McLaren's last Can-Am car and Porsche's sole Works challenger in 1973 ...

[Wouter Melissen]

Although officially known as the Canadian American Challenge Cup, the Can-Am series was known for years as the 'Bruce and Denny Show'. That was a reference to the absolute domination by Team McLaren and its drivers Bruce McLaren and Denny Hulme. The arrival of Porsche's turbocharged 917/10K in 1972 finally brought an end to five seasons of domination. Clearly 'outresourced', McLaren did not go down without a proper fight. Gordon Cuppock developed the M20, which was the first all new McLaren Can-Am car since 1968. Following contemporary F1 design, it featured side-mounted radiators, focusing all the weight around the centre of gravity of the car. In pre-season testing the M20 shattered all its predecessors' lap records. Very light and relatively nimble, the new McLaren at times managed to keep up with the turbocharged Porsche 917s, which had an additional 200 bhp on tap. Early in the season Denny managed to score two wins with the M20 but he could not challenge George Follmer for the remainder of the year. McLaren withdrew from Can-Am at the end of the year. Two years after Denny's last win, an M20 fittingly took Can-Am's final win. Earlier this year we caught up with one of the three M20s built for Team McLaren in 1972.
With McLaren gone in 1973, the sole remaining challenger for the all conquering Roger Penske entered Porsches was the Shadow team. During previous seasons, the all-black machines only really stood out due to their unusual designs, which always looked fantastic on pape. By employing British designer Tony Southgate some much needed convention arrived at the Don Nicholls run team. Southgate's first Can-Am design for Shadow was the DN2. In an attempt to match the Porsche's for power our feature car is fitted with a twin-turbocharged version of Chevrolet's big block engine. Sadly it never was close to reliable and the naturally aspirated version was blasted out of the water by the latest Porsches. With turbos virtually banned, Shadow won all but one race in 1974 with the DN4, which was a development of the DN2.

Enjoy the links:

1972 McLaren M20 Chevrolet - Images, Specifications and Information

1973 Shadow DN2 Chevrolet Turbo - Images, Specifications and Information

[Matra et Alpine]

EXCELLENT Articles boys -- AGAIN

Especialy kudos for the pic of the tuned length trumpets ... Didn't realise they used angled differing lengths on it. So used to seeing equal length parallel. GREAT PIC

[Wouter Melissen]

Apparently it was quite an art to get the right length of the trumpet, which could make a substantial difference in performance.

[csl177]

I remember Road Atlanta in '73 when Hobbs' M20 was clearly outshone. He finished 4th IIRC. It didn't matter, everyone knew the 917s would dominate. We just didn't expect them to kill the series. (Can-Am of the '80s was something completely different.)

Those stacks were tuned to each cylinder's exhaust tube frequency, something Hilborn first sorted out in dragster applications.
Can't think of a BBC McLaren without calliope pipes!