Sherman M4A2 diesel engine designation

[Larry Hayward]

Some references I have seen, say that the M4A2 which the British & Canadians used in Italy had twin General Motors 6-71 diesel engines while others say they had General Motors 6046 diesel engines!

Where these the same and if so why have the different designations? Was this anything to do with early and late model variations.? Which is correct?

Originally posted by Larry Hayward
Some references I have seen, say that the M4A2 which the British & Canadians used in Italy had twin General Motors 6-71 diesel engines while others say they had General Motors 6046 diesel engines!

Where these the same and if so why have the different designations? Was this anything to do with early and late model variations.? Which is correct?

Ah, Hanno is the man for this, but as I see it the 6046 was a civvy truck engine and the 6-71 is just a modification of this.

It seems this unit is some 420 cu.in or 6.883 litres and rated for 187hp in the Sherman, looking at various websites they seem to rate it as 180 (nominal hp) which is close enough.

Its not bad at all for a diesel of that era at some 27hp/litre, being a scavenged two-stroke does give it a head start though.

Quite apart from the M4A2, the USN used them by the thousand in landing craft and generators.

R.

[Richard Farrant]

Originally posted by FV623
but as I see it the 6046 was a civvy truck engine and the 6-71 is just a modification of this.

R.
I am pretty sure that 6046 refers to the twin engine pack and not the individual engines. 6-71 is actually number of cylinders and swept volume of one cylinder in cu.inches. The 6-71 is still around today and I have had experience with them in new earthmovers in Eighties.

Richard F

[John McGillivray]

It is my understanding that the Canadians did not use the Sherman III (M4A2) in Italy. Most Canadian units in Italy used the Sherman V (M4A4), while one unit, the Governor General's Horse Guards, used the Sherman II (M4A1).

The Sherman III (M4A2) was used by the 2nd Canadian Armoured Brigade in Normandy and NWE.

Originally posted by Richard Farrant
R.
I am pretty sure that 6046 refers to the twin engine pack and not the individual engines. 6-71 is actually number of cylinders and swept volume of one cylinder in cu.inches. The 6-71 is still around today and I have had experience with them in new earthmovers in Eighties.

Richard F

Yes, that makes sense. 71 cu.in a hole equates to the nominal 420 cu.in quoted for the engine.

All of the DDA two-stroke diesels serve to baffle the casual observer since the presence of valve gear and rockers suggests they _must_ be four strokes.

This inlet ported but exhaust valved configuration seems to be unique to DDA and I wonder why no other manufacturer ever went down this avenue. Certainly one bang a rev as opposed to every other rev made them markedly potent for their size at the time.

I wonder why they never made it over here too, I know of no on-road production application of any DDA diesel here although one prototype fire appliance did a V6 unit rear mounted, and is owned by my neighbour. Quick it is, we bottled out at an indicated 80mph having still not met the engine governor.

R.

[Hanno Spoelstra]

Originally posted by FV623
Ah, Hanno is the man for this, but as I see it the 6046 was a civvy truck engine and the 6-71 is just a modification of this.

Well, it seems I am no longer needed - Richard N. & Richard F. are perfectly capable of dishing out all the details!
All I can add is a confirmation that the 6046 was the twin power pack version of the 6-71 engine for the M3A3, M3A5 and M4A2 medium tanks and M10 and M36 SP guns. The "power pack" was merely a common base for two engines, which drove a common drive shaft through their own clutch.

H.

Originally posted by Hanno Spoelstra
Well, it seems I am no longer needed - Richard N. & Richard F. are perfectly capable of dishing out all the details!
All I can add is a confirmation that the 6046 was the twin power pack version of the 6-71 engine for the M3A3, M3A5 and M4A2 medium tanks and M10 and M36 SP guns. The "power pack" was merely a common base for two engines, which drove a common drive shaft through their own clutch.

H.

Arrrrgh, wouldn't want to upset the Dutchman, he's bigger than I am. . . . . . . . .

Now, Carl (Gas-Axe) Mulitbank-Brown's M4A2 and the T55-Tiger got a long airing on TV last night, the essence was a comparison of the Sherman vs Tiger. At least the SFX people didn't have to rig either for smoke. . . . . . . . . . . . . .

At one point the presenter rolled up in an old Ford V8 Pilot and said the Sherman was so successful because it used common car parts and could therefore be readily repaired from stocks, even the (car) engine was used in the Sherman he said. Now even Mrs. Notton looked a bit surprised at this statement; surely they haven't confused the titchy old 95hp flathead V8 with the somewhat larger Ford GAA ?

Trying to be positive, I wasn't aware that the flathead even did duty as an aux generator and seeing how the weeny Morris 8 in derated form serves a Cent, it seems unlikely that 95 aux horses are needed in a Sherman.

McSpool ? :

R.

[Hanno Spoelstra]

Originally posted by FV623
Arrrrgh, wouldn't want to upset the Dutchman, he's bigger than I am. . . . . . . . .

Fear not, I don't hit old people

Now, Carl (Gas-Axe) Mulitbank-Brown's M4A2 and the T55-Tiger got a long airing on TV last night, the essence was a comparison of the Sherman vs Tiger. At least the SFX people didn't have to rig either for smoke. . . . . . . . . . . . . .

Cool - did you tape it?

At one point the presenter rolled up in an old Ford V8 Pilot and said the Sherman was so successful because it used common car parts and could therefore be readily repaired from stocks, even the (car) engine was used in the Sherman he said. Now even Mrs. Notton looked a bit surprised at this statement; surely they haven't confused the titchy old 95hp flathead V8 with the somewhat larger Ford GAA ?

Trying to be positive, I wasn't aware that the flathead even did duty as an aux generator and seeing how the weeny Morris 8 in derated form serves a Cent, it seems unlikely that 95 aux horses are needed in a Sherman.

On second thought - ditch that tape. Common car parts, huh? Indeed the manufacturing of the Sherman was done with mass production principles, which Henry Ford pioneered for car manufacture. Ford developed a V12 aero engine which wasn't as succesfull as the RR Merlin, so he hacked off 4 cylinders to create an 18-litre 500 hp V8 tank engine. Other than that, Ford's contribution to Sherman tank production was not terribly impressive number-wise. They did manufacture the initial version of the M4A3 Sherman (1,690 examples between June 1942 - Sept 1943) and M10A1 SP guns, introducing a lot of improvements to the design to make it more suitable for mass production.

The Sherman's auxiliary generator was a Homelite single cylinder, 2 stroke engine with a 30 Volt 1500 Watt output. Nope, that titchy old 95hp flathead V8 did not come near the Sherman - they were all used to power that other tracked icon, the Universal Carrier.

McSpool

[Tony Smith]

Wasn't there a Chrysler W30 multi-bank engine fitted to some versions of the M4? This was made up from 5 Chrysler Royal 6 cylinder car engines arranged around a geared crankshaft.

Originally posted by Tony Smith
Wasn't there a Chrysler W30 multi-bank engine fitted to some versions of the M4? This was made up from 5 Chrysler Royal 6 cylinder car engines arranged around a geared crankshaft.

Like this.

And the other side (if MLU doesn't crash on me again.)

[Hanno Spoelstra]

Originally posted by Tony Smith
Wasn't there a Chrysler W30 multi-bank engine fitted to some versions of the M4? This was made up from 5 Chrysler Royal 6 cylinder car engines arranged around a geared crankshaft.

Ah yes, the wonderful Chrysler A57 multibank! Here's a picture of Richard "FV623" Notton checking Carl's multibank for any oil leaks (source: Surviving Shermans > Beltring 2000).

[Richard Farrant]

Originally posted by FV623
This inlet ported but exhaust valved configuration seems to be unique to DDA and I wonder why no other manufacturer ever went down this avenue. Certainly one bang a rev as opposed to every other rev made them markedly potent for their size at the time.

I wonder why they never made it over here too, I know of no on-road production application of any DDA diesel here although one prototype fire appliance did a V6 unit rear mounted

Fodens produced a straight 6 two stroke on the same lines as a 6-71, they were in production during the 50's and 60's, easily recognised by their wonderful exhaust note. Detroit Diesels were fitted in production trucks in the UK, they were options in Bedford TM and Scammell Crusaders, probably others I cannot think of at present. I seem to think they were all based on a German design, was it Junkers?

Richard F.

Originally posted by Richard Farrant
Fodens produced a straight 6 two stroke on the same lines as a 6-71, they were in production during the 50's and 60's, easily recognised by their wonderful exhaust note. Detroit Diesels were fitted in production trucks in the UK, they were options in Bedford TM and Scammell Crusaders, probably others I cannot think of at present. I seem to think they were all based on a German design, was it Junkers?

Richard F.

Yes the Fodens indeed had a two-stroke, but wasn't this the Foden Uniscavenge which relied on the Kadency Effect? There was the flat 3 opposed piston device in the Commers during the same time using rockers on the pistons to connect to a common, underslung crank, these had a reciprocating scavenge pump though unlike the DDA Rootes blower arrangement.

The DDA option on TMs and Crusaders must have had little take-up, I cannot ever remember the two-stroke howl from one of these.

I'm not sure about the Junkers connection with DDA though, Junkers aero diesels were always vertical opposed piston, twin crank and piston ported, even the early 1913 - 1916 engines are recognisable as nearly identical to the L60 which you know.

The early engines were injected and spark ignited but by '26 they were all compression ignition, in '31 the Junkers FO4 became the Jumo 4 and was both built under licence by Napier and developed by them into the Culverin.

All these Junkers diesels had very good hp/lb figures and of course excellent fuel economy, the Jumo 205 and 207 powered the JU86.

It is surprising how the L60 could be such an unreliable dog when its aero heritage was entirely different with lighter engines of greater power and very good reliability.

Take a look at http://www.enginehistory.org/Diesels/CH1.pdf as its a fascinating piece on aero diesel history and with many surprises too.

R.

[Richard Farrant]

Originally posted by FV623
Yes the Fodens indeed had a two-stroke, but wasn't this the Foden Uniscavenge which relied on the Kadency Effect?

I know we are getting off the thread now, although still slightly military in topic, because I think the British Army did have a few Foden 6 wheeler transport lorries with the FD6 in. The engine is of similar design to a 6-71 in that it has exhaust valves in the head and a supercharger forcing air into ports at the bottom of the cylinders. The only obvious difference is that Fodens used a conventional F.I. pump where GM had separate pumps for each cylinder, as Cummins.

Richard F.

[Rod Diery]

Originally posted by Richard Farrant
I seem to think they were all based on a German design, was it Junkers?

I definitely don't think this is right. According to a 1943 book of my Dad's called The Oil Engine Manual (diesel was a dirty word then, a bit too German), the Junkers engine was a 6 cylinder, 12 opposed piston engine. While it was a two stroke it used a centrifugal blower to scavenge the engine.

The 71 series engine has it's roots in designs drawn up by the Winton Engine Company in the early 1930s. General Motors acquired this company and merged it with some other new acquisistions to form Cleveland Diesel. It later merged Cleveland Diesel yet again with the Electro-motive Corp to form it's own Electro-Motive Division in about 1935. EMD produced the highly successful 567 2 stroke locomotive diesel which remained in production for more than 40 years.

The 71 series engine was developed in about 1937 using the same principles used in the 567, 2 stroke, unit fuel injection and the unique scavenging system which was patented and I seem to recall was called Uniflow. This system uses a Roots type blower to scavenge the exhaust gases out of the cylinders via an air box, bottom cylinder ports and overhead valves.

According to Fred W Crimson's US Military Tracked Vehicles of 1992, the 6046 is indeed the paired 6/71 engine pack. This is interesting because when I used to look after an LCM8 landing craft a few years ago powered by no less than four 6/71s in the same arrangement of two twin packs, each engine pack was referred to by it's makers as one engine, ie a 12 cylinder engine.

Cheers
Rod

[Rod Diery]

It doesn't show a lot but this is a snap of part of the twin 6/71 engines known as the 6046 engine pack in a Grant dozer tank [Dozer, Grant III (Aust) No. 1, Mk 1) at the Army Tank Museum in Puckapunyal, Victoria, Australia
Cheers
Rod

[David_Hayward (RIP)]

The London Public Records Office contains a file number ADM 227/316 of 1940 relating to the testing of G.M. 2-stroke Diesel engines by the British Admiralty that G.M. Limited were proposing to supply to meet a particular need. Limited had in fact submitted a marine version of the three-cylinder 3-71 design to the Admiralty for type tests. Clearly the location of the Southampton Plant operations was advantageous here. However the success of the trials came to the attention of the War Office as post-Dunkirk there was concern by July 1940 to ensure an uninterrupted supply of power units for the Vickers ‘Valentine’ Infantry Tank Mk. IIIA, orders for which had been placed in Canada. The Valentine was a 1938 design that initially used AEC petrol or diesel engines. The W.O. became interested in the Detroit-Diesel design in its 6-cylinder form as an alternative power unit and so Limited worked with the ‘Detroit Technical Staff’ in procuring a 6-71 engine which was redesigned into the tank to be interchangeable with British power units. Field tests carried on by the W.O. and presumably Ministry of Supply in collaboration with G.M. Overseas Operations and General Motors Limited resulted in the first application of G.M. Diesel engines to tank usage, as the Model 6-71S. This was later superseded by the more powerful 6-71A. The alterations and design called for the changing of the fuel, water and exhaust connections, mounting brackets and clutch and gear controls. The Ministry of Supply forwarded complete drawings of the modifications to G.M.O.O. in order to determine whether G.M. would supply the 6-71 in quantity. James D Mooney was still in his position at G.M.O.O. at the time and was presumable involved with the negotiations that took place over five months between the G.M.O.O., the Detroit Diesel Division, Canadian Pacific Railroad who had been commissioned to build the Canadian Valentines, and British officials. This culminated in an initial order from the British Purchasing Commission or B.P.C. on 27 September 1940 for 250 engines. G.M.O.O. consequently invested as a consequence $50,000 for a sample engine in Autumn 1940.

...from JAMES D MOONEY: A MAN OF MISSIONS by David O Hayward.

This is from my thesis relating to GM Limited, Southampton from 1947:

Many profitable activities had been developed by capitalising on uses for war-surplus stocks of G.M. manufacture remaining in the U.K. However, in addition to the U.K. Government supplies, lots of surplus parts acquired included the bulk of the U.S. Army vehicle stocks at their main base in the U.K., the Admiralty’s surplus Detroit Diesel marine engine parts, parts for Detroit Diesel Series 71 Diesels as used in ‘Sherman’, ‘Vanguard’ and ‘Valentine’ tanks [6-71 in the Valentine Mark III Infantry Tank] , and parts for the Cleveland Diesels. Series 71 parts from two depots alone was to amount to between U.S.$4 and $5 million U.S. list value [but in line with the disposal of U.S. parts, these would have been acquired at 25% value].

[Tony Smith]

There is currently an original manual for sale on e-bay for the 6046 engine pack.