UK Karting - Notice Board (General Karting) : Re: How To Convert Bar To Compression Ration

Notice Board (General Karting)

Re: How To Convert Bar To Compression Ration
Posted by 'SimonS' on 24 Mar 2013 @ 09:53

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SimonSJoined: December 2004
Total Posts: 4
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"If an engine records 8 bar on a compression gauge does that mean it has a compression ration of 1:8 ?"

No. Compression is measured the 'other way round", ie Eight to one or 8:1.

Compression is the ratio between the volume at the bottom of the stroke and the volume at the top of the stroke. e.g: if you had a total volume of 1000cc, 900cc being in the cylinder and 100cc being the area above the piston at the top of the stroke then your compression ratio is 1000:100 or 10:1.

You won't get 10:1 on a compression gauge because air leaks down the sides of the piston and gets pushed out of the ports as the piston moves.

Additionally, compressing the air heats it, increasing the pressure measured, a 10:1 engine will measure a theoretical 25.1 bar on a compression gauge.

What a compression gauge does is measure the actual pressure, by knowing the theoretical pressure and the best pressures produced from a 'best' engine one can gauge the state of your engine at a given moment.

see http://en.wikipedia.org/wiki/Compression_ratio

"Lastly how high can you take the compression (non MSA engine) before detination becomes an issue."

Theoretically, up to about 10:1. that's only possible with variable timed ignition, The limitation is the octane rating of your fuel, the timing system you have set, and so on to delay detonation. Compression ratio alone is not the problem.

Message Thread:

How To Convert Bar To Compression Ration by 'KartCrazyCoUK' (24 Mar 2013 @ 9:02)

Re: How To Convert Bar To Compression Ration by 'SimonS' << You are here!

Re: How To Convert Bar To Compression Ration by 'lard ass bob' (24 Mar 2013 @ 20:01)

Re: How To Convert Bar To Compression Ration by 'raceinstructor' (25 Mar 2013 @ 7:49)

Re: How To Convert Bar To Compression Ration by 'KartCrazyCoUK' (25 Mar 2013 @ 8:37)

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