Is this displacer gap too big?
Posted: Wed Oct 07, 2009 11:52 am
Hi everyone,
Just edited the numbers, sorry for any confusion :???:
The displacer was going to be a fire extinguisher body, but it is too heavy.
The displacer piston now is a stainless steel biscuit barrel with a lid that can be easily sealed.
168mm tall (6 5/8 inches)
136mm diam (5 3/8 inches) at widest point - top
133mm diam (5 1/4 inches) at narrowest point - base
Weight 13oz.
The steel tube for the cylinder is heavy wall (3mm) 6 inch OD - 5 3/4 inch ID pipe.
The gap between the top of the piston and the cylinder wall works out at approx. 4.5mm or 3/16 of an inch.
The gap between the base of the piston and the cylinder wall works out at approx. 6mm or 1/4 of an inch.
Would the engine run with this gap?
Another tube of the same size could be cut longways and pushed into the first tube. This would take down the ID by 6mm (1/4 of an inch). This would mean the gap at the narrowest point would be 1/16 of an inch all round. This would be difficult I think to set up without the piston contacting the cylinder wall (no lathe or machine tools to help). So I'm hoping a slightly wider gap would be ok.
All this if my working out is correct.
Many thanks,
YB
Just edited the numbers, sorry for any confusion :???:
The displacer was going to be a fire extinguisher body, but it is too heavy.
The displacer piston now is a stainless steel biscuit barrel with a lid that can be easily sealed.
168mm tall (6 5/8 inches)
136mm diam (5 3/8 inches) at widest point - top
133mm diam (5 1/4 inches) at narrowest point - base
Weight 13oz.
The steel tube for the cylinder is heavy wall (3mm) 6 inch OD - 5 3/4 inch ID pipe.
The gap between the top of the piston and the cylinder wall works out at approx. 4.5mm or 3/16 of an inch.
The gap between the base of the piston and the cylinder wall works out at approx. 6mm or 1/4 of an inch.
Would the engine run with this gap?
Another tube of the same size could be cut longways and pushed into the first tube. This would take down the ID by 6mm (1/4 of an inch). This would mean the gap at the narrowest point would be 1/16 of an inch all round. This would be difficult I think to set up without the piston contacting the cylinder wall (no lathe or machine tools to help). So I'm hoping a slightly wider gap would be ok.
All this if my working out is correct.
Many thanks,
YB
