Harnessing the power

Formula One demands the ability to adapt quickly to ever-changing circumstances, and Gordon Murray had few peers in this art he describes to Keith Howard how he designed a Brabham to cope with huge power outputs – and develop it into a championship-winner

It was a particularly loony time, says Gordon Murray, a comment which encapsulates two quite disparate emotions: a fond recollection of his part in it, tempered by a clear understanding that it was a path leading nowhere.

Both 1981, the development year for the BMW M12/13 turbo engine, and 1982, its first season on the attack, were difficult ones for Brabham and BMW, Murray and Paul Rosche. Nobody doubted the potential of the engine, but its fragility strained relations almost to breaking point. Without reliability, the engine could never be a race-winner, nor could it be developed to extract more power. Straight out of the box, it produced more grunt than the Cosworth DFV, but it was heavier and lacked the normally-aspirated engine’s immediate throttle response. Consequently the M12/13 in the BT50 was no quicker than the Cosworth-powered BT49C/D — a situation that persisted until the reliability problem was cracked, and BMW could concentrate on extracting more oomph. For Murray, designing a car to carry a turbo unit brought a whole basket of unfamiliar problems. The first was the intense heat. “You’ve got a lot more cooling to do. You’ve still got to cope with the normal heat rejection from the water. You’ve got a little more heat rejection from the oil. The big problem is the turbo itself

“Paul [Rosche] was adamant the single turbo route was the right way to go, and we started using a KKK truck unit. The packaging problems around having this eight-kilogramme lump of metal running at 1000 deg C in the middle of the car — next to the engine, next to the fuel system — plus the extra heat rejection from the intercooler, were enormous. Radiated heat was easy enough to deal with: you began sticking heat shields on anything the turbo could ‘see’. But the heat soak problem was another matter. The heat would leak from the turbo to whatever it had a path to. The first thing that suffered was the bearing between the turbo and the compressor — all the tolerances just went right out the window. “So one of the first things we had to develop was some form of turbo cooling system. When we began experimenting with pitstops, the car was stationary for about 15 seconds and the turbo seized every time. Because we had air jacks, we took a tiny bleed off the air line and built our own air ejector — a venturi into which you introduce a small amount of high velocity air which then drags up to nine times the volume of air through it. This blew air across the bearing housing.

“There were dozens of heat management problems like that, some of them an issue when the car was stopped, others when the car was running.”

Paul Rosche had promised massive increases in power once the engine’s reliability issues were sorted. This and the banning of skirts for 1983 heavily influenced Murray’s design approach when penning what was to be the first championship-winning F1 turbo car, the BT52.

“We’d never have won the ’83 championship with a complicated, fragile car that drivers wanted to fiddle with because we’d not have had the time to solve the engine problems. The BT52 was the least adjustable racing car in modem Fl history, I think. Apart from the fact we had to design and build it in three months because skirts were banned after we already had the BT51 ready, I deliberately kept it simple. It was almost a bloody-minded statement: we’re going to have a hell of a year sorting the engine integration, so I am not going to make the car fully adjustable.

“You could adjust the ride height, damping and only the flap on the front wing; it had a fixed front anti-roll bar, no rear anti-roll bar and you couldn’t adjust the rear wing. Because we were losing 60 to 70 per cent of our downforce with the skirts gone, I realised we wouldn’t want to take any oft so it was maximum all the time. I made a conscious effort to get as much traction as possible. I thought: I’m going to move seven per cent more weight on to the back axle, which is the most! could get, and run the fixed rear wing. The B version had little winglets on the side to generate even more downforce.

“I said to Bernie [Ecclestone], ‘We’ll get to the first race and everybody will have done this, put all the weight on the back’. But no one had. I just couldn’t believe it. That’s why the BT52 said goodnight to all the rest at Rio. “People were just slow to understand the ramifications of losing so much downforce. As we’d generated more and more sidepod downforce with sliding skirts, the centre of pressure had moved further and further forward. You had to keep the centre of gravity in line with the centre of pressure, so every year you’d struggle to move more weight forward. We had 19-inch-wide rear tyres and only 500bhp or so from the DFV so, except off the line and in hairpins, traction wasn’t an issue. We ended up with only 53 per cent of the weight on the back axle of the 49D but we were generating over two tonnes of downforce. Losing two-thirds of that, and gaining all that power, required a complete rethink.”

So did the transmission. “With any turbo racing engine, but particularly one with a single turbo, you can’t afford to lose turbine inertia you’ve got to keep it spinning. We went to a six-speed box and later a seven-speed. The six-speed box was to keep the engine on the boil; the seven-speed box was a reaction to the increasing power differences between qualifying and race engines, so that we didn’t have to keep changing ratios between practice, qualifying and the race. “The other massive problem as the power escalated was mechanical failure. Long before the engine reached its limit we had driveshafts twisting through 360 degrees and CV joints being destroyed. Putting twice the torque through the gearbox meant we trashed them. So we needed stronger gears, stronger shafts, stronger CVs. We then stopped breaking things, but once we had over 1000bhp, we ran a gearbox just once and that was it. After qualifying with a gearbox, you didn’t rebuilt it, you threw it away. Everything had stretched and stayed stretched.” And as the difference between race and qualifying power widened, the team also had to rethink attempts to alter the car’s set-up in response.

“We gave up in the end. Even today you could not design a chassis to cope with the difference in power between qualifying and the race. Nelson said, ‘You’re wasting your time anyway. I don’t drive the car in qualifying. I come out of the corner, wait until the car is absolutely straight, get it back to the middle of the circuit and then floor it. That’s all I do. I leave myself plenty of room to brake for the next corner and just go around it in the middle of the road. You can’t drive the car, you just aim it.” So was this Formula One, or drag racing in disguise ? Whatever your view, the boost pressurelimiting valve would very soon put an end to it.