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# Stirling Engine Blowby?

## Stirling Engine Blowby?

(OP)
Hello all! I have been trying to do some research on this subject but cannot seem to find much. I understand there is some blowby in a gasoline or diesel engine, but what about a Stirling Engine? Since it is an enclosed system of gas, how is that handled? Is the force too low for there to be a blowby effect because of the gases traveling between pistons so the force is dissipated before it can blowby?

### RE: Stirling Engine Blowby?

They've never achieved commercial success, hence the lack of much information.

The ones that I've read about are completely hermetically sealed including the crankcase (if there is one) or integral alternator/generator (if there is one). Any leakage past pistons gets contained in the crankcase and the pressure and contents of the crankcase is the average of the engine's operating pressure, so leakage will be in both directions and average out to zero. The BMEP of a Stirling engine is pretty lousy and the difference between peak cylinder pressure and minimum cylinder pressure isn't much, so sealing of piston rings (given that the crankcase has the same gases in it) might not be so critical.

No one has put one in the hands of the average consumer and put 200,000 miles on one.

### RE: Stirling Engine Blowby?

No, but they have put them in space and let them run continuously for years.
The delta P is so low that leakage is nearly nonexistent.

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P.E. Metallurgy, Plymouth Tube

### RE: Stirling Engine Blowby?

Small test ones have, they have never been the primary power on a project.
There are ones here on earth that have been run for years in testing also.

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P.E. Metallurgy, Plymouth Tube

### RE: Stirling Engine Blowby?

Stirling Biopower in Ann Arbor, Michigan have been making Stirling engines in low volume for years.
They were called STM when I visited them about 20 years ago, and had several units running durability at the time.
I think they sell the complete generator sets to landfills and livestock farms etc.

PJGD

### RE: Stirling Engine Blowby?

Model Stirling engines with low pressures use bellows instead of pistons and rings. Not sure how scaleable that is.

je suis charlie

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