Ford’s Gargantuan 18-Liter V8 Engine Had 32 Valves, Four Camshafts, Two Ignition Systems, And Someone Tried To Put It In A Mustang

As I’ve said before, I really don’t believe most automotive conspiracy theories. The notion that General Motors killed trolley cars to sell more buses doesn’t really wash with me, and I don’t think the “Pinto Memo” was the smoking gun some say it was.

Having said that, I do believe that large auto manufacturers are holding back on technology they could give us now, but will wait forever to finally offer. I even have proof: Ford mass-produced an impossibly high-tech motor way back in 1940, yet it took them over fifty years to build an engine with similar specs for an American street car. Talk about stonewalling.

You Call That Advanced?

The new-for-1992 Crown Victoria seemed like a spaceship next to the car it replaced, but the most astonishing thing to us at the time was the 4.6-liter “modular” V8 powering it.

This was a rather impressive motor for Ford. I remember looking under the hood of a new Crown Victoria and marveling at the Mercedes-like all-aluminum block and heads with single overhead cams, soon to be double camshafts on later versions with four valves per cylinder, as in the Lincoln Mark VIII.

At the time, I was driving a nine-year-old Panther body with an old pushrod Windsor V8 which, incidentally, was of virtually the same design as the 289 in the 1965 Mustang that brought me home from the maternity ward many years before. Ford seemed to have jumped ahead decades with this new motor into what was for them uncharted territory.

Hardly. Thousands of vehicles had already been built by Ford with an engine not unlike the 4.6 V8, except this earlier twin-cam aluminum V8 was the largest gasoline-powered engine ever produced by Henry’s firm. If you’ve never heard about the Ford GAA, get ready to be shocked.

Just Plane Big

Two situations that tend to bring out the most advanced thinking from automakers. One is motorsports competition, and the other is competition of a more dangerous nature: battle for world dominance. World War II saw combustion-engined technology pushed to the limit.

In the early part of the twentieth century, aircraft were primarily powered by air-cooled radial engines with pistons arranged in a circle around the propeller shaft, but this was starting to change.

A shift to inline or V-format liquid-cooled engines began with the aircraft that were being developed for what would become World War II. The famous British Spitfire fighters featured a massive 27-liter V-12 called the Merlin, built by then-engine-builder Rolls Royce. Sure, the jets you’ll see in Top Gun are impressive, but if you’ve ever been to an air show and heard a Merlin-powered craft fly over you at low altitude, the noise just stirs your soul; you really feel those twelve cylinders as much as hear them.

England needed help in making more of these powerplants from their allies here in the states, and Ford had factories in the UK at the time. During WWII, these Ford factories produced 30,400 Merlin motors in England, but Old Blighty wanted more. This example for sale some time ago came with all the specialized tools needed to keep it running.

At the very least, English manufacturers wanted Americans to make complex parts for the Merlin (crankshafts, for example) but they ran into issues. US companies like Packard simply didn’t want to produce anything other than complete engines. Ever-obstinate Henry Ford figured that he’d invented the freaking assembly line and didn’t have any interest in making an engine designed by someone else in a country we had declared independence from. Besides, he saw this as an opportunity to get into the aircraft engine market himself. In retrospect, he probably should have done some homework first.

Ford Motor Company went down a path to develop a motor that was very similar to the Merlin. Named the XV-1650, this 60-degree liquid-cooled V-12 displaced 1,650 cubic inches and was packed with technology that was mind-blowing for the time: aluminum block and heads, dual overhead camshafts and four valves per cylinder. Contemporary reports said the so-called Merlin copy was anything but; it was actually modified and ostensibly improved in every way over the British engine. Ford was convinced that this would be the ideal powerplant for not just military but civilian aviation moving forward.

Henry Ford being Henry Ford, he proceeded with this work without checking to see that the contracts the US government had with other manufacturers were rather ironclad and protracted, meaning all of this work was seemingly for nought. Or was it?

Tanks A Lot

Despite being spurned by the aircraft makers, Ford went back to what he did best: ground-based vehicles. In an odd turn of events, there was a need for the Ford aircraft engine, or at least half of it. Hard to believe, but the then-current M4 Sherman tanks were powered by Wright R0975 Whirlwind: a 9-cylinder radial engine!

Supply issues with the Whirlwind sent the Army looking for additional providers, and Ford had an idea. The XV-1650 was too large for the application, so they chopped four cylinders off to create a huge V8; the GAA V-8 was born.

Despite losing a third of its pistons, it was still massive, with a displacement of 1,100 cubic inches (18 liters), making the largest gasoline engine Ford had ever built in any major numbers. If you thought that a Windsor 351 V8 was a big motor by modern standards, the GAA just dwarfs it. At nearly four feet tall and five feet long, it’s twice the length and height of the popular Ford automotive mill, as the scaled comparison below shows.

The fully cast-aluminum GAA had all of the tech from the XV V-12 it was derived from, including double overhead cams actuating 32 valves on the flat-plane crank motor. There were twin Stromberg NA-Y5-G carburetors and crossflow induction.

Redundancy was a big deal: the GAA had dual magnetos and two spark plugs per cylinder making up a complete dual ignition system. Don’t forget: On the battlefield, you can’t stop to change plugs.

Power? You got it. Ford rated it as having 500 net horsepower at 2,600 rpm, but the more astounding figure was 1000 pound-feet of torque from idle up to 2,200 rpm. Here’s a video that digs in a bit deeper if you’re interested:

The Sherman M4A medium tank received the GAA, but with the British desperately needing motors for their own tanks, there was an effort to supply the giant Ford engine to English manufacturers as well. In an odd twist similar to the initial impetus for the GAA, the British builders of the Merlin developed their own land-based version of their aircraft engine called the Meteor. This was a V-12 motor, and with four extra cylinders compared to the GAA, it easily produced over 600 horsepower. Ford claims that they could have increased the power of their own engine to match, but British tests apparently uncovered what they described as teething problems. Whether you believe that or not, it’s just more proof that regardless of both Ford and Rolls-Royce having a common goal in beating the evil Axis powers, the tenet of “not invented here” was and always will be far stronger.

Ford didn’t give up, though. As a last gasp, it developed what was called the GAC: a 1,650 cubic inch (27 liter), 48-valve V-12 that produced 770 horsepower. Of course, now the war was drawing to a close, and Ford had the battle for American civilians’ wallets versus GM to contend with. Only four of the GAC mega monsters were reportedly built, and the GAA followed into oblivion after 1950.

Maybe It Was A Mach XVIII Mustang?

Looking at an engine that’s nearly four feet tall with the displacement of a kiddie pool, your first response as the deranged Autopian that you are is likely to install this powerplant into a car. This is a horrendous idea, and naturally with thousands of Ford’s tank mills built and many still existing, someone has done just that.

I would imagine an F-350 or something similar might be the best Ford street vehicle to even attempt to do such an insane feat, but it turns out that a 1970 Mustang was the vehicle of choice for the conversion. The whole idea is so stupid that it makes perfect sense. Here’s a video of this thing running:

My assumption is that the GAA Mustang was able to actually move under the power of the tank engine, but I couldn’t find any footage to prove this. I doubt that it would pass emissions here in Chicago, so you’d have to register it in Montana or something. Well, it makes more sense than a jet engine if nothing else.

You Got Better But Never BIgger

You might think that as a specialized production engine, the total number of Ford tank engines produced would be limited, but by the time the last GAA rolled off the line, Ford had made between 28,000 and 30,000 GAAs. According to Mac’s Motor City Garage, 500-1000 still exist today. If you see an old Sherman tank parked in front of a VFW hall near your house, Ford’s monster may be lurking within.

Ford has never mass-produced another gasoline engine as big as the GAA, a fact that makes this one of the most legendary Ford motors ever made, even if it wasn’t for the street. But Ford did eventually give us the GAA’s battle-proven technology, albeit in taxi cabs and cop-car ‘Vicks, even it took them nearly half a century to do so.

Kind of makes you wonder what they’re keeping from us today, doesn’t it?

Top graphic images: Wikimedia/Alf Van Beem; Heidrich Performance/Kevin Heidrich