Rorstan Mk1a Porsche 2…

Posted: June 7, 2021 in Obscurities, Who,What,Where & When...?
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Bryan Falloon’s Rorstan Mk1a Porsche at rest in the Pukekohe paddock during the 1972 New Zealand Grand Prix weekend.

I’ve written about this rare car, built by Bob Britton at Rennmax Engineering in Sydney on his Brabham BT23 jig in early 1968. The story of the car is here, including poor Bryan’s demise on this Pukekohe weekend; https://primotipo.com/2020/08/17/rorstan-mk1a-porsche/

The rare colour photograph was too good to simply add to the existing piece.

By 1972 this 1967 spaceframe design – a modified F2 car was an old-clunker among the latest F5000s which made up the bulk of the field. But the impecunious Ian Rorstan / Bryan Falloon combination were having-a-crack.

The car was powered by a Porsche Type 771 twin-cam, two-valve, flat-eight. The design started as a 1962 1.5-litre F1 engine fitted to the Type 804. Engines grew to 2-litres – and here 2.2-litres, as measured by Alan Hamilton – for Porsche 907 sports-prototype use later in the sixties.

Incredibly complex in terms of bevel-drive operation of the camshafts and auxiliaries – Hamilton advises that the factory allowed 240 hours for the assembly of each engine – Rorstan bought the engine off Porsche Cars Australia when looking for a replacement for the geriatric Coventry Climax 2.5 FPF which powered the machine before.

The engine looks bulky and heavy, it is not – of magnesium and aluminium construction, it’s light. The disposition of horizontally opposed cylinders pops the weight nice and low too. The vertically mounted Bosch high-pressure fuel injection pump – driven off the inlet cam – and fuel metering unit add to the impression of size. Inboard of that, hidden, are eight-inlet trumpets.

Note the throttle linkage and small wing – given its shallow shape and chord, you wonder how much downforce was generated.

I’m intrigued to know exactly how Britton mated the engine and chassis, critical of course. Clearly, from the way he has strengthened the roll bar area, by bracing it down into the cockpit, the top horizontal mount heading aft is important.

More questions than answers of course, my curiosity about this car is at least partially stated!

Porsche 771 cutaway, yes it’s wonky, best I could find. Note, inter alia, the bevel-drive to the cams

Credits

Bill Mason

Finito

Comments
  1. prn31 says:

    Hi Mark,

    Curiosity sated here as well!

    I know that buying the Porsche Type 771 engine was an opportunistic move by Rorstan – it was there. But it was so left field bonkers, really.

    Specialist knowledge of these engines and gearboxes in the Antipodes – next to negligible.

    Engine and gearbox spares package – er, no. Phone Weissach and cross your fingers.

    Development potential – see answer above!

    Solution? Buy a McLaren or Lola. Even a T142!

    Paul

    • markbisset says:

      P,
      It really was a dopey decision!
      Even if the engine was cheap the maintenance needed a back-yard oil well, Clampett style. Must have been some seriously good-gunga doing the NZ rounds that week.
      m

  2. David E M Thompson says:

    This engine looked so neat and tidy in the ’62 Porsche F1 car.

    • Terry Sullivan says:

      The engine in the Rorstan is completely different to that in the F1 Porsche that DAn Gurney won the 1962 French GP
      That engine was of only 1.5L, whereas the Rorstan engine was 2.5L.
      Also the FI engine being for a single seater was much more streamlined and much attentio paid to reducing its size.
      The engine in the Rorstan was from a sports car so no need tomake streamlined.

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