Valentine diesels

[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.

[Lynn Eades]

I can't help you there Chris, but for the record:
The TANK INFANTRY MARK III* was powered by the AEC A.190 Comet Mark III* engine.
This tank appears to be an all British development and I am confused about the "*".
I thought all things suffixed by the "*" were Canadian (as in Carriers and Weaponry)
I am ready to be enlightened......

Wartime New Zealand had Mk IIs, MkIIIs and MkVs. The first two were AEC powered, and the MkV being powered by the said 6-71 Jimmies. Numbers totaled about 266 Valentines inclusive of the 11 bridge layers.

Now back to your questions Chris. (I'm waiting for Andrew's input)

[David Herbert]

Lynn,
The addition of a star to a WW2 British vehicle designation just indicates that it is a slightly different version of that vehicle, and in almost any way ! They really did get themselves into a bit of a mess with these designations so don't look for patterns, there aren't any !

The GM two stroke diesels in Valentines were, as mentioned above, of various different power outputs. These were standard variations available from GM from the start and basicly differed in the settings of the injectors and govenors. The M3 / M4 Medium tank twin 6-71 unit was the most powerfull available from the start but again was a standard variant, designed initially for generator and pump sets and even as quad sets. After the war these engines were offered with different cylinder liners with better gas flow and then four valve heads (all exhaust) and eventually with turbochargers as well as the superchargers. Finally they were killed off by emissions regulations.

It should be mentioned that the fitting of the GM engine instead of the AEC engine in the Valentine resulted in almost the entire instalation being redesigned, including a new (much better) gearbox. It was never possible to swap engines into an existing tank as is hinted at by a reference above.

David

[Chris Camfield]

Hi Lynn,

Thanks for your reply!

I am not sure about the "*" designation. I don't think it necessarily means Canadian - maybe it depends on the context? For instance, among unproduced British tanks were the TOG vehicles - designed by the men who designedthe tanks in WW1, hence The Old Gang or The Old Group - and there was a TOG 2 model and TOG 2* which different armament.

[Chris Camfield]

David, thanks for your reply also! I'm half asleep here.

Do you know what effects there were by changing the engine to produce more horsepower? Did it consume (proportionately?) more fuel?

[David Herbert]

Hi Chris,

Short answer is yes ! The different power outputs of these engines was done by effectively just opening the throttle more. More fuel in made more power and of course used more fuel.
This will have reduced the range but the extra mobility was well worth it. Remember that the Valentine was originally designed as an infantry tank and so did not need great range or speed (or firepower). Quite quickly it became necessary to improve the firepower and it then began to be used as a more general purpose tank but it was never going to be one to do long distances or high speeds so range was not too critical.

David

[Chris Camfield]

Brilliant, thank you!

[Chris Camfield]

Hmm, so I thought to check what information I have on the Archer vs Valentine engines.

According to the specs in the handbooks:

Valentine IX: "S" type, 130 BHP at 1850 RPM
"A" type, 165 at 1850
Fuel consumption(road): 2.5 MPG

Valentine X: 6-71A, 165 BHP, 2.5 MPG

Archer: 6-71M, 192 BHP at 1900 RPM, 2.9 MPG

More horsepower, and better fuel consumption. They must have done something to improve the engine, but I do not know what.