Valentine diesels

[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.

[David Herbert]

Remember that fuel consumption testing in those days was not the science that it is now. The tank was simply driven around a course and the fuel used measured. Speeds and rates of acceleration were left up to the driver. No attempt was made to allow for temperature or the condition of the course, though both would be recorded. An Archer is roughly the same weight as a Valentine but with the extra power is vastly nicer to drive and so the driver can be in the optimum gear much more easily and will need to change down less for heavy going. That in itself will make a significant improvement in consumption.

As I said the difference between the different versions of the WW2 6-71s is basicly that the more powerfull ones get more fuel and are allowed to rev harder.

David

[Chris Camfield]

Ah, interesting point, thanks David.

Chris

[Andrew Rowe]

When I have rebuilt Valentines, with the 671, you can indeed upgrade the injectors to the later "N" - series to increase the horsepower to 190 to 200.
This still uses the original 6004 engine block and 2-valve head and original governor, but you also do a change of the piston liners to the latter "slotted" version with a 17:1 compression ratio.
I would also state that it is entirely possible without too much problem to change out an AEC engine for a 671. The front engine and gearbox mount holes are identical, the only real difference in the engine compartment is the 2-lugs welded on the side for the oil cooler in front of the radiators and the main water pipe to the engine water pump is on a different side. Steering clutches and everything else will just line up.
There would be a couple of extra throttle linkage brackets to change and the gearbox gate shifter housing would have to be changed over as well, but all controls front to back remain the same, Cheers Andrew.