Ford GT40: The Tech


Words: Neil Siner

When it hits the shelves next year the Haynes Ford GT40 Owner and User Manual will have taken fifty years to publish. For those of you who just can’t wait, here are some essentials on the classic 1966 Ferrari-beating Mark II.

Power, in factory spec, was delivered by a massive cast iron, 427 – cu. In. (7 litre) V-8, which was based on the one Ford were using in their stock-car program. This seriously heavy engine (weighing in at 600lbs or 270KG) comfortably produced 485 bhp at 6,200 revs, meanwhile at the lower end delivering a staggering 475 foot pounds of torque at only 5000 revs.

Power2 There’s an industrial grit to the GT40s business end…

What this beast gave away in efficiency it refunded in reliability. At Dearborn, Ford’s HQ in Michigan, engineers chucked one engine after another onto a dynamometer and ran them until they blew. They finally developed the 427 after modelling that it would be able to run a 4 minute lap at La Circuit de la Sarthe for an unprecedented 48 hours solid.

The heavy engine forced Ford into designing a new transaxle, also adding weight, so that the Mark II would hit the start line at a hefty 2700 lb, or 1200 KG. This created some un-heard of breaking issues.

The hot seat. This is the one owned by Steve McQueen and that featured in his 1971 classic ‘Le Mans’. Last year this car sold for $11M – a record for an American car.

In the approach to the hairpin at the end of Mulsanne, the car needed to lose 185 mph in 7 seconds. This would send brake disc temperature to an immense 1500 Fahrenheit. To counter this Ford developed their own 11.5 inch ventilated discs which reduced temperatures and could be changed in an instant for speedy pit work.

superformance-gt40-mkii-70-liter-windsor-v-8-engine-photo-257042-s-1280x782-1 and there’s poetry to the twists of that manifold…

The beautiful lines of the GT40 were the result of many hours of wind-tunnel and track work at Riverside Raceway, California and Daytona Beach. The body was sculpted out of 0.65mm steel sheets with square tube stiffening to form a semi-monocoque chassis. At 414cm long, the winning Mark II design was a slightly shortened version of the Mark I, the 5 cm reduction adding up to 8mph to the top end.

With originals changing hands for seven figure sums, if you have got one it’s probably worth investing in that Haynes manual next year. If only to make sure you are using the right polish on your ‘Gurney bubble.’

The Gurney Bubble. Rave legend Dan Gurney needed this to fit his lid. Race totem created.
The Gurney Bubble. Rave legend Dan Gurney needed this to fit his lid. Race totem created.