Compresion Pressure.
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- True Blue
- Posts: 122
- Joined: Thu Jul 10, 2008 3:40 pm
- Location: Lincolnshire, England
Compresion Pressure.
What is the correct cylinder compression pressure for the Perkins engine. One of my cylinders is well below the other two. Also, if there's trouble with one, is there likely to be trouble with the other two?
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- Site Governance Team & Expert Team
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- Location: Montague Calif. USA
I don't know for sure what the compression pressure is, but here's my best guess. The compression ratio is 16.5 to 1. Atmospheric pressure at sea level is 14.7 psi. 16.5x14.7= 242.55. Subtract 14.7 for the atmospheric pressure and you have 227.85 psi. Even a new engine is not 100 percent efficient, so it should be a little less than that.
Anyone else want to guess?
Anyone else want to guess?
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- True Blue
- Posts: 122
- Joined: Thu Jul 10, 2008 3:40 pm
- Location: Lincolnshire, England
Cylinder Pressure.
I read that a pressure difference between cylinders of more than 10% is indicative of a problem.Ambidextarous wrote:One of my cylinders is well below the other two. Also, if there's trouble with one, is there likely to be trouble with the other two?
As to the actual cylinder pressure values, it seems to be quite a complicated subject because the compression is approx adiabatic (ie no loss in heat) so the air heats up, which increases the pressure, but it also depends on valve timing etc. So JC's worthy effort above may be a bit out! Unfortunately I can't suggest a better value so maybe the difference between cylinders is the most reliable indicator
All the best,
Bensdexta - 1961 working for a living!