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Location:
Euroka NSW Australia
Registered:
May 2002
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compression
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Mon, 27 May 2002 03:54
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can someone give me the formula for working out the compression by using the cubic capacity and compression ratio of an engine?
Some clever person out there must know?
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I supported Toymods
Location:
I renounced punctuation
Registered:
May 2002
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Re: compression
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Mon, 27 May 2002 04:06
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By compression, I presume you mean dynamic compression as measured with a comp guage....no, there isn't a formula because it is dependent upon a swag of other things, not all of them tangible. You need to check your engine manual to know what it should be.
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Location:
Euroka NSW Australia
Registered:
May 2002
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Re: compression
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Mon, 27 May 2002 11:41
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OK thanks for the info. I would have thought it would be a simple matter of multiplying the cubic capacity by the compression ratio then dividing by something or other. Guess I've got a lot to learn about engines.
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Location:
Tasmania
Registered:
May 2002
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Re: compression
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Mon, 27 May 2002 14:16
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The valves don't open and shut at TDC. Plus the air speed of the air entering the chamber is not constant. Plus the air density changes with heat. And air leaks past the pistons. Its a very dynamic thing. But surely there would be a rule of thumb, considering compression ratio and camshafts used?
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I supported Toymods
Location:
I renounced punctuation
Registered:
May 2002
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Re: compression
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Mon, 27 May 2002 23:03
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John, it's incredibly variable from engine to engine, for exactly all the reasons you have outlined. The best you can say is that dynamic compression is directly related to the compression ratio, to a point. Also, it has nothing to do with the cubic capacity of the engine.
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