Father of the modern F1 engine: interview with Keith Duckworth

One of the most satisfying aspects of researching and writing about motor racing history is that I get to meet many of my idols from the era when I went to see a lot of races in the 60s, 70s and 80s. One of the less palatable facts is that these people do not live forever. The recent death of Keith Duckworth, the 'worth' in Cosworth and designer of the most successful engine in Formula One history, underlines this.

I only became acquainted with Keith late in his life and, in April 1998, I paid a visit to his Northamptonshire home to talk about the Ford Cosworth DFV [Double Four Valve] Formula One engine he designed, and its role in the success of the car it was first used in, the Lotus 49. When I heard of his death, I revisited the transcripts of that interview and what follows are some extracts from it.

Keith was in a very affable mood that day. He had just finished cutting the grass aboard his motorised lawnmower, the weather was fine and the view from his house across the open countryside was stunning. However, he was still bristling with indignation over the fact that his beloved Ford Sierra Cosworth had recently been stolen from the drive in front of his house. The irony that he, in having created the Cosworth legend, was indirectly responsible for the car being so attractive to car thieves, was not lost on him...

We sat down with a pot of tea and began to talk. I wanted to know some detail about how the DFV engine came about and the reasoning behind the concept. From his reply, it was clear that this was no ego trip, but a commercial arrangement, albeit one of benefit to both parties. Also interesting was that the engine that formed the basis of the DFV design, the FVA, would have been built regardless of whether the DFV project went ahead or not.

MO: When did you first discuss the possibility of a Formula One engine with Colin Chapman?

KD: "It was in 1965 that Colin came along and said, did I want to have a go at a Formula One engine and how much did I think I needed to design and develop it?

"And, in our great scientific costings of that era - I asked my co-directors, Mike, Bill Brown and Ben Rood, how did £100,000 [equivalent to around £1.2 million at late 2005 prices] sound? Yes, we should be able to do it for that. So Colin said he'd try and see whether he could raise £100,000 from somewhere. We went to see David Brown [the owner of Aston Martin at the time]. I think he is one of the few we saw, before we saw Ford.

"In the meantime, I was designing the FVA [Four Valve, A series]. The argument was, that if that went well enough and gave 200bhp or thereabouts, it seemed fairly reasonable that we could get over 400bhp from a Formula One engine. The Repco single overhead camshaft engine was around then and winning races with only about 360bhp.

"The discussion was that I would do it but I was going to do my Formula Two engine first, anyhow, because that was commercial. The contract wasn't actually signed until halfway through 1966, by which stage we had it (the FVA) running!"

Although 'doubling up' the FVA engine sounds quite simple, I wanted to know how easy this had proved in practice and what, if any, parts and principles the two engines shared. As it transpired, not too many...

MO: How much, if anything, of the FVA was carried over into the DFV?

KD: "We learnt that our four valve general system worked. From the start, we obviously were going to make the V8 a single plane crank, because then it meant that you had two four cylinders and therefore the exhaust systems that we had on the FVA, we just had two of them on the DFV and the tuning was the same principles, the firing orders down the banks were the same as two fours. So the exhaust tuning was there, the intake lengths and things like that were there, as the rpm we were talking about when we started was very similar.

"Unfortunately, Formula 2 was 1,600cc, whereas F1 was 3 litres, so two 1,500ccs, and I was keen on trying to keep the pistons flat at that time and, therefore, in order to do the flat piston and to maintain the compression ratio with the reduction in swept volume, I closed the valve angle up from 40 degrees included on the FVA to 32 degrees on the DFV.

"The valves and springs and all the valve gear bits were the same, the bore was the same but the stroke was reduced. So, other than bits of valve gear and principles, there wasn't much carry over. And, obviously, that was the first 'clean sheet of paper' engine I'd done, where I was designing the block and the heads - well, all the bits - from square one."

Even though they were both regarded as geniuses in their own spheres of operation, it is clear that Chapman and Duckworth were slightly uneasy bedfellows with quite different philosophies on life. I wanted to know how Keith found working with the Lotus boss. Surprisingly, while on a personal level there were clearly differences - indeed Duckworth was quite scathing about Chapman's detail design abilities - they were as one when it came to saving weight.

MO: How easy was it to work with Chapman?

KD: "He got up much earlier than most people! He could marshal his arguments in a superhuman fashion. You'd be having a discussion about something and he would say 'Well this follows' and I would look doubtful, without having been able to sift into my mind why I didn't like what he said.

"At that stage, realising that he might be out-argued, or that there was something fallacious about what he'd said, he would change the subject and throw in a red herring and I would lose the main argument while chasing this useless red herring. And I'd find that I'd agreed to something which I shouldn't have done! I gradually learnt that all I could do was to say 'Yes Colin, I've heard your arguments, I need time to think about them. I'll let you know my view in the morning.' And, with that proviso, there wasn't a problem.

"I didn't understand why, during 1967, when we went around to all the GPs together and were frequently wandering around the paddock, he'd tell different tales of what had gone wrong with the car and/or engine to various journalists. I decided in the end that he just wanted to complicate life because he found it too simple if he told the truth all the time. I almost think that 'a stranger to the truth' is what I have thought might be a description. His dealing fibs of course made it very difficult for most commercial or most straightforward people, he gave them great difficulty in living with him. Which of course was of great value to me, why I was able to get Mike Costin to join me, because he couldn't really live with Colin's deviousness.

"But certainly the most brilliant conceptual engineer that I've known. He wasn't a detail designer and never had any ideas of limits and fits. For mechanical fits, lots of things require clearances to be about right to work and you've got to make bits to within reasonable limits to make certain the greatest and biggest fits and differences will still operate. And he never seemed to take the disciplines of detail design on board."

MO: I suppose that is one reason why his cars were often flagged as being 'underbuilt'?

KD: "Yes, he was totally wedded to getting cars down to the weight limits. And also, nobody had a lot of money in racing in those days therefore you were also trying to manufacture pieces by cheap manufacturing methods. You didn't whittle everything from solid in those days and there were fairly simply welded up structures and other things and quality control on those was very difficult.

"He was trying to design light cars to win races. And, unless you start off light, and see whether it fails...if you start off light and it breaks, then you will in fact strengthen it up, the pieces that break. An awful lot of bits that you might have thought would have broken, won't break. And that is the only way of getting a light car.

"If you start off by designing everything conservatively and nothing fails, there is no way that you are ever going to lighten your car. You never lighten things under those conditions and therefore you don't learn quickly enough.

"While people talk about being able to stress cars - and by this stage we're all into these computer stress calculations - the only problem is that you don't know how hard your driver is going to hit kerbs in general or you can't work out what the loads from hitting a kerb on any occasion are going to be and, if you design it such that it will hit brick walls in all directions all the time, you will never win a race.

"Therefore you actually have to hang it out if you want to make a race winner. Then, I think you've got to look at pieces sufficiently often so that your failures should really be fatigue failures from a number of cycles and not be an instant, ultimate failure.

"With your mechanics and your system of looking at your cars and preparing them, you should be able to catch most things at the stage that, either some stretch in the material - it's collapsed a bit - has occurred, or there is a crack forming and you can catch the crack before it is a disastrous failure. The only real way is to design light and then to have loads and loads of inspections and certainly lots of crack detection and other things like that."

Another popular misconception is that Duckworth was the only person who had any meaningful input into the design of the DFV engine. The contributions of Mike Costin and Ben Rood should not be underestimated. The way Keith saw it, each had their own particular strengths which they brought to the table.

MO: What was the division of labour on the DFV between you and Mike Costin?

KD: "Well, I am innovative and numerate, whereas Mike is an incredible intuitive engineer and he just knows whether something will work. I've caused everybody who is close to me to think very hard about how things work. My thing is you never do sums before you understand what the problem is and you just sit and try and work out what is happening.

"The Mikes and Bens of this world are very quick to pick up the analysis and thinking about problems. Ben is a machine shop man, an incredibly intuitive engineer. He just knows G-forces and can feel what's happening. Mike knows how much metal will bend, twist, shape under what load and knows whether things will work.

"We had this communication system over the phone where I could say 'I've thought of a way of doing this. Picture this. Have you got a pencil? Well, we've got this here, that there, and so on' and Mike would draw what he thought I was saying. And then say 'What I've got is this, that and the other' and I'd say 'Do you think it's any good as an idea?' and he would perhaps just check on another bit and say whether he liked it or he didn't think it was very good.

"And if he didn't think it was very good, or thought there was something wrong with it, he would say that he didn't like it. He wouldn't in a lot of cases explain why he didn't like it, but I reckon he was right about 96% of the time and if he didn't think something would work or something didn't sound right, I would then go through it all and generally speaking sooner or later, I'd find something wrong with it.

"Therefore, at all stages, if I was doing something that was innovative or not standard, I would put it to him as to whether he thought that it was sound or not and get his answer. We are wonderful joint operators because we are sharp enough to see that you spend a fair amount of time wrong in this life - or up your whatsit as we normally refer to it - and we can both point out when each other is 'up it'!"

Given that, at the time, the trend seemed to be towards multi-cylinder engines of 12 or even 16 cylinders, I asked Keith why he had chosen to opt for an eight cylinder layout for the DFV. His answer reveals that there was little to choose between an eight and a twelve and that, if the minimum weight limit had been slightly higher when he started the project, the design could well have ended up being a twelve, robbing fans of that beautiful DFV engine note...

MO: There was a lot of surprise when the engine was revealed as a V8, wasn't there?

KD: "Well, the argument had been, with Colin and I, 'Do you think you can make a 12 [cylinder engine] down to weight [500kg] and get the fuel in the right place, with 200 mile races, is that possible?' Doesn't look possible. Right, we can make an eight [cylinder engine] down to it.

"Next thing: I know how much power I can get because it is effectively two fours as regards the breathing and the tuning of the intakes and the exhausts. If you make a flat crank, it's the same as two fours. We know a lot about fours, therefore we know that we can get into this area of power doing it that way.

"Therefore, I'm not that happy to make a 12 but I'm quite happy to make an eight and I think that, carrying your whole fuel for the race, the extra power of the 12 will be cancelled by its extra weight and extra fuel consumption and the difficulties of designing a sensible car. And, as I am a 'total concept' man, I'm there. The right decision was an eight. If they'd said 550kg then I'd have changed it to 12 possibly. So, you've got to look at the whole picture."

What many people forget about the DFV engine is that it had a very difficult birth, with several teething problems delaying its racing debut. Whereas the history books record a win first time out, in fact there was a lot more to the story. As Duckworth recounted, it was an extremely fortuitous win, perhaps aided by the mechanical sympathy of Jim Clark.

MO: I believe you experienced some troubles with the first engines?

KD: "I hadn't made reasonable provision for getting oil and air down from the cam boxes into the sump and air from the crankcase and we filled the heads with oil! We needed to improve the methods of getting air back into the head because oil and air came down from the head and we couldn't return any air and it all went wrong.

"So the first engines had these big pipes up the side and into the little tin boxes fabricated on the top. Mike and I were in at weekends and things like that. He was welding up and things and we were testing engines on weekends with marks of various oil attempts at trying to cure that one. So that was the thing that perhaps stopped us appearing the race before we did.

"Then we had trouble with the cam drive gears. We were lucky to win at Zandvoort first time out. Graham's was an older engine and that lost two teeth next to each other and lost the drive to a cam, therefore it ground to a halt.

"On the way back to the garage after the race - because you drove along the road from Zandvoort circuit back to the garage in the town of Zandvoort itself - I could hear a severe rattle coming from Jim's car. It turned out that it also had two teeth missing but fortunately there was one standing in between and therefore the drive was maintained, but it was obviously fairly touch and go with finishing..."

The subject of the relative mechanical sympathy of the two Team Lotus drivers in 1967 - Jim Clark and Graham Hill - was one I wanted to explore further. I wondered what Keith's viewpoint was on this. From his response, it was clear that he admired both, for different reasons. However, he seemed particularly taken with Clark's dramatic drive in the Italian Grand Prix.

MO: Comparing the two drivers, most of the people I have spoken to observed that Jim Clark was easier on the cars that he drove than Graham Hill?

KD: "Yes, you could actually tell the difference between a Graham Hill engine and a Clark engine by the fact that Clark would have apologised for having over-revved it on two or three occasions and the valve gear would show no signs of having been over-revved, whereas Graham's had never been over-revved and the valve gear was quite often tatty!

"I think Clark, he just changed gear gently, didn't he? There was never any hurry about anything; he had bags of time because he was incredibly good. Graham was really an exceedingly courageous driver because I think that he was running at a higher percentage of his 'tenths' than Jim ever did. I think Jim had prodigious natural ability, whereas Graham was working hard at it."

MO: What did you think of Monza '67, when Clark had his puncture and made up his lap and then lost the lead on the final lap?

KD: "He ran out of fuel...he ran out of fuel!! Chapman would never have more than the odd extra ounce of fuel in and Clark's absolutely masterful effort, he was obviously going 'Harry Flatters' everywhere, meant that he used more fuel, in catching up this lap and a half, than he would have done normally. An absolutely brilliant performance."

Eventually, the problems with the gears were overcome, but it took several years before they were properly conquered. What few people know is that the option of culling the engine was seriously considered before a typical piece of Duckworth thinking provided the solution - one which, incidentally, he believed has featured in many subsequent leading Formula One engine designs.

MO: What did you do to get round the problem with the cam drive gears breaking?

KD: "We improved the strength and accuracy of the gears. And supports fell off the heads then and so we increased the strength of that and we redesigned and changed the gear supports, which were originally cantilevered off the block, and they were then built into a cover on the block and still failures occurred.

"The engine was nearly abandoned. It was getting almost impossible to run and it was at that stage that I designed the quilled hub, which has some elasticity and damping. It went in the middle of the V8 where the cam drive split and that rescued the whole of the valve gear and it carried on.

"I might point out that all gear-driven F1 engines, I'm fairly certain by now, embody a fairly similar piece of kit. The Renault certainly does. In fact there is somebody who has made a fairly substantial living out of redesigning my quilled hub to suit other people's engines!"

The rest, as they say, is history. The Ford Cosworth DFV-engined Lotus 49 took pole position in every 1967 Grand Prix it started, winning four of them. The engine went on to be released to other teams, and during 17 seasons scored an astounding 154 Grand Prix victories, with the short-stroke DFY derivative scoring a further win.

And it wasn't even another normally aspirated engine which ousted the DFV from its position of dominance, but turbocharged ones from the likes of Renault, Ferrari and, later on, TAG-Porsche and Honda. This was something that always irked Duckworth, who once reportedly said turbochargers were for people who couldn't build engines!

The undisputed fact is that the DFV's record of success, which is unlikely ever to be matched, has left a lasting legacy in the form of UK dominance of motorsport and is a fitting testimony to the engineering genius of Keith Duckworth.

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