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Auto Union 2-stage superchargers


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#1 Roger Clark

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Posted 21 October 2011 - 13:31

Does anybody know at which races the 1939 Auto Unions used 2-stage supercharging? I understand that they first appeared at the French GP but I don't know whether all the cars were so fitted. I read somewhere that the 2-stage supercharged engine could be recognised by an additional air intake trunk under the right hand bank of exhausts but I don't know whether this is a reliable indication. Photographs showing this side of the car are infuriatingly rare. Later cars also had a larger intake above the drivers head but I don't know whether this indicates 2-stage supercharging.

Muller's car at the French GP definitely had the right hand intake trumpet, as did Nuvolari's at the German GP.

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#2 Tim Murray

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Posted 21 October 2011 - 14:06

I've always assumed that the trunking on the right-hand side meant two-stage supercharging. There are photos in Chris Nixon's Auto Union Album and Le Leggendarie Auto Union by Cancellieri and De Agostini which show that, in addition to the cases mentioned by Roger, Nuvolari's car at Reims and Müller’s car at Belgrade had the trunking, but Meier's car at Reims did not.

#3 Roger Clark

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Posted 21 October 2011 - 15:12

Stuck's and Muller's cars at the German GP also had the trunking (Robert Fellowes Collection).

#4 Vitesse2

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Posted 21 October 2011 - 15:45

I've always assumed that the trunking on the right-hand side meant two-stage supercharging.

That's what it says in Kirchberg's "Grand Prix Report: Auto Union 1934-39", which includes three pictures of cars all numbered 4 - front and back views - two are unidentified, but I'd guess both of those are from the German GP. The third is from Belgrade where, according to the post-race technical report, both cars which ran were Doppelkompressor.

#5 GIGLEUX

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Posted 21 October 2011 - 17:01

At the Belgium GP it seems that Nuvolari had the two stage supercharged engine.

#6 Roger Clark

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Posted 21 October 2011 - 17:26

At the Belgium GP it seems that Nuvolari had the two stage supercharged engine.

That is very interesting because it contradicts the frequently made assertion that the new engine first appeared at Reims. However, a caption in Monkhouse's Mercedes-Benz Grand Prix racing says that Nuvolari had it at the Eiffelrennen!

Monkhouse also says that Caracciola's Mercedes had two stage supercharging at Livorno in 1938, but I hope we can ignore that.

Edited by Roger Clark, 21 October 2011 - 17:27.


#7 Allan Lupton

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Posted 21 October 2011 - 17:35

Without doing a lot of research I can say that most of what one reads implies that two-stage blowing was the 1939 standard.
One might ask what evidence is there that single-stage was used at all in 1939, and if so why as there would not be any advantage once a two-stage system had been designed, built and proven.

#8 Allan Lupton

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Posted 21 October 2011 - 17:43

Monkhouse also says that Caracciola's Mercedes had two stage supercharging at Livorno in 1938, but I hope we can ignore that.

Again without research, I think I remember that the M154 had two blowers and that might have misled Monkhouse into a mistake.

#9 Tim Murray

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Posted 21 October 2011 - 18:27

That is very interesting because it contradicts the frequently made assertion that the new engine first appeared at Reims. However, a caption in Monkhouse's Mercedes-Benz Grand Prix racing says that Nuvolari had it at the Eiffelrennen!

The Nixon Auto Union Album has a photo showing the start of the Eifelrennen, and Nuvolari's car clearly has no trunking. However, as AU took six cars to the Ring (there's a photo showing all six) perhaps one of the cars might have been fitted with the new engine and tried in practice.

#10 Roger Clark

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Posted 21 October 2011 - 18:42

Without doing a lot of research I can say that most of what one reads implies that two-stage blowing was the 1939 standard.
One might ask what evidence is there that single-stage was used at all in 1939, and if so why as there would not be any advantage once a two-stage system had been designed, built and proven.

Availability is the answer to that.

Quicksilver Century says that Mercedes' system first appeared in Lang's car at the Eifelrennen and in other cars from the next race, the Belgian GP. Knowing Karl Ludvigsen's access to Daimler-Benz archives I think we can be confident that he is correct, particularly as he says that the new engine was not ready for Pau, nor for von Brauchitsch's car in the Eifelrennen.

With Auto Union, we don't have the same level of information, but most sources say that two stage supercharging first appeared at the French Grand Prix. If we are correct in believing that the extra intake trunking indicates two stage supercharging, then Nuvolari didn't have it at the Eifelrennen.

Auto Union were always short of money in comparison with Mercedes and it seems reasonable to ask whether two stage superchargers were available on all the cars, even after they had been proven.


#11 monoposto

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Posted 22 October 2011 - 16:59



It is possibly easier to ascertain what cars didn't have two-stage supercharging.

In the four end of season races ( France, Germany, Switzerland and Yugoslavia ) AU entered five cars in the French and German GP's for Nuvolari , Müller , Stuck , Hasse and Meier ; four cars in the Swiss omitting Meier ; and only two in Belgrade for Nuvolari and Müller.

Hence only Nuvolari and Müller competed in all four, and in each instance were so equipped.

There is photographic evidence that Stuck's car in the German GP had it, but I have so far not found evidence that he had it in the French of Swiss though it would seem likely.

Meier's car in the French GP did not have it ( as noted earlier ) nor at the German GP along with Hasse, so it would seem likely that Hasse's car didn't have it at the earlier French GP either, which would point to only three cars having been built to that specification.


#12 Vitesse2

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Posted 22 October 2011 - 17:22

The AU Belgrade report identifies the two chassis there as 76010 and 76011.

Müller drove 76011 in the race and Nuvolari 76010. However, it seems both men drove both chassis in practice. Bigalke also drove 76010 in practice.

Edited by Vitesse2, 22 October 2011 - 17:28.


#13 GIGLEUX

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Posted 22 October 2011 - 19:44

From photographic evidence Stück had it in the Swiss GP.

#14 GIGLEUX

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Posted 22 October 2011 - 22:09

In the Swiss GP Hasse, too, had a 2-stage supercharged engine.

#15 Roger Clark

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Posted 23 October 2011 - 05:22

Summarising, of the four races from the French GP:

Nuvolari and Muller had two stage supercharging at all races
Stuck: Reims not known, two stage in Germany and Switzerland
Hasse: Reims not known, Germany single stage, Switzerland two stage.
Meier single stage in France and Germany.

We also have Gigleux' assertion that Nuvolari had two stage supercharging at the earlier Belgian GP. May I ask the source for that?

Some more questions, to which somebody may already know the answers:

I assume that all identification was done on the existence or otherwise of the air trunking under the right hand exhausts. Some cars seem to have a lager intake above the driver's head. Was this also an indication of two stage supercharging?

What was the purpose of the two intakes? Did the feed air into the supercharger or were they for cooling purposes?

Do the replicas built in recent years have two stage superchargers?

We know that Mercedes swapped engines between cars from race to race (see the current W154 thread). Did Autu Union do the same or was the car/engine combination a fixed entity?

Did the Auto Union drivers tend to keep the same car or did they change from race to race?

#16 Doug Nye

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Posted 23 October 2011 - 06:51

Without getting too involved with verifying all of the above I believe that only one of the Crosthwaite & Gardiner V12 cars features two-stage supercharging, and this is the 'least replaced' one - the car owned by Abba Kogan that has been offered for sale in recent years via Christie's (withdrawn) and then Bonhams (unsold). The original basis of the engine used was NOT a two-stage unit, and the casting had to be modified to provide the necessary supercharger drive. Original two-stage engines used a crankcase/block casting that differed at one end from the preceding single-stage design.

DCN

#17 Tim Murray

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Posted 23 October 2011 - 08:26

I assume that all identification was done on the existence or otherwise of the air trunking under the right hand exhausts.

... which includes the 'bulge' in the bodywork behind the exhaust on the r/h side which I assume covers the extra manifolding etc required by the two-stage configuration.

Some cars seem to have a lager intake above the driver's head. Was this also an indication of two stage supercharging?

I don't think so. There are photos of Hasse in Belgium and Meier in France where both cars appear to be fitted with the larger intake above the driver's head.

Edited by Tim Murray, 23 October 2011 - 08:29.


#18 Allan Lupton

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Posted 23 October 2011 - 09:22

There's a photo here which is too big to post and which shows how the side intake gets the air past the exhaust pipes to the carbs which are on the right of the LP blower.
Can't find a photo of the single stage installation but an air duct from behind the driver's head past the centre of the engine to the blower and its carb(s) would seem likely

#19 Roger Clark

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Posted 23 October 2011 - 09:53

... which includes the 'bulge' in the bodywork behind the exhaust on the r/h side which I assume covers the extra manifolding etc required by the two-stage configuration.

The bulge was to clear the carburettor which was on the right side of the first supercharger. On the single supercharger cars it was behind the blower.

[I posted this before I saw Allan's post, but I think they're saying the same thing]

Edited by Roger Clark, 23 October 2011 - 09:55.


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#20 Tim Murray

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Posted 23 October 2011 - 11:19

The bulge was to clear the carburettor which was on the right side of the first supercharger. On the single supercharger cars it was behind the blower.

Yes indeed. It was only after Allan posted that I bestirred myself to hunt down the photos I took of the (then) Neil Corner-owned car at Shelsley in 1986, which I thought would show the single-stage supercharger layout. I'd completely forgotten that this car actually had a two-stage supercharged engine, so here are a few more photos to complement Allan's:

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All photos copyright Tim Murray

Interesting that the car in Allan's photo has the duct under the exhaust but the Corner car does not.

Edited by Tim Murray, 23 October 2011 - 11:23.


#21 Roger Clark

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Posted 23 October 2011 - 11:49

The Nixon Auto Union Album has a photo showing the start of the Eifelrennen, and Nuvolari's car clearly has no trunking. However, as AU took six cars to the Ring (there's a photo showing all six) perhaps one of the cars might have been fitted with the new engine and tried in practice.

According to Sheldon, the Auto Union race numbers were 2 (Nuvolari), 4 (Stuck), 6 (Muller), 8 (Hasse), and 10 (Bigalke). Only even numbers were used and Caracciola was 12. Nixon says that Meier was entered but non-started, but what number would he have had?

#22 David McKinney

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Posted 23 October 2011 - 12:14

8 (according to Sheldon :) )

#23 Vitesse2

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Posted 23 October 2011 - 12:18

Meier was there as a reserve. After Stuck twisted his ankle playing skittles he was supposed to take over Stuck's car, but it apparently succumbed to a mechanical malady, so Meier non-started:

http://www.kolumbus....man/gp393.htm#8

#24 GIGLEUX

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Posted 23 October 2011 - 15:00

We also have Gigleux' assertion that Nuvolari had two stage supercharging at the earlier Belgian GP. May I ask the source for that?


Simply because I have a picture!

For those interested by photograpic evidences of Nuvolari in the Belgium GP, Stück and Hasse in the Swiss GP, all with 2-stage supercharged engines, give me your e-mail address by the way of PMs and I'll send you scans of the pictures!

I also red that Müller too had such a device at the Belgium GP.


#25 GIGLEUX

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Posted 23 October 2011 - 16:42

According to Sheldon, the Auto Union race numbers were 2 (Nuvolari), 4 (Stuck), 6 (Muller), 8 (Hasse), and 10 (Bigalke). Only even numbers were used and Caracciola was 12. Nixon says that Meier was entered but non-started, but what number would he have had?

From official programme:

2 Nuvolari 4 Stuck 6 Müller 8 Meier 10 Bigalke

#26 Vitesse2

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Posted 23 October 2011 - 16:54

I also red that Müller too had such a device at the Belgium GP.

Clearly visible in a picture in Jean-Paul Delsaux' Belgian GP book.

#27 Roger Clark

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Posted 23 October 2011 - 18:34

Simply because I have a picture!

For those interested by photograpic evidences of Nuvolari in the Belgium GP, Stück and Hasse in the Swiss GP, all with 2-stage supercharged engines, give me your e-mail address by the way of PMs and I'll send you scans of the pictures!

I also red that Müller too had such a device at the Belgium GP.

Well, that proves a lot of people wrong!

If they had two such cars at Spa, is it possible that the spare at the Eifelrennen also had two stage supercharging? THey could have put Meier in the spare after the ex-Stuck car developed problems, but perhaps it was too new to race, as Tim Murray suggested.

#28 Peter Morley

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Posted 24 August 2012 - 08:32

According to the latest Octane, Audi have now saved up enough to buy the two stage car from Abba Kogan for their static collection.
Presumably that means all the work by C&G + H&H in getting it running won't matter and the only chance of seeing an original Auto-Union running is if someone finds another one or the ex-Neil Corner/Samsung car re-appears.

#29 Garsted

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Posted 25 August 2012 - 12:13

Yes indeed. It was only after Allan posted that I bestirred myself to hunt down the photos I took of the (then) Neil Corner-owned car at Shelsley in 1986, which I thought would show the single-stage supercharger layout. I'd completely forgotten that this car actually had a two-stage supercharged engine, so here are a few more photos to complement Allan's:

Posted Image

Posted Image

Posted Image

Posted Image
All photos copyright Tim Murray

Interesting that the car in Allan's photo has the duct under the exhaust but the Corner car does not.


Is that the top of a Hewland geaerbox I can see? if so, can we assume the car was incomplete when Neil Corner acquired it?

Steve