Why Are V6 Engines Difficult To Build

The V8 engines were built for more power or rather for more torque for heavy vehicles. However, as technology evolved the V6 was able to generate equal or even more power with the help of turbochargers. Take the Ford Ecoboost V6 for example. It produces more power than many traditional V8 engines.

What is a V6?

However, what makes a V6 engine a V6 engine? Well, the ‘V’ in the V6 indicates the position of the cylinder in an engine. ‘6’ denotes the number of cylinders. Hence, there are two sets of three cylinders arranged on opposite sides in a V-shape or position. If it's a V8 engine, just add one more cylinder on each side.

Why are V6 Engines difficult to build

The V6 engines have evolved a lot since its inception in 1906. It is fitted in various cars mainly SUVs like the Nissan Murano, the Jeep Grand Cherokee, and more. However, they might not be the best engine to go with in the future. Below, we evaluate and compare the V6 engine’s built, performance, pros, and cons against V8, Inline-4, and Inline-6 engines to find out why V6 engines are difficult to build.

V6 vs V8

As the technology evolved, the V8 was chopped off and two cylinders were removed. Now V6 was the smaller version of V8 which was more compact and less loud. Its horsepower gain from a V6 to a V8 was minimal. The new V6 engines were able to offer almost the same towing power as the V8 and they were also stable. Hence, V6 is a better option for light-duty work because they are lighter, less noisy, and has a competitive towing capacity compared to the V8.

However, don’t start counting the sheep yet since there are some major problems with the V6. The V6 motors have inferior cargo capacity compared to the V8. Furthermore, the V6s have less of a perpendicular angle in the engine compared to the V8 counterpart. The V6 also has a lower power ceiling and they are not as balanced during the operation as the V8 engine. That is why mostly in trucks or heavy automobiles where the higher torque is required the V8 engines are preferred.

V6 vs Inline 6?

Although both V6 and V8 engines are getting phased out for many reasons mainly due to higher emissions, they are still in very much use in various cars. However, Inline or straight-configuration engines are making a comeback and their demand is increasing every day. It is not far that Inline-4 and Inline-6 engines will be taking over the market. The Inline-4 and -6 engines are different than the V6 engine because their cylinder is arranged in a straight line, unlike the inclined arrangement of the V6.

Mercedes-Benz is one of the most famous manufacturers of straight or inline engines. In the 2023 AMG GLA 45 SUV model, the 2.0L Turbo Inline-4 engine makes 382 horsepower and 354 lb-ft of torque. Additionally, the 2023 BMW 5 Series 540i Sedan has a 3.0L Turbo Inline-6 engine which churns out 335 horsepower and 332 lb-ft of torque.

Now compare these figures with the 3.5L V6 and 3.5L V6 engines in the Nissan Murano and the Jeep Grand Cherokee which make only outs out 260 horsepower and 293 horsepower respectively. Hence, it is pretty clear that with the right tuning and developed design, the smaller inline engines can easily replace the V6 motors.

However, one more reason the V6 engines are difficult to build compared to the Inline-4 and Inline-6 engines is the manufacturing cost. Due to commonalities, companies can use the same production line for the Inline-4 and the Inline-6 engines and save the manufacturing cost. Hence, there is no need to invest in the V6 as well.

However, despite its inherent advantages, the inline engines are long. Hence, how can we fit these engines with longer displacement under the hood which was originally designed for the V6? Well, you reduce the bore size of the cylinder and you are good to go. Furthermore, the V6 engines find it more difficult to balance primary and secondary forces compared to the Inline-6 engines. Additionally, Inline-6 is also good at balancing primary and secondary moments.

At the same time, the V6 engines are mechanically more complex. Hence, manufacturing them is also difficult. On the other hand, just like V8 and V10 engines, the V6 engine also has two cylinder heads. It also has four camshafts, two exhaust manifolds, two catalytic converters, and two turbochargers. Meanwhile, the Inline-6 engine cuts all these elements in half. Hence, making power production simpler and smoother.

The V6 engine build is also difficult to make due to their firing order which is generally 1-2-3-4-5-6 or 1-6-5-4-3-2. It also needs counterweights to combat vibration. On the other hand, the Inline-6 engine has a more balanced firing order of 1-5-3-6-2-4. The Inline-6 also produces fewer vibrations.

Furthermore, the new Inline-4 and Inline-6 engines are coming with a mild hybrid system which makes them more efficient than the V6 engines. The small motor attached to the engine can act as a generator which can get the ride of the accessory belt that is present with the V6. Hence, not only reducing the bore but also adding an electric motor with the I-6 helps save space in the engine bay.

The V6 engines are also difficult to work with. Manufacturers have to worry about their angles and all these extra parts. On the contrary, Inline-4 and Inline-6 have much easier construction and access.

Having said that, the V6 is phasing out more and more quickly. Brands like Audi, BMW, and Mercedes-Benz are adopting more and more Inline-4 and -6 engines with hybrid systems in their models. Although V6 does offer some obvious advantages, it is still a noisy mechanically costly difficult-to-build engine configuration.