compression ratio
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Senior User
Joined: Dec 2002
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From: my house
compression ratio
Ok guys I hate to ask more dumb questions but I'm still learning engines, and I dont really get this compression ratio, what is it a ratio of? And why do you want to get it lower to add boost to an engine? Thanks for the help. 
marti
marti
Elder User
Joined: Jul 2002
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From: Kingsland, GA
compression ratio
Compression ratio is defined as the ratio between the largest the combustion chamber gets during running (BDC for that cylinder) to the smallest it gets (TDC for that cylinder). In other words, a motor with a CR of 9.5 would have a combustion chamber that is 9.5 times larger at BDC then at TDC. A high CR is typically associated with an engine that is very efficient and "high performance". However, engines with a high CR are more prone to knocking and detonation and are typically referred to as "high-strung". A motor with a turbo or a blower on it must have a lower CR to resist the knocking and detonation that are MUCH easier to cause with forced induction. You CAN have a maotor with a high CR and a turbo/blower, but it would have to be tuned so well that it would cost $$$$$$$. Hope this helps.
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Joined: Jan 2003
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compression ratio
Here ya go http://auto.howstuffworks.com/engine.htm
Study up on that, it'll give you a good foundation, so this stuff at least makes sense..
Study up on that, it'll give you a good foundation, so this stuff at least makes sense..
