I was there : When BL investigated rotary engines

Rotary engine - the Citroen GS Birotor unit

Sometime around 1974, Longbridge’s Advanced Engine Design Team was given the job of critiquing the Wankel engine (BL were probably considering a licence at that time). We hung out in the TIB (Technical Information Bureau) one floor down from the Engineering floor.

We read all the serious technical books and in one book a typical American V8 engine was compared with an equivalent Wankel engine. It showed that the former engine had 150 moving parts to the Wankel’s 10. (The figures may be wrong but I believe they were of this magnitude).

This was pretty impressive stuff. Actually, it was Wankel’s own propaganda, revealing a Wankel engine’s strong-point.

Was it all an illusion?

Later, with more knowledge of Wankel engines, I concluded that the engine and its exclusive ‘Club’ of members, was a marketing illusion. It was also inconceivable that Norton would have the funds and technical ability to do anything commercial with the Wankel.

After all, of those motorcycle brands taking out Wankel licences – IFA/VEB (Feb 1965), Suzuki (Nov 1970), BSA (Jul 1972), Yamaha (Sep 1972) and Kawasaki (Oct 1972) – only two produced mass-production quantities (say more than 1000 units). Hercules (part of the IFA/VEB group) produced under 2000 units in its three-year production run while the Suzuki RE5 (below) was quickly withdrawn from its catalogue.

Production numbers are unknown but, with a cautious 620 units ordered by the UK importer. it is doubtful that total production exceeded 3000 units. The remaining brands chose not to exercise the manufacturing rights their Wankel licences provided, or they produced miniscule quantities. If the remaining big spenders couldn’t make the Wankel work as a viable product, what chance Norton?

Suzuki RE5

Fans at BL despite the failures

Nevertheless, Harry Webster (BL’s Engineering Director) was a big fan of Felix Wankel’s rotary and an early adopter of the rotary principle. He even designed his own rotary engine.

On the day I joined Advanced Engine Designs in the Roundhouse at Longbridge (around 1974), I couldn’t use the footrest of the new drawing board due to a large wooden crate (about 30in x 15in x 12in) stored beneath it. This steel-bound and padlocked box was so heavy that a colleague had to give me a hand. He told me the following story of what was inside the crate.

With ‘Rotary’ the buzz-word of that era – think Felix Wankel, think Ralph Sarich (Orbital) – and with an NSU Ro80 (below) already tested by BL, Harry Webster designed his own rotary engine. Webster’s rotary is probably the engine described in BL’s Patent No GB1275544A – ROTARY-PISTON INTERNAL COMBUSTION ENGINES (published in May 1972) which names Webster as its inventor.

NSU Ro80
NSU Ro80 was tested by BL and had fans within the firm

Finding BL’s rotary hidden in a crate

As BL’s Engineering Director, Webster was well-placed to have his own engine patented, detail drawn, and its prototype manufactured and tested in his own departments at Longbridge. It was Webster’s rotary engine that was locked inside the wooden crate beneath my drawing board.

The reason it was locked away was the maxim that an engine must produce enough power to overcome the frictional resistance of its moving parts at all given speeds. If it doesn’t, the engine will slow down and stop.

The Webster Rotary produced so much internal friction and so little power that it couldn’t idle under its own steam. Changes were made but the engine was a faux pas. It cannot have been easy for some Development Engineer to tell Webster, his ultimate boss, that the Webster Rotary was fundamentally flawed.

Good idea but fundamentally flawed

It was Webster’s defunct rotary engine that had been locked inside a wooden crate stored beneath an unused drawing board in reputedly, Longbridge’s most secure building, the Roundhouse. Well, it did have a magnetic card entry system with a password keypad, both quite revolutionary for the early 1970s.

Too much friction and resultant heat. That was the problem with Rotaries and, in my later experience with Suzuki’s rotary engine RE5 model, that was always the issue.


  1. My Dad had a 1973 Mazda RX4 coupe with Rotary engine. Lovely car and smooth power. I got to drive it a few times, though it was thirsty (around 20 mpg as I recall). He kept it till 1978 and never had any mechanical problems. The Wankel engine was another of those creations which were revolutionary but never achieved huge success.

    • The problem with rotary engines is the tips of the rotary arm. They have to give a good seal for the engine to work effectively, however the heat and friction against the block would wear them down. Mazda did get it a lot better using newer materials on the RX8, with the tips lasting a lot longer. But it’s packaging advantages are really outwayed by its fuel consumption.

      • You have obviously not realized that NSU solved the problem with the apex seal already in 1970 when they together with their licens customers started to use the material ferrotic. The car was in production for 7 years after this. It can be good idea to have some knowledge about the subject before making such statements.

        • Really? NSU design for Apex seals damaged the casing and therefore killed the engine. It was why NSU was forced into the arms of VW, due to the compensation costs were going to bankrupt the company. As I said Mazda sorted it, sort of, making the engines last a lot longer.

          • The Norton road bikes had trouble with the side-seals of the rotor severely damaging the engine cases, a workmate bought a Norton and had the misfortune to become a member of the Norton bike / no engine club.
            Another aspect of the Norton Rotary was lubrication, Shell Rotella crankcase oil by a 2-stroke pumped total-loss injection system, it was said that anything else would lead to a written off engine within 1000 miles

          • You pull things out of thin air, I am sitting on first hand knowledge of the subject. NSU used exactly the same material in Apex seals as Mazda. Exchange of information was part of the license conditions NSU set when they sold Wankel licences. NSU didn’t go bankrupt either, they merged with Auto Union and Audi. The company was named Audi NSU Auto Union AG until 1985 and the NSU Werke in Neckarsulm was also the headquarters of the company until then and it was moved to Ingolstadt. There is absolutely no car factory in the world that hasn’t struggled financially at one point or another. I have personally been to the NSU Werke factory several times and personally know former factory employees and test drivers from the factory that today produces the largest Audis. At the time of the merger, NSU had a fully developed NSU K70 which VAG, with its stock mariotet, chose to take as its first water-cooled front-wheel drive car. The same fate befell the NSU 50, which became the Audi 50 and later the VW Polo, one of the world’s most popular cars. There was more VAG that needed the technology NSU put in rather than the NSU that needed VAG. You can deny real facts that can be documented as much as you want. but please don’t spread things you’ve only heard bits and pieces about and don’t know documented facts about.

          • Well every article on the Internet about NSU, the wankel engine and Mazdas improvements to said engine in the late 79s and 80s must be codswallop then?

    • The huge “success” of the motor car Rotary engine was the number of adopting car companies who entered or skimmed bankruptcy , NSU, Mazda, Citroen.

  2. It’s simple really. Whilst a reciprocating piston goes up and down by double its stroke for each crankshaft revolution, the Wankel’s rotor tip seals rub against the inside of the epitrochoidal chamber which is a much greater distance. This adds to the heat created by friction. It also means that tribology plays a major part in the Wankel’s reliability, longevity and lubrication.

    In 1976 I raced a Suzuki RE5 Wankel-engined motorcycle in a long distance race around Cadwell Park. This supposed 500cc engine returned just over 20 mpg fuel consumption and consumed 65 miles/pint of engine oil and boy did everything run HOT-HOT-HOT! This is not good for an engine. The heat is supposed to be contained within the engine and converted into useful power instead of radiating outwards where its energy is dissipated to the atmosphere.

    Whatever people may think, I know from a theoretical and practical level that the Wankel engine was a bit of a con on the part of Felix Wankel. If it was all that good, we’d all be driving Wankel-engined cars by now but despite its ‘club’ members sharing solutions to its inherent problems, it was soon considered a non-starter other than (notably) by Mazda.

    • Re your racing experience of the Suzuki RE5, you must be one of a tiny number of riders who cam[campaigned an RE5 on a racing circuit, the RE5 was more of touring motorcycle than a racer, the RE5 was very heavy and bulky, how did the RE5 fare against the lap times of bikes such as the Yamaha RD400?
      Also 30 years since Steve Hislop won an Isle of Man TT race on a Norton Wankel Rotary. The epic race battle against Carl Fogarty riding a Yamaha may be found on Youtube

      • If you’re interested in this youthful caper that I undertook soon after leaving Longbridge for pastures new, here’s a link to some more detailed information of the tale.


        Why? It was just a jaunt. Something new;something everyone said was stupid; it was fun. It was also difficult to put together but when you’re young that’s just part of the challenge.

        The RE5 won its class (500cc) and was only beaten overall by a Ducati 900 so if there was an RD400 in this long distance (600 mile) race, the RE5 beat it too.

        I’ve always admired Yamaha RDs. I owned an RD250 production racer that I used in club events alongside my trusty vintage machines (more races per event).

        • CORRECTION – The July 1976 BFRC Long Distance event was actually a 700km (432 mile) race run over 2 days, a total of 288 laps of Cadwell Park’s club circuit.

          Did the Suzuki RE5 beat the Yamaha RD400?

          Here are the published results of that race:

          1. D Noyes / J Knowles (864 Ducati SS) 6h 35m 21s 65.S6 mph
          2. J Wilkinson / R Battersby (497 Suzuki RE5) 280 laps
          3. G Page / G Wood (498 Honda CB500) 278 laps
          4. H Evans / A Ayers (812 Honda CB750) 276 laps
          5. J Oldfield / T Robinson (231 Benelli 2C) 273 laps
          6. S Noon / L Williams (750 Triumph T150) 268 laps
          7. M James / C Leough (247 Suzuki GT250) 263 laps
          8. T Moring / G Roberts (347 Yamaha RD350) 260 laps
          9. M Hepworth / M Welford (498 Honda CB500) 255 laps
          10. J Musson / L Reed (398 Yamaha R0400) 250 laps
          11. P Franklin / R Tomlinson (748 Ducati Sport) 237 laps
          12. S Fry / B Griffiths (750 Ducati SS) 236 laps

          Greg Page (3rd) recently said of the 500cc Class race on Facebook: “They won with a flat rear tyre for the last few laps, beat us by about a lap. John Wilkinson (RIP) still achieving about 90 on Park Straight with rear flat. Bike was super quick.”

          Yamaha news was not good. An RD400 finished 10th overall, beaten by a 250cc Benelli, a 250cc Suzuki and also an RD350. Such short ‘endurance’ type races can easily be won or lost in the pits. Thankfully, we had practised our stops and all went well.

          One or possibly two others have raced a Suzuki RE5 rotary. I heard on the rumour mill that an American had road-raced an RE5 but despite much searching, found nothing in print, nothing on the web and have only a blurred indistinct front view of what appears to be an RE5 in a race. In 2002, a Swiss rider called Hans Reusser started racing a Suzuki RE5 in continental ‘classic’ events.

          • ray,
            I have placed an order for your book.
            Did you ever meet the Suzuki Works rider John G Williams?
            JG had a number of issues when teamed alongside Barry Shene.
            JG, his best friend worked in the Laboratoy department next to mine, during tea breaks we would hear of the underhand tricks BS used to maintain stature with Suzuki. JG “cracked”, took revenge, and trounced Sheene at the Belgian 500 Gp
            I used to have an RG500 road bike, fuel consumption, 3 gallons an hour, the faster I drove the better the mpg typically 22 mpg

          • Motorcycles tales are probably off-piste here but for completeness, I’d like to say that on joining Suzuki, I was told not to race my Yamaha RD250.
            Fair enough I suppose.
            That’s when I had the crazy idea of racing the Suzuki RE5.

    • In a conventional 4-stroke, the piston rings play a part in the transfer/conduction of heat from the piston to the cylinder wall. The rings conduct heat. How is the Wankel rotor cooled? Do the hard-working seals conduct heat too. From the team manager, the TT winning Norton rotary of Steve Hislop ran so hot, at night, the exhausts would glow dark red. the Suzuki RE5 had an unusual double-skinned exhausts with a cooling air system for rider safety such was the heat output of the RE5

      • The Suzuki RE5 ran hot too. Its double-skinned mufflers each had special air intakes to drive cool air into the annular gap between the skins. This was a warning sign that things were not well.

        The high levels of exhaust noise alongside the poor efficiency of the RE5 rotor and the resultant high fuel consumption, suggest that the exhaust port probably opens well before combustion has ended. This allows hot, high pressure, expanding exhaust gases and some unburned fuel to enter the exhaust system before it had produced more useful power within the combustion chamber.

        If this theory is correct, it would explain the RE5’s low combustion efficiency, sizzling hot exhaust and lamentable fuel economy. Combined with the excess heat generated by internal friction, the Suzuki RE5 literally radiated heat energy into the air surrounding the motorcycle.

        • Ray can you recall the details of lubrication oil used for the race event by the RE5?, Was the oil standard 2-stroke oil, (I think Suzuki retail oil was called Suzuki Golden Film), did the RE5 have a unique 2-stroke oil, or did you use something more exotic, Castrol R or a GP500 racing spec oil.

          • I regret that I cannot be specific. Castrol sponsored the effort and their decals were prominent on the fuel tank. This could have so easily upset Texaco, (my employer’s main GP racing sponsor) but thankfully didn’t. So I’m pretty sure we used Castrol oil of some type as recommended by their technical sales guy Ian Robinson. I doubt it was R because that would have meant draining, flushing and otherwise removing all traces of the usual mineral oil first. The RE5 was bought new, run in and was racing within a few days. It was prepared in my own domestic workshop. So I had no time; no tools; no know-how.

            Could it have been an EP90 lubricant to withstand the pressure and heat? We certainly used the EP90 type plastic bottles with flexible tube to inject the oil during each pit-stop. So possibly, but I’m no lubrication expert. This is why the oil spec will forever remain a mystery.

      • Heat distribution in a rotary engine is completely different from a piston engine.
        In a piston engine the combustion chamber alternatingly has contact with fresh mixture and hot exhaust gases and gets cooled on every second stroke on a four-stroke. In a rotary engine there’s one part of the trochoid that always and only has contact with fresh mixture (and is therefore called the ‘cool arc’) and another part always and only is exposed to combustion heat (and is called the ‘hot arc’). In modern rotary engines the cool arc has no cooling at all and the hot arc gets all the coolant.

        Combustion in a rotary engine is extremely inefficient due to the shape of the combustion chamber, leading to dirty and very hot exhaust gases, high fuel consumption and a terrible thermo dynamic efficiency where lots of the power stored in the fuel gets converted to heat and hot to mechanical power.
        This additional heat partly escapes the engine via the exhaust system which gets much hotter than in a piston engine. That’s why Wankel engines have exhaust systems made from high quality material and that’s why you can look into the tailpipes of an RX-7 and see the yellow glow of the baffles in the silencer.
        A large part of the thermal energy heats up the rotor which needs active cooling. Cooling can either be done by oil as in the NSU, Comotor or Mazda engines. Then you have the cooling oil flow through the inside of the rotor, cooling it and lubricating the trochoid’s sidewalls in one go (the large area of the sidewall and the amount of oil adhering to it and then getting burnt are the reason for the high oil consumption of an OCR – oil cooled rotor- type Wankel).
        Alternatively you can have an air cooled rotor as in Fichtel&Sachs Wankel and its derivatives as in BSA and Norton motorcycles which are direct descendants of the F&S engine. Here fresh air is guided throgh the rotor and then through the carburettor, cooling the rotor but heating up the mixture. Such an engine also has to be run with petroil for lubrication of the trochoid sidewalls. The big advantage of the F&S engine is that it can operate in any position which is very useful for large (Stihl) chainsaws where the lack of vibration also puts less stress on the workers.
        On their racing bikes Norton fed fresh and cool air through the carburettor and used a venturi system in the exhaust silencers to suck cold air through the rotors.

        The problem with the apex seals was not the seals themselves but the small leaf springs behind them. These were necessary to press the seals against the trochoid at low engine speeds. At higher speeds centrifugal forces and gas pressure from combustion working from behind the seal pressed them against the trochoid. If there was not enough pressure the seals would rub chatter marks into the trochoid’s surface.
        In case of a seal failure a rotary engine will continue to run (opposed to a piston engine which will just stop to run with broken piston rings), albeit with less power, which makes it a favourite with the snow mobile fraternity.
        NSU saved the wear problem by using sintered iron (ferrotic) for the seals and nikasil for the trochlid, Mazda used sintered carbon for the seals and hard chrome for the trochoid, a much cheaper and simpler solution.
        The latest wankel development by Audi is the Wieland ‘sheet steel’ engine. Here the trochoid sidewalls are made from stampings of stainless steel sheet material, the trochoid is made from a strip of stainless steel bent into form and laser welded into a seamless surface. Cooland runs in sections of stainless steel tube and all is glued and laser welded together. Even the rotor is welded up from stainless steel pressings, finally putting an end to the Wankel’s problem of disproportionately high production costs. The Wieland engine also has apex seals made from tubular material that do a rolling movement against the trochoid instead of scrubbing over it. The latest application of this engine was shown in the Audi A1 e-tron show car that used a tiny Wieland wankel as range extender.

        • Mmmm. Like I said…
          ‘…the Wankel engine was a bit of a con on the part of Felix Wankel. If it was all that good, we’d all be driving Wankel-engined cars by now.’

          By setting an unattainable and arbitrary deadline, our non-technical politicos have given an undeserved boost to incredibly profitable EV sales by forcing EVs down the throats of well-meaning motorists. It was the same lot that previously boosted diesel sales on a false premise some years ago so their EV caper is unforgivable.

          I am ceratin that when the 2030 deadline for the mandatory sales of new EVs is extended or cancelled, the cars chosen by the market to fill the gap will not be powered by a Wankel rotary engine.

          • I happily agree that Felix Wankel was not a pleasant person to work with (to be polite) and his engine is an answer to a question nobody ever asked.
            That’s why we aren’t driving around in vehicles powered by rotaries.
            The rotary engine’s problems are rooted in its concept, not in execution.
            No amount of development can navigate around the thermo dynamic inefficiency of rotaries and all the fundamental problems associated with it.

            I’m far from being a fan of rotary engines but I’m annoyed by all the urban myths and old wife’s tales surrounding it. Most of these tales are nonsense and much of them come from a lack of understanding of the basic principles of this engine – and that’s something that can be put right.

  3. The poor fuel consumption seemed to leave rotary engines in a niche for high performance engines, as occupied by Mazda & a few others.

    I remember reading a book on motor racing which had a proposed Formula 1 car of the future with a Wankel engine, I presume before they were outlawed by a change in regulations.

  4. Rotary engines are still being made in the UK, company called Rotron in Wiltshire, mainly for UAVs / Ultralights

    • The cynical side of me says that if an ‘ultralight’ is related to a microlight in that it flies, then I genuinely hope that it can be safely glided to terra firma in the event of engine problems.

      I’ve heard that rotaries are being used for target aircraft (drones) where they are ultimately sacrificed. That seems a more appropriate use for me.
      Felux Wankel was considered a ‘rotary’ expert even before WW2 and is epitome, for me, was his disc valve torpedo engine that fitted inside a 21 inch torpedo. Very clever, though that engine too was designed for a very short life.

  5. Rotron could be Norton, the maker of the Wankel engined Norton road motorcycles.
    Notice Rotron is almost N-o-r-t-on when written right to left, a mere coincidence?

  6. Ralph Sarich, as late as 1998 when Rotary engines were considered commercially nonviable in motor cars, Ford engaged with Sarich and built a small batch of cars either Fiesta or Escort with the Sarich Orbitel engine, it is said the cars were under test with the Essex Police Force, and the Ford Ka was the intended model for the production Orbitel engine.
    The project came to some sort of end and the Ka received a modernised version of a long-running Ford pushrod OHV from the days of the Ford Anglia 105. So the rotary made a reappearance in the form of a modified form of Wankel engine.
    here is a link to the Orbitel and the Ford connection:

    • Just to clarify a common misconception, the “Orbital Engine Companies” two-strokes that were being tested in the late nineties, were basically conventional two-strokes fitted with Orbital’s (the company) direct injection system. They were not ‘Orbital Engines’ in the strict mechanical sense since that original idea had long since died.

  7. Reading around the Orbitel, there are posts about a Jaguar supercharged 2-stroke V6
    “Jaguar had engaged Orbital on a project for a supercharged two-stroke V6 engine for its mid-sized sedans”.
    The project “died” before or during the Ford takeover.
    I do not think AROnline has covered the topic, can anyone confirm the existence of the V6 2-stroke project

    STOP CLIMATE CHANGE, A HOPE FOR THE FUTURE. ========================================================



    I am looking for help to develop a new WANKEL rotary engine with the ideas of the “BRUNTOR” project.

    The three most important ideas of the “BRUNTOR” rotary engine project are the following:

    1ª.The new BRUNTOR GAS DISTRIBUTION with its small ports with a very reduced eliminates all the problems of peripheral sealing of the rotor and reduces the noise of the evacuation of burned gases.

    If the idea called “RAMP” is applied to these small ports, their “SURFACE” area and working “TIME” will increase very significantly. ========================================================

    2ª.The new BRUNTOR ROTOR SIDE SEAL improves crankcase tightness and reduces burned oil. ========================================================

    3ª. The idea NEW DESIGN FOR THE VERTICES OF THE ROTOR has already been put into practice to eliminate the problem of peripheral sealing that originates in the huge evacuation port of the SACHS rotary motor with excellent results.

    Although in the BRUNTOR project this idea is not necessary to ensure permanent tightness, this idea will be put into practice to reduce the centrifugal displacement of the rotor apex seals, thereby reducing wear. ========================================================

    Thank you for your attention and receive a cordial greeting: BRUNO. ========================================================

    BRUNTOR. BRUNO-ROTOR. ELIAS BRUNO RIBEIRO. ========================================================

    Imagination can create knowledge,
    but knowledge can limit the imagination. ==============================

Leave a Reply

Your email address will not be published.


This site uses Akismet to reduce spam. Learn how your comment data is processed.