Meet an adventurer extraordinaire in the world of race engine technology. He makes engine components on a 115-year-old LeBlond combined mill and lathe which he bought for a mere £250. He has installed an HP Andersen water turbine dyno in his garage and has even established his in his family home.
John Ellwood with his latest Hybrid motorcycle (Photo: Victor Gotbring)
Although he is a family man with no outside financial support, John Ellwood has turned dreams of alternative engine technology and record-breaking into an ongoing physical reality. His story should be an inspiration to anyone with similar ambitions but who has so far lacked the drive to turn bold ideas into practical reality.
Ellwood was born in Frosterley, northern England, in 1962. Through part-time study, he attained a degree in Physical Electronics at the age of 26. Then, after a brief spell in South Africa, he moved to Sweden, where he still lives, in Stockholm. He works freelance in the electrical and instrument industry, often abroad.
Ellwood relates that while working in Kazakhstan in 1994 he suffered badly from a combination of extreme cold, chronic toothache, dubious Russian dentistry and ‘medicinal’ vodka. Nevertheless, he recalls waking up one morning “with a delirious vision of how to build a new type of engine”.
This was a two-stroke/four-stroke hybrid. It operates on the four-stroke cycle but pumps its charge air through the crankcase in two-stroke fashion. The crankcase is fitted with two reed valves (or sets of reed valves), one to admit air from the atmosphere, the other to allow air to be transferred from the crankcase to the intake valve externally, via what we can consider the plenum.
The fact that this type of hybrid works on a four-stroke cycle means that for each opening of the intake valve on a downstroke there are two upstrokes of the piston on which air is admitted to the crankcase. The exit reed ensures that on both upstrokes air is admitted only from the atmosphere; it cannot be drawn back into the crankcase from the plenum. Thus is a form of supercharge obtained.
Ellwood manufactures much of his engine on this ancient LeBlond combined mill and lathe (Photo: Victor Gotbring)
Mind you, RET’s technical consultant feedback is that in practice if the plenum is large enough to cause little restriction to the air flowing into it then even after two filling strokes its pressure may be little over atmospheric; and if the plenum is sized to allow significant pressure above atmospheric then it’s likely to create restriction to flow into and out of the crankcase. And this does not account for the additional pumping losses to the thermodynamic cycle.
Mind you, Ellwood later discovered that others have successfully used the concept. His 1994 vision was the first he knew of it. “I have since discovered that way back to 1912 there was a secret boxer twin hybrid for military use in Sweden,” he says. Since 2010, the concept has been applied by Shindaiwa in the form of its Hybrid 4 motor technology, this application closely following the Ellwood pattern.
There will be those who decry the concept, pointing out that compared with running in normal, naturally aspirated form there is the complexity of additional plumbing, a loss of intake and exhaust tuning potential, and additional work being done by the piston. But the point is that Ellwood didn’t just have this idea – he has turned it into his own practical reality. He is a true ‘Special Builder’, and to be admired for that.
Shindaiwa has applied the concept across 18 types of sub-100 cc low-revving power tools. It claims that it offers close to the same power density as a two-stroke with a fatter power curve, while the more precise valving timing is said to enhance fuel economy and significantly reduce emissions. Also, pre-mix lubrication avoids the complexity of a conventional oiling system and allows the engine to run in any orientation.
The Ellwood 1173 cc Hybrid seen from the timing drive side. Two of the three throttled and reed-controlled intakes to the crankcase are visible, also (at 45º to the main axis) the single reed-controlled charge exit. The third intake is hidden underneath (Photo: Victor Gotbring)
Returning home from Kazakhstan, Ellwood established his first hybrid concept engine by paying £80 for an ageing methanol-fuelled, naturally aspirated, 499 cc Godden Speedway four-stroke single (RET 17, September 2006). In his spare time, over 3 months in 1995, he converted this 10,000 rpm chain-driven overhead-cam four-valve engine.
That included welding reed valves to its thick aluminium crankcase. “A hacksaw, drill and file were enough to slaughter it; a bit of rubber pipe, two reed valves from a [Yamaha] RD350, a crankcase seal and a Rotax carburettor converted the relic into a hybrid,” he recalls.
A trip to Hasse Holmqvist’s nearby Dynojet facility and using an 8:1 compression ratio revealed a maximum output of 30 bhp at 6000 rpm (as measured at the crank), compared with a maximum of 25.7 bhp at 5500 rpm with the system disconnected – a gain of 16.7%.
“The following year we changed the inlet reed to a bigger Husky 250 cc size, which gave an instant increase of 16 bhp at 7000 rpm,” Ellwood reports. “Anything over 7000 showed a decline in horsepower, although it did rev cleanly to 10,000 rpm. Hasse was impressed with the response on acceleration and deceleration, and it could hold steady revs without misfiring and still rev to 10,000 rpm.”
Ellwood also built a frame suitable for road racing to house the engine. He wasn’t permitted to road race in Sweden in 1996 so went drag racing instead, where he found the only class the bike was eligible for was Top Fuel Motorcycle. “Lining up in front of thousands of spectators on a bike that looked like it had been extracted from hibernation in Rip Van Winkle’s woodshed was somewhat daunting,” he says.
In 1997, the authorities allowed Ellwood into Supermono road racing. “I had a great time tootling around the track, picking up points, creating smoke screens that a steam engine would have had a hard time matching, and doing a lot of makeshift mechanic-ing,” he says. “I always made it to the finish line – in last place – but I was content that the engine held.
“It hadn’t been easy converting from methanol [used in speedway] to petrol, there were so many factors – compression ratio, cam timing, percentage of two-stroke oil, jetting and timing, and so on. The BSA gearbox with cork clutch plates was deplorable, and most races had to be done stuck in second gear. But the engine was tractable and could pull from a hairpin to full revs by the end of a straight.”
The old gearbox was eventually replaced by a Quaife four-speed plus a Hemmings clutch. There was experimentation with computer-programmable Haltech fuel injection and Ignitor electronic ignition in 1998 “but the more technology I had, the worse things got!”
Ellwood uses an Aspin-type rotary valve, replacing his original Cross type
Then Ellwood bought a mid-1980s Jawa speedway bike, which he converted to hybrid, "so that I could concentrate on methanol again”.
The Jawa was used in speedway in Norway and Sweden. “I 'raced' with the old boys but most of those had been professionals in their youth. They all seemed to like the [hybrid] idea, although at times it smoked like a chimney, broke down more than it ran, and the throttle liked to stick at the end of the straights,” he says.
“The engine had total-loss oiling with a pump to send oil to the big end and the head, and the smoke problem was cured by a simple on/off tap. That prevented oil seeping through the pump and filling the crankcase when the engine wasn’t running.”
In 2001, Ellwood was given an extra Godden engine, donated by Mike Larsson, which was converted to hybrid as a spare road race engine, so there have been three speedway-based hybrids. “All three ran without breaking under normal conditions, and demonstrated brutal bottom-end torque.”
The original Godden hybrid has seen action in Sweden’s answer to Bonneville, Glenn Ocklunds Landracing.se, an annual flying kilometre speed contest on a frozen lake. That started in 2009, when Ellwood set a record at 111.34 kph riding it with nitrous oxide assistance in the under-500 cc supercharged and/or nitrous oxide class.
In 2012 he upped the class record to 156.487 kph, with a top speed 162 kph. “That was despite almost falling off, missing the gear change twice, losing contact with the laughing gas button, and fighting through 6 in of water and slush on top of the thawing ice,” he says. Since then he has experimented with a rocket sled, but that is another story.
Bespoke engine
The hybrid road racing adventure continued on and off through to 2007, when it concluded at his favourite track, Oliver’s Mount in England, “with a practice wipe-out and three DNFs”. That was the year Ellwood decided to build his own-design hybrid motorcycle engine.
He says, “The whole journey since 1994, when I dreamed of this type of engine, has been a slow learning curve of how to do it, what works, and what doesn’t. Obviously I have to do my day job, and look after my wife and four children, fix the car and so on, so the new bike has taken me more time to design, build and perfect than I had hoped.”
Supermono is normally for single-cylinder engines of up to 800 cc, but the Supermono GB club in the UK allows Ellwood up to 1300 cc. He has taken advantage of that and has subsequently been given dispensation to run in Swedish Supermono races with what will be a 1173 cc bike.
When he started design, a 116.5 mm piston was the largest readily available, and that was combined with the longest feasible stroke, which was 120 mm for 1279 cc. It is now 110 mm for 1173 cc. “This mid-build change put space between the front wheel and the head of the laid-down engine, allows the engine to rev an extra 1000 rpm and reduces the harsh power pulses on the rear wheel.”
He adds, “Because this engine supercharges itself it should work very well as a 1173 cc single. I have designed it to be a slogger instead of a revver. I think that will give it reliability and power.”
As such, the crankshaft is balanced for running between 5000 and 6000 rpm. “Everywhere else it will probably vibrate like a stone crusher!” he says.
It is envisaged that, aside from running on E85 in Supermono races, it will be able to run on regular petrol, methanol and even nitromethane or diesel. Everything is therefore heavy duty – for example, the cylinder bolts are 16 mm diameter. The crankshaft runs in four ball bearings, two on each side. The crankcase is 40 mm thick.
Ellwood says, “I’ll be disappointed if she doesn’t put out 150 bhp at 6000 rpm on E85 using an 11:1 [static] compression ratio, and she may be able to develop as much as 400 bhp on nitro. Experimentation is necessary to obtain optimal compression ratios, which might go as high as 15:1”
He hasn’t just designed the engine, he has engineered an entire bike around it. With the engine laid down, there is no space for a gearbox, which is just another cost to his mind. “The engine is 600 mm long, and if I had a gearbox the wheelbase would be OK for drag racing but too long for road racing. I now have a BDL heavy-duty clutch on her [set into the swing arm] and I’ll just slip the clutch on the hairpins.”
The 500 cc engines got as far as having double intake reeds on the crankcase, and the 1173 cc has triple reed intakes, each having its own throttle body with the three butterflies mechanically linked. There is a single reed-controlled exit to the plenum.
To minimise the thermal loss inherent in compressing the charge, Ellwood uses an air-to-air charge cooler. He says, “I have a whopping intercooler situated under the tank, while [ahead of that] under the saddle is a massive ‘boost reservoir tank’ [plenum] to even out the pulsed supercharging from the underside of the [single] piston.”
Downstream of the charge cooler are four fuel injectors, “to be batch fired on each stroke, ensuring thorough fuel sufficiency.” As with the previous hybrids, Haltech injection and Ignitor ignition are used, and there is also water mist injection into the charge to help cool the engine as well as add oxygen.
It was originally envisaged that the con rod would be aluminium, but for dependability this is now a bespoke CP-Carrillo steel forging, driven by a CP-Carrillo forged alloy piston. The flat-top slipper piston carries two rings. It runs in a cast iron liner produced by Westwood.
The one-piece head and vertically split crankcases are machined from billet, while the cylinder head is machined from castings produced using Ellwood’s own small foundry. The castings were made from melted-down alloy car wheels he had salvaged, he and fellow volunteer foundry operators surviving a sudden explosion caused by pouring into a damp mould!
Ellwood even makes the steel crankshaft himself using his ancient mill/lathe, albeit with splines machined by Stirep and Sala Hardarna hardening the crankpin and nitriding the flywheels – both Swedish companies assisting “for free”.
The built-up crankshaft is pressed together cold, using 15 ton pressure. Local speedway engine specialist The Dudes of Speed lent him its hydraulic press, “together with a crank-balancing jig, a copper hammer and a solid chunk of aluminium for whacking the crankshaft straight”.
The same total-loss oiling approach as in his speedway hybrids is used, albeit with a 12 V K&N pump sending two-stroke oil to the crankshaft and from there to the big-end needle roller bearing. “That bearing likes a good supply of fresh oil,” Ellwood notes.
Other 12 V pumps are for the water injection and the water cooling, which is purely for the liner. The rotary valve head requires, in Ellwood’s words, “only air cooling, aided by cool E85 fuel.”
The use of rotary valving keeps the cylinder head simple. Initially a belt-driven Cross-type rotary valve was used (RET 004, Spring 2004). Ellwood says, “Machining that [Cross] valve tube from solid aluminium, and milling/lathing her out while holding a telescopic mirror, took a bit of doing. The hard-anodised finish on the valve made her look the dogs bollocks though!”
Alas, when the engine was started up for the first time in December 2019 it blew its graphite rotary valve seals – “after only 15 seconds!”
After three failed start-ups, Ellwood reluctantly abandoned the Cross concept and went for the Aspin one instead. Invented by Frank Aspin, this is a form of rotary valve that rotates on the axis of the cylinder bore rather than perpendicular to it. Instead of a Cross-type ported cylinder it uses a horizontal disc atop the cylinder, having a window that as it rotates uncovers the inlet port and then the exhaust port.
“Having to make an alternative Aspin head – with a bevel drive from the timing belt – put the project back the best part of 6 months. The only thing holding back testing now is the fuel injection programming. My ancient MS-DOS-fired laptop necessary for the old Haltech F9 has crashed and it is very difficult to find a replacement nowadays. Maybe I will have to save up for a new EFI system!”
Future plans
At the time of writing, Ellwood was starting dyno testing of his 1173 cc engine; we will bring a report of that in a future issue. Ellwood notes that the 1173 cc engine has also been designed to power a snow scooter. Aside from Supermono racing, he also aims to run the 1173 on ice using a nitromethane-methanol fuel mixture.
Ellwood hopes one day to run at Bonneville “in true Burt Munroe style. Everything is possible in your dreams. In reality you can seldom fulfil all of them, but together with a good gang of mates you can have a fun time along the way.”
DATA SHEET
Ellwood hybrid
Single cylinder
116.5 x 110 mm = 1173 cc
Naturally aspirated/crankcase supercharged
E85 fuel (road racing)
Aluminium block and head
Cast iron liner
Four main bearings
Steel crankshaft
Steel con rod
Aluminium alloy piston, two rings
Belt driven Aspin-type valving
One (dual-purpose) valve, one plug
40 mm intake valve inlet tract, 38 mm exhaust outlet tract
Analogue electronic ignition
Electronic injection
11:1-plus compression ratio
Maximum rpm, 8000-plus
SOME KEY SUPPLIERS
Piston: CP-Carrillo
Liner: Westwood
Con rod: CP-Carrillo
Fuel injection: Haltech
Ignition: Ignitor
Oil pump: K&N
Crankshaft spline machining: Stirep
Crankshaft hardening: Sala Hardarna
Flywheel nitriding: Sala Hardarna
Clutch: BDL
Dyno testing: Hasse Holmqvist/Dynojet