Davide Nativo
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These engines were a spectacular engineering showcase but, unfortunately, did not translate into successful projects as well.
We all know Enzo Ferrari to have been an engine enthusiast. He always put them ahead of every other part of his cars, whether this represented a bonus or a malus at times. Having grown up, as a kid, while drivers like Nazzaro and Boillot competed all over Europe, and then mastered himself the racing technique during the years in which champions like Ascari, Campari, Bordino, Benoist were at it, meant of course a powerful imprinting in the mind of young Enzo. Back then, building a racecar was much more a matter of engine rather than chassis, which was still a reminiscence of the carriages in which motor vehicles have their ancestral origins. It was not before the ‘30es, with German manufacturers of the like of Autounion and Mercedes, that the sportscar development was really studied under all aspects and no longer focused entirely or mostly on the "horses" powering it.
We can forgive Ferrari this one then, especially considering the prolific heritage he produced by focusing so much on the engine of his cars. This made the birth of a legendary icon like the Ferrari V12 possible, but also of the different V6 types and of the V8, originally reworked from Lancia. We must not forget the unbeatable IL4 too and the less fortunate and never put in action, but still entered into the myth, IL2. Besides, just like the IL2, which has an entire legend of its own revolving around it, there is another engine Ferrari tested but never actually raced. I am talking about the Ferrari Dino V6, radial valves, F2 engine.
First, we must clarify what a radial valves engine exactly is and how it actually works.
The radial valves engine, also called “Apfelbeck Head”, was originally born from the mind of Ludwig Apfelbeck, an Austrian engineer working for BMW. This ingenious idea was brewing in his mind since 1939, and was finally refined in 1965, ready for the soon to be born European F2 championship. It meant putting four valves per cylinder in a specific alternated order (I-E-I-E), 90° apart from each other, shaping the chamber hemispherically so that it could allow an internal flow to better cool the valves. The air-fuel mixture would infact travel across the cylinder heads through the inlet valves, reaching on its path the adiacent exhaust valves too, thus lowering their temperature.
This design results in having a dedicated inlet trumpet for every intake valve, and a dedicated exhaust tube for every exhaust valve, thus duplicating these parts compared to a standard engine. The better thermal resistance and higher valve lift achieved by this specific design, combined with a stronger compression ratio thanks to an increased height into the piston crown, made possible to get a spectacular cylinder filling ability at high revs, giving BMW a strong edge against its competitors and producing a very powerful engine overall.
However, all of this came with a big con. The precise arrangement of the valves meant, in fact, that specific camshafts had to be built in order for the engine to work properly. Apfelbeck had a patent since 1935 for an innovative camshaft design that allowed it to work under these unusual circumstances (one-half had to operate an intake valve and the other half an exhaust valve). Nevertheless, as one can imagine, it was very expensive to produce, being useful only on this very specific engine head, and it was problematic to setup as well. Another problem was also the dimension of the cylinder head itself, which was very large, and the peculiar piston crown used, which was heavier. These two factors combined meant a bulkier engine, which is a big downside. In addition, it also meant that while at high rpms the cylinder was, again, operating in a spectacular fashion, it would on the other hand largely disappoint at low rpms due to slower velocity of the air-fuel mixture. In conclusion, while being a technically brilliant idea, it never actually succeded on large scale, and so in the end it never reached mass production. It did perform, however, very well on the racetrack, under the M10 tag, causing some fuss among BMW competitors.
These were the Apfelbeck M10 IL4 specifics:
Capacity 1991 cm3 (bore x stroke: 89 mm x 80 mm) – Power: 260 HP at 8500 RPM – Max Torque: 236 Nm at 8000 RPM.
Mauro Forghieri, who was back then head of the development team inside Ferrari, decided during 1969, a year that proved essential for the revolution the Scuderia experienced in the ‘70es, to work on this idea, seeing if it was possible to improve it in any way and make it overall more successful for their F2 single-seaters too. Starting from a 2-litre engine configuration derived from the Dino 206 Sport, and adapting the radial valves solution onto it, he went on and tested the prototype at the Modena and Monza racetracks.
These were the Ferrari Dino V6 24 valves specifics:
Capacity 1986 cm3 (bore x stroke: 86 mm x 57 mm) – Power: 253 HP at 9000 RPM – Max Torque: unavalaible.
The engine was a peculiar display of exhausts coming out of top and from the bottom of the engine, while the inlet trumpets were housed in a chessboard-like style. Nevertheless, the tests were, unfortunately, unsuccessful. Forghieri then claimed “we only succeded in making a much more complicated engine”[1], thus resulting in abandoning the project without literally ever racing it.
Exactly on the other side of the globe, around the same time, Repco too noticed the benefits of cross-flow gas paths, and dediced to try to exploit them with their new ’50 Series’ heads for their 1968 F1 programme instead. Results on the dyno were promising but not impressive, and along the usual problems of the radial valves configuration, the new 750 V8 was also a nightmare to install in the Brabham’s spaceframe chassis. Eventually, the Australians as well decided to give up on this particular engine layout.
However, it is to be noted that the Ferrari Dino V6 24v and the Repco 750 V8 are still to this day the only engines to have ever tried this solution on these particular cylinders arrangements (the Apfelbeck was in fact an IL4, a much simpler design). It is then a shame that they simply did not perform, and that they have been forgotten to this very day. It would have been interesting to see the Germans and the Italians confronting their radial valves engines versus one another, and Repco having a shot against the competition in the top series, F1. Alas, all we can do is daydream about what could have been, but unfortunately never was.
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Notes:[1] Ferrari 1947-1997 – The Official Book, New York, Rizzoli Intl Pubns, 2003, p. 50.
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