Image courtesy of the State Library of Western Australia
Perth, Western Australia, 1972. A locally born engineer/inventor named Ralph Sarich won Inventor of the Year on the ABC TV program “The Inventors” for his Orbital engine design.
The resulting media coverage and later investments by State governments and the large mining company BHP allowed him the funds to further develop the engine with a view to mass production.
Image courtesy of the State Library of Western Australia
The engine operated on the four-stroke principle, you can see the ports and the tops of the rockers above each of the seven chambers. The Orbital differs from the Wankel rotary engine in that the center rotor orbits around the “crankshaft” rather than rotating, avoiding the high tip speeds that was always the bugbear of the Wankel engine. The sliding and hinging vanes separate each working chamber from the others. While it was light & compact for its capacity, it suffered from poor “cylinder” & combustion chamber shapes and cooling issues which in the end prevented it from becoming a competitor to the traditional and well developed conventional piston engine.
Image courtesy of the State Library of Western Australia
Here Ralph Sarich himself on the left appears to be assisting with inserting the rotor into a prototype engine. You can clearly see the rockers operating the poppet valves; I believe this unit had a capacity of around 3.5 liters so it was clearly a very compact unit.
Image courtesy of the State Library of Western Australia
Photo of Sarich’s Orbital Engine Company in Balcatta, Western Australia in 1973. Centre right is a unit on the bench. Also you can see a much smaller 5 chamber unit on the bench to the left. During this further development, Sarich, ever the inventor, came up with a novel fuel injection system which at the same time as directly injecting the fuel also delivered a shot of compressed air, greatly increasing the atomization of the fuel and also providing a stratified charge. Unfortunately in the end the company could not overcome problems with the engine such as overheating and sealing of the sliding vane system.
It was eventually realized that this Orbital Combustion Process was the real innovation and subsequently the company pivoted from the original orbital engine concept to applying the OCP injection system to the two-stroke engine.
The conventional crankcase compressed, port scavenged two-stroke, while temptingly light, simple & blessed with a high power to weight ratio has always been hampered by poor combustion efficiency and poor emissions due to the fact that the fuel mixture along with lubricating oil is inhaled into the crankcase & then pushed via the transfer ports into the cylinder before compression. Despite careful design like loop scavenging some of the unburnt fuel mixture can inevitably escape before the exhaust port closes.
The chief advantage of the Orbital Combustion Process in a two-stroke engine is that a combustible air fuel mixture is directly injected only after the exhaust port is closed, this stratified charge burns clean without exhaust dilution. A small oil pump is added, which supplies lubricating oil directly to the big end and main bearings, further reducing (but not eliminating) oil contamination of combustion.
In 1998 Sarich announced he had signed a licensing deal with Ford Motor Company for the use of the technology.Ford and OCP built a batch of Fiestas with a 1.2 litre 3 cylinder two-stroke for fleet and journalist evaluation.
Ford was planning to market this model as the Orbital Ecosport
One of the few survivors of this batch resides in the Motor Museum of Western Australia near Perth.
Originally Orbital used a modified 3 cylinder Suzuki outboard motor to develop the system but eventually designed & built their own motor – see schematic above.
Another variation of the concept is this 6 cylinder supercharged version transplanted in to a BMW 3 series on display at the same museum.
In the end there were insufficient advantages in the OCP two-stroke to supplant the incumbent 4 stroke engine for automotive use, as around the same time electronic fuel injection in combination with more sophisticated sensors and controls meant that the efficiency of the traditional engine kept improving year on year.
But that was not the end of the Orbital Combustion Process two-stroke engine. In the outboard engine world, two-strokes were well established mainly because of their inherent power to weight ratio. OCP had licensed the technology to Mercury Marine were it was added to existing motors and was marketed as the Optimax engine on their higher power outboards.
In addition to this, Mercury also built a spark ignited diesel version of the Optimax V6 but it was only supplied for military use.
Orbital Engine Co still exists but now as Orbital UAV, developing and supplying a modular propulsion system for unarmed aerial vehicles (drones) using the OCP two-stroke but adapted for multifuel use in a similar manner to the Mercury diesel outboard. Orbital currently has a tie-up with a Boeing subsidiary and has recently announced a tie-up with Northrop Grumman to develop a hybrid propulsion system for VTOL UAV.
Orbital UAV still has its head office in Balcatta, the same suburb of Perth where it all began nearly 50 years ago.
Ralph Sarich sold out the bulk of his interests in the company in 1992, and would go on to become one of Australia’s wealthiest men.
Chysler (U.S.A.) has also played with the technology. The were p;ans to use an Orbital engine in the Neon. Big writeups in the auto news of the time. Then- gone. The engine never appeared in a production form.
https://www.allpar.com/neon/stroke.html
I remember the press at the time mentioned Orbital prominently but the Allpar story only mentions Mercury. The article from OZ does say Orbital sold Mercury a license.
There was the EBDI (External Breathing Direct Injection) engine around that time. I remember reading that a Chrysler engineer named Joe Goulart was involved with it. I don’t know what relationship it had to the Orbital engine, if any.
yeah, IIRC that was Chrysler’s own design, not Orbital’s. The EBDI was a closed-crankcase blower-scavenged two stroke, like the Detroit Diesel truck engines.
This is so interesting. Thank you for the essay.
When Orbital did it’s first outboards with Mercury, They used that BMW at a bunch of the events basically touting that outboards were getting tech before the automakers.
That said the Optimax Merc’s were fantastic engines.
Remember reading about an experimental mk3 Ford Fiesta Orbital Two-Stroke prototype both online and in UK Autocar Mag 27/01/93 as well as on a very old episode of Top Gear in 1992-1993.
https://www.facebook.com/2strokemadess/posts/what-is-a-mk3-ford-fiesta-doing-on-our-page-well-this-is-one-big-piece-of-histor/715591791847738/
Also recall the mk1 Ford Ka was reputedly intended to be powered by the Orbital Two-Stroke engine before issues with the engine / emissions / etc caused Ford to revert to the Kent-derived Endura E engine.
Thanks for a fascinating read. I was quite aware of the Orbital two-stroke but not about its origin, which of course explains its name. The two stroke was a compelling solution at the time to take advantage of the two-strokes inherent compactness and lightness. But the downsized turbocharged triples made all that irrelevant, separate from the issues encountered. I bet Ford’s “suitcase” triple is no bigger or heavier than the Orbital engine they were considering.
I doubt the two-stroke will ever be resuscitated.
Fascinating reading – the original Orbital 4 cycle is such an elegant solution, it is a shame they could not manage to perfect it.
I recall reading something in C&D about novel engine designs in the ’90s such as the Rand Cam, Kauertz rotary vane, and others. Sealing and lubrication was always the “gotcha.” the one thing pistons enable that trips up all of these other designs (including the Wankel) is a piston with rings can keep the sliding surfaces lubricated *and* keep oil out of the combustion chamber.
I used to watch The Inventors, and remember the sensation Sarich’s engine idea caused, and the subsequent developments certainly got plenty of media attention. Australia seemed to have such a ‘can-do’ attitude in those days – now it’s like we outsource all our thinking to overseas.
Just one small correction, the Orbital EcoSport, as shown in the poster and in the metal, is a Festiva (Mazda 121) not a Fiesta (‘real’ Ford).
These fellows in their classic shorts and long white socks look a lot like Bank Johnnies!
Thank goodness that’s a fashion we don’t see now.
Thank goodness it was partly obscured by the workbench.
Yeah, we sure lived in the land of the long white socks when I was little. Every mayor or principal or Scout leader came out of their (flaired) winter chrysallis each summer resplendent in the socks, shorts, short-sleeved shirt, beer-gut, and tie, as if it’d all been on underneath during the cold, and all looking as if they should be kept out of the reach of children. It wasn’t a pretty sight.
Say, what’s a Bank Johnny, a free franger from your local financial institution? (Surely they’re meant to give you interest, not arouse yours, so to speak?)
Bank Johnnie is just a fellow working for a bank in the ’70s… (bound to screw you over too)
Did you come up with “land of the long white socks” spontaneously? Very clever if you did. I assume you’re alluding to “land of the long white cloud,” the English translation of Aotearoa, the Maori name for New Zealand?
Saw a lot of that look in Queensland in the 70s, all the male teachers at my school dressed like that, like most white-collar guys. Glad that fashion trend died.
Well that’s me in the middle of the 3 on the right!
That’s me in the middle with my sock pulled up high!
The Orbital Company’s fuel injection technology was also used on Fords final EcoLPi LPG fueled six, which enabled it the have the same power output as the Petrol version.
I loved The Inventors as a kid. It was a big show at the time, though I doubt I actually recall the ’72 winner as I was only four. They often seemed to have car-related ideas, or so it seemed to my car-distorted little brain.
Sarich always seemed to be a humble, genuine sort of character, and never liked PR or interviews much. He also made determined efforts to try and keep the manufacture of any of the injection stuff local, though ultimately without success, as I think it’s only the US companies who have used it.
I certainly didn’t know he became a billionaire later on, largely through re-investment of his Orbital money in real estate. But only 32nd richest man in Oz, Wiki says, (just 25 million-odd folk ahead of me then, so there’s hope yet).
I never did understand how that engine worked. In fact, in my kid-mind, in that era, it looked like a scary piece of space junk from Dr Who.
Thanks Peter
Yes you are correct,i knew it was a Festiva but for some reason typed it as a Fiesta.
The parallel universe of marine outboards deserves more investigation,there have been some very impressive high power multi cylinder two-strokes built.Although the 4 strokes seem to be taking over now especially at the top end of the market.
50 years ago were very innovative times for Ralph Sarich and his band of technicians. I for one am very disappointed to see two stroke engines losing favour now to 4 stroke. I am about to put a 75HP Evinrude ETEC on my old (1971/2) Wiltshire Commodore, as my old 1976 Mercury 500 finally succumbed to water jacket erosion.
Of course BRP stopped making the ETEC last year and Mercury Optimax has also gone. What next for the Inventors? Presumably a Fuel-Cell or Electric Outboard.