Model Engine Maker

Help! => Specific Engine Help => Topic started by: BaronJ on March 23, 2014, 04:43:46 PM

Title: Piston Stroke to Bore ratio for steam Engine
Post by: BaronJ on March 23, 2014, 04:43:46 PM

Hi Guys,
What would be the best piston stroke to bore ratio for a double acting stationary steam engine ?
I am thinking of using a cast iron cylinder with a 20 mm bore but have no idea what length to make it for optimum performance.

Thanks:

Title: Re: Piston Stroke to Bore ratio for steam Engine
Post by: Tin Falcon on March 23, 2014, 07:38:27 PM

There are lots of stationary engine designs. 
Depends on if you want the engine to run fast or slow.
1:1 ratio or square as it is called is IMHO the most common.
so 20 mm bore 20 mm stroke  or 10 mm ctc crank shaft center to crank pin center.
if you are building a waling beam they tend to have a longer stroke in the 1:1.25 to 1:1.5 range.
Tin

Title: Re: Piston Stroke to Bore ratio for steam Engine
Post by: sbwhart on March 23, 2014, 07:52:38 PM

Small engines tend to run fast so I  usually use a 2-1 or 2.5-1 ratio boreu 20mm stroke 40 or bore 20mm stroke 50mm

Stew

Title: Re: Piston Stroke to Bore ratio for steam Engine
Post by: BaronJ on March 23, 2014, 08:46:27 PM

Hi Tin, Stew,

Thanks for your reply's.

So based on your suggestions, if I go for a stroke length of 30 mm with a 5 mm thick piston I shouldn't be too far out.

I'm thinking marine type engine here with four cylinders.