Valentine diesels

[John McGillivray]

I beleive that these are the Valentine diesels used in the Canadian built tanks.

[Geoff Winnington-Ball (RIP)]

I have a copy of the original Data Book covering the Valentine and other 'tank-type vehicles of Canadian Manufacture'. It lists the Valentine engine as being a single 'General Motors Two Cycle Diesel 6004 Special 6-71 Series Engine modified for tank use'. It doesn't say where they were manufactured, but David ought to be able to sort that out from his detailed research.

The twin 6-71 diesel powerpack was used in the M4A2 Sherman family but is not mentioned in this book because the tanks were of US manufacture, so I don't know its numeric designation.

[Hanno Spoelstra]

Originally Posted by Geoff Winnington-Ball

It lists the Valentine engine as being a single 'General Motors Two Cycle Diesel 6004 Special 6-71 Series Engine modified for tank use'. It doesn't say where they were manufactured

These engines were manufactured by General Motors' Detroit Detroit Diesel Engine Divisionin Detroit, Mich., USA. Designed in the late 1930s, the GM Detroit Diesel 71 series was built in one, two, three, four, and six cylinder inline models. The 6-71 obviously was the six cylinder version.

I suspect "6004 Special" refers to a the configuration needed for it to fit in the Valentine, e.g. different oil pan, exhaust manifolds, engine mountings etc.

Hanno

[Hanno Spoelstra]

Originally Posted by Hanno Spoelstra

I suspect "6004 Special" refers to a the configuration needed for it to fit in the Valentine, e.g. different oil pan, exhaust manifolds, engine mountings etc.

Like the "6046 Twin Diesel" was the configuration as fitted in M3 and M4 series Medium Tanks: two 6-71 engines combined in a single power pack (also see Sherman M4A2 diesel engine designation).

H.

[David_Hayward (RIP)]

Thanks! You guys might like to know this snippet of info about the connection between GM Limited in Southampton and GM:

... An Admiralty file of 1940 relates to the testing of GM two-stroke diesel engines by the Admiralty that GM Limited were proposing. Limited submitted a marine version of the three-cylinder Detroit-Diesel 3-71 design to the Admiralty for type tests. However the success of the trials came to the attention of the War Office post-Dunkirk as 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 six-cylinder form as an alternative power unit and so Limited worked with the Detroit Technical Staff in procuring a 6-71 engine which was then redesigned for the tank and to be interchangeable with British power units. Field tests carried on by the W.O. and presumably Ministry of Supply in collaboration with GM Overseas Operations and Limited resulted in the first application of GM 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 MofS forwarded complete drawings of the modifications to GM Overseas Operations in New York in order to determine whether GM would supply the 6-71 in quantity. Negotiations then took place over five months between GMOO, 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 on 27th September 1940 for 250 engines. The GMC 6004 diesels were used it seems in production Mks IV, V, VII-XI.

It seems that twin 6-71s were fitted in the M3A3 (Lee IV/Lee V) as well but none would have come here.

[Lynn Eades]

I dont know what it means, but the 6-71 as used in the Mk4 and mk5 Valentine is/was refferred to as a "6-71 low head". (at least here in N.Z.)
For those that are interested and dont already know, Detroit Diesels have been built in many configurations. the first digit refers to the number of cylinders, and the following 2 digits refer to the cubic capacity of the cylinder in cubic inches.
They were built in 3 sizes (that I know of) 53cu.in., 71cu.in., or 92 cu.in. So the 6 -71 was a 6 cylinder (in inline motor with a swept volume of 71 cubic inches per cylinder. In the case of the "V" motors, the "v" followed the number of cylinders. So for example, an engine could be an "8V92" or a "6V53".

[Paul Singleton]

Here is some interesting history with a couple of photographs from the war!

http://www.detroitdiesel.com/about/history.aspx

[Chris Camfield]

Hello,

I know I'm resurrecting an old thread (is that considered bad, here?) but I have some related questions/historical info.

I'm not sure of the whole sequence of events - did Canadians play a part in locating the 6-71 as a possible replacement engine for the Valentine? Or not?

Anyway I was just looking at a file I copied from LAC a while back and found this which might be of interest:


"The Canadian model [of Valentine] will be provided with a G.M.C. two-stroke C-I engine, the experimental development of which was carried out at the A.E.C. works under the supervision of the Directorate. After very satisfactory trials, a pilot vehicle with the G.M.C. engine was despatched to Canada towards the end of the year." - Directorate of Tank Design, First Progress Report, covering to Dec 31, 1940


"Some successful experimental trials have been completed with the C.I. engine adjusted to provide increased power and speed. With an output of 150 b.h.p at 2,000 r.p.m., reliability and cooling have not been adversely affected, and a market improvement in average speed across country has been obtained. The General Staff consented to trials in the Service, the results of which are awaited."

The first production G.M.C. two-stroke C.I. engine has reached this country and is being installed in a tank. In view of the successful trials referred to in the preceding paragraph, the second pilot engine is also being installed in a tank for trials at its maximum rating of 165 b.h.p. at 2,000 r.p.m. to ascertain reliability under these conditions."
- Directorate of Tank Design, 2nd Progress Report, covering to March 31, 1941


What I'm trying to get straight in my head is designations for the engine in the Valentine and the Valentine SP aka Archer and what were actually the differences between them.

Despite the above, according to Dick Taylor's book Into the Vally, all marks of Valentine up until late Mk IXs had the engine tuned to output just 138 BHP. And I've seen this first version referred to as a 6-71S which was replaced with a 6-71A (outputting 165 BHP). And in the Archer it was a 6-71M and it's also referred to as a Type 6062. Somehow, GMC (I presume) got it to produce 192 BHP but how they did it I have no idea.

S for Special makes as much sense as anything else... A? M? I haven't a clue.