too many cylinders?

[YellowMaranello]

if you just kept making engines with more and more cylinders, would it ever actually reach a point when they would become inefficient? for example, say someone somehow managed to make an engine with like 50 or 60 cylinders. would all that extra power be helpful? or would you not be able to actually harness all that power? would you just be better off with like a v12? this is all while assuming that somehow you could fit it into a car or bus. its just a thought that i came up with while my history teacher droned on and on. so the actual question is, is there a point when too many cylinders would just prove to be usless?

[Heep]

I've thought about that as well. But consider engines of the exact same size...a 6 liter 8 cylinder, or a 6 liter 60 cylinder. I assume the 60 would have a FAR higher redline, but that the 8 would have FAR more torque. Just what I'm assuming, anyway. Input?

[V.S.]

I'm assuming the "efficiency"(in all the ways its used in this post) depends more on the individual cylinders than the number of them. A 1L V-100 doesn't seem very good, but neither does a 100L single cylinder. But a normal size engine(whatever configuration it might be), assuming it was properly balanced, could be "lengthened" along the crankshaft without much harm being done.


I also believe that the torque/redline would depend more on the bore/strock than the displacement of the cylinder in itself. But assuming the bore:strock ratio were kept the same then you'd be right afaik.

[MercCougarXR7]

Imagine having to change plugs on a 60 cylinder motor ?

[Heep]

lol

Imagine how small the plugs would have to be on a 4 liter v-60 Imagine the distributor!

[MercCougarXR7]

Coil on Plug . No distributor.

[TheMan5952]

yea, but weight for the block an manifold/headers, nopt to mention the length of the engine. It would be come in-efficent, cadilac had a V-16 at a time.

[YellowMaranello]

but bugatti has an efficient enough 16 cylinder in the veyron. although the cylinders are in a W like formation as opposed to a V. but how awesome would it be to have a school bus, with all the seats replaced by one giant engine? think of how that thing would sound when you revved it at a stoplight.

[Porsche]

Sort of an answer to this question. The Lycoming XR-7788 (?) was an aircraft engine developed during or after WW2. It had 56 Cylinders and 127L of displacement. I think hp was up around 4000-6000. This is based on my knowledge, there was a question about this a while ago. RR also made a few monster, they took two flat12's and mated them together, thus producing a Double-Decker flat 24. Quite impressive.

[Heep]

Originally posted by MercCougarXR7
Coil on Plug . No distributor.

Yeah I know, I thought of that after posting. Oh well. Just imagine the distributor if it had one

[enginerd]

The most I've ever seen was a 28 cylinder engine for airplanes. I think it displaced 3,500 cubic inches.

[Thunda Downunda]

I recall reading something about this excellent question.

Riccardo, one of the 20th century's most notable engine designers/engineers produced studies claiming that, in purely theoretical terms, the optimum balance of efficiency between friction area vs swept volume lay in a cylinder size of about 330cc. Of course his tenet becomes progressively less relevant for ever-larger engine capacities, due to packaging size, weight, complexity and cost factors.

I don't know how this is affected by recent developments like ultra-low friction materials though.
To me, one of the most fascinating engines is the intriguing (and apparently successfull) plastic Polymotor from the 1980s - anyone remember what happened to that?

[JD@af]

Seems kind of a bummer that most of the experimentation with internal combustion cylinder configurations passed earlier this century. I know, for example, that a one-cylindered, 4+ liter engine was made. There was also the experimentation by Henry Ford with the X8 engine (four banks of two cylinders, arranged in an "X" shape). So, in general, the auto manufacturers have just used the most simple and efficient designs as the tried and true methods for engine configurations. In light of that, I applaud some manufacturers (Porsche and Subaru, for the flat 4s and 6s, Mazda, for the Wenkel rotary, even BMW, for sticking with the inline 6 when almost every other manufacturer abandoned the design for the 60-degree V6, and now Volkswagen, for the W8 and others) for resisting the status quo and sticking with the unconventional.

Like some who have read about this, I am anxious for Coates rotary valvetrains to be phased into mainstream automotive design (see http://www.coatesengine.com/ for more information). I foresee much higher rpm capability using them (coupled with phasing in of forged steel connecting rods to support the forces accompanied by high rpm use), though perhaps a loss in "tunability" of the cylinder head. Anyway, with Coates valvetrains, poppet valves, valve guides, valve springs, cotters, cam followers, rockers, lifters, camshafts, and even engine oil will all be a thing of the past, and thankfully so, in my book.

[Hudson]

Large displacement engines have been found to be inefficient. Sure a 4-litre one-cylinder engine sounds cool, but it's dreadfully slow. And it has been discovered that once the bore size of a gasoline engine cylinder moves past 4-inches, emissions begin to skyrocket.

The whole "conventional" engine design was not settled upon mainly for its conventionality, but these are the most efficient designs. "X" and radial engines aren't as compatible to passenger cars as inline and vee designs primarily because of their high crankshaft positions and unique oiling characteristics.

Inline and vee (horizontally opposed is an extreme vee) allows for the crankshaft to sit low enough to keep the engine's center of gravity as low as possible. It also allows for a oil pan where all of the oil can pool up and be redistributed throughout the engine.

While the rotary valvetrain concept was a great idea ten years ago, it will lose its way very shortly when cars begin converting from 12-volt systems to 42-volt systems. This will begin happening over the next few years and will allow for more electronic controls of engines leading to electronically activated valvetrains. This allows for infinite adjusting of intake and exhaust valves at any speed in all conditions with few restrictions. It would also help aid in the future development of variable displacement engines and flexible fuel systems.

For the next great step in powertrain technology, you have to look outside of the internal combustion engine. Steam power and electric power were overlooked a the beginning of the 20th century when it was found that ICEs had more benefits in fueling times, starting times, all-weather driveability, and maintenence. Steam and electricity have their benefits but their negative points have not been overcome. The next generation will be combining electricity (wide torque bands, smooth operation, the ability to do without a transmission) and fluid fuels (quick refueling, easy storage, long range), like fuel cells.

[JD@af]

Great info, Hudson. Thanks for the knowledgeable post!