calculations for a new cc size rotary

[modelbox]

the BIG question : ?does anyone know what the formula is for calculating a new cc size rotor and housing

[Bob]

The stroke volume is given by the difference between the maximum and minimum values of the volume of the working chamber,The volume of the working chamber can be approximately calculated in practically sufficient accuracy by taking R1 = R+aR1= 71.5 mm ( R= 69 mm + a=2.5 mm ) : e= 11.6 mm ( shaft throw) : b=68.2 mm (housing width) :Vh = 294 cc ( Stroke or swept volume) With the Norton the major axis of the housing A = 166.2 = 2(R1+e) : the minor axis B= 119.8 = 2(R1-e)The simplified formula being .Vh = 0.005196 * e * R1 * b : per rotorThe swept volume change, the changing of R, R1 e or a needs close consideration, as this changes the angle of oscillation and will become smaller as the trochoid constant becomes greater and vice versa, these greatly effect the apex seal performance and apex seal spring breakage and wear.The simplest way to change the volume is to change the width and it is direct ratio to the change that you require, say you wanted to make your Norton into say a FIM 998 cc you would work this out by taking the standard cc 588 * 1.5 (FIM loading uplift) =882 cc, but you are allowed to race with say 998 cc take the Housing width 68.2 * (998 new /882 old) =77.17 mm You can see from this that you would need to increase the housing and rotor widths by 8.97 mm each.I hope that this helpswith help from Kenichi Yamamoto book Rotary EngineBob

[Bob]

I did attache a spreadsheet that you could use, this also give an as yet unproven Compression Ratio for the Rotary engine, the swept volume being well proven.BobI will try to add the file call COMP.XLS again on this post.I see that the extension XLS is not allowed so I have ZIPPED the file to see if this is uploaded