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Happy centennial, four-valve DOHC!


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#1 Henri Greuter

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Posted 27 June 2012 - 07:34

Should have posted it yesterday.

Yesterday it was 100 years ago that the Peugeot L76 won the Grand Prix of France.

The debut race of the Peugeot. And thus also the debut race for the world's first ever eninge with Double Overhead Camshafts (DOHC) and 4 valves per cylinder.
The concept that for a long time time set racing engines apart from others and still is the classic concept for modern days engines.
A century old by now.

Someting worth to remember, celebrating it is probably too much to ask I'm affraid.

Credits to Paolo Zucharelli, Georges Boillot, Jules Goux and Ernest Henri, the fathers of this concept that appears to be too modern for some engine builders nowadays.....


henri

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#2 Roger Clark

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Posted 27 June 2012 - 08:43

It is a very significant anniversary and I'm glad that someone has taken the trouble to commemorate it. THe speed with which the Peugeot's rivals copied its concepts, and sometimes the detailed design, has been told many times and is a fascinating tale. Borgeson's writings are particularly recommended.

However, we shouldn't forget that the four valve per cylinder Grand Prix engine was swept aside by FIAT and their followers in the early 20s and, with a couple of exceptions, didn't become fashionable again until the 1960s. Also, it is difficult to argue with those who point out that FIATs were faster than the Peugeots on both days of the 1912 Grand Prix.

It would be nice to think that we will see something at Goodwood this week to mark this anniversary.



#3 Henri Greuter

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Posted 27 June 2012 - 11:22

It is a very significant anniversary and I'm glad that someone has taken the trouble to commemorate it. THe speed with which the Peugeot's rivals copied its concepts, and sometimes the detailed design, has been told many times and is a fascinating tale. Borgeson's writings are particularly recommended.

However, we shouldn't forget that the four valve per cylinder Grand Prix engine was swept aside by FIAT and their followers in the early 20s and, with a couple of exceptions, didn't become fashionable again until the 1960s. Also, it is difficult to argue with those who point out that FIATs were faster than the Peugeots on both days of the 1912 Grand Prix.

It would be nice to think that we will see something at Goodwood this week to mark this anniversary.




True.
I wonder, could that have been related with the extreme long stroke that the Peugeots hung on to, thus never benefitting maximally from all the benefits that Fourvalve DOHC offered.
And on the other hand, in the early 20's the engine capacity became so small (2 and 1.5 liter) that when using more than 4 cylinders the bores became so small that two larger valves offered more potential than using 4 smaller ones, given the state of the technology of the time. Just the fact that only half of the amount of components could break down....


Henri



#4 D-Type

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Posted 27 June 2012 - 11:49

Did I read somewhere (on here perhaps?) that the L76 valve gear and actuation actually featured a year or two earlier on a Peugeot motorcycle? Or is my memory playing tricks?

#5 arttidesco

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Posted 28 June 2012 - 10:31

Congratulations for remembering all those at Peugeot who made the 4V DOHC a racing success, coincidentally I have just started reading Mike Oliver's Lotus 49, The story of a Legend, in which Frank Costain is quoted as saying this layout dates back to 1898 does anyone know which (non racing ?) engine Frank is referring to ?

#6 Roger Clark

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Posted 28 June 2012 - 11:16

I assume that, by Frank Costain, you mean Mike Costin.

I don't think he was referring to any specific engine, just saying that Duckworth designed from first principles and did not follow any precedents.

#7 Ray Bell

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Posted 28 June 2012 - 11:39

Originally posted by Roger Clark
It is a very significant anniversary and I'm glad that someone has taken the trouble to commemorate it.....


As a genuine Peugeotphile I'd be remiss if I didn't agree with you, Roger...

There was much ado at the time of the FVA about it following the Peugeot ideals, but it's undoubtedly true that Cosworth worked everything out themselves from a vast bank of knowledge and information available to them.

#8 arttidesco

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Posted 28 June 2012 - 12:12

I assume that, by Frank Costain, you mean Mike Costin.

I don't think he was referring to any specific engine, just saying that Duckworth designed from first principles and did not follow any precedents.


Quite correct Roger, got my Costains in a twist, it is Mike not Frank who made the comment :blush:

Edited by arttidesco, 28 June 2012 - 12:12.


#9 AAGR

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Posted 28 June 2012 - 12:21

As Keith Duckworth, of Cosworth, was quoted in COSWORTH, THE SEARCH FOR POWER : 'I am responsible, by a completely original piece of thinking, for the modern narrow-angle 4-valve head ....'

However, he did not claim to have invented the four-valve twin-cam layout, for : 'When I came to design my first 4-valve head, I looked around, said "Well, hemispherical heads, they should have been turfed out yonks ago, they're wrong, and those angles are all wrong ....'

Incidentally, when certain individuals who had been connected with Weslake read those words, they claimed to have reached similar conclusions at the same time ....

#10 Ray Bell

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Posted 28 June 2012 - 12:28

Of course, there was logic and it had to prevail...

Compression ratios of the early times allowed the wide angle, but by the mid-sixties they were looking to cram metal in there in place of air and reducing the angles became necessary.

That it helped the porting is undoubtedly not coincidental.

Edited by Ray Bell, 28 June 2012 - 12:29.