In the late 1960s, the Commission Sportive Internationale was concerned that speeds of Group 6 prototype sports cars running at Le Mans and elsewhere were becoming too high. It therefore decreed that from 1968 for four years, the International Championship for Makes would be restricted to three litres. However, to allow for manufacturers which would not have cars ready in time, it permitted Group 4 sports cars of up to five litres.

This directive from the CSI inadvertently gave rise to the building of one of the greatest and most dramatic racing cars ever — the mighty Porsche 917.

The new Porsche first appeared in 1969, and unlike the Ford GT40 of that period it was not built with a central monocoque tub, but in the older but well-tried system of a very light spaceframe chassis similar to that of the Porsche 908. Weighing just 42kg, the chassis tubes contained pressurised gas, a pressure gauge enabling any cracks to be easily detected. Low weight was paramount: the glass-fibre body was very thin and even the gear knob was made of balsa wood. To power it Hans Mezger designed a brilliant new 4.5-litre flat-12 engine, utilising the lightest metals. Initial output was 580bhp, but it was quickly enlarged to 4.9 litres with an output of 600bhp, then to five litres and 630bhp. Later, when the 917/30 was developed with twin turbochargers for the Can-Am series, the engine delivered more than 1550bhp in qualifying spec and a ‘mere’ 1100bhp in race trim. It could accelerate from standstill to 60mph in 2.2 secs.

But back in 1969 the Porsche 917 was not yet reliable enough to conquer Le Mans, allowing Jacky Ickx and Jackie Oliver to give the GT40 its famous final win. It was Richard Attwood and Hans Herrmann who scored the first 917 Le Mans victory in June 1970, which makes this year the 40th anniversary of that great win.

To celebrate this occasion and to learn something of the early problems drivers had with the Porsche 917, Richard Attwood and Jackie Oliver, both of whom had considerable success in the car, joined me at Mallory Park. To jog their memories back four decades, Adrian Hamilton brought along his John Wyer Gulf Team Porsche 917K (Kurzheck or Short Tail), the actual car in which Attwood placed second at Le Mans in 1971. And for comparison we had a new-build GT40 constructed by Gelscoe Motorsport to the precise specification of the 1969-winning Ickx/Oliver JW Gulf Team car.

After enjoying the wonderful sound of both the 4.9 Porsche flat-12 and the great Ford Weslake 4.7 thumper, both drivers returned their cars to the Mallory Park paddock.

Climbing out Attwood comments: “Feels like home, just like a normal racing car. A normal 917 racing car, anyway.”

Reflecting on the two cars, he adds: “I raced the GT40 from 1964 to ’67, but Porsche decided to make something a lot lighter, so they took a few tubes and some glass-fibre and stuck it all together. I always said that if I were going to have a big shunt I’d rather have it in a GT40 than a 917. When the 917 was mooted, no one wanted to drive it. I suppose we felt the 908 would have won most things at that time anyway, and it was a lot easier to drive — nimble, and no roof.”

There were problems with the early Porsche 917. What was the worst thing about it?

ATTWOOD: “The shape. It was aerodynamically unstable. We all told them that at anything over 200mph it was virtually off the ground. Porsche tested it at an airfield, but they were only managing about 175 by the end of the runway and up to that speed it was OK, so they didn’t believe the drivers and told us it was now fine. We tried it again and it was the same. Still hopeless.”

OLIVER: “In 1969 Ickx and I didn’t think that we were ever going to be able to beat the new 917s with the GT40.”

ATTWOOD: “Well, if the 917s had been running at the finish you wouldn’t have had a hope.”

OLIVER: “Actually, the Porsche 908 should have beaten us. I don’t know why Hans Herrmann couldn’t get in front of Jacky [Ickx]; he was faster on lap times. I think that Wyer’s teamwork and planning, always looking after our brake pads, was probably crucial. I have a feeling that Herrmann was running out of brakes, because Jacky kept passing him under braking at the hairpin. But you have to admit it was a magnificent ending for the GT40 story.”

It seems odd that after the years of winning Le Mans cars having a modern central monocoque tub, Porsche built a car based on a space-frame again.

OLIVER: “Yes, one had an old truck engine with a modern chassis and the other had a chassis that was a lot of cock but with a modern engine. If you put the two together you’d have had a better car. It’s funny how evolution comes about. But both cars were pre-aerodynamics; Porsche got away with it because of their mechanical brilliance, but the 917 started out as an aerodynamic disaster, as Dickie found out. It was a learning curve.”

ATTWOOD: “Yes, that’s right, it was the early days of the way things were about to go in the future with ever-higher speeds.”

OLIVER: “Everyone thinks that the 917 was difficult to drive, but that was only before they managed to get the aerodynamics right. John Wyer and his engineer John Horsmann sorted it by fitting a reshaped front bonnet and the reshaped Short Tail. I then ran flat through Whitehouse; apart from being more stable and having less drag, the car must have been developing downforce at the back. Wyer clearly understood aerodynamics better than Porsche.”

After all the handling problems of 1969, when you brought the 917 home in first place at Le Mans in 1970, the reaction from Porsche must have been pure joy?

ATTWOOD: “It was. It had been an ongoing saga for so long. Porsche was trying to win Le Mans with small-engined cars and a 3-litre simply wasn’t going to be enough. Then there was the birth of the 917 as a result of that ridiculous formula. The CSI never thought that a manufacturer would make 25 cars to go and win a silly championship. But that is exactly what Porsche did. And then unbelievably Ferrari did the same, which of course led to a wonderful era of Porsche versus Ferrari, the like of which has never been seen since and will probably never be seen again. It was a marvellous period.”

At the 1970 Le Mans it was raining heavily. What was it like driving the Porsche 917 in those conditions?

ATTWOOD: “Well, you just had to drive according to the conditions. The trouble with this sort of car is the tyre widths. They were affected so much more than if you were on narrow tyres, so that made it more difficult. You would suddenly find the smaller cars starting to overtake you. You just had to be really careful; it’s a long race, not a sprint race where you tended to take more risks. The main problem we had with the 917 in the rain was that the water kept getting into the electrics and therefore it was misfiring a lot. We tried to keep the heat in the engine artificially by revving it while we were not going very rapidly — completely the opposite to what you need to do when you are driving in the wet. I would have preferred to get into higher gears all the time. It was difficult, but we coped with it, just doing what we could in the hope that it would dry out and we’d be able to go a bit faster. But we had no other problems and that’s how you win Le Mans. Stay out of the pits. Just keep going round and round and round. Boring. But that’s how you do it.

“But the 4.5-litre was slow on Mulsanne. It was probably only getting to 215mph. After qualifying I thought we hadn’t got a hope in hell; we were about 8sec out. But it was a crazy race with a lot of incidents and retirements that happened long before it rained. We had that massive fight between the Ferrari 512s and the Porsche 917s — it was just like a Grand Prix. I couldn’t believe the way people set off at the beginning. I could not understand the mentality of those drivers who were going so fast — Le Mans is — a 24-hour race and they were treating it like a two-hour sprint. They were all mad, driving far too fast, trying to win on the first lap. I didn’t start the race so I was watching and I honestly couldn’t believe what I was seeing. There were so few classified finishers. We didn’t win it, everybody else lost it, simple as that.

“I remember hearing that three Ferrari 512s had gone off in the same accident. Three cars! Potential winners, all of them. Derek Bell was in one. I think someone spun and he avoided everything but inadvertently over-revved it and his engine went. Siffert famously missed a gear in a hurry to get by some slower cars while passing the pits. I saw and heard that. I knew he wouldn’t be coming around again. Actually, he did come round, but very slowly.”

You started your car in 15th place on the grid. Were you surprised when you got the P1 sign?

ATTWOOD: “I couldn’t believe it. It was just ridiculous. We were in the lead after 10 hours and we never should have been anywhere near the lead. We didn’t so much climb up the board, the others just dropped out. Some might have been six laps ahead but they all dropped away.”

Do you think your mentality, and therefore how you drove the race, was a key factor?

ATTWOOD: “I suppose 20 per cent was probably the way we were driving but the other 80 per cent was that the car wasn’t fast enough. It just could not keep up with them that year because we had the small engine and the Short Tail.

Did you consider using the Long Tail for the 1971 race?

ATTWOOD: “Well, John Wyer was running the team and he decided who did what in 1971. I drove with [Herbert] Muller and we lost the race by five minutes after a gearbox problem held us up for 45 minutes.”

Jackie, you and the Porsche 917 still hold the record for the fastest lap at Le Mans at 3min 13.6sec, with an average speed of over 250km/h (155mph), and you regularly hit over 240mph on the Mulsanne. Were you aware that you were going so quickly?

OLIVER: “I had no idea. Once you are over 100mph it doesn’t make any difference. Depends how close you are to the wall.”

ATTWOOD: “You just hang on to the steering wheel. The first time you do it you really wonder if something goes wrong here where are you going to end up, but it soon just becomes normal daily life really, and not a problem.”

What made the 917 so iconic?

OLIVER: “The name Porsche. When Porsche came into racing it turned everybody’s head. They immediately thought that because it was Porsche it would be successful. It was too, but it was John Wyer who really made that Porsche work properly. In 1971 after half the race three JW Porsches led. Jacky [Ickx] and I were two laps in front but even in 1971 Helmut Flegl, the Porsche engineer, was still worried about the back of the car aerodynamically. He said, ‘Just be careful that the front wheels don’t come off the ground going down the Mulsanne Straight because I think we’ll be doing 380km/h [236mph]. That would probably be in top gear, maybe at about 7000rpm.’ I told him I’d wiggle the wheel every time the rev counter flicked up to around 7000 down the straight just to make sure the front wheels were still in contact, and that’s actually what we did. Next time I came back in I told him it was OK and still steered at 7800rpm. So he said, ‘that’s fine, then.”

What did the 917 do for your careers?

OLIVER: “Not a lot, to be honest. I wasn’t keen on long-distance racing, I thought there were better things to do in the middle of the night…”

The results speak for themselves. You still have the wins to your record.

OLIVER: “Looking back on it, it was Porsche or Ferrari or Ford that won the races, not the drivers. It was the constructor. You were just another nut behind the wheel.”

ATTWOOD: “I agree that it was a team effort. Once the flag goes down there’s no one else involved. At the time the Le Mans 24 Hours was just another race, but it has since become more important to me, more relevant to the success of my career. However I didn’t win Le Mans, the whole team won Le Mans. I probably drove better at a lot of other races and got no results at all.”

OLIVER: “The most fantastic thing about cars such as the Porsche 917 was that they were so fast — particularly when developed for Can-Am — that they became quicker than Formula 1 cars at that time. Clearly that was going to be a problem.”

ATTWOOD: “That’s right, but the engine was the best part of the car. As drivers we preferred the bigger engines.”

OLIVER: “Yeah. We wanted to go quicker, not slower. That’s why the 917 is still probably the most iconic sports car around.”

Today, the Porsche 917 must stand together with those other German racing icons, the great Silver Arrows Grand Prix cars of the 1930s. And the men who drove the 917 to victory in period surely should be counted as the Titans of the ’70s.

Thanks to Richard Attwood, Jackie Oliver, Mallory Park circuit, Adrian Hamilton at Duncan Hamilton Ltd and Gelscoe Motorsport for their help with this feature.