too many cylinders?

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?

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?

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.

Imagine having to change plugs on a 60 cylinder motor :)?

lol

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

Coil on Plug :). No distributor.

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.

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.

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.

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 :D

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

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?

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.

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.

Great info, Hudson. :D Thanks for the knowledgeable post!

I would like for us to have individual electronically-acutuated rotary valves, in fact. Seems like the best of both worlds.

Originally posted by 454Casull
I would like for us to have individual electronically-acutuated rotary valves, in fact. Seems like the best of both worlds.

You could make some and make millions, that is, if internal combustion engines stick around...

Going back to the mucho-cylinder engine... i was thinking, how big of a gas tank would i need to travel say... 100miles or wahtever? Also, as the car begin to carry more gas, its also increasing weight, both through the fuel itself, and also the tank inwhich to contain it... :rolleyes:



obviously, if such an engine were really made, it probably won't be a street car, but drag/race-only type...

Originally posted by 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?

The '60 would have a spaghetti noodle for a crankshaft - it wouldn't last.

Also, as you break the displacement up amongst more and more cylinders, you increase the surface area. Sooner or later, you'll be sending nearly all of your fuel energy into the cooling jackets instead of the crankshaft.

Maybe that's why cylinders are cylinders and not rectangular prisms. :)

Originally posted by 454Casull
Maybe that's why cylinders are cylinders and not rectangular prisms. :)

LMAO! Some old lego cars had some square ones.


So going the opposite way, why don't we have 1 Cylinder 6 liter engines? Or more practically, as in old steam ships, the 3 Cylinder (I know cars aren't steam powered, so it would just be a 3 Cylinder rather than the triple Expansion three cylinder.) My frined's dad said he saw a bus with a 3 Cylinder, massive, is this right? I thought buses were all 6, 8 and 10's.

I'm sure that there are several thousand single cylinder 6L engines in the world.

Most buses that I'm familiar with use straight-six diesel engines (although there are some I4's around too, and probably some others that don't come to mind).

For most applications, steady delivery of torque is desired. Having multiple cylinders (3 or more) makes this goal easier to achieve. It is also common to want smooth, vibration-free operation, and engines with 6 or more cylinders have a leg up on the competition in this department. Packaging concerns also play - a single cylinder engine is squat, while an inline six is long and slender.

The largest-displacement engine that I have direct experience with was a natural gas fired 22L/cyl V18 (396L total).

The largest-displacement engine that I have direct experience with was a natural gas fired 22L/cyl V18 (396L total)
Oh, you saw it? I had it in my toy train set. I wonder where it is now...

I saw your post on the CSRV rotary valve system and thought you should know that Porsche has already stepped up to the plate and has bought a license for the system. You may be able to take one of the new models for test drive in the near future

Originally posted by ivymike1031
For most applications, steady delivery of torque is desired. Having multiple cylinders (3 or more) makes this goal easier to achieve .. The largest-displacement engine that I have direct experience with was a natural gas fired 22L/cyl V18 (396L total).

.. and then there's the famous Honda 125cc 5cyl GP race-bike engine from the 60's

More cylinders equals more complexity, more moving parts and the associated reliability and friction losses...

In some cases, particularly with smaller displacement engines the gains from the additional cylinders is offset by this issue. I'm thinking particularly of the Mazda I4 1800cc vs the Mazda 1800cc V6 (the twin cam 4 was a much better engine than the little 6) and the Altezza (Lexus IS200) which is available with either a I4 or and I6. The I4 is a torquier and more powerful engine but less smooth than the 6.

Incidentally...

The Southward Car Museum at Paraparaumu in New Zealand has a replica of a Chitty Chitty Bang Bang supercharged Mercedes 28/95 cars (built in 1914) with 6 cylinders. The engine was based on a Zeppelin aero engine and displaced 23 litres! That's the entire displacement of a Commodore V6 PER CYLINDER with 162mm bore and a 202mm stroke or in inches 6.377 inch bore and nearly 8 inch stroke... yikes!

hehe awesome :)

http://www.bigbikeriders.com/48cyl.htm

Most large ocean-going (non-military) ships these days use huge internal combustion engines where each cylinder has a bore and stroke of 3 to 4 feet or more. They burn bunker sea oil, which is something like diesel that didn't quite make the grade.
They turn at about 60 rpm, with very heavy flywheels. They are very efficient in producing huge torque numbers over a narrow rev range while burning a very low-grade fuel.

Compare that to something like an older Honda CB 400 motorcycle where each of the 4 cylinders displaced just 100 CC. The ship engine is more efficient for its application.
The question here is what is the measure of efficiency?
Cost of operation?
Cost of manufacture?
Power output?
Fuel economy?

Obviously, there is no one best answer, it depends on application.

I'm going to go out on a limb and actually respond to the question here.
In my opinion, as there are more cylinders, I don't think that they would eventually become insignificant, rather than just less significant. Saying that all things are equal, and that such an engine was tuned perfectly, no cylinders should really be unable to account for any power. An engine as such-with 50 or 60 cylinders, could be experimented with in such a way that the power could become tremendous thanks to the individual cylinders. Two or more cylinders could be firing at once, amplifying the thrust effect on the crankshaft, or the cylinders could be configured to fire at close radius degree proximities to eachother, producing en ever-active force on the crankshaft. Any way this would work could be made to produce more power, no matter the number of cylinders. The thing is that after a while, after all the parts and stress on them from such an amount of power, the engine would become extremely impractical. It would waste fuel like crazy, produce far too much emissions, and be plain out impractical to use on anything. This is just a theory, though.

One thign that limits the amount of cylinders you cna have is your crank shaft. a reason manufacturers dont make straight engines like straight 8s or anything more than a 6 is because the longer you have the crankshaft the more it winds up as each cylinder goes through power stroke. a 60 cylinder engine wouldn't have a crank strong enough to harness the power succesfully.
4 cylinders are optimum in my oppinion, 3 cylinders are not as smooth and cant haul round bigger cars, 6 is propably second to 4 but pretty much anything you can do with 6 a 4s not far behind, and an 8! god dont get me started on the modern american car with its v8! bad performance+bad economy=bad engine :loser:

BMW still uses the inline six, but it is also rwd. Its a lot harder to stuff a long inline 6 into a fwd car. A V6 (which is generally more complex with parts, lack of smoothness, more expensive) is more compact allowing to package easier which cut cost around other areas including using a fwd drivetrain.

Inline6's are actually very good engines. They are about the smoothest engines their are alongside the V12's and HO's.

My parents drive a 10 year old toyota with a 2 litre straight 4. i wouldnt notice anything smoother than it. i do notice however how jerky my mates mums 800cc 3 cylinder daewoo matiz is at idle. for the modern world, i think the 4 cylinder from about 1000cc to 2500cc is optimum. A modern day jap 2 litre puts out about 140+ hp thats enough to haul a 1200 kilo (theres 2.2 pound to kilo for you guys not in the modern world yet :p ) and 5 average adults 120 mph + easily. thats excessive enough, when you can only do 70 legaly. all this and returning good mpg. on a recent run to manchester from south wales (250 ish miles) my parents 10 year old carina E done 70-85mph (3000-3700 rpm in top gear) all the way and give us 39.5 mpg!

So I'd say yes and no, you can have too many cylinders, no doubt an engine could be made to take 4000 or so cylinders but what would you need it for? if you want it for a car and fuel economy means somethign to you a 4 cylinder fits the bill nicely. :2cents:

ZO6's make 400hp and will haul 2 adults at 170Mph+ easily, and still get 28 mpg, not to shabby!

not as good as 40-50mpg that a 2 litre can get nowa days and the 175 mph thing, when or where the would you find out the if you or your cars capable of that kind of speed. I think that anythign that can do 110mph or more is fast enough.

If everyone just cared about fuel economy, we'd all be driving turbo diesels and hybrids. Obviously v6s/v8s/I6s etc serve another purpose... accelleration! Hell my car will never break the 20mpg barrier, but thats not what its meant for... its meant to haul ass!

Well wats the question then? too many cylinders for what?

Detroit deisel engines are able to run either direction and they can be piggy backed together they do this mostly in commercial apps but you could run several of them in line. this makes lots of power and would be no more in efficient each engine draws some power from the next and carries its own load.

haha just make a bigger crank shaft :) make it out of some space age strong ass metal... lets see... if u put the cylinders in a X pattern and make them go in a W shape like ' . ' . ' . ' . u could probably cram 30ish cylinders into a car... but the walls of the cylinders would be hela small...