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.

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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

5 Answers

Anonymous 0 Comments

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.

Anonymous 0 Comments

What it really boils down to is packaging and materials. V-configuration engines are easier to package and fit into an area than an inline configuration, as well as using less material since things like cooling pathways, cam set-ups, intake/exhaust manifolds etc. can utilize the same space on the inside of the V. For the whole more cylinders = better argument, that is not necessarily true. The old adage “no replacement for displacement” is being disrupted by hybridization, downsizing & turbocharging, and advanced controls & technologies. One real benefit of more cylinders though is that, for instance, V6 vs V8, it is easier to balance vibration from the engine felt by the passengers for each bank of cylinders to have an even number of cylinders, a V6 has 3 on each bank and results in two cylinders moving up while the other is moving down, while a V8 has two and two. If the engine were opposed (boxer) configuration, it would be able to mitigate vibration even better, but again, boxer uses more material and space.

Source: Graduating with M.S. in Automotive Engineering in December

Anonymous 0 Comments

There’s a limit to how many cylinders of a size you can line up and still have them fit in the engine compartment.

More cylinders generally means more power. It also means smoother running. Eight little bangs is smoother than four big ones.

Anonymous 0 Comments

A straight six is typically considered more balanced than a V-6, but there’s a physical limitation to how long an engine can be. A straight six engine has all the cylinders aligned in a row, and is a physically large engine.

A straight eight is an even more powerful engine and this design was quite popular in the early 20th century.

As you might imagine, these engines are massively long and the much more compact V-8 design became popular to get similar power numbers out of a much smaller unit.

Straight 10 and 12 engines are absolute monstrosities reserved for WWII heavy bombers.

More cylinders are usually better because it provides a larger volume for compression, and thus more power without the need to run the engine faster.

Anonymous 0 Comments

>Bonus points if you can explain why more cylinders is better.

Application of power. One cylinder is an impulse, a tug. Many cylinders are a smooth pull.

A V engine consumes less space per cc or l of displacement. That old inline 6 isn’t a bad design, it just takes a mile of space to fit under a hood.