compression ratio
Senior Member
Joined: Jul 2004
Posts: 6,200
Likes: 39
From: Easton, Pa.
Comperssion ratio is just that, a ratio of two volumes.
The total volume including the combustion chamber when the piston is fully at the bottom of it's stroke to the volume when the piston is at the top of the stroke.
The compression part of it is is the air/fuel that is compressed from the large volume to the small volume then ignited by the spark.
Additional info for you.
The higher the compression ratio the higher the power output from the same fuel charge.
But; this brings with it other requirement such as increased fuel octane rating, possible change in ignition advance rates, change in camshaft profile to maximize the intended use of the engine etc.
The reason for the increased fuel octane is that the flame speed increases under higher compressions and so needs to be slowed down by the higher octane fuel rating.
The subject is complex when all things are considered.
Hope this has provided some usefull info.
The total volume including the combustion chamber when the piston is fully at the bottom of it's stroke to the volume when the piston is at the top of the stroke.
The compression part of it is is the air/fuel that is compressed from the large volume to the small volume then ignited by the spark.
Additional info for you.
The higher the compression ratio the higher the power output from the same fuel charge.
But; this brings with it other requirement such as increased fuel octane rating, possible change in ignition advance rates, change in camshaft profile to maximize the intended use of the engine etc.
The reason for the increased fuel octane is that the flame speed increases under higher compressions and so needs to be slowed down by the higher octane fuel rating.
The subject is complex when all things are considered.
Hope this has provided some usefull info.