HRH Prince Phillip during a ‘cooks tour’ of Coventry Climax Ltd, Widdrington Road, Coventry on 21 June 1966…

I tripped over these photographs searching for shots of the FWMV four-valve heads- that 1.5 litre V8 was the engine Jim Clark used to win his 1963 and 1965 F1 titles in the rear of Lotus 25 and 33 chassis, the second of his cups was won using the four-valver.

Unsuccessful as i was in my search for an image of one of the final iterations of this lauded engine, i did find this beauty of a ‘normal’ two valver with HRH alongside- who are the technicians exchanging cam timing details with the chief i wonder?


The one below of the Prince wandering towards the 1.5 litre, still-born, FWMW Flat-16 made me chuckle as it reminded me of a DC Nye anecdote which goes along the lines of the Climax hierachy showing off the ultimate expression of their design and precision engineering capabilities- which was singing its supreme song on the test bed, but conversation was impossible, so Climax Managing Director Leonard Lee instructed revs to be cut back- a fatal mistake as 5000rpm or more was needed, below that critical number savage torsional vibration caused the quill shaft to break with plentiful mechanical mayhem following shortly thereafter- which it did. Whilst not an engineer the royal understood that something was amiss, making soothing sounds of sympathy, he wandered further along the corridors.

Check out the engines below- FWMV show engine, FWMW 16 in the right foreground, an outboard to the left of Lee, but what is the Amal fed four in front of the Prince?

Coventry Climax MD, Leonard Lee, HRH, Wally Hassan with hands in suit pockets behind and others- any clue folks? (Getty)


Prince Phillip sussing a CC dyno before sixteen cylinder carnage sets in (Getty)

None of the four FWMW engines laid down ever found their way into the cars designed for them- oil drainage, pumping and windage losses and time pressures ensured that- the 1.5 litre formula ended and Climax decided not to continue in racing so the Lotus 39, Brabham BT19 and Cooper T80 never raced with the sixteen cylinder engine for which they were designed but with a 2.5 Climax FPF four, 3 litre Repco Brabham 620 V8 and 3 litre Maserati V12 instead.

Theoretical advantages of higher revs, greater piston area and better breathing of the sixteen were never realised, but that FWMV four valve V8 delivered the goods even if its advantage over its more conventional sibling was marginal, mind you, in 1.5 litres 5 bhp makes a difference particularly if Clark J was behind the wheel of the car to which said engine was fitted.


What a jewel of a thing and what might have been had the 1.5 litre formula lasted another year? FWMW 16 on the test bed in 1965.

The antecedent engine of the Flat-Sixteen conceived by Climax Technical Director Wally Hassan and Chief Designer Peter Windsor-Smith was the 38hp ‘Featherweight’ 1020cc, SOHC four- from little things do big things grow. The two men set about design and construction of a 1.5 litre, twin-cam, two-valve, fuel injected sixteen cylinder engine with central power take off with projected power of circa 240-250bhp @ 12,000rpm after extrapolating the power of the best of the FWMV’s to the greater piston area of their proposed new engine.

Whilst twelve and sixteen cylinder engines were considered, the sixteen modelled best using the bore/stroke ratio of the successful Mk3 FWMV of 0.76:1- this provided for a bore and stroke of 54.1mm by 40.64mm giving a piston area of 23cm. Using the previously achieved 4.5bhp per square inch of piston area gave the 250bhp projection.

Lets not forget competitive pressures were the cause of this exciting engine’s birth- both Ferrari and Honda were racing twelves which showed promise, but 1964 ended up a battle of V8’s- Ferrari, BRM and Coventry Climax of course, with John Surtees’ Ferrari 158 taking the titles by the narrowest of margins.

The design influence of the Ferrari Flat-12 engine showed in that Climax contemplated the motor being used as a stressed member so chassis mounting points for the combined crankcase and cylinder block were provided on the crankcase and heads, of which there were four- four sets of four cylinders.

The crankshaft had central take off to minimise the torsional vibrations of such a long piece of exotic metal- the crank was laid out as two, four-throw single plane-units running in five main bearings but turned through 90 degrees to each other with their inner ends shrunk onto a central spur-gear. The spur gear passed power to an output shaft running below the crank at 80% of engine speed to suit the gearing of the ZF and Hewland transmissions used contemporarily.

1954 ad for the Coventry Climax Featherweight powered firepump unit. In 1951 the prototype 1020cc OHC, two valve, single carb, inline four produced 36bhp @ 3500rpm and delivered twice as much water as an existing unit which weighed double the weight of the Climax FW


Vic Berris cutaway showing the elegant simplicity…of the Climax FWMW Sixteen- oh what mighta been! Specifications as per text

The heads, as described above, used two valves and a single plug- the included angle between the valves was 48 degrees with inlet tracts designed for the port type Lucas fuel injection with which the designers were well familiar- Lucas also provided the transistorised ignition system.

Trains of spur gears running off the central power takeoff drove oil pressure and scavenge pumps down below and and the twin overhead camshafts and auxiliaries above the takeoff. Auxiliaries were located outta the way atop the crankcase comprised twin fuel injection pumps, the distributors and alternator- whilst the motor sounds huge it was small- only one inch longer than the FWMV at 30.9 inches and 22.6 inches wide.

Design commenced in 1963 with the first run on the dyno in late 1964- the major problem, as Prince Phillip will attest, was severe torsional vibration at low revs. A stronger replacement took too long and also failed- the best seen on test was 209bhp, none of the problems were insurmountable but the 1965 season was underway with developments of the good ole FWMV good enough to do the job.

Richie Ginther’s Honda RA272 V12 win at Mexico City in the very last Grand Prix of the marvellous 1.5 litre Formula in late October 1965 was perhaps a portent of what may have been an amazing battle between the Ferrari and Honda twelves and Climax sixteen in 1966 had the Formula run one more year, ignoring the small matter of Climax’ withdrawal from racing of course…


(M Hewitt)

Further research- not exactly the shot of the heads I was after but a great view of the four-valver’s camshafts, plugs and gear driven cams which were characteristic of this Mk6 engine used by Clark and the Mk7 allocated to the Brabham Racing Organisation- the two only 1.5 litre FWMV four valve engines.

The mechanic (who is it folks?) got the Lotus 33 back together in time for Jim to win the Dutch Grand Prix the following July 1965 day from Jackie Stewart’s BRM P261 and Dan Gurney’s Brabham BT11 Climax.


Denis Jenkinson eliciting information on the specification of the three Lotus 33’s at Spa in June 1965.

The #17 machine is Jim’s race car fitted with the four-valve engine- note the low level exhausts fitted to his two cars whereas the #18 Mike Spence 33 has a much earlier spec Climax fitted with two-plane crank and crossover exhaust.

Jim won come raceday from Stewart and McLaren’s Cooper T77 Climax with Mike seventh on a circuit where the extra 10bhp or so would have made a hellluva difference.


Still in the Spa paddock, note the distinctive ribbing on the cam covers of the four valve engine compared with the two valve motor shown in the drawing below. Low level exhausts, Lucas fuel injection- output of this FWMV Mk6 was quoted as 212bhp @ 10,300rpm and 119 lb/ft of torque at 8,900rpm.

ZF five speed transaxle, rubber donuts at the driveshaft inner ends, outboard non-ventilated disc brakes and rear suspension comprising single top link, inverted lower wishbone, two radius rods, coil spring/damper unit and magnesium upright- period typical and oh-so-effective, the rear end bite, traction of the 25/33’s was said to be one of the performance differentiators compared with the BRM P261.

Lotus 25 and early FWMV Weber carbed Mk1 or 2 V8 drawn (unattributed)


Getty Images, Doug Nye, M Hewitt, MotorSport, Vic Berris, Coventry Climax, ‘1 1/2 Litre Grand Prix Racing: Low Power, High Tech’ Mark Whitelock



A capable pilot, Prince Phillip about to leave Coventry, no doubt he had promised the Queen he would be back in London before afternoon tea- Westland Wessex ‘chopper?


  1. DIDIER LOURDE says:

    Perhaps the engine near prince Philip is FWMC. It was used at Le Mans in 1961. it was fitted with Amal carburators.
    742 cc, 83 bhp at 7500 rpm. twin overhead camshaft…

    may be…..

  2. David E.M. Thompson says:

    Has there ever been a successful sixteen cylinder engine, in motor racing or aviation?

    • DIDIER LOURDE says:

      Jimmy won the united states GP in 1966 with the H16 BRM

    • markbisset says:

      Hi David,
      As Didier wrote, the H16 had that one win in the back of Clark’s Lotus 43 at Watkins Glen in 1966.
      So, on one measure, given the vast number of engines in Grand Prix racing since its inception in France never won a GP, the motor was and is a success, but i’m not so sure the design met the expectations of Tony Rudd and its other parents however delighted they were with the Team Lotus win!

      • David E.M. Thompson says:

        Mark, I think that Jim, Graham, and Jackie, by the US GP in ’66, had very low expectations for the H16. Clark was out of the WDC, and found the H16 was quicker that the 2-liter Climax. He qualified on the front row, but the H16 blew, so BRM offerred a clapped out spare. Everyone was surprised that, in a race of attrition, the H16 was the survivor.

    • jon farrelly says:

      The Auto-Union V-16 was pretty successful. 😉
      There various plans for V-16 aero-engines but none really came to much.
      Harry Miller putzed around with some ideas, and basic drawings were done by Leo.
      Fiat built the AS.8 V-16 for a speed record aircraft that wasn’t completed.

      • DIDIER LOURDE says:

        Yes, you are right…V16 auto union ….Bernd Rosemeyer

      • LOURDE says:

        Bernd Rosemeyer had a dog…he taught it to show him “heil Hitler” with its leg…

      • David E.M. Thompson says:

        Jon, I was thinking of inline (including V and X) aero engines. But radial, two-row 18-cylinder engines were very successful. And the four-row, 28-cylinder Wasp Major was okay.
        I did forget about the V-16 Auto Union.

  3. DIDIER LOURDE says:

    Doug Nye and Des Hammill have a different opinion.

    In his book “Coventry climax racing engines” (page 164) Des Hammill said that the 16 didn’t start…So Prince Philip heard instead the FPF. Too noisy for him…without earplugs.

    After prince Philip had gone, Joe Parker try to start the 16 but nothing at all…

    who said the true story ? I don’t know and it’s not very important.

    • markbisset says:

      Poetic licence but on whose part- I’m happy to stick with Doug’s version!

      • DIDIER LOURDE says:

        Yes, Doug Nye is a great historian. I like him, too..

        Des write that Richard Hassan, Wally’s son, uses the 16 crankshaft as a door stop in his house…

  4. jon farrelly says:

    The helicopter is a Westland Whirlwind HCC.Mk.12 of the Queen’s Flight. It was a VIP version of the HAR.Mk.10 troop transport. The Flight had two, XR486 and XR487, the latter machine crashed in July 1967 killing the two crew plus their passengers, Capt. of the Flight Air Commodore John Blount and the Flight’s Engineer Officer. The Whirlwind was a license built Sikorsky S-55, this being one of the variants powered by a Bristol-Siddeley Gnome H.1000 turboshaft engine.

  5. bill HOLLINGSWORTH says:

    With the unfortunate title Climax in Coventry. Walter Hassan’s book gives a pretty good history of the Coventry Climax story.

    • DIDIER LOURDE says:

      Bill, you are right ans Mark also !!!

      In his book “climax in Coventry”, Walter Hassan says this (page 128) :

      “There was an amusing sequel. In 1966,Coventry climax received a visit from HRH Prince Philip, Duke of Edinburgh, and M. Lee decided that we should put on a really outstanding technical display for him; we were to bring the flat 16 FWMW out of retirement, and run up it up the Weddrington road test-bed for his benefit.

      Thus we did, and when prince Philip reached the test house the engine was well warmed up and howling away spendidly.

      Unfortunately, this was followed by what we used to call “expensives noises” and the engine came to a sudden and grinding halt. I’m sorry to say that such was the pressure of work on non racing matters by then that we never stripped the engine to find out what was happened.

    • markbisset says:

      Thanks Bill,
      It is a good book, must have bought it twenty or so years ago. Its funny ones habits, even though I have the book the research for the article was all using online sources- I didn’t even think to look at that one, but I should have!
      The very best of books (Nye’s epics for example) have stood the test of time as to factual and contextual accuracy but some of the lesser shite is best avoided in favour of online sources like ‘The Nostalgia Forum’ where many ‘facts’ have been debunked by knowledgeable enthusiasts debating issues before landing on particular conclusions.

  6. Jonny'O says:

    Thank you very much for the post, photos and valuable comments. I imagined that the 16 cylinder had never awakened, that it was a mackeup, I am happy to know that it was a real engine !!!

  7. DIDIER LOURDE says:

    Thank you, Jonny’O !

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