Potvin Blower - Why?

[chunkypeanutbutter]

Why did the Potvin blower ever come around? Is it superior in performance to a regular situation on top of an engine?

[astroracer]

Why does anything happen when the quest for more power and greater speed is the driving factor? Superchargers actually originated on airplane engines. So did nitrous oxide. Hot rodders simply took that technology and applied it to their car engines.

And, to actually answer your question, the blower does add a "bit" more performance to a normally aspirated engine... And Potvin's were generally front mounted when they first came onto the scene.

Mark

[disabled modeler]

Blowers/Superchargers make power from compressing air or air and fuel into the cylinders which gives it a larger fuel/air charge to fire on and actually to a point pushes the pistons where a normally aspirated engine has to draw the fuel/air into it which is drag. In other words the blower is kind of a compressor to a point but the boost or pressure is much less in most cases...a healthy stock engine can handle around 7 pounds of boost if its compression of the engine is not too high to start with. 7 pounds of boost may not sound like a lot but it adds loads of horsepower.

I wish I could find one that is like a Paxton for our truck that mounts like a alternator.

[astroracer]

Blowers/Superchargers make power from compressing air or air and fuel into the cylinders which gives it a larger fuel/air charge to fire on and actually to a point pushes the pistons where a normally aspirated engine has to draw the fuel/air into it which is drag. In other words the blower is kind of a compressor to a point but the boost or pressure is much less in most cases...a healthy stock engine can handle around 7 pounds of boost if its compression of the engine is not too high to start with. 7 pounds of boost may not sound like a lot but it adds loads of horsepower.

I wish I could find one that is like a Paxton for our truck that mounts like a alternator.

Here you go... Vortech also owns Paxton now.

http://www.vortechsuperchargers.com/

Also...

https://www.procharger.com/

Mark

Edited May 6, 2015 by astroracer

[ZTony8]

The main disadvantage to a Potvin type blower system is that,unlike a top mounted blower set-up, the drive ratio cannot be changed.The blower is always driven at crankshaft speed.

[Crazy Ed]

I think the question was WHY a Potvin style Front Mount instead of the most often seen Top Mounted Belt Drive setup, not what it did. As Tony said the top mount affords the chance to vary pressure by changing the drive ratio where the Potvin has a fixed psi vs rpm. The Potvin'd have 2 advantages over a Belt Driven unit. One being a Direct Drive there'd be less parasitic loss through the drive gears and belt and the other being a lower profile making for less aerodynamic drag in use.

[Snake45]

I think the question was WHY a Potvin style Front Mount instead of the most often seen Top Mounted Belt Drive setup, not what it did. As Tony said the top mount affords the chance to vary pressure by changing the drive ratio where the Potvin has a fixed psi vs rpm. The Potvin'd have 2 advantages over a Belt Driven unit. One being a Direct Drive there'd be less parasitic loss through the drive gears and belt and the other being a lower profile making for less aerodynamic drag in use.

Good answer!

[bobthehobbyguy]

Also the potvin allowed better visibilty for driver. Also a better profile for aerodynamics.

[Art Anderson]

Why does anything happen when the quest for more power and greater speed is the driving factor? Superchargers actually originated on airplane engines. So did nitrous oxide. Hot rodders simply took that technology and applied it to their car engines.

And, to actually answer your question, the blower does add a "bit" more performance to a normally aspirated engine... And Potvin's were generally front mounted when they first came onto the scene.

Mark

Actually, superchargers came about a good 25 years BEFORE the Wright Brothers made their first flight! In fact, the "positive displacement" blower was patented by Philander and Francis Marion Rootes, of Connersville Indiana in 1860, as a means of forcing fresh air into coal mines. This, the "Rootes Blower" is the basic type of supercharger most of us know as a GMC Blower. The first application of a supercharger on an internal combustion engine was in 1878, by one Dugald Clerk, who used it on the first 2-cycle internal combustion engine. In 1885, Gottlieb Daimler recieved a German patent for supercharging an internal combustion engine. In 1902, Louis Renault received a French patent for a supercharged engine. Louis Chadwick from Pennsylvania built a supercharged automobile in 1908.

The first serious use of superchargers on aircraft engines didn't begin development until after WW-I, using "centrifugal" blowers that were mechanically driven.. This was to alleviate the loss of horsepower as airplanes climbed every higher into the atmosphere. This is the type of supercharger commonly used in racing in the US, starting in 1924 with the first supercharged Duesenberg 122cid straight 8 which won that year's Indianapolis 500, and reached its pinnacle with the legendary NOVI supercharged V8. A centrifugal supercharger is very much like the impeller in your vacuum cleaner.

Art

[Greg Myers]

[Greg Myers]

What iconic dragsters did these front blowers find their rides in?

Edited May 6, 2015 by Greg Myers

[Greg Myers]

And some were done as model kits

Edited May 6, 2015 by Greg Myers

[Greg Myers]

a little on the goofy side.

[chunkypeanutbutter]

^ Planning on building a near-replica of that... Was my profile picture a while ago.

[Longbox55]

Don't forget the Blower Bentley 4 1/2 Liter from the late '20s/early '30s.

Little known fact, unless you read the original books, a 1930 Blower Bentley was James Bonds personal car, rather than the Aston Martin that he is most commonly associated with. The car only appears in one of the films, either Dr No or From Russia With Love (been a while since I've seen either one).

[Art Anderson]

A lesser known racing sports car, built by Bob Carnes, the BOCAR Stilletto, used a 283 Chevy with a 6-71 mounted via the Potvin setup--for not only both visibility and aerodynamics, but to also move the engine (and CoG) rearward. That thing was a trackburner when it hit the road racing circuit.

Art

[Longbox55]

This isn't an automotive application, but that big unit mounted to the end of this engine is the blower. Before anyone asks, this is for a Cannon class destroyer, the USS Slater. This engine also saw use in submarines, my Dad used to service them on the USS Chivo (the Goat Boat) back when he was in the Navy.

[espo]

Art makes a good point about the Potvin super chargers. They had an advantage of better forward visibility and less power loss to drive them. But I remember reading about some of the early uses of the Potvin years ago. One of the things found at that time was that the runners from the blower to the engine as opposed to a top mounted blower was that there was a slight loss of boost because of the runners. I don't recall how much, but it was enough that top mounted blowers seem to become the norm.

[Greg Myers]

If it was so good why don't they still use them? Haven't seen one used since the early sixties.

[disabled modeler]

Here you go... Vortech also owns Paxton now.

http://www.vortechsuperchargers.com/

Also...

https://www.procharger.com/

Mark

Love to have even a used one...cant afford them...bummer. I built a 355ci Chevy with a 671 and old Hillborn plate injection once...have photo if someone can post it for me.

[Greg Myers]

and five carbs

[jbwelda]

well personally I think a front mounted supercharger has a lot to overcome in the way of well mixed air/fuel delivery when you consider how long and twisted those intake plenums are. its a wonder the fuel doesn't condense on the top wall of the intake tubes and just turn into drops instead of staying mixed in a good combustible mix. that's one reason why for instance the Mooneyes dragster above really improved its performance when they went to the conventional setup after the original front mount which was mostly for low profile and streamlining effect. and it seems to me that's why the form is rarely used anymore except in nostalgia cars like this one I shot at a recent meet in California

jb

[Ace-Garageguy]

Couple things nobody has mentioned yet that are important...

1) Until the advent of the big Gilmer belts for top-mounted blower-drive applications, the only other choices were multiple V-belts or a chain. V-belts slip, getting several of them EXACTLY the same length and tension is almost impossible, and when they slip, they heat up and disintegrate...or you don't get full design-boost at a given engine RPM. Chains are heavy, they stretch, and they're really kind of scary. Ever see a chain blower-drive fail? I have. Cut right through a frame tube.

The Potvin setup avoided all of these problems. (Potvin made the drive setups, but the blowers themselves were mostly GMC units).

2) There ARE considerable pumping losses with the long tubes to the manifold on a front-driven blower setup (mentioned above). However, with direct-port fuel injection, fuel mixture disturbances can be overcome.

3) Do the numbers on the drag of a big ol' blower sticking out of the hood at 200 or 300 MPH, as opposed to the same car with a front-mounted unit. While you may lose a little power with the front-mounted setup, the savings in aero drag, and the resulting horsepower freed to make the car go faster, is considerable.

Edited June 12, 2015 by Ace-Garageguy

[Greg Myers]

Now that looks safe

Edited June 12, 2015 by Greg Myers

[unclescott58]

Saw a Potvin on a old hot rod last summer for the first time. One of the things the owner pointed was the lack of noise compared to belt driven superchargers. Fired the car up. And it was a lot quieter. Nice for use on the street, other than you need to find someplace away from the engine for your radiator. His radiator was mounted in the back of his rod. Just a T shell in front of the supercharger. I though it was pretty cool.

Scott