View Single Post
  #4  
Old September 28th 06, 06:02 PM posted to rec.autos.misc
[email protected]
external usenet poster
 
Posts: 35
Default Stroke vs Bore for a Given Displacement?


wrote:
> I was thinking along the lines of fluid/hydraulics. If there is more
> surface area then force is increased which would increase torque. Don't
> know if this applies to internal combustion engines though. If it did,
> would this greater force outweigh a marginal increase in the stroke
> (i.e. crank offset)?


The longer the stroke, the higher the torque because the offset on the
crank will need to be greater to accommodate the longer travel - like
having a longer wrench or adding a cheater bar to break loose a stuck
nut. The greater the bore the higher the torque because there's more
piston face for the gas to push on.

Now, whether these two numbers have any bearing on how two given
engines will compare is improbable. Engine design is so much involved
than bore & stroke that this isn't even a preface to getting a desired
output torque. What if I had a single piston with a 24" of stroke and
18" bore but connected that to the crank with a paperclip for a wrist
pin? What kind of power could I expect from this engine?

Matthew

Ads