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?
I remember my dad and all his car sales mates wore the long white socks too. A uniform as such. Hahaha. Dad sold Holden’s from 64 to 2004.
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.
If memory serves, Jaguar had engaged Orbital on a project for a supercharged two-stroke V6 engine for its mid-sized sedans. Once advantage of the Orbital two-stroke over normal two strokes was a much wider power band.
Unfortunately, the compromises with the engine meant it was not as adaptable as it needed to be for a road vehicle. You could get good fuel economy, you could get good power and torque, you could get good emissions, BUT you could not get more than one at any one time from a design, much better for outboards and scooters. Also, in cars, it just wasn’t superior enough to justify a new engine line.
Orbital did develop some impressive design software whilst developing the system, I do not know if this became an income earning opportunity.
Phil Irving (Vincent motorcycles and various racing motorcycles AKA the Sliderule) took Ralph Sarich to task on his efficiency claims, citing Ralph having left out the thermal rejection though the piston crown in his calculations – oopps!
Sorry you have your facts wrong. The Jaguar designed V6 two stroke was an impressive engine that delivered all expected outcomes of performance, fuel economy and emissions. The project was cancelled when Ford took over Jaguar as Ford was developing an in line 6 supercharged 2 stroke that was fitted to a lightweight Ford Taurus and gave 50mpg.
While you are correct that Phil Irving took Sarich on his argument on heat rejection into the piston was wrong . The surface area to volume ratio of the orbital was less than a piston engine and the piston was well cooled by oil.
I would like to see the report on the performance of the Jaguar V6, I had known about it for some time but could find no official detail on its performance. I did not think it survived all the way to the Ford takeover, but I must admit I have not recently looked at the Jaguar timeline. Also, it would be interesting to see what those performance expectations looked like.
Ford did an enormous amount of work on the orbital engine design and my understanding was that they could not get all three advantages at any one time and could only optimise one in any single design. If this was the case, and the engine was still being developed by Jaguar at takeover time, I can see a reason for them terminating it.
I would also like to see any official information on the Ford inline two-stroke six, an unusual choice for a two-stroke design. I will have to think about the high harmonic vibratory modes of the crankshaft given its length.
In any case, the condition of Jaguar’s production facilities must have taken first place in their concerns at the takeover, I often wonder if they had any idea of what they had got themselves into until it was too late.
Two strokes may find a home as range extenders in electric vehicles, where they can be run in a very narrow rev range allowing highly optimised combustion. However, they would have to compete against other engines such as microturbines, Wankel engines including the original Wankel design, and optimised 4 strokes. Quite frankly, I can really only see 4 strokes winning that battle.
As to the heat rejection of the piston crown, this was and is still a major part of the calculation of engine efficiency, and well cooled pistons reduce efficiency through non-work producing heat loss.
These issues have been known for a very long time, all ICEs are heat engines and primary design usually involves considerable work on heat flows, I can’t see why anyone would not include piston crown loss, it may have been less than other designs (I have not investigated it so do not know), but it can’t have been insignificant.
Any references will be gratefully received.
Hi Bob
I can’t readily lay my hands on the Jag engine details but from memory is was 2.8l and 145kW.
As for this statement “Ford did an enormous amount of work on the orbital engine design and my understanding was that they could not get all three advantages at any one time and could only optimise one in any single design.”
That is a total myth perpetuated by individuals at Ford Cologne who were dead against the idea of a 2 stroke auto engine. We had a fleet of 100 cars launched in the mid 90’s that accumulated over 5 million kilometers. Most were decommissioned at the end of the trial but some are still running today. I tuned one up last year – all it needed was new spark plugs and it ran as well as the day it was first run. The only issue with the car was a failed Ford shock absorber!!
Okay, I will take your word for it.
The problem remains, a lack of reliable data. I am used to this as I am interested in WWII aircraft engines, I would estimate that 95% of the documentation for these engines is lost and that is just the allied engines (perhaps American records are more complete). For some German ones it is close to 100%. Many arguments rage over claims for these engines with no real way of proving who is right, some threads get downright mean.
For instance, as far as I am aware these are no engineering drawings of a complete Napier Sabre engine with just a few drawings of an early mark block surviving. One well known author has to rely on German analysis of captured engines, as most Napier information was destroyed in the various takeovers.
It would be interesting to see how much data is retained by modern manufacturers for defunct lines of research.
I remember reading about the Jaguar engine at the time the development was being done, but, alas, that information has been lost to me courtesy of travelling Australia for 12.5 years permanently in a motorhome. The leadup to this showed that most houses are Tardises as I am sure that we got rid of more cubic metres of stuff that the total volume of the house. Some of those things, I deeply regret getting rid of, magazines was not one of them, I could never find the one with the article I was looking for.
I am still thinking about the crankshaft modes of a straight six 2 stroke. Of course, I am sure that there is software available that can do basic analysis but nothing beats building and testing the engines as many manufacturers have found out.
Do you have any detailed information on this Ford engine? I am far fonder of straight sixes than bent ones, although, 2 stroke bent sixes are a different kettle of fish.
By modern standards, the Jag V6 specs (if you remembered correctly) are behind modern production naturally aspirated 4 strokes. This raises the question of just how much development space was left in the design. Was it as much as then contemporary four strokes?
Was the Orbital as free-revving as traditional 2-strokes?
All my Saab 96’s were V4’s, but ca. 1977 a guy let me drive his 2-stroke for a few minutes at a Saab owners’ meet. It was a blast! For a while there I was rooting (in the American, not Australian, sense of the word!) for the Orbital to catch on.
Keep in mind that two-strokes always sound like they’re revving twice as fast as they really are, so it’s common to assume that they’re screaming at high revs.
Actually the Saab two-strokes revved no faster than the rather low-tuned V4. The two strokes (both the regular and the high-output Monte Carlo) developed their max. hp @ 5000 rpm. The V4’s power peak was at 4700 rpm, an insignificant difference.
The V4’s torque peak @ 2500 was a bit lower than the two stroke’s peak @2800 (3800 for the M/C).
The regular Saab two-stroke developed 44 hp vs. 73 for the V4, so although it may have sounded faster, it undoubtedly wasn’t.
Two strokes inherently are rather low-revving engines, as their breathing is much more challenged than a four stroke, especially ones with a hemi head or four-valve head. They make up some of the difference due to having twice as many power pulses per any given rpm, but that’s often not enough to make up the difference.
The Saab 2-stroke’s 841cc was well more than half the displacement of the V4’s 1498 cc. Yet it didn’t come close to making as much hp (44), even the highly tuned three carb Monte Carlo (60 hp).
But yes, they sound wicked.
“But yes, they sound wicked.”
My brother for GM 4I53 diesels in his boat, wet exhausts but no mufflers. He likes nothing better than the harsh bark of these engines as they start, followed by the more refined (relatively speaking) burr as they run at low revs, gun them and any refinement disappears into an over the top cacophony. EVERYBODY around where he moors the boat knows when he is leaving.
The other thing is that the Jimmies build up oil in the airboxes around the inlet ports if you run them as low to medium revs for some time. If you then gun them, the greater supercharger flow blows the oil out of the airboxes into the cylinders, so big clouds of smoke.
At 78, you would have thought he had grown out of this, alas, no!
Yes it was but it also had very good low down torque and quite a flat torque curve through the use of a flap valve in the exhaust.
The supercharged versions were even better.!
Yes it was but it also had very good low down torque and quite a flat torque curve through the use of a flap valve in the exhaust.
The supercharged versions were even better.!
Apiliamotorcycles used anorbital engine in a production scooter too.
Just stumbled on this. site. I was there for the Evinrude/Orbital project, It never made it to production but should have. Replaced by FIcht , it led to the OMC bankruptcy in 2000.
I also worked briefly as a consultant at Orbital on their 3 cylinder engine in 1994 and am very familiar with the Ford two-stroke program.
I agree with most of the comments above, except for the statement that two-strokes are not revvers. We (OMC) built 4 liter V-8 two-stroke race outboards that made almost 400 HP at 10,000 RPM. No valves to float!
The marine application is the toughest there is for an engine. It is the only one that requires – and sees – continuous WOT operation at redline.
An engine can be designed to have a desired power curve and red line. It just takes money.
Hi Don
I’m glad your recollection of history helps fight the various critical comments about the great work we all did. It’s a great pity Evinrude didn’t progress with the Orbital system!
Ken
Ps remember the toupee moment! 😏
Yep 2 strokes can rev like crazy and pull hard doing it. I was a marine mechanic, and my first job was working for a guy who did outboard racing. The Merc 2.4 and 2.5 v6 engines would pull thru the mid-range like a freight train. So fast to rev and would run all day at 7500 to 8k rpm, in drag racing they got up to 10k rpm. Some of the 4 strokes now have the pull but with a lot more weight then the old 2 strokes.
It wasn’t just boats either some of the 2 stroke ATV engines and motorcycle engine could rev too, A friend had a modified Honda 250R that would pull 9k rpm.