Scale Capacity

[dibbers006]

The initial message was deleted from this topic on 17 December 2023 at 11:48

[Wills2]

The same power as in 50% or still the 200bhp? I can't see it staying at 200bhp

a 200bhp 2l 4cyl engine at 50% scale is a 1l 4 cyl engine, isn't it?

Oh I've no idea...

[mattnunn]

Power is essentially how fast an engine can make torque, torque is a factor of the leverage applied to the crank, so no, it won't make 200bhp, if that's what you were asking.

[Gruber]

Isn't the cylinder capacity only quarter that of the original (given that volume = pi x depth x r squared)?

[Galveston]

Capacity will be an eighth of the original.

Edit: That's 50% cubed. I think torque would be proportional to capacity, but you could probably rev the smaller version a lot faster so you'd be able to get back some power, but only a bit.

Edited by Galveston on Tuesday 10th April 17:46

[mattnunn]

It's ambigious to say power has nothing to do with capacity, but the relationship is not direct.

Power


Power (Hp) = force x distance / time

because distance is in there you have to consider everything from the size of the wheels to the gearing etc...

The simpler question is to ask at a certain RPM will the engine make proportionally the same torque - forget power for now.

from wiki

Loosely speaking, torque is a measure of the turning force on an object such as a bolt or a flywheel. For example, pushing or pulling the handle of a wrench connected to a nut or bolt produces a torque (turning force) that loosens or tightens the nut or bolt

The force apllied to the crank via the piston is generated by the fuelling and spark timing of the engine, it's a pretty hurrendously indepth question you've asked without a simple or meaningful answer.

[tvrolet]

Galveston said:

Capacity will be an eighth of the original.

this

I started to work out the volumes on the basis of a 'square' 86mm bore and stoke (near as dammit 2L, so 200BHP possibe), versis 43mm bore and stroke then had a 'doh' moment - pi cancels itself out and it is indeed an 8th of the capacity for half the bore and half the stroke.