Following from my post on those Brian Stonebridge photos, in particular the one showing the unusual pipe that his son Ian found so intriguing when he saw it, I dug out this pic I have of some early expansion chamber exhaust pipes. (I've also attached the BGS pic again for reference and comparison.) I think the similarities are really interesting....
The pic was taken outside Walter Kaaden's race shop, from where he conducted the MZ racing effort. Kaaden of course, is widely known as 'the father of the modern two stroke', and his experiments using resonance and harmonics (instead of mechanical valves), tuning the shape of the pipes to make the engine 'sing' like a musical instrument and thus extracting the maximum power available from the gas charge, led to his 1961 125 GP bikes being the first to produce 200 bhp per litre without supercharging!
Walter Kaaden learnt a great deal from his work developing the Nazi secret weapons at Peenamunde, alongside Werner Von Braun, which included the V1 'Doodlebugs' that caused so much terrible devastation during the London Blitz. It was after the RAF bombed Peenamunde out of existence that Kaaden was then 'free' (bearing in mind this was in Communist Germany) to develop his motorcyle racing endeavours with MZ, which of course continued into peacetime and much success in Grand Prix roadracing. Kaaden's work on the exhaust of the 'Pulse Jet' engines employed on the V1's led directly to his expansion pipe exhaust designs for racing motorcycles.
One of Kaaden's disciples was of course renowned two stroke tuner Hermann Meier, who in turn took a young Brian Stonebridge under his wing (at BSA) where BGS was to learn so much of his trade, applied with great success on that early 'giant slaying' Bantam scrambler with which he proved his theories that a lightweight small capacity two stroke could take on (and beat!) the big four stroke scramblers of the day. Following on from this, BGS's tuning talents went on to establish Greeves at the forefront of competition of course, as by all accounts BSA had shown so little interest in Brian's ideas at the time.
I have always found this 'connection', from Kaaden to Meier and then Brian Stonebridge fascinating. So much of what they did back then was seen as a mysterious 'black art' (still is to me!!!) with constant trial and error, utilising the dynomometer to test (and test again) all the different pipe shapes and porting arrangements to get the best out of them. It was as much 'art' as engineering in my view, and as a musician I find the similarities in 'tuning' concepts very interesting indeed. Ernst Degner, Kaaden's right hand man in the race shop and later World GP Champion of course, was also a musician, and reportedly was able to use his 'ear' to great effect when race tuning their engines. (Wish I knew as much about two stroke porting as I do music.....!!!
) Indeed, when Hermann Meier was developing the Royal Enfield GP5 two stroke racer in the mid 60's, he was able to tell if riders were over reving the engines by matching the exhaust note to a mouth organ! (I wonder what note it was....?!)
According to Rob Carrick and Mick Walker's new 'Villiers' book, BGS certainly tried a Meier pipe sometime around the 1958 season, along with several other designs (and a Vale-Onslow 250 conversion), although in the pic attached the bike has a round barrel of course...Sadly, I don't know when (or where) the pic was taken either.
Anyway, hope this is of interest. Incidently, for anyone that would like to know more about Walter Kaaden, Ernst Degner and MZ, and how Degner defected to the West, taking with him all that hard won knowledge and passing it on to the Japanese, I can't recommend Mat Oxley's fantastic book 'Stealing Speed' enough (ISBN 978 1 84425 689 1), it's a cracking read.
Brian.
The pic was taken outside Walter Kaaden's race shop, from where he conducted the MZ racing effort. Kaaden of course, is widely known as 'the father of the modern two stroke', and his experiments using resonance and harmonics (instead of mechanical valves), tuning the shape of the pipes to make the engine 'sing' like a musical instrument and thus extracting the maximum power available from the gas charge, led to his 1961 125 GP bikes being the first to produce 200 bhp per litre without supercharging!
Walter Kaaden learnt a great deal from his work developing the Nazi secret weapons at Peenamunde, alongside Werner Von Braun, which included the V1 'Doodlebugs' that caused so much terrible devastation during the London Blitz. It was after the RAF bombed Peenamunde out of existence that Kaaden was then 'free' (bearing in mind this was in Communist Germany) to develop his motorcyle racing endeavours with MZ, which of course continued into peacetime and much success in Grand Prix roadracing. Kaaden's work on the exhaust of the 'Pulse Jet' engines employed on the V1's led directly to his expansion pipe exhaust designs for racing motorcycles.
One of Kaaden's disciples was of course renowned two stroke tuner Hermann Meier, who in turn took a young Brian Stonebridge under his wing (at BSA) where BGS was to learn so much of his trade, applied with great success on that early 'giant slaying' Bantam scrambler with which he proved his theories that a lightweight small capacity two stroke could take on (and beat!) the big four stroke scramblers of the day. Following on from this, BGS's tuning talents went on to establish Greeves at the forefront of competition of course, as by all accounts BSA had shown so little interest in Brian's ideas at the time.
I have always found this 'connection', from Kaaden to Meier and then Brian Stonebridge fascinating. So much of what they did back then was seen as a mysterious 'black art' (still is to me!!!) with constant trial and error, utilising the dynomometer to test (and test again) all the different pipe shapes and porting arrangements to get the best out of them. It was as much 'art' as engineering in my view, and as a musician I find the similarities in 'tuning' concepts very interesting indeed. Ernst Degner, Kaaden's right hand man in the race shop and later World GP Champion of course, was also a musician, and reportedly was able to use his 'ear' to great effect when race tuning their engines. (Wish I knew as much about two stroke porting as I do music.....!!!
) Indeed, when Hermann Meier was developing the Royal Enfield GP5 two stroke racer in the mid 60's, he was able to tell if riders were over reving the engines by matching the exhaust note to a mouth organ! (I wonder what note it was....?!)According to Rob Carrick and Mick Walker's new 'Villiers' book, BGS certainly tried a Meier pipe sometime around the 1958 season, along with several other designs (and a Vale-Onslow 250 conversion), although in the pic attached the bike has a round barrel of course...Sadly, I don't know when (or where) the pic was taken either.
Anyway, hope this is of interest. Incidently, for anyone that would like to know more about Walter Kaaden, Ernst Degner and MZ, and how Degner defected to the West, taking with him all that hard won knowledge and passing it on to the Japanese, I can't recommend Mat Oxley's fantastic book 'Stealing Speed' enough (ISBN 978 1 84425 689 1), it's a cracking read.
Brian.
Attached Files
Very interesting indeed to hear the 'inside story' though, and reminds me of how much R and D the biking public often did on behalf of the factories back then as I recall, so quickly were new products rushed out the door during that era...!
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