Question for the motor gurus

[Aaronw]

I'm wondering if the Allison V-12 in the parts pack would be of any value for building one of the 30-40's truck V-12s, Hall-Scott, Waukasha (sp?), Seagrave, American LaFrance etc? I know it was an aircraft engine but wondering if it has anything in common with the big truck motors of the period other than being a big V-12.

[george 53]

Allisons were AIRCRAFT engines only, they were used in a few Elco PT boats but mostly designated to the aircraft industy. They were TOO important to the war effort to use in other applications, thats why the PT boats mostly ran the big Packard V-12's. At least thats what I've read.(I wasn't around during WWII)

[Art Anderson]

I'm wondering if the Allison V-12 in the parts pack would be of any value for building one of the 30-40's truck V-12s, Hall-Scott, Waukasha (sp?), Seagrave, American LaFrance etc? I know it was an aircraft engine but wondering if it has anything in common with the big truck motors of the period other than being a big V-12.

The Allison V12 was designated, by US Army Air Forces, as the V-1710, and I bet you can't guess what the "1710" refers to, can you? That's right, 1,710 cubic inch displacement--pretty large for any truck.

Of the engines you mention, I believe that Hall-Scott and Waukesha only made inline engines, 6's and straight 8's. Seagrave fire apparatus after about 1937 or so, until about 1965, used variants of the Pierce Arrow V12 from the 30's. American LaFrance bought the tooling and manufacturing rights to the Auburn-Lycoming V12, as used in '32-'33 Auburn Salon series of sedans and boattailed speedsters.

Art

[Aaronw]

I figured someone would know. I knew it wouldn't be a direct relation but though it might have shared some features. I did know what the 1710 stood for, that was pretty typical of WW2 era aircraft motors (P&W R-2800 for example, radial engine, 2800 cubic inches) however I didn't rally think to compare it to any truck motors, yes that is a big'un equal in displacement to about 3 Detroit Diesel 8V71s

Thanks, I guess the big car motors from the 30's would be a better place to be looking.

[CAL]

Not really.

That was about all that they had in common was 12 cylinders.

The case was different. the head design was completely different, it had a dry sump, and many carried a turbo or super charger. The Allison was more round in shape and the Pierce-Arrow was much boxier. Plus the intake/carb/charger system was completely different than anything found on the road. Notwithstanding, an Allison needed to operate upside down, which all hung off the back of the motor where a transmission would go.

The biggest thing was size it was about twice the size of the V12s you are comparing it to.

[Art Anderson]

Not really.

That was about all that they had in common was 12 cylinders.

The case was different. the head design was completely different, it had a dry sump, and many carried a turbo or super charger. The Allison was more round in shape and the Pierce-Arrow was much boxier. Plus the intake/carb/charger system was completely different than anything found on the road. Notwithstanding, an Allison needed to operate upside down, which all hung off the back of the motor where a transmission would go.

The biggest thing was size it was about twice the size of the V12s you are comparing it to.

The Auburn and Pierce Arrow V12's were both 60-degree engines, as was the Allison. However, the Allison was single overhead cam, the Auburn was OHV, and the Pierce Arrow was a flathead. As for the Allison, yes those are drysump setups, but no Allison V12 was ever mounted upside down in use in aircraft. What makes it look that way is that the Allison engine has a gear-reduction propellor drive, that mounts the propeller shaft above the nose of the crankshaft. Allisons, like any other aircraft engine, were mounted "backwards" to automotive applications though, due to the propellor being in front of the engine, so the crankshaft has to come out that end of the engine. But, WAY too large for truck application, an Allison, even with all it's aluminum and magnesium castings, weighs in at nearly 2000 lbs. An Auburn V12 tips the scales at nearly 1000lbs, and I would assume that the Pierce Arrow V12 is only slightly lighter than the Auburn.

Art

[CAL]

The Auburn and Pierce Arrow V12's were both 60-degree engines, as was the Allison. However, the Allison was single overhead cam, the Auburn was OHV, and the Pierce Arrow was a flathead. As for the Allison, yes those are drysump setups, but no Allison V12 was ever mounted upside down in use in aircraft. What makes it look that way is that the Allison engine has a gear-reduction propellor drive, that mounts the propeller shaft above the nose of the crankshaft. Allisons, like any other aircraft engine, were mounted "backwards" to automotive applications though, due to the propellor being in front of the engine, so the crankshaft has to come out that end of the engine. But, WAY too large for truck application, an Allison, even with all it's aluminum and magnesium castings, weighs in at nearly 2000 lbs. An Auburn V12 tips the scales at nearly 1000lbs, and I would assume that the Pierce Arrow V12 is only slightly lighter than the Auburn.

Art

No it wasn't mounted upside down, but it was flown upside down. It did operate upside down.

They did, however, mount DBs upside down.

Edited November 30, 2008 by CAL

[BigGary]

I've seen the Allison V-12 in a few drag cars from the 60's. The TV show "My Classic Car" had segment on one of Jay Leno's cars that has a 12 cylinder Chrysler tank engine from the 50's. Car weighs 9500 lbs and is mostly medium truck components.

Gary

[Art Anderson]

No it wasn't mounted upside down, but it was flown upside down. It did operate upside down.

They did, however, mount DBs upside down.

Yup, the Allison could be flown in any aerobatic or combat maneuver, due to it's carburetion, which was floatless. By contrast, the early Rolls Royce Merlins could not, until they got fuel injection.

The real reason for dry-sumps in aircraft engines has more to do with oil consumption than it does the positioning of the engine, or the flight attitude of the plane--those are engines set up really rather loosely for long-running reliability, which also translates into oil usage that we'd not tolerate in a car. Also, having a remote oil tank (and oil cooling radiators) allowed designers to much more easily balance the plane they were engineering, by putting the weight of oil either somewhere near the balance point, or in the after fuselage, thus offsetting some of the weight of the engine. And yes, the Daimler-Benz DB601 and Junkers Jumo V12 aero engines were almost always mounted inverted, for aerodynamic reasons, mostly I believe. A Messerschmitt Bf-109 is a MUCH smaller aircraft than a Spitfire, smaller than a P-51 Mustang, and positively miniscule next to a P-47 Thunderbolt.

Art

[Jairus]

Pretty sure the Allison had carb floats and it was the Rolls Royce Merlin which could fly inverted. At any rate, the Junkers DB engine was much better designed due to it's variable speed turbo supercharger and fuel injection.

Here is some interesting pics....

Oh, wait! How'd that get in here?

[Art Anderson]

Pretty sure the Allison had carb floats and it was the Rolls Royce Merlin which could fly inverted. At any rate, the Junkers DB engine was much better designed due to it's variable speed turbo supercharger and fuel injection.

Here is some interesting pics....

Oh, wait! How'd that get in here?

Jairus,

Neither the Daimler Benz DB601 (Messerschmitt Bf109) or the Junkers Jumo's were turbocharged, but rather used conventional engine-driven centrifugal superchargers, much as did the Merlin and the Allison. The only turbocharged V12 aircraft engines of WW-II that I can think of were the Allison V1710's used in the Lockheed P-38 Lightnings. All the other turbocharged engines of WW-II were American radials, the Wright Cyclones, Double Cyclones, and the Pratt & Whitney Wasp, Double Wasp and the Wasp Major (that 28-cylinder "corncob" engine).

The Germans perfected fuel injection, while the Allison used what we later knew as a throttle body system. The earliest Merlins used a float bowl carbruretor, which limited their flying to anything BUT inverted, until changed in mid-summer 1940, just in time for the Battle of Britain.

Art

[Jairus]

Read what I wrote again please. I said "Turbo supercharger", but I suppose should have said turbine? I understand what you are saying but sometimes the word turbo can be confused. The Germans used a centrifugal fan that was powered by a small hydromatic like transmission. It allowed controlling the boost pressure. Very cool.

[Art Anderson]

Read what I wrote again please. I said "Turbo supercharger", but I suppose should have said turbine? I understand what you are saying but sometimes the word turbo can be confused. The Germans used a centrifugal fan that was powered by a small hydromatic like transmission. It allowed controlling the boost pressure. Very cool.

Well, considering that the word "Turbosupercharger" is used to describe a centrifugal supercharger driven by hot exhaust gasses run through a turbine connected to the supercharger impeller, it's not hard to use that definition.

Whether driven by a direct gear drive (as most all centrifugal blowers were--and BTW, it was GE who developed the centrifugal blower into a viable power-boosting unit, and a ton of the development work was done on racetracks like Indianapolis, and the wooden "board" superspeedways of the 20's here in the US) or a form of automatic transmission drive, the German superchargers did use power from the engine, mechanically, to drive them. Perhaps one real reason for this compact arrangement was that the Bf109 for which the DB-601 was primarily designed, was anything but a large plane--if you have ever seen one in person, it's only about 3/4 the size of a P51 Mustang--a fully grown 6' man can practically wrap his arms around the empennage (rear most part of the fuselage, just ahead of the tail surfaces) and lock his hands together, that Messerschmitt is THAT small.

On the other hand, turbocharged engines used in US Army and US Navy practice in WW-II were also variable in boost, but by a much simpler method--called a "waste gate". These, witht the exception of the Allison V1710 variants used in the P-38, were all radial engines, which powered much larger planes--if you've ever seen a P-47 Thunderbolt, you have probably wondered just how a single engine could get 13-tons of massive fighter plane off the ground!

The rationale behind varying the boost in an aircraft engine isn't as much for the purpose of gaining additional bursts of power, as in "war emergency" power--that was handled by the throttle, and at the extreme end, by injecting a water/methanol fuel blend directly into the carburetor or air intake. Rather, the superchargers and turbochargers were there to provide pressurized air, pretty much at sea level atmospheric pressure, or slightly higher, at high altitudes. It just wasn't wise to use them for any more than a few seconds to give extra boost for more HP--not very productive to endanger the engine in an aircraft when there isn't any place to pull over and stop if you blow the engine (Mercedes racing engines of the late 20's-early 30's, with their Rootes type superchargers (same principle as the famed GMC Jimmy blowers drag racers used for years, BTW) suffering catastrophic engine failures when forced to run their blowers for any extended length of time in a race.

Rolls Royce, with the Merlin, as with Bristol's radial engines, and the awesome H-16 engines used in the Hawker Typhoon and Tempest fighters, used a 2-stage centrifugal supercharger, the second stage being variable in boost as well, for these same reasons. However, the early Merlins were handicapped by their rather primitive (for military aircraft use) carburetors, which would simply stall the engine if rolled even 90-degrees from horizontal without going through a very tight turn which would keep the fuel in the float bowl where it would be if straight and level. Once that problem was cured, Merlin-powered fighters could treat the Bf109 like "meat on the table". Merlins continued to serve in the USAF and the RAF to the end of the 1950's in fighters (the last P51-D Mustang was retired to the USAF Museum from the West VA ANG in 1958), and in RAF Shackleton patrol bombers into the 1960's, until those were replaced by the Nimrod, itself a modification of the DeHavilland Comet jet airliners of the early 1950's. Incidently, the last Messershmitt Bf-109's built used Merlins (some of those performed as Luftwaffe fighters in the movie "Battle of Britain", provided by the last air force to use the design, the Spanish Air Force).

The failing of the Allison was that the US Army Air Corps specification called for a single stage centrifugal supercharger, to be augmented by a turbocharger, with waste gate controls to give the boost necessary to maintain sea level power at altitude. However, in it's first use, that being the Curtiss P-40 "Kittyhawk, Tomahawk, Warhawk" series of fighters, that airframe (itself adapted from the somewhat smaller radial engine powered Curtiss P-36 Hawk 75 of 1936) lacked any room in it's rather small fuselage for a turbocharger and the large and heavy exhaust ducting to get the power to the turbo. Nor did the rather radical, but compact Bell P-39 and P-63 Airacobra and King Cobra fighters. Only the Lockheed P-38 Lightning had the airframe space, and the size to take advantage of the added turbocharger the Army brass insisted the engine be designed around, and it did that in spades, being the first operational fighter aircraft to reach (but not exceed) the speed of sound in a power dive.

Art

Edited December 3, 2008 by Art Anderson

[CAL]

Well, considering that the word "Turbosupercharger" is used to describe a centrifugal supercharger driven by hot exhaust gasses run through a turbine connected to the supercharger impeller, it's not hard to use that definition.

Whether driven by a direct gear drive (as most all centrifugal blowers were--and BTW, it was GE who developed the centrifugal blower into a viable power-boosting unit, and a ton of the development work was done on racetracks like Indianapolis, and the wooden "board" superspeedways of the 20's here in the US) or a form of automatic transmission drive, the German superchargers did use power from the engine, mechanically, to drive them. Perhaps one real reason for this compact arrangement was that the Bf109 for which the DB-601 was primarily designed, was anything but a large plane--if you have ever seen one in person, it's only about 3/4 the size of a P51 Mustang--a fully grown 6' man can practically wrap his arms around the empennage (rear most part of the fuselage, just ahead of the tail surfaces) and lock his hands together, that Messerschmitt is THAT small.

On the other hand, turbocharged engines used in US Army and US Navy practice in WW-II were also variable in boost, but by a much simpler method--called a "waste gate". These, witht the exception of the Allison V1710 variants used in the P-38, were all radial engines, which powered much larger planes--if you've ever seen a P-47 Thunderbolt, you have probably wondered just how a single engine could get 13-tons of massive fighter plane off the ground!

The rationale behind varying the boost in an aircraft engine isn't as much for the purpose of gaining additional bursts of power, as in "war emergency" power--that was handled by the throttle, and at the extreme end, by injecting a water/methanol fuel blend directly into the carburetor or air intake. Rather, the superchargers and turbochargers were there to provide pressurized air, pretty much at sea level atmospheric pressure, or slightly higher, at high altitudes. It just wasn't wise to use them for any more than a few seconds to give extra boost for more HP--not very productive to endanger the engine in an aircraft when there isn't any place to pull over and stop if you blow the engine (Mercedes racing engines of the late 20's-early 30's, with their Rootes type superchargers (same principle as the famed GMC Jimmy blowers drag racers used for years, BTW) suffering catastrophic engine failures when forced to run their blowers for any extended length of time in a race.

Rolls Royce, with the Merlin, as with Bristol's radial engines, and the awesome H-16 engines used in the Hawker Typhoon and Tempest fighters, used a 2-stage centrifugal supercharger, the second stage being variable in boost as well, for these same reasons. However, the early Merlins were handicapped by their rather primitive (for military aircraft use) carburetors, which would simply stall the engine if rolled even 90-degrees from horizontal without going through a very tight turn which would keep the fuel in the float bowl where it would be if straight and level. Once that problem was cured, Merlin-powered fighters could treat the Bf109 like "meat on the table". Merlins continued to serve in the USAF and the RAF to the end of the 1950's in fighters (the last P51-D Mustang was retired to the USAF Museum from the West VA ANG in 1958), and in RAF Shackleton patrol bombers into the 1960's, until those were replaced by the Nimrod, itself a modification of the DeHavilland Comet jet airliners of the early 1950's. Incidently, the last Messershmitt Bf-109's built used Merlins (some of those performed as Luftwaffe fighters in the movie "Battle of Britain", provided by the last air force to use the design, the Spanish Air Force).

The failing of the Allison was that the US Army Air Corps specification called for a single stage centrifugal supercharger, to be augmented by a turbocharger, with waste gate controls to give the boost necessary to maintain sea level power at altitude. However, in it's first use, that being the Curtiss P-40 "Kittyhawk, Tomahawk, Warhawk" series of fighters, that airframe (itself adapted from the somewhat smaller radial engine powered Curtiss P-36 Hawk 75 of 1936) lacked any room in it's rather small fuselage for a turbocharger and the large and heavy exhaust ducting to get the power to the turbo. Nor did the rather radical, but compact Bell P-39 and P-63 Airacobra and King Cobra fighters. Only the Lockheed P-38 Lightning had the airframe space, and the size to take advantage of the added turbocharger the Army brass insisted the engine be designed around, and it did that in spades, being the first operational fighter aircraft to reach (but not exceed) the speed of sound in a power dive.

Art

Actually the DB601AA was a gear driven supercharger. There was also a Turbocharged DB601 used in the D017