Cylinder question (stupid)!

[Guest]

I was thinking, how does a 600cc cylinder produce so much more power than that of a 125cc cylinder? I mean, there would be more fuel and air, but i cant understand how it would create that much more power?

Please explain

[dredge3]

I was thinking, how does a 600cc cylinder produce so much more power than that of a 125cc cylinder? I mean, there would be more fuel and air, but i cant understand how it would create that much more power?

Please explain

 

You said the answer..more fuel and air...bigger bang = more power

[Guest]

Yeah, but there cant be that much more fuel and air to boost the power up that much, can there ?

[Guest]

Nearly 5 x as much is a big increase.

[Guest akey]

Fuel / air ratio stays constant so for if we compare 100 to 600cc then the 600cc bike will be 6x as powerful. now its not that simple because of the other mechanics involved but on a simple level more air and fuel means more power.

This is also how superchargers and turbos work as they cram more air and fuel into the same space.

[Bill_on_a_bike]

BUT, in a great big 600cc single, the air and fuel haven't got enough time to spread out properly, so the combustion tends to be less completel. You can over come this a few ways. 2 inlet valves helps to get the fuel air in to more of the cylider in one go. Audi used to have a valve system that sent the gas in spinning so it would spread out more evenly and burn more evenly.

Also, a great big piston like that can't rev as fast as a smaller one, just because moving that much metal that fast is technically much harder to do than moving a small piece of metal that fast. I know yamaha had problems with prototype SR 500 engines with the piston cracking at higher RPMs.

All sorts of far out stuff to consider with these things. I can't wait 'til i know more about them all.

[Guest]

Cool, thanks for the answers

[jamesw]

It's also worth considering that power is a function of force and time. So in simple terms an engine which is able to rev higher (and most 600s will rev higher than most 125s) is able to produce more power given that all other things are equal.

So with an increased capacity and an ability to rev higher, a 600cc engine will make substantially more power than a 125cc engine.

[dredge3]

This thread could get messy Don't forget compression ratio

[Bogof]

Nobody has mentioned turbo yet either

[chrisgatguis]

Id say the bottom line is basically what every one has said.

Its 5 X bigger therefore generates "5 x more power" or equivalent.

think of a 1 litre car, versus a 5 litre car..

seemples

[Guest]

Id say the bottom line is basically what every one has said.

Its 5 X bigger therefore generates "5 x more power" or equivalent.

think of a 1 litre car, versus a 5 litre car..

seemples

 

But it would also use 5 times more fuel, i guess they just have big tanks!

[chrisgatguis]

In theory maybe,

but in reality its a lot harder (more revs) for a 125 to cruise at 60mph,

compared with a 600 cruising at the same speed your probably talking half the Revs (or less)

so it pans out in the end.

saying that a 125 will probably do twice if not three times more MPG than a lot of other larger bikes.

my CBR125 would get 98 mpg consistantly, my GS500 managed 80 once and 60 once, so it varies on how you ride it.

Not sure what my 600 can do

[jamesw]

but in reality its a lot harder (more revs) for a 125 to cruise at 60mph,

compared with a 600 cruising at the same speed your probably talking half the Revs (or less)

 

but then that depends on the gear ratios!

 

This thread could get messy

 

[chrisgatguis]

but in reality its a lot harder (more revs) for a 125 to cruise at 60mph,

compared with a 600 cruising at the same speed your probably talking half the Revs (or less)

 

but then that depends on the gear ratios!

 

This thread could get messy

 

 

Fine fine, well if we're getting petty the real reason is this:

on your 125 your are approx 0.5 inches lower down (hence closer to the earths core) than on the no doubt bigger 600.

Due to this you get a increased gravitational pull on the pistons in your engine, (horizontal mounted may be different ) therefore you only get 14 bhp if you are lucky.

It is in deed nothing to do with the size of the engine........

[jamesw]

But that would make the induction and power strokes more efficeint (assuming the engine is mounted with the piston crown facing vertically upwards )

[Bogof]

Being further away from the sun would mean that the engine would run colder though

[dredge3]

Also colder intake temparature increases power.......here we go. Not looking at this thread anymore. More cc = more power, unless...

[Guest akey]

Colder intake = more power, only if your fuel system takes account of the air density (cold air being denser than warm air hence has the potential to produce more power, if more fuel is put in).

he he sorry

[Pete]

What a truly thrilling installment this is! I'm on tenterhooks waiting for the next exciting, yet informative episode...

[Guest]

Well, at least i learnt something through all this mess.. bigger CC = more power no questions asked

[Bill_on_a_bike]

Hmm, 'fraid not

the brough superior 11.50 I rode had 8 horse power, about 2 thirds what a 125 knocks out.

[jamesw]

Also colder intake temperature increases power.......

 

...don't forget the effects of atmospheric pressure (and therefore altitude) and quite possibly (but on a much smaller scale) air and fuel composition

[Colin the Bear]

Isn't the simple answer that the 125 is restricted in its power output to conform to legal requirements.

[Bill_on_a_bike]

Also colder intake temperature increases power.......

 

...don't forget the effects of atmospheric pressure (and therefore altitude) and quite possibly (but on a much smaller scale) air and fuel composition

 

This is exactly why aeroplane engines have to be supercharged or turbo charged, to get enough oxygen in to burn a useful amount of fuel.

the term "inter-coolers" comes from aero' engines having several superchargers, with coolers inbetween them to make the air denser. The prefix inter is now obselete as there's rarely more than one supercharger per intake manifold. We should call them "after-coolers".

Spot the engine geek.