The M8A is powered by a special aluminium 7-litre Chevy V8. "Don’t ask us where we got it from," says McLaren with a grin, "which should produce around 650bhp". The interesting thing about its installation is that, like the Ford Formula 1 engines, it is a stressed part of the car’s chassis. The forward face of the engine bolts to a sheet of magnesium, and A-frames running back from the rear of the chassis (it stops abruptly behind the cockpit) bolt to the rear of the engine. A fabricated sub-frame mounts over the bellhousing and carries the rear suspension, while long radius arms run from the rear up rights forward to the back of the monocoque. Although the monocoque appears to extend back past the cockpit, this extra ‘shelf’ on either side houses the oil tank for the dry-sump set-up, and the various pumps and electrical impedimenta to keep the engine sparkling. In fact, the magneto is mounted vertically behind the injection manifolding on top of the engine vee, and the metering unit for the fuel injection pokes back horizontally from the back of the engine.
The high stacks of the McLaren-modified fuel injection are quite fantastic. They look like a bunch of eight shot-blasted stainless steel lilies curving a full 12 in. above the engine – flower power in a big way. The exhausts run into a pair of big-bore stove-pipes that run out on either side of the gearbox below the body. On the M7A the exhausts curled up over the drive shafts, and exited through the tail bodywork.
The Hewland LG500 gearbox has specially tailored internals for the McLarens. Instead of the normal five cogs, this new box has only four special gears (and reverse) with a high bottom speeder’s control. A sump-puller first gear is not needed since all the Can-Am starts are rolling ones behind a pace car.
The new McLaren wheels are the ultimate in fatties. They get more like buckets with every new model! As tested at Goodwood, the M8A had rear wheels 15 in, in diameter and 15 in. across the rim. A sort of round square, if you know what I mean! And they plan to take a set of 16 in. rims with them as well. Front rims are 9 x 15.
To cope with the increasing number of punctures in racing, the new wheels are knock-ons in place of the normal bolt-on wheels. A specially made bar has been made up to undo the single large locking nut. The Goodyear rears measure 14½ in. across the tread.
The stopping department is very effectively catered for with a set of the biggest disc brakes and callipers you’ve ever seen. Made by Lockheed (who also makes brakes for McLaren’s Formula 1 cars) the big ventilated discs measure 11½ in. across on the rears, and 11 in. on the fronts. The discs are 1 1/16 in. thick.
Testing on the cars was delayed when McLaren spun his car into a bank in the wet at Goodwood. The programme soon caught up with itself and Hulme and McLaren began attacking their testing records at Goodwood and Silverstone before the cars were shipped to America for the first of the Can-Am races.
Article first published World's Fastest Sports Cars No 8
