When it comes to automotive internal combustion engines, 16-cylinder engines are a special breed. They come in a number of configurations, with the V16 being the most common by sheer volume. Generally, 16 cylinder engines on this list were designed by either combining two inline-eight-cylinder engines into various configurations, or by butting up two V8s end to end. Or, as you’ll see in one case, four inline-four cylinders fanned out and arranged into something resembling a W.
But when it comes to what is currently the most potent production configuration, the nod goes to the wildly popular-in-pop-culture W16 from Bugatti. Read on to explore some of the most interesting 16-cylinder engines ever produced.
Ignoring the wrapper this V16 engine came in is difficult since it has such an interesting story, but after all, this is EngineLabs. The Cizeta V16T is a genuinely amazing design, consisting of a cast-aluminum engine block, which housed two banks of eight 0.5-liter cylinders for a 6.0-liter total displacement, thanks to an oversquare 86mm (3.386 inches) bore and 64.5mm (2.539 inches) stroke.
Based heavily on the Lamborghini Urraco V8 engine, the V16T shares a number of parts with it, including cylinder heads. Instead of two eight-cylinder heads, the design team opted for four of the proven Urraco dual overhead camshaft cylinder heads. That adds up to eight camshafts and 64 valves. The output of the beast was rated at 540 horsepower at 8,000 rpm and 400 lb-ft of torque at 6,000 rpm.
Auto Union V16
The Auto Union V16 program was a pre-World War II Grand Prix racing effort that saw two variations on the V16 program. The first three iterations, dubbed Type A, B, and C, were Roots-supercharged V16s displacing 4.4 liters, 5.0 liters, and 6.0 liters, respectively, with a shallow 45-degree bank angle. The peak performer of the group, the Type C, made 520 horsepower at 5,000 rpm, and as its undersquare design might suggest, a whopping 627 lb-ft of torque.
The final iteration of the Auto Union effort was the Type D, which was radically different thanks to new Grand Prix rules. The Type D’s displacement was halved compared to the Type C, with only 3.0 liters of swept volume, from only 12 cylinders, but with a second supercharger. While that disqualifies it from this list, we felt the 485-horsepower effort was worth mentioning.
Bugatti Type 45 U16
The first Bugatti on this list, the U16 is unique in that it is one of very few U engines ever produced. Essentially a pair of inline-eight engines mounted vertically (so a zero-degree bank angle) into a common crankcase. Both banks had their own crankshafts which were connected to a common output shaft.
Displacing 3.8 liters thanks to a very undersquare 60mm (2.362 inches) bore and 84mm (3.307 inches) stroke, this wasn’t Bugatti’s first U16 attempt, as they had developed a much larger version of the engine in 1917 for aviation use, but the engine wasn’t particularly successful as an aviation powerplant. Instead, a decade later a much scaled-down version got a pair of Roots superchargers for a 250-horsepower Grand Prix racing effort. Unfortunately, the Type 45 engine was even less successful than the original aviation design.
BRM P75 H16
One of the stranger engines on the list (and that’s saying something), the BRM P75 engine was the outfit’s attempt at an H16 engine for Formula 1 in 1966. By combining a pair of their successful 1.5-liter flat-eight engines on top of one another and gearing them together, the team hoped to have a successful 3.0-liter powerplant. On paper, it looked great, featuring a 68.5mm (2.70 inches) bore and a 50.8 (2.00 inches) stroke with 11.5:1 compression.
The first attempt was a two-valve configuration, with the 32 total valves producing 395 horsepower at 10,250 rpm. Once they switched to a four-valve configuration they were able to produce 420 horsepower at 10,500 rpm. However, it was the heaviest powerplant in the field and saw poor performance within the field, largely due to a lack of reliability, for the two seasons it was run.
Jimenez Novia W16
Carrying the distinction of having the most valves of any engine on this list, the Jimenez Novia W16 is a one-off creation of French motorcycle racer Ramon Jimenez. While dubbed a W16 engine, realistically, it bears more resemblance to a K laying on its side than a W. Consisting of four 1.0-liter inline four-cylinder Yamaha FZR1000 motorcycle engines fanned out and joined by two crankshafts, the Novia engine displaced 4.1 liters in its final configuration.
The proven engines have a 76.5mm (3.01 inches) bore and 56.0mm (2.20 inches) stroke with five valves per cylinder (that’s 80 valves, in total). When complete, the interesting beast produced 560 horsepower at 10,000 rpm and 318 lb-ft of torque, to the rear wheels, through a six-speed manual. Only one was ever created, and it took a ridiculous amount of time and money, but proved that with enough of both, anything is possible.
The currently produced Bugatti W16 is probably the most famous modern 16-cylinder engine on the planet. Extremely unique in that it is two VR8 engines (which are incredibly unique on their own) joined at a 90-degree angle to make what the company has dubbed simply a W16. The engine has undergone various facelifts and trim changes in its 16 years of production, with the current 2021 Bugatti Bolide variant being the pinnacle of the design.
The engine has been a square 86mm (3.39 inches) design throughout its lifespan, making for an 8.0-liter displacement. One of its hallmarks has been the four turbochargers that adorn the engine, helping to give the powerplant its massive power ratings. Currently, the Bolide variant is boasting 1,824 horsepower at 7,000 rpm and 1,364 lb-ft of torque, which is the highest output ever offered by the powerplant and puts it into overall very rarified air, with only three other production powerplants surpassing its output.
While these six W16 engines are definitely impressive, be sure to watch the video in its entirety, as there are four more W16 engines highlighted which are equally impressive.