The M4 Sherman Tank Epic Information Thread.. (work in progress)

[Meplat]

19 hours ago, Jeeps_Guns_Tanks said:

I just put this together too

 

The Chrysler Engine that could have been: The A-65 V12, if the war had gone on, there could have been some hotrod Shermans.

Chrysler Corporation had a big impact on the war, and US Tank production. They produced the first, and the model for the others, Tank Arsenal CDA.  They also came up with the A-57 multibank tank motor, that powered a significant number of Sherman tanks. They produced this fantastically complicated, but also reliable motor in a very quickly, and even though the US Army and Marine Corps thumbed their noses at it,  it was well liked by the British.

Chrysler on their own dime came up with a water cooled, V12, tank motor, and offered it to the Army.  It took them about a year to come up with three trial motors.  These 1568 cubic motors started out at 650 horsepower at 2600 RPM and 1485 pounds of torque at 1600 RPM on the test stand.  They came in around 3840 pounds, but there was a proposed all aluminum version that have dropped nearly 1000 pounds.  Designing and producing the prototypes, cost a grand total of 358,000 bucks, that’s over 5 million in today’s dollars. During the dyno testing period, they had a few problems with the fan drives, but these were solved with improved oiling and rolling bearings, and these seemed to have solved the problems.

They used an M4A4 as a test vehicle, and had to stretch it another 9 and 1/2 inches to fit the new motor. Installed and ready to roll the thing came in at 69,170 ponds, and a stock M4A4 came in at 69,640 pounds!  Installed, the early versions had 549 horsepower, but they upped the compression ratio and got it to 580, and it was improved even more with some carburetion changes. They made the compression change by swapping and a cam change during the in vehicle testing phase. Further testing led to the intake and carb changes.  All the while the motor was being swapped in and out, and driving tests done.

The automotive tests were very successful, and that was using the stock powertrain of the Sherman, though with so much power, they decided a gear change would help. By swapping the original 3:53:1 gears for 3:05:1 gears, they A65 was still able to beat an M4A43 in a drag race!  The engine was so promising, it’s an interesting mystery why the Army never developed it further.  Much like the GAA, there was much more performance potential in this motor, and the Army never took it any further.

I suspect what ultimately killed this motor, was the same thing that killed the GAA, the Army was looking at air cooled motors for the future, because you can save a lot of weight, if there is not liquid cooling system needed.

Special thanks goes out to Chris R, one of our readers and a source contributor, sent me a nice little history on the motor.  Thanks again Chris, sorry it took so long!!

Sources:  Sherman, by Hunnicutt, and 1943 A-65 Tank Engine History

 

An aside, the use of 80 octane fuel by the U.S. meant that a lot of their mills were "overcarbureted". As in "running rich".

The "jeep (MB/GPW) ran around on 80 octane mil-std with a ~ 6.5/1 compression ratio. I've shaved the heads and stems on one mill and had it run strong on the shit gas we have now. 

 

The radials used in U.S. armor could have run with higher compression (or boost ratios, since they had blowers), but it was felt that it would lead to excessive damage/wear if they had to run on other alliy's fuel. 

 

 

All that aside, the thought of a V-12 M4 tickles me in all the right places. 

[EnsignExpendable]

[EnsignExpendable]

What do you do when you really want a Firefly, it it hasn't been invented yet?

 

 

Edit: a year later they sent towed 17-pdrs to the CACRU instead of tank ones. Turns out they're not the same!

[EnsignExpendable]

Smugness intensifies

 

[Meplat]

5 hours ago, EnsignExpendable said:

What do you do when you really want a Firefly, it it hasn't been invented yet?

 

 

Edit: a year later they sent towed 17-pdrs to the CACRU instead of tank ones. Turns out they're not the same!

Interesting to note that postwar,nearly all U.S. armor mounted towing pintles.

3 hours ago, EnsignExpendable said:

Smugness intensifies

 

I'd consider that an insult to SPG's...

[EnsignExpendable]

This is a pretty impressive prototype Sherman engine. Did it ever go into production?

 

[Meplat]

4 hours ago, EnsignExpendable said:

This is a pretty impressive prototype Sherman engine. Did it ever go into production?

 

Looks like the forum ate my post-

 

Used in the M4A6.

Here's the manual for the engine.

RD1820

[EnsignExpendable]

Interesting, I always though that was a post-war design, but I guess not. Who used it?

[Meplat]

2 minutes ago, EnsignExpendable said:

Interesting, I always though that was a post-war design, but I guess not. Who used it?

Just the U.S., only 70 some were made, and most languished in CONUS testing and training units.

[EnsignExpendable]

Weird, I thought that putting a huge engine that barely fits and gunning it at full volume was a proud American tradition.

[Meplat]

20 minutes ago, EnsignExpendable said:

Weird, I thought that putting a huge engine that barely fits and gunning it at full volume was a proud American tradition.

Making it work plays a part of that tradition.

There were drivline issues, and clutch problems iirc.  And you still "run out of revs". It's a diesel based on an aircraft engine, so high RPM does not make it happy. You do have loads of low end grunt though.

 

I believe it was one of the faster M4 variants though, and could hit around 30 MPH. Most of my books are still in boxes, a quick look in Hunnicutt's book should give you more info than what I can scratch from the brain housing group. 

[Jeeps_Guns_Tanks]

Plus the US Army was super conservative and didn't hot rod their tanks.  It's a little weird, there was much more horsepower potential in the Ford GAA. 

 

 

I've been fixing images with a lot of scanning artifacts, and noise, and then replacing the originals, I can do one a night, and for or five a day on the weekends. Its strangely relaxing. 

 

 

Here are some others I've done:

 

 

 

 

 

 

[Jeeps_Guns_Tanks]

A few more

 

 

 

 

 

 

 

 

[EnsignExpendable]

I just converted Soviet fuel expenditure figures for the Lee and Sherman to compare them to the Canadian data. Seems that the Soviet drivers were driving a lot more carefully, since the average speed is slower and fuel expenditure is lower in Soviet trials.

[Jeeps_Guns_Tanks]

On 8/18/2017 at 9:24 PM, EnsignExpendable said:

I just converted Soviet fuel expenditure figures for the Lee and Sherman to compare them to the Canadian data. Seems that the Soviet drivers were driving a lot more carefully, since the average speed is slower and fuel expenditure is lower in Soviet trials.

 

 

Is that just on diesel tanks, cause the canucks got A4s too? 

[Jeeps_Guns_Tanks]

some more cleaned up pics

 

 

 

 

 

 

 

 

 

 

 

 

 

[EnsignExpendable]

7 hours ago, Jeeps_Guns_Tanks said:

 

 

Is that just on diesel tanks, cause the canucks got A4s too? 

 

I don't have Soviet data on M4A4 mobility trials. They might not have performed full trials, since the conclusion was "this is like an M4A2 but worse, do not order".

 

Also, do you have any data on the Grizzly? I'm raking in a ton of material on Canadian vehicles, and I'm thinking of writing an article for Warspot.

[EnsignExpendable]

Speaking of Canadian Shermans, I found a request to take CT150503, a 75 mm Sherman back to Canada from Holland, but modern photos of CT150503 show a Firefly. There is a Firefly in the request, a CT232254, but I can't find any info on it. I wonder if they got mixed up.

[EnsignExpendable]

Argh, the Canadian archives suck. I discovered a topic (which there is no index of, by the way!) called 13/AFV SHERMAN GEN/1. Sounds perfect, right? Except as far as I can tell, only topic groups 1, 3, 6, and 8 are online, and even then partially. Are the missing topics in other collections? Do they even exist? WHO KNOWS

[EnsignExpendable]

[Meplat]

16 hours ago, Jeeps_Guns_Tanks said:

some more cleaned up pics

 

 

 

 

 

 

 

 

 

 

 

 

 

People gab about "German Technology" in WW2, but have never seen the innards of a GAA. 

 

 Shaft driven DOHC V8 with pent-roof valves and a domed piston, fed by dual carbs.  In WW2, and reliably mass produced.

 

Still fucking amazes me what a work of art it is.

[Meplat]

1 minute ago, EnsignExpendable said:

It's umm, missing some bits...

[Jeeps_Guns_Tanks]

4 hours ago, Meplat said:

People gab about "German Technology" in WW2, but have never seen the innards of a GAA. 

 

 Shaft driven DOHC V8 with pent-roof valves and a domed piston, fed by dual carbs.  In WW2, and reliably mass produced.

 

Still fucking amazes me what a work of art it is.

 

 

Oh hell yeah!  Dual overhead cam 4 valve V8s are still not a common thing in automobiles.  They could have thrown a third carb on it and upped the compression a little and gotten a reliable 600 horsepower too I bet.  Plus its all shafts, no chains, and all aluminum!  It's an amazingly advanced motor for its time and is still pretty trick now., 

 

The HL230 was total dog shit in comparison. 

[Jeeps_Guns_Tanks]

12 hours ago, EnsignExpendable said:

Speaking of Canadian Shermans, I found a request to take CT150503, a 75 mm Sherman back to Canada from Holland, but modern photos of CT150503 show a Firefly. There is a Firefly in the request, a CT232254, but I can't find any info on it. I wonder if they got mixed up.

 

 

I wouldn't be surprised, no one but tank people would know a regular Sherman from a firefly! 

[Meplat]

1 hour ago, Jeeps_Guns_Tanks said:

 

 

Oh hell yeah!  Dual overhead cam 4 valve V8s are still not a common thing in automobiles.  They could have thrown a third carb on it and upped the compression a little and gotten a reliable 600 horsepower too I bet.  Plus its all shafts, no chains, and all aluminum!  It's an amazingly advanced motor for its time and is still pretty trick now., 

 

The HL230 was total dog shit in comparison. 

Nahh, run it on that old 145 octane "grape juice", with 9,5 to 1 compression, and blow it. Then run a big bendix  pressure carb.

 

Even the mild boost from a 6/71 blower should get ~750/800 HP with decent fuel and some huff. 

Then decent headers, and all the boxheads would hear and fear is the snarl of M4's coming at them at ~50 MPH, or going from dead stop to huge roostertails of sod and 30 MPH in a few seconds.  .. (assuming the transmissions and final drives did not shit the bed, which they MIGHT.  But they were still miles ahead of the Kraut shit. )