of the results from the motorcycle engine project.
The results above were recorded for top gear Road Load conditions. Data is presented at simulated 30mph (48km/h) and 50mph (80 km/h) riding conditions. The chart below shows a comparison of our target oil consumption at full load 7500 RPM operating conditions against the measured consumption of the precision metered conventional engine.
The G8 Portable Fire Pump engine achieved an oil consumption level approaching an equivalent of 200:1 during independent 200 hour full load endurance testing. Further information on this engine can be seen on the Industrial/Marine Engines page of this Website.
When Bernard Hooper was approached by Dennis Poore to become the Chief Engineer of Norton Villiers he was tasked with development of parallel twin cylinder engines in 350 cm3, 500 cm3 and 750 cm3 capacities (after he had developed the Norton Commando). The 500 cm3 prototype unit can be seen below. This machine later became known as the Norton Wulf.
Following dynamometer development the prototype engine was installed into a motorcycle with a ground breaking monocoque frame. The bike pictured above was tested to 103.15 mph on the acceleration test strip at the Motor Industry Research Association (MIRA) proving grounds near Nuneaton. The bike was under-geared due to the NVT Board imposing use of a standard 4 speed Norton Commando gearbox, despite the original design layout encompassing an integral 5 speed gearbox. The Wulf was also put through an LA4 emissions drive cycle whilst at MIRA and confirmed extremely low NOx emissions of 0.025 g/mile with carburetter fuelling.
The Wulf was later launched to the media in attempts to save the Norton factory at Marston Road as shown below.
The Wulf motorcycle shown above is in the build shown to the Press in 1975. The tank was resprayed from the earlier prototype orange tank colour to a newly released Ford metallic brown colour that was attractive at the time. New lines and a twin stepped piston logo were added to the tank. This machine is owned by Peter Hooper and is on loan to the National Motorcycle Museum at Solihull in the UK. The later developed liquid cooled BHE Wulf II is also on loan to the Museum and can be seen below.
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