HEMI. You probably think of a Chrysler or Dodge V8 engine when you hear this. For Chrysler, it’s a series of engines that powered cars are far back as the 1950s with a revival in 2003 with the 5.7L. The Hemi design itself dates back to the early 1900s.
But, just because the Hemi engine is nearly synonymous with Chrysler and now Dodge doesn’t mean that other companies didn’t experiment with this style of engine. In fact, Toyota mass-produced a V8 engine in the 1960s to power a new upscale four-door sedan to compete with the big American cars that many wealthy Japanese businessmen were driving at the time. There’s a pretty good chance that you’ve never even heard of Toyota’s Hemi V8, so let’s get into it.
What is a HEMI Engine?
Before we get deep into the Toyota Hemi V8, I think it’s quickly worth noting what a Hemi engine is, so we’re all on the same page. The word “Hemi” is just a shortening of the word Hemispherical, which simply refers to the use of a hemispherically shaped combustion chamber which is quite a bit different from a conventional engine.
Most cylinders have a flatish design which, although it is cheap to manufacture and works just fine, it allows more fuel to touch the cylinder walls. This extra contact means that more heat can escape from the chamber and reduce pressure within the cylinder. Essentially letting power from the fuel go unharnessed, at least in theory.
Using a hemispherical design instead of a flat design reduces the volume of fuel making contact with the walls and thus reduces power loss. Part of the reason that Chrysler introduced this is that many automotive manufacturers were struggling to find good ways of producing more power in the 1950s.
Chrysler’s Hemi engines ultimately dominated NASCAR in the 1960s, and that led to great commercial success because of this. That’s a story for a different time, but that should give you a good idea of what a hemi or a hemispherical engine is.
The New Toyota Century
Toyota was among the companies in the 1950s and 1960s that were experimenting with hemispherical-combustion-chamber heads. More specifically, in the mid-1960s, Toyota launched its flagship car, known as the Toyota Century.
Part of the reason for the launch of the Toyota Century, as we mentioned near the start of the video, was to compete with large American cars in the Japanese market. These cars were pretty popular with wealthy businessmen, and rather obviously, Toyota saw an opportunity to offer them a big luxurious car produced at home in Japan.
With that idea, though, they’d need a powerful V8 engine to compete with the American cars in the Japanese market, which is where they started the development of their new V8 engine. Up until that point, though, Toyota hadn’t really produced and experimented with V-shaped engines and especially V8 engines.
Supposedly, they got their hands on a few American V8 engines and disassembled them for reverse engineering purposes. But, as the story goes with many Toyota engines of the past, they ended up working with Yamaha to finalize the design of the engine and help with manufacturing.
The “V” Engine Launches
Fast forward to the 1963 Tokyo Motor Show, and the new Toyota Crown Eight was introduced as a larger and more upmarket version of the second generation Toyota Crown, and at the heart of this new engine was the all-new 2.6L Toyota V Hemi engine, which then went on sale one year later in 1964.
A very important thing to note here is that the Toyota V engine is an aluminum block design, which is way different from American V8 engines of the time, which were iron. This makes the V engines very lightweight compared to their “competition.”
Rather obviously, there was already one problem with this new engine from Toyota, and that’s that it only had 2.6 liters of displacement, which led to a pretty embarrassing power figure of 113hp and 145lb-ft of torque. Not bad considering the engine’s size, but not great compared to what it could be with more displacement.
Improvements
Because of that, the original V engine only lasted from 1964 to 1967, when we saw the introduction of the new and improved 3V engine. With the 3V, we saw increased piston stroke to 78mm, which made the 3V a square engine. This is something we see very often in modern engines. However, square bore and stroke weren’t nearly as common back then.
The new increased displacement led to an increased power output of 148hp and 173lb-ft of torque. Still not great by any means, but much more respectable and usable compared to the original V engine’s power output.
As the Toyota Century was continually improved, they also continued to improve upon the engine. That takes up to 1973, when the 3V was discontinued in favor of the new 4V variant. Yet again, the cylinder bore was increased, this time to 83mm, which brought total displacement up to 3.4L and a power bump to 177hp and 205lb-ft of torque. That’s right; we’re now in the 200s for torque output!
Then again, jumping forward in time, we saw the introduction of the new 5V version of this engine in 1983. This final version of the engine was the most powerful and largest of them all, with a 4.0L displacement thanks to the 83mm bore and 78mm stroke. With the new engine, we also saw the introduction of overhead valves and electronic fuel injection. All these things helped push the power to 188hp and 239lb-ft of torque.
Lower Power Output and Reliability
For comparison’s sake, the Toyota 5V had a power output of roughly 1/3rd of the Chrysler 426. Granted, the 426 is quite a bit larger in displacement, but it still demonstrates that the V engine and the 5V, specifically, had a strangely low power output for the given displacement, and Toyota actually did this on purpose.
Toyota put reliability over power in terms of importance with these engines, and as such, the V engines are very reliable but obviously very lower on power compared to roughly similar American Hemi V8 engines.
What’s even more impressive than anything, in my opinion, is that this engine made it all the way to 1997 before it was replaced when the Century received a major redesign and a complete switch from their Hemi V8 engine to an all-new V12 engine. And uncharacteristically, for Toyota, there was never a successor to this engine.
We had the V, the 3V, the 4V, the 4V-U, the 4V-EU, and the 5V-EU. This was Toyota’s first ever attempt at producing a V8 engine, and their second V8 engine, the 1UZ-FE, shares nothing with the 5V.
No Successors
And you might be wondering, why was this engine never followed up with a proper successor? And really, the answer is that there wasn’t a reason to have a successor with this engine. The V engine, as a whole, was a kind of funky, designed a little weird, and pretty underwhelming in terms of performance.
By the time they released the 1UZ, they had a much better design and frankly didn’t need to follow up the Hemi design.
And with that, you might also be wondering why you’ve probably never heard of this engine, especially compared to the 1UZ or really any other Toyota engine, for that matter, and it’s simply because the Toyota V engine is kind of rare. It was only ever available in two applications, the Crown Eight and the Century, both of which were only available in Japan, and they were both upscale cars.
No Aftermarket Support
That means that in terms of production numbers, there aren’t that many of these engines laying around, and because of the application and the production numbers, these engines have nearly zero aftermarket support, which means they were never adopted by enthusiasts and basically no one really cares about these engines.
Sure they’re reliable, but so are other Toyota engines, and those other engines are often more powerful and have more aftermarket support. On top of that, Toyota no longer services these engines, which means parts and gaskets generally have to be custom-made.
And I think it’s also worth noting that this wasn’t Toyota’s only hemispherical engine from this timeframe. A good example of this is the Toyota T engine, which is a family of four-cylinder heads that use HEMI heads.
So, that’s the story of the Toyota V8 Hemi engine you’ve probably never heard of.
Smokey Yunick made some Hemi 302 motors back in 1968/9 for the Z28 Camaro.
Forgot to add. What’s not to love about a Hemi. LS and Hemi swap the world!