Spec’ing Cams over the years - David Vizard
Posted: Sat May 27, 2017 11:17 am
Some interesting extracts below taken from a recent article on Minis and cam developments over the years by David Vizard:-
"Way back when I was a new student to the science of engine development (late 1950’s) I wondered why engines would have differing optimal valve event timing. What, I asked myself, were the factors involved. Well back in those days I had much else to concern me as far as my education on developing engine performance was concerned. I had already built a crude but effective flow bench which was teaching me heaps of go-fast tech in terms of cylinder head mods. It was not until successful and nationally recognized UK engine builder Harry Ratcliffe of BVRT happened to mention to me that he had noticed that the short stroke big bore Ford 105E range of engines generally like to have the Lobe Centerline Angle at 109 degrees where as the long stroke ‘A’ series engines that powered the Mini Coopers of the day were more disposed to 104 or so. This comment from Harry was actually what got me started on my quest to find out what factors affected the optimal opening and closing points any particular spec of engine needed for the strongest power curve in the desired rpm range."
"All the forgoing was back somewhere in the mid 1960’s. Over the next 30 years my involvement in the cam aspect of engine development became ever deeper and more involved. In 1971 I began, as an outside consultant, working with the UK division of Chrysler, or more accurately their competition department. That year they introduced the then new-from-the-ground-up Avenger. Loosely my job description here was to popularize it as a performance vehicle. That was all very well but there was almost no speed equipment in existence for this engine and certainly close to zero know-how on what was needed to make it perform. I went to work investigating this somewhat unorthodox engine and making modifications accordingly. My efforts here rapidly outpaced the factory’s. They must have liked my efforts because the first simple projects lead to more ambitious ones. Eventually I was developing an ultra wide power band version of the production line Avenger engine and a turbo version of such to put Ford’s Lotus Cortina twin cam in it’s place (i.e. behind an Avenger). As it happened I pulled off both projects with apparently great success. Motor Magazine tested my ultra wide power band Avenger (useable power from 400 rpm to 8000 and I am still waiting for a VVT engine to match that). Even at 1500 cc it whooped the butt off the newly introduced 1600 Cosworth BDA Escort in every respect. The differences were far from marginal, and, as the magazine’s road test editors put it, embarrassing for Cosworth. As for the Turbo Avenger this project went very well producing an emission legal 0-100 mph in 13 seconds.
With Chryslers Competition Dept., supplying whatever I asked for I found I was in the best position to-date to do some experimentation with cams. I had learned a lot from building race winning Mini and Ford engines in the dozen or so years to this point and built on that."
"All the forgoing with Avenger engines gave me an additional window into the workings and requirements of an engine very different to the Ford and ‘A’ Series engines I had worked with to date. It also allowed me to make a direct comparison between the requirements of a normally aspirated engine versus a turbo one. By the time my year as a driver/car constructor in the British Touring Car Championship came up I had, though still far from mathematically quantified, a good handle on what any particular engine needed for maximum performance. This proved itself out in a very public way. In spite of being a privateer against a field of factory entered cars my BTCC 1600 Avenger Tiger was the fastest by far in the class even though it was (other than the factory entered Avengers) the only pushrod, all iron, motor competing. In six of the races I broke a motor in during practice forcing me to start way back as far as 28th on a 32 car grid. On each occasion I was up to first or second in class by the end of the first lap. The most dramatic of these through-the-field charges was at Brands Hatch where the BTCC event was the main supporting race of the British Grand Prix and was televised. Again breaking in a motor put me on the last row but one. If ever there were doubters to the possibility that I may have an inkling on how to make hp this should have been a convincer that I could – and one of major proportions at that. From my 27th starting spot I took my 1600 cc racer to joint first between two 350 Z28 Cameros – by the first corner! Yes you read right – I passed 24 cars in the time it took for the start lights to turn green and my arrival at turn #1 (Paddock bend). As for witnesses – well several million TV viewers saw this happen. As you might expect I am by this time starting to actually justify the nickname of Vizard-the-Wizard or Mr. Horsepower."
"The stunt at Brands though was hardly the first time I had pulled off something like this. A couple of years previous, I had, on a damp track at Prescott and in my 1293 cc Mini Cooper, beaten all the times of the F1 cars. The only single seater to beat me was a four wheel drive Formula 5000 car which bettered me on a drying track to the tune of a scant nine thousandths of a second! (that 1293 had one of my cams in it as well as a DV ported head and a bunch of other stuff I made because I could not afford to buy it.)"
"All through the 1970’s I built on my successes in the cam and head departments of high performance engines. By the time the 1980’s rolled around I am seeing work come in from notable cam companies. I get cam testing assignments from the likes of Iskenderian (known Ed Iskenderian since 1972 and he still refers to me as ‘Young Vizard), Crane, Comp Cams and the like in the US and Piper and Kent in the UK. At first the cams being tested were only in ones and twos to maybe a dozen or so. The reason, as I was told, that these cam companies came to me or were very willing to work with me is because my dyno testing was meticulous to a point."
In the early 80’s I did a cam makeover project for Piper cams in the UK. The results were dramatic both in terms of improved performance and sales. To quote Pipers boss ‘the results were beyond our wildest dreams!’
"About 3 years on from the Piper deal I wrote an article in Cars & Car Conversions (a magazine I used to write for regularly until some conflicts with editors and staff who unthinkingly put me in a position of making things even harder to generate new and exciting material) that stated, in big bold wording, that I thought it a poor deal that neither the factory (British Leyland) nor England and Europe’s leading cam grinders actually knew what they were doing when it came to cams for the ‘A’ series engine (which at that time was the most popular engine to hop up by a country mile). Wow – think about that – here is a mere motoring journalist (I am actually an engineer not a journalist but whatever) is saying – in a very public forum and using my own name, not hiding behind the anonymity of some pseudo name, and saying the factory, and virtually all others, do not know what they are doing to a sufficient degree to be anywhere near optimum for the duration figures involved. I don’t suppose for one second that you will have a hard time believing that this stirred up a hornet nest."
"When questioned by potential customers and the press the guy at British Leyland just blew it off by saying that as a journalist I need to write something sensational and that I would not – and probably could not back up such an obviously outlandish claim. The reality was that I was tired of being polite as it got me no where. I was getting ticked off by BL’s Competition Departments near lack of any apparent capability to advance the state of art and the very thing I wanted them to do was to take me up on it so I could show them what they were missing out on. I had commented several times to the guy that made the dumb press statement that I would love to go through their cams and update them from the Stone Age to something at least a couple years in advance of the then current state of art. He just blew off any suggestion that they wanted, or even needed, to update anything especially with the aid of a journalist! Back then BL’s race profiles dated to pre 1958 era. What a bunch of go getters they were!"
"The comments from BL’s staff did not really hold any great surprises but I was rather surprise of the cool reception my magazine comments had from Piper as I had already proved what I could do with only a minor budget to work with. On the other hand Kent cams Bob Munt called me up and said “let’s see if you can put your money where your mouth is”. So we struck a deal. Bob was to find the most successful ‘A’ series engine builder in the country and ship him and a selection of representative dyno mules over to my shop in Riverside California. There I was to show just how much better my cams were than whatever was currently being used. The engine builder Bob Munt chose was an extremely successful ‘A’ Series engine builder that had, that year, (and several previous and subsequent years) virtually cleaned up in any class where a Mini was eligible. I seem to remember that out of four championships this guys engines took the first four spots on three of them and the first three in the remaining championship. This highly successful engine builder was the now famous (in European circles) Dave Mountain of Mountune Racing in Malden just east of London, England. Dave was also one of my protege’s. If I ever needed to offer proof that I can teach not just race but championship winning engine building technology then Dave will, I’m sure, bear witness to such."
"During the 6 weeks or so I worked with Dave Mountain and with the valuable assistance of my good friend David Anton (of Advanced Performance Technology in Riverside CA) I developed a range of conventional cams for the ‘A’ Series that simply out powered anything out there by a very substantial margin. (My eldest daughter Samantha, scored an 88% win record with her street weight 1275 Mini GT and was never beaten by anything less than 3.1 liters. No pro built mini, even at race weight, nor a factory entered mini could hold a candle to it) Cam sales at Kent went through the roof! If I remember rightly in some four months their sales about quadrupled!"
"The rest of the year I got a number of smaller cam test jobs but the following year I was re employed by Kent to develop the ultimate ‘A’ Series cams, cams for the MGB engine and the 2 liter Pinto engine (used in Ford UK’s Cortina and Escort RS 2000). The most novel of these cams were the Scatter Pattern cams for the ‘A’ Series. This engine, because of it’s port layout of 2 intake ports and three exhaust means that every cylinder has a different valve event requirement. The inspiration for the scatter pattern cams was once again the venerable Harry Ratcliffe who had tried this some 20 years previously. Well with the equipment of the day I was sure that Harry was really up against the odds of getting it all right-on so David Anton and I, equipped with a really up-to-the-minute dyno tackled the problem of determining how to figure the optimal events for an engine that did so much port sharing and consequently inter-cylinder robbing. We really could have done with in-cylinder pressure measuring gear but it was well beyond my budget back then. So I had to come up with another method to get to where we had to go. I won’t detail it here as I am saving it for my techno memoirs should I ever get around to writing them. The scatter pattern cams really worked out well and I believe David Anton and I progressed the state of art quite some way from where even the talented Harry Ratcliffe left off. These cams simply blew away any then available into the weeds – and nothing much appears to have changed in this quarter since."
The full article here:-
http://www.motortecmagazine.net/a-new-w ... peed-spec/
Dave Vizards Race Mini
Dave Vizards BTCC Avenger Tiger
"Way back when I was a new student to the science of engine development (late 1950’s) I wondered why engines would have differing optimal valve event timing. What, I asked myself, were the factors involved. Well back in those days I had much else to concern me as far as my education on developing engine performance was concerned. I had already built a crude but effective flow bench which was teaching me heaps of go-fast tech in terms of cylinder head mods. It was not until successful and nationally recognized UK engine builder Harry Ratcliffe of BVRT happened to mention to me that he had noticed that the short stroke big bore Ford 105E range of engines generally like to have the Lobe Centerline Angle at 109 degrees where as the long stroke ‘A’ series engines that powered the Mini Coopers of the day were more disposed to 104 or so. This comment from Harry was actually what got me started on my quest to find out what factors affected the optimal opening and closing points any particular spec of engine needed for the strongest power curve in the desired rpm range."
"All the forgoing was back somewhere in the mid 1960’s. Over the next 30 years my involvement in the cam aspect of engine development became ever deeper and more involved. In 1971 I began, as an outside consultant, working with the UK division of Chrysler, or more accurately their competition department. That year they introduced the then new-from-the-ground-up Avenger. Loosely my job description here was to popularize it as a performance vehicle. That was all very well but there was almost no speed equipment in existence for this engine and certainly close to zero know-how on what was needed to make it perform. I went to work investigating this somewhat unorthodox engine and making modifications accordingly. My efforts here rapidly outpaced the factory’s. They must have liked my efforts because the first simple projects lead to more ambitious ones. Eventually I was developing an ultra wide power band version of the production line Avenger engine and a turbo version of such to put Ford’s Lotus Cortina twin cam in it’s place (i.e. behind an Avenger). As it happened I pulled off both projects with apparently great success. Motor Magazine tested my ultra wide power band Avenger (useable power from 400 rpm to 8000 and I am still waiting for a VVT engine to match that). Even at 1500 cc it whooped the butt off the newly introduced 1600 Cosworth BDA Escort in every respect. The differences were far from marginal, and, as the magazine’s road test editors put it, embarrassing for Cosworth. As for the Turbo Avenger this project went very well producing an emission legal 0-100 mph in 13 seconds.
With Chryslers Competition Dept., supplying whatever I asked for I found I was in the best position to-date to do some experimentation with cams. I had learned a lot from building race winning Mini and Ford engines in the dozen or so years to this point and built on that."
"All the forgoing with Avenger engines gave me an additional window into the workings and requirements of an engine very different to the Ford and ‘A’ Series engines I had worked with to date. It also allowed me to make a direct comparison between the requirements of a normally aspirated engine versus a turbo one. By the time my year as a driver/car constructor in the British Touring Car Championship came up I had, though still far from mathematically quantified, a good handle on what any particular engine needed for maximum performance. This proved itself out in a very public way. In spite of being a privateer against a field of factory entered cars my BTCC 1600 Avenger Tiger was the fastest by far in the class even though it was (other than the factory entered Avengers) the only pushrod, all iron, motor competing. In six of the races I broke a motor in during practice forcing me to start way back as far as 28th on a 32 car grid. On each occasion I was up to first or second in class by the end of the first lap. The most dramatic of these through-the-field charges was at Brands Hatch where the BTCC event was the main supporting race of the British Grand Prix and was televised. Again breaking in a motor put me on the last row but one. If ever there were doubters to the possibility that I may have an inkling on how to make hp this should have been a convincer that I could – and one of major proportions at that. From my 27th starting spot I took my 1600 cc racer to joint first between two 350 Z28 Cameros – by the first corner! Yes you read right – I passed 24 cars in the time it took for the start lights to turn green and my arrival at turn #1 (Paddock bend). As for witnesses – well several million TV viewers saw this happen. As you might expect I am by this time starting to actually justify the nickname of Vizard-the-Wizard or Mr. Horsepower."
"The stunt at Brands though was hardly the first time I had pulled off something like this. A couple of years previous, I had, on a damp track at Prescott and in my 1293 cc Mini Cooper, beaten all the times of the F1 cars. The only single seater to beat me was a four wheel drive Formula 5000 car which bettered me on a drying track to the tune of a scant nine thousandths of a second! (that 1293 had one of my cams in it as well as a DV ported head and a bunch of other stuff I made because I could not afford to buy it.)"
"All through the 1970’s I built on my successes in the cam and head departments of high performance engines. By the time the 1980’s rolled around I am seeing work come in from notable cam companies. I get cam testing assignments from the likes of Iskenderian (known Ed Iskenderian since 1972 and he still refers to me as ‘Young Vizard), Crane, Comp Cams and the like in the US and Piper and Kent in the UK. At first the cams being tested were only in ones and twos to maybe a dozen or so. The reason, as I was told, that these cam companies came to me or were very willing to work with me is because my dyno testing was meticulous to a point."
In the early 80’s I did a cam makeover project for Piper cams in the UK. The results were dramatic both in terms of improved performance and sales. To quote Pipers boss ‘the results were beyond our wildest dreams!’
"About 3 years on from the Piper deal I wrote an article in Cars & Car Conversions (a magazine I used to write for regularly until some conflicts with editors and staff who unthinkingly put me in a position of making things even harder to generate new and exciting material) that stated, in big bold wording, that I thought it a poor deal that neither the factory (British Leyland) nor England and Europe’s leading cam grinders actually knew what they were doing when it came to cams for the ‘A’ series engine (which at that time was the most popular engine to hop up by a country mile). Wow – think about that – here is a mere motoring journalist (I am actually an engineer not a journalist but whatever) is saying – in a very public forum and using my own name, not hiding behind the anonymity of some pseudo name, and saying the factory, and virtually all others, do not know what they are doing to a sufficient degree to be anywhere near optimum for the duration figures involved. I don’t suppose for one second that you will have a hard time believing that this stirred up a hornet nest."
"When questioned by potential customers and the press the guy at British Leyland just blew it off by saying that as a journalist I need to write something sensational and that I would not – and probably could not back up such an obviously outlandish claim. The reality was that I was tired of being polite as it got me no where. I was getting ticked off by BL’s Competition Departments near lack of any apparent capability to advance the state of art and the very thing I wanted them to do was to take me up on it so I could show them what they were missing out on. I had commented several times to the guy that made the dumb press statement that I would love to go through their cams and update them from the Stone Age to something at least a couple years in advance of the then current state of art. He just blew off any suggestion that they wanted, or even needed, to update anything especially with the aid of a journalist! Back then BL’s race profiles dated to pre 1958 era. What a bunch of go getters they were!"
"The comments from BL’s staff did not really hold any great surprises but I was rather surprise of the cool reception my magazine comments had from Piper as I had already proved what I could do with only a minor budget to work with. On the other hand Kent cams Bob Munt called me up and said “let’s see if you can put your money where your mouth is”. So we struck a deal. Bob was to find the most successful ‘A’ series engine builder in the country and ship him and a selection of representative dyno mules over to my shop in Riverside California. There I was to show just how much better my cams were than whatever was currently being used. The engine builder Bob Munt chose was an extremely successful ‘A’ Series engine builder that had, that year, (and several previous and subsequent years) virtually cleaned up in any class where a Mini was eligible. I seem to remember that out of four championships this guys engines took the first four spots on three of them and the first three in the remaining championship. This highly successful engine builder was the now famous (in European circles) Dave Mountain of Mountune Racing in Malden just east of London, England. Dave was also one of my protege’s. If I ever needed to offer proof that I can teach not just race but championship winning engine building technology then Dave will, I’m sure, bear witness to such."
"During the 6 weeks or so I worked with Dave Mountain and with the valuable assistance of my good friend David Anton (of Advanced Performance Technology in Riverside CA) I developed a range of conventional cams for the ‘A’ Series that simply out powered anything out there by a very substantial margin. (My eldest daughter Samantha, scored an 88% win record with her street weight 1275 Mini GT and was never beaten by anything less than 3.1 liters. No pro built mini, even at race weight, nor a factory entered mini could hold a candle to it) Cam sales at Kent went through the roof! If I remember rightly in some four months their sales about quadrupled!"
"The rest of the year I got a number of smaller cam test jobs but the following year I was re employed by Kent to develop the ultimate ‘A’ Series cams, cams for the MGB engine and the 2 liter Pinto engine (used in Ford UK’s Cortina and Escort RS 2000). The most novel of these cams were the Scatter Pattern cams for the ‘A’ Series. This engine, because of it’s port layout of 2 intake ports and three exhaust means that every cylinder has a different valve event requirement. The inspiration for the scatter pattern cams was once again the venerable Harry Ratcliffe who had tried this some 20 years previously. Well with the equipment of the day I was sure that Harry was really up against the odds of getting it all right-on so David Anton and I, equipped with a really up-to-the-minute dyno tackled the problem of determining how to figure the optimal events for an engine that did so much port sharing and consequently inter-cylinder robbing. We really could have done with in-cylinder pressure measuring gear but it was well beyond my budget back then. So I had to come up with another method to get to where we had to go. I won’t detail it here as I am saving it for my techno memoirs should I ever get around to writing them. The scatter pattern cams really worked out well and I believe David Anton and I progressed the state of art quite some way from where even the talented Harry Ratcliffe left off. These cams simply blew away any then available into the weeds – and nothing much appears to have changed in this quarter since."
The full article here:-
http://www.motortecmagazine.net/a-new-w ... peed-spec/
Dave Vizards Race Mini
Dave Vizards BTCC Avenger Tiger
