southpier Posted June 13, 2015 Share Posted June 13, 2015 anyone have a picture of a potvin blower set up on a flathead? i had one from HAMB, but it wasn't real clear how the manifold was configured. or how it mounted - completely front cover supported or any brackets to the frame? thanks Quote Link to comment Share on other sites More sharing options...
Greg Myers Posted June 13, 2015 Share Posted June 13, 2015 (edited) Edited June 13, 2015 by Greg Myers Quote Link to comment Share on other sites More sharing options...
Crazy Ed Posted June 13, 2015 Share Posted June 13, 2015 OK, Now That's PRETTY!! Quote Link to comment Share on other sites More sharing options...
southpier Posted June 13, 2015 Share Posted June 13, 2015 thanks. love the spinney one. this one too: http://www.jalopyjournal.com/?p=22133 not sure many were manufactured Quote Link to comment Share on other sites More sharing options...
Greg Myers Posted June 14, 2015 Share Posted June 14, 2015 Quote Link to comment Share on other sites More sharing options...
Ace-Garageguy Posted June 14, 2015 Share Posted June 14, 2015 Check out the minuscule belt-wrap on the pulley of the SCoT blower on the top photo in post #30. That's really gonna slip. And that's not gonna make any boost at all. Notice that even the centrifugal blowers in the lower shots have 3 and 4 pulley sheaves. Quote Link to comment Share on other sites More sharing options...
Reegs Posted October 1, 2015 Share Posted October 1, 2015 Another reason to abandon front-supercharging: on those occassions when the intake valve would hang open all the fuel in the runner would ignite. Quote Link to comment Share on other sites More sharing options...
Bernard Kron Posted October 1, 2015 Share Posted October 1, 2015 (edited) If I had to guess, Potvin's approach was determined by the most common high performance applications of the period, which was immediately of the second world war. During the 20's and 30's when supercharging was the go-to strategy for significantly increasing the output of an engine of given displacement, the distinction between blown and unblown motors was less prejudicial and supercharging was considered no different an option than multiple carburetion, for example. The most prevalent mounting strategy was a geared mechanical drive, either off the front as on the blower Bentley or via a shaft off the front cam tower and accessory drive with the blower mounted on the side of the engine block to reduce length (on Alfa Romeos for example). The potential deficiencies of belt and chain drives are well covered above. Top mounted blowers emerged when the challenge of fitting supercharging to a pre-existing chassis or engine compartment space became an important design consideration, for example as seen in the aftermarket oriented S.C.o.T. blower setup. It is simpler to cut a hole in the hood of a car than to relocate the cooling system or modify the chassis or suspension.A major disadvantage of a front-mounted blower in drag racing applications became apparent as drag racers found it desirable to concentrate weight over the rear wheels and towards the back of the car. I believe this, as much as anything, led to the demise of the front-mounted blower, and the Potvin in particular, during the 1960's. The advent of reliable toothed belt technology then assured that issues of cost, weight and pumping losses also would have hastened its exit from the drag racing world. Edited October 1, 2015 by Bernard Kron Quote Link to comment Share on other sites More sharing options...
Ace-Garageguy Posted October 1, 2015 Share Posted October 1, 2015 (edited) Barney Navarro is widely credited as being the earliest user of the now ubiquitous GMC blower. Navarro built his own line of flathead V8 speed equipment after the war (WW II, for those of you who may be history-challenged). The story goes that in 1948, Kong Jackson (Kong Ignitions, if anyone remembers) showed up at Navarro's place with a GMC 3-71 salvaged from a surplus landing-craft diesel. Navarro built an intake manifold and multiple V-belt drive for it, clearanced the case, raced the setup successfully, and the rest is history.Navarro DID have many and ongoing problems with the drive belts shredding however. The hot-rodding speed community was pretty close-knit in those days, and everybody who was anybody know what the other guys were doing. The continuing V-belt problems Navarro had may have figured heavily in the decision to develop the front-drive setups like Potvin.The pumping-losses inherent in a front-drive setup weren't thought to be as important, back then, as we now know they are either. Look at headers of the late '40s and early '50s, and you'll see that gas-flow wasn't managed as carefully as it is now, because it simply wasn't understood as well. Well into the '70s, some engineers still believed that good porting, clean-short-straight intake manifold passages, and tuned equal-length header primaries just didn't matter on supercharged engines. Edited October 1, 2015 by Ace-Garageguy Quote Link to comment Share on other sites More sharing options...
Bernard Kron Posted October 1, 2015 Share Posted October 1, 2015 (edited) The Navarro blower setup, thought to have first run in either late 1946 or early 1947: Navarro was one of hot rodding's sharpest minds, creative on a level rivaled by few in his field or his generation. His articles in the first issues of Hot Rod Magazine and Hop Up are masterpieces of scientific education. Not only was he an inventor, machinist, and racing driver but he was involved in the early days of fuel chemistry as well. His articles on combustion, fuels, valve timing and supercharging are must-reads even today. Navarro was an early convert to turbocharging and consulted to Garret AirResearch, Alfa Romeo, and the Ford Motor Company on the matter. In later years he also developed heart-lung machine technologies using his extensive knowledge of fluid dynamics. He died in 2007 at the age of 88. His company, Navarro Engineering, survived him, continuing to manufacture nostalgia racing parts, including his famous High-Dome flathead racing heads. The legendary blown flathead not only figured in Navarro's roadsters own record runs but was loaned out to others who made their mark in the early days of hot rodding, including Tom Beatty's lakester and the SoCal Speed Shop crew (Alex Xydias and Dean Batchelor) for their streamliner. Barney: The Navarro roadster doin' the business: The master at work: Navarro (left) and Tom Beatty at El Mirage in 1948 working on the Navarro blown flathead installed in Bob Trammel's '27T: Edited October 1, 2015 by Bernard Kron Quote Link to comment Share on other sites More sharing options...
Greg Myers Posted October 1, 2015 Share Posted October 1, 2015 Few more with better "Belt wrap" Quote Link to comment Share on other sites More sharing options...
Greg Myers Posted October 1, 2015 Share Posted October 1, 2015 Only thing that came to mind on this one was an old saying : " Ifn' it Don't Go , Chrome it." Quote Link to comment Share on other sites More sharing options...
Art Anderson Posted October 2, 2015 Share Posted October 2, 2015 Barney Navarro is widely credited as being the earliest user of the now ubiquitous GMC blower. Navarro built his own line of flathead V8 speed equipment after the war (WW II, for those of you who may be history-challenged). The story goes that in 1948, Kong Jackson (Kong Ignitions, if anyone remembers) showed up at Navarro's place with a GMC 3-71 salvaged from a surplus landing-craft diesel. Navarro built an intake manifold and multiple V-belt drive for it, clearanced the case, raced the setup successfully, and the rest is history.Navarro DID have many and ongoing problems with the drive belts shredding however. The hot-rodding speed community was pretty close-knit in those days, and everybody who was anybody know what the other guys were doing. The continuing V-belt problems Navarro had may have figured heavily in the decision to develop the front-drive setups like Potvin.The pumping-losses inherent in a front-drive setup weren't thought to be as important, back then, as we now know they are either. Look at headers of the late '40s and early '50s, and you'll see that gas-flow wasn't managed as carefully as it is now, because it simply wasn't understood as well. Well into the '70s, some engineers still believed that good porting, clean-short-straight intake manifold passages, and tuned equal-length header primaries just didn't matter on supercharged engines. And, the concept of mouting a Rootes-type blower on the front of the engine, driven off the crankshaft was just about the earliest setup--most notably on the Blower Bentley's of the late 1920's/early 30's. Mercedes and Mercedes-Benz also drove this style of blower off the nose of the crankshaft all the way from the first SSK to the last 540K, as did the 1930's Auto Union V16 grand prix cars. Bugatti was another maker who used this sort of setup. So, it does seem rather natural that postwar hot rodders would have at least looked at that sort of setup.Art Quote Link to comment Share on other sites More sharing options...
Force Posted October 3, 2015 Share Posted October 3, 2015 If it was so good why don't they still use them? Haven't seen one used since the early sixties. I think the main reason they stopped using the Potvin style drive was that it was a fixed drive where the supercharger and crank shaft rotates at the same speed and that's a disadvantage as you get moore boost if you overdrive the supercharger, with a belt drive it's easy to change the gear ratio and over or underdrive the supercharger depending on how much boost you want.NHRA has a limit for supercharger overdrive in the nitro classes at 1.5:1, (1.7:1 in Denver Co) and the supercarger rotates at 12,450 rpm at an engine speed of 8500 rpm and delivers about 60 psi of boost (4 atmospheres). Quote Link to comment Share on other sites More sharing options...
disabled modeler Posted October 3, 2015 Share Posted October 3, 2015 I like the odd or old small blowers...just fascinated with them...love to find one I could rig up on our truck that mounts like a alternator. Quote Link to comment Share on other sites More sharing options...
Crazy Ed Posted October 3, 2015 Share Posted October 3, 2015 I like the odd or old small blowers...just fascinated with them...love to find one I could rig up on our truck that mounts like a alternator. Here ya go Mark, http://www.paxtonauto.com Quote Link to comment Share on other sites More sharing options...
disabled modeler Posted October 3, 2015 Share Posted October 3, 2015 Here ya go Mark, http://www.paxtonauto.comEd... I wish I could afford one even a used or old style one off a junkyard car or..? Our truck needs another 75HP which one would easily add to it. Quote Link to comment Share on other sites More sharing options...
Richard Bartrop Posted October 7, 2015 Share Posted October 7, 2015 Why did the Potvin blower ever come around? Is it superior in performance to a regular situation on top of an engine?The guys with practical experience would probably have a better idea about this, but how much of it was simply due to the limitations of belt technology at the time. Blowers make lots of power, but there also use lots, and the bigger the boost, the more power you're going to need, and maybe it was just the case a direct connection to the crankshaft could handle more power than a smooth belt relying on friction with a pulley. The Potvin style blowers seem to have fallen out of favour about the time the Gilmer belts because popular, so maybe there's something to it Quote Link to comment Share on other sites More sharing options...
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