Talk:1971 24 Hours of Le Mans

1971 24 hours was the Le Mans edition with more laps recorded in the competition all history. esaranha —Preceding unsigned comment added by Esaranha (talk • contribs) 21:26, 21 April 2008 (UTC)

Error in the result?
While doing a minor edit I noticed that the position for 15 & 16 are switched in comparision to the site I would use to check this information. Does anyone a RS which could be used to confirm the results? I certainly consider www.formula2.net a good source of information. Bjmullan (talk) 17:13, 11 October 2010 (UTC)

Top speeds - motor racing myth.
This article plays pretty fast and loose with claims of top speeds and needs to be changed. The highest speed reached in practice, as recorded by l'Automobile Club de l'Ouest who set up the speed traps, was 359 km/h (222.6 mph) by a Ferrari. This rather flies in the face of increasingly ludicrous claims made for the 917. The highest top speed achieved in the race was a 917 at 362 km/h (224.4 mph). This represents an error of 9% over some claims, which is statistically absurd. If the Porsches were so much faster, why did anyone else even bother to turn up, especially when one considers the fact that the straight at Le Mans was so long?

http://www.mulsannescorner.com/maxspeed.html

The source of this claim seems to me to be the April test session from 1971 when it was revealed that the S.E.R.A. computer, which had done the aerodynamic calculations for the new bodywork, had predicted a theoretical top speed of 239 mph (384.663 km/h). From there came the legends of the car actually achieving 240 mph. Then came the added colour: it was Jackie Oliver who did it, he did it in night practice (did they even do this?), that it was Vic Elford and finally, claims by Derek Bell that he hit 246 mph! I guess we all want to believe it but...

None of this has ever been substantiated with speed trap figures. Emails by me to get the real figures from the Porsche Museum in Stuttgart have gone unanswered and Porsche themselves make no such claim for their car. An email from me to l'Automobile Club de l'Ouest, requesting any speedtrap figures from the April 1971 test weekend, has not yet produced any results.

In line with Wikipedia guidelines, "Encyclopedic content must be verifiable" so for this article to remain as is, some speedtrap figures will need to be provided or the claims removed.

I'll give it two weeks from today. Flanker235 (talk) 22:24, 18 February 2014 (UTC)
 * A few things: Yes, night practice is a requirement at Le Mans, as all drivers must make 3 laps at night in order to participate in the race. The night practice/qualifying session is generally where the pole position is won due to the better temperatures for the cars.


 * Second, the source given on Mulsanne's Corner is Autotechnica's Le Mans annual, so from there we have a reliable source for the fastest speeds in 1971 (222 in practice and 224 in the race). The 240+mph speed claim likely comes from the fastest lap of the race being an average of 244.4km/h, and someone messing up the units.  The pole position and fastest lap of the race were indeed both made by Jackie Oliver, but that does not inherently equate to setting the highest trap speed.  Although the Mulsanne is long, it is only about 1/3rd of the overall length of the track, so one can make gains and losses elsewhere, especially on the long straight between Mulsanne Corner and Indianapolis.


 * If we have the Autotechnica source stating that the Porsche only mustered 224mph, then there is no real need to wait. The359  ( Talk ) 03:57, 19 February 2014 (UTC)


 * Thanks for your reply. Very interesting response and very plausible explanations. On the issue of a night run, my question related not to the qualifying session for Le Mans but to the April test session when these speeds were claimed to have been achieved. This does not discount the possibility that a night session was done. I'm just asking whether it was actually done in April. Sorry for not making that clearer. The Autotechnica Annual is, I understand, produced by the ACO, the authority who sets up the speedtrap. If anyone has a copy of the annual from that year, it would be very helpful. As it is probably worth its weight in gold, I don't have one. Flanker235 (talk) 10:09, 19 February 2014 (UTC)


 * The following paragraph has been altered:




 * This has been done to reflect what can be gleaned from the actual ACO speedtrap figures provided by the Autotechnica Annual, i.e.: what can be proved and what cannot. I have also removed it because there is too much conjecture about why the Sunoco Ferrari ended up where it did. The leap of logic is too improbable. Here's my reasoning: if the 917s were doing 240mph (390 km/h) on the straight - and we have proof they were not, it would take them slightly less than one minute to cover that distance, of which perhaps 15-20 seconds might be spent at terminal speed. If the Ferrari could not reach that speed, it might spend 30-40 seconds at terminal speed and then have to pick all that up in the slower sections. It would be more than 500 metres behind! It would have to make up a spectacular amount of time through Mulsanne, Indianapolis, Arnage, the Ford Chicane, the Esses and Tertre Rouge. The difference in speeds through those sections would have to be in the tens of miles per hour which is simply beyond the realms of probability so while the inference is there, there is nothing obvious about it. In fact, as the speedtrap figures show, it is based on a false premise.


 * In any event, it is not our job to reason or interpret so some simple statements of what we know will suffice.


 * I have not tried to change the part about the rolling start because, although I know it to be accurate, I can find no reference to confirm it. However, since the speedtrap figures show that the fastest 917 in the race did 224 mph (362 km/h), the reference to Elford doing 239.8 mph has also been removed. No reference was provided for the original claim. I have not attempted to edit the final (182 word) sentence of the Race section because I cannot understand it! Flanker235 (talk) 10:33, 4 March 2014 (UTC)


 * Here is a point which might explain the discrepancies between the claims and the validations. Many Porsche fans and a few drivers, including Derek Bell, claim the 917 was good for 246 mph, while the official ACO speed trap figures report 362 km/h (224.4 mph). I don't doubt Bell's sincerity but I suspect there is a problem with the way they have calculated it. It seems it was done using only gearing charts and someone forgot to factor in tyre slip (vehicle dynamics). If you factor in a slip of 1.1:1 - or roughly 10%, you go from 246 to almost exactly 224. The figure of 246 is not feasible. I don't expect anyone to include my back-of-the-envelope calculations in a reference-grade article though. One thing I always ask claimants of the 240 mph myth is why the Ferrari 512 recorded the highest top speed in qualifying. Never had a reply yet! Flanker235 (talk) 04:58, 25 January 2016 (UTC)

And so we're back to the 240 mph claim again only this time it's 246... This was never accepted - officially or unofficially - as the top speed of the 917 at Le Mans. According to Derek Bell, this figure was the result of a quick 'n' dirty calculation done by Norbert Singer. Singer had asked the drivers how many revs they were pulling. Bell replied, "8,100", to which Singer responded "That's good because at 8,200 it blows up." When Bell asked what the speed was, Singer apparently produced a slide rule and said "Allowing for tyre growth, about 396 km/h". Bell tells the story in imperial units and that's where the 246 figure comes in (Singer did not factor in tyre slip).

https://www.youtube.com/watch?v=3mM1Ms0vqjc&t=3s

The ACO speed trap - the only speed trap at the circuit - recorded the fastest car in Friday practice as a Ferrari at 359 km/h. This was eclipsed in the race by a Porsche at 362 km/h - about 225 mph.

http://www.mulsannescorner.com/maxspeed.html

Official or not, the only provable figure is the one from the speed trap and for the purpose of this article, it should be the only one which matters. I recommend the 246 claim be removed as it is not verifiable. Flanker235 (talk) 12:16, 26 June 2018 (UTC)


 * The following sentence has been removed:

"His 917L had reached 396 kp/h (246 mph) down the Mulsanne Straight [8][10]"


 * The reason for this edit is that the references provided are reflective of contemporary hear say. They are not definitive references in the same way as the ACO speed trap figures, using a calibrated instrument. Flanker235 (talk) 14:56, 4 April 2020 (UTC)