If You Thought Replacing Your V8’s Spark Plugs Was Bad, How About 30 Spark Plugs Across 30 Cylinders? COTD

The gasoline engine has taken so many different shapes and forms over history, from familiar inline-fours and V8s to beautiful radials. But someone has to maintain these things, and more elaborate engines may be equipped with dozens of spark plugs. Chrysler once made a tank engine that had 30 of them!

The Bishop wrote about the glorious Ford GAA, but he really only scratched the surface of tank engines. Hoser68:

This wasn’t even the weird engine for the Sherman. The Sherman had 4 main engine options:

The 9-cylinder radial (earlier variants M4 and M4A1).
Two 6-cylinder 2-stroke diesels next to each other (M4A2).
The giant V-8 (M4A3).
A 20.5L 30-cylinder 5-bank monstrosity that used 60 spark plugs (M4A4). Chrysler A57 multibank – Wikipedia.
The US tested all the engines. They liked the GAA, and almost all GAA engines (M4A3s) went to the US Army. The Russians wanted the diesels, and they got them. The USMC would take whatever they could get and generally got M4A2s as well.

The Brits got strapped with the M4A4. Not only was the engine a lot heavier (all cast iron) and thirstier than the GAA, it produced 130 less horsepower and was a nightmare because it tended to eat sparkplugs (and needed 60 each change). Oh, and it was such a big engine, the tank body had to be lengthened which added even more weight to the tank.

However, in a sign of the problems with the British tank development, the Brit’s LOVED their Shermans because they were more reliable and easier to work on than their homebuilt tanks (until the Meteor came out in the Comet.)

Now, this engine did not have the most spark plugs per cylinder. The Lycoming XR-7755 airplane radial, for example, had 36 cylinders and two plugs per cylinder. Toss a bunch of radials on one aircraft, and you have hundreds of plugs!

Peter wrote about building an RC Jeep. Disphenoidal offered a hilarious improvement:

Headline should have been “I only have 2 days to finish this Jeep and drive it 500 feet.”

Jason wrote about the extra taillights that VW Beetles used to have. Who Knows:

Ah, so the idiotic placement of turn signals and such down low in the bumper of some newer cars such as my Bolt where they are easy to block with bike racks and such is actually a retro feature, trying to emulate the old people’s car…

I wrote about the tiny airplane built by Ray Stits. The Stig’s Misanthropic Cousin:

… or that Stits was too scared to fly it. Nope, he was just too big to fly it.

“Yeah, I would absolutely love to fly this deathtra… (cough, excuse me…) record-setting experimental airplane, but I’m too heavy so I’m looking for a smaller test pilot. I’m trying to drop some weight so I can fly it someday, though.”

Two minutes later at the local drive-thru…

“I’ll have three cheeseburgers, one order of medium.. no, large… french fries, and a chocolate shake… with extra sugar and a side of lard.”

Rich Hobbs:

Pilots’ motto:
Landings should equal takeoffs!
Great article Mercedes…as per usual.

Andy Individual:

“The secret to flying is throwing yourself at the ground and missing.”

– Douglas Adams.

OrigamiSensei:

A good landing: one you walk away from.
A great landing: one where you can reuse the plane.

And, the zeroth law of aviation: “Thou shalt maintain thy airspeed, lest the ground rise up and smite thee.”

Cars? I’ve owned a few:

Also: Takeoffs are optional. Landings are mandatory.

Have a great evening, everyone!

Top graphic image: U.S. War Department

Correction: Upon closer inspection, our ecstatic reader got their math wrong, and so did we. The A57 is five inline-six engines mashed together, but they are not dual-spark engines, so 30 cylinders equals 30 spark plugs. We regret the error.