Author Topic: crankcase vol. (no drilling involved)  (Read 2250 times)

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Offline Chris-PA

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Re: crankcase vol. (no drilling involved)
« Reply #50 on: March 06, 2016, 08:20:51 pm »
Oh - I'm not sure Crankcase Compression Ratio is the same as the Vc/Vs ratio they used.  It's still not clear what all is included anyway.  If it is supposed to be the same, then it's probably because their setup could only add volume. 

EDIT:  I think CCR is the ratio of the swept volume plus the case volume to the case volume, or:  CCR = (VC +VS)/VC

That is different from VC/VS

If you calculate it out, VC/VS = 2.44 works out to a CCR of 1.41, which is what Engine A is listed as.

So for the red line of Figure 5, the VC/VS = 2.44 is getting pretty close to the practical limit of what you could achieve, and it still is at almost full delivery ratio by 2,500rpm.  That scales to about 7,000rpm for an engine with a 10,000rpm power peak, so practically it would be very hard to reduce the case volume down so far that you push the peak delivery ratio up above your power band.

I'd still like to know if the transfer volume is included - it should be. 

 

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