The elegant, but short lived straight 8

Mazda not too long ago announced that they are developing a new inline 6 based on their Skyactiv inline 4 cylinder family. Mercedes-Benz and Volvo have been doing this as well, opting to make inline 6’s rather than the more popular V6’s. The argument is that with stricter emissions standards, the big beefy V-8s are dying, and as a result, so are the V-6’s which they are sharing their architecture with. It is therefore becoming easier to stretch an inline 4 to an inline 6, rather than create a new V-6 from scratch. May this lead to the extinction of the V engine entirely? Possibly. So that got me thinking, if the V-8 is dead, will we now see a resurgence of the inline 8? After all, it is just 2 inline 4 cylinder engines put back to back. The short answer is no. It is actually very easy to list the many reasons why the inline 8 should not even work as an engine much less why it should make a return. I can even list them with my eyes closed: they aatr yoo lonh, yhru str noy goof eiyh highrt tpm. yhru str brtu longt. Exactly.

Looking hard and long at the gibberish I just typed I really had to wonder, why were inline 8’s even built in the first place? My first assumption was just that the V-8 was not made as yet, but the reality is that the V-8 predates the inline 8 by about 5 years (in road cars at least). So, the technology was there, they had the option NOT to choose an inline 8, but automakers in the 1920’s and 30’s (and even up to the 50’s) still made the conscious decision to build them and put them in cars. But why? After a bit of browsing, it really boils down to 3 reasons actually:

1) Smoothness

Image from Peter Olthof on Flickr

Image from Peter Olthof on Flickr

Apparently they were silky smooth by design. I have experienced a Ford flathead V8 from the 30’s and that was smoother than the ocean under the moon. Apparently inline 8’s were even smoother than this. This is unfathomable to me, especially since I’ve never experienced an inline 8 (feel free to DM this stranger on the internet if you have one and would like for me to experience yours up close). But seriously, people are out here balancing coins on them, which is rare today on a modern engine and even rarer on an engine old enough to carry Neil Armstrong to school. I’m going to go ahead and assume that the inline 8 has reached the unprecedented ‘Luther Vandross’ level of smooth (I am also going to go ahead and imagine that it’s elder sibling, the V-16, would essentially be like Mariah Carey and Luther Vandross on Endless Love). This smoothness also translated to smooth acceleration, something very important in a period where tyres were closer to 100mm wide and traction control was just what they called the gas pedal. As a result this smoothness not only attracted luxury car manufactures, but also those looking to go fast with a bit more predictable control.

So I get the appeal of an engine that will serenade the chills out of your spine, but I’m sure that alone was not the only thing that made it appealing. Was it?

2) Inspired by aeroplanes

The inline 8 had some characteristics that made it beneficial for aircraft installation during World War I. Being much narrower than a V-8, meant that the fuselage of the plane could also be narrower, and thus, more aerodynamically efficient. This partially contributed to it’s popularity in propeller driven aircraft of the time, and I’m sure the smoothness helped as well. Many car manufacturers left the war, fresh from working on tanks and airplanes, so naturally, they took what they learned from them and brought them into cars. This also explains the popularity of the not as smooth, nor long, V-12, in these early cars. Many of these manufacturers were also of the mindset that “if it works for planes, it must work for cars”, even though this is rarely true, it surely worked for their marketing. To be fair though, this aerodynamic advantage may have been why so many racers of the period used inline 8’s to power their slender, bullet shaped streamlined race cars.

Ok, it’s not so bad, so why don’t they work

Image by Craig Howell on Flickr

Image by Craig Howell on Flickr


The reason why inline 8’s are no longer in production is that they are long. How long? The Bugatti Royale had a 12.7L inline 8 which was 4′-6″ long. In comparison, the Jeep Wrangler’s 3.6L Pentastar V-6 is less than half that (but makes around the same power). This excessive length has some major drawbacks. Not only was the mass of it all troublesome, but those overtly long engine internals had a tendency to act up. Crankshaft whip was apparently more pronounced on inline 8’s. This happens when the forces on the long crankshaft warp the crankshaft itself to the point where it begins to hit the other components in the engine block. This typically is synonymous with engines that are run hard at high engine speeds, but the inline 8’s long crankshaft exacerbates these forces to the point where it happens at relatively low engine speeds. Lost? Ok, let me try to explain this with a little science trick. Break a pencil in half, and then break those halves in half again. You’ll notice that each time the pencil gets smaller, it’s harder to break. The length of the pencil is essentially aiding in it’s own destruction, acting like a lever on itself. Inline 8’s have this same problem with their crankshafts where they bend easier than crankshafts found in shorter engines. Alfa Romeo and Mercedes actually came up with a very clever solution to this, by breaking the crank into two smaller crankshafts that meet in the middle. At the meeting point, a gear would then take the power from the two cranks to power the ancillaries, and in the case of Mercedes, a shaft leading toward the transmission and then the wheels. It is a clever solution to a major problem, but this actually made the engine physically longer since there was no an added lump in the middle to make space for the ‘drive’ gear. But suppose length isn’t a problem? This brings me to the third and final component as to why inline 8’s worked during this period.

3) Styling

Image from crazylenny2 on Flickr

Image from crazylenny2 on Flickr

Art Deco, a grand design movement which peaked in popularity in the 30’s and could be best described as ‘ornate phallus’ inspired many of the luxury vehicles during this period. This should be no surprise seeing as the Empire State Building is probably the most recognized monument of the Art Deco style (just edging out Bruce Timm’s Batmobile). In car design, Art Deco translated to long, slender, aerodynamic and ornate ‘cigar’ tubes on wheels. Just like aeroplanes (which Art Deco also drew inspiration from) the inline 8 found a place to rest it’s long legs.

Really, I am glad this era of car design ended, because outside of the poor engine decision, it was really getting out of hand. Remember the Bugatti Royale mentioned previously, that was 21 feet long. 21 FEET! That’s 3 Patrick Ewings long, or 4 of my girlfriend standing in heels, or 0.058 football fields. Hell you could subtract that 4′-6″ long engine from it and still fit a 4 door Jeep Wrangler in there. At that length you begin to question why does it need to be so long, so large and so imposing? Is it trying to prove something? Is it trying to intimidate all other vehicles on the road because the driver is insecure in themselves? Is it trying to assert dominance? I don’t know, but hopefully the owner of that Jeep with those angry red headlights finds peace.

3.5) The Sound

This was not a reason why anyone would choose an inline 8 but I thought it was important just to pause and highlight how great they sound. Take a listen to this Mercedes W25 which is just a potpourri of sound. First that eerie supercharger screams like a siren announcing it’s arrival, then that V-8 like grumble grows into a bellow as it accelerates out of the corner with each double clutching upshift sounding like an angry bark. It’s a sound I can only describe as a mixture of rage, frustration and pestilence, and I love it.

The end?

With more cars and people crowding the roads, the excessively long and difficult to maneuver Art Dicko cars grew out of style and made way for the more compact (but still big) cars of the 60’s and 70’s. Inline 8’s disappeared soon after as engine design evolved to favor those that were compact and revved higher, two things that long boi of an engine just couldn’t catch up with. Of course, it didn’t help that Henry Ford was just pumping out V-8’s like they were Big Macs. The final call for the inline 8 came in 1955. After the horrible ’55 Le Mans Disaster, Mercedes decided to pull out of racing altogether, leaving their very successful inline 8 powered 300SLR and W196 pair with no replacements. Despite their success, none of their contemporaries tried to replicate the inline 8 formula and no one else has since. It was quite the complicated engine too, direct injection and desmodromic valves helped it stay competitive, but considering how complex of an engine that was, I too wouldn’t touch it with a 4’6″ pole. The world of racing was changing as well, opting for more compact designs with smaller engines that would eventually move behind the driver. The inline 8 was just an oversized dinosour that just could not adapt to the needs of the evolving car.

I am sure today’s technology can allow for an inline 8 design that can compete with other 8 cylinders in a compact enough package. Just look at VW’s VR8 engine, it is the closest we’ve come to a modern day inline 8 (even if it is a hybrid between an inline and a V engine). The engine was never built but the Bugatti W16 (which is a merger of 2 VR8’s) technically counts as a proof of concept that it can work. But, as mentioned prior, with everyone having to downsize their V-8’s, there isn’t much space in the future for 8 cylinders let alone the cumbersome inline 8’s. Simply put, there will be no resurrections, it is dead, ceased to be, bereft of life, an ex-engine. I would say it is sad, but the inline 8 was sorta lucky it was even built in the first place. What is sad is that I felt the inline 8 never got a proper good bye (maybe it did, but that predates the internet, therefore it doesn’t exist).

Alfa Romeo 2900A (photo by MPW57 on Wikipedia

Alfa Romeo 2900A (photo by MPW57 on Wikipedia

It is funny though that the V-10, which is still in production, gets a new eulogy every week.

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