Why are V formation engines (V6/8/12) considered better than having the cylinders in a different formation, such as in a straight 6. Bonus points if you can explain why more cylinders is better.

Question

Why are V formation engines (V6/8/12) considered better than having the cylinders in a different formation, such as in a straight 6. Bonus points if you can explain why more cylinders is better.

In: Engineering

Answer 1

There are pros and cons to engine orientation as they greatly change the type of torque and horsepower delivery. Engine size also is determined by the layout.

Rotational mass is an enemy and a tool depending on what you’re looking for. Tractors and semis for example will use their rotational mass to deliver high torque smoother and with less opportunity for the engine to stall as its nearly turning over just by its weight alone. Tractors especially can chug along at very low rpms under enormous load thanks to this.

A formula 1 engine on the other hand may have extremely light rotational mass, allowing it to spin up and down at mind bending speed, while also allowing extremely high max rpms.

V engines usually can run at lower rpms, and still deliver torque/hp better than inline. Inline engines can be designed to do it as well, but they need to be higher displacement and rotational mass. They’ll be longer, heavier, and slower to build rpms with a lower max rpm than a similar v engine.

Tying into your bonus question, you only have so much fuel that you can spray into a space with so much air, and your limit on power becomes either how much air(and then fuel) you can get into a cylinder, or that plus how quickly you can get those cycles in and out. More cylinders isn’t always the best though. For a lot of race cars, rather than using a ton of cylinders they use small displacement and rotational mass, allowing them to scream along at high rpms, and being easier to force inject the air into as well.

You can’t make a formula one engine that will work in a tractor trailer. Similarly an engine designed for high torque and towing won’t ever have screaming high and responsive rpms.

Tl;dr. It’s not so much that v formation engines are better, it’s that in a lot of driving situations they are easier to make work and lead to a better vehicle than alternatives. In a few situations like tractors and big trucks, they largely are more popular and easier to build to the tasks at hand.