hi, a question, the mean area is in question, the degrees of crankshaft rotation, not the piston, so lets say a engine port open at 89* atdc, the "mean area, gonna be 133.5* in crank degrees, it is right? (89/2):44,5 (89+44,5):133,5*
Port open degrees and port open area are two different things and should not be confused together although they do have a light relationship. Go to this page to see how I measure the port area which is constantly changing as the piston lowers. The old method was brutally crude and inaccurate by only considering the whole area instead of doing it the meticulous and time consuming way which then could be input into mathematical formulas but you're talking maybe 2 to 3 hours of work which is why I created my porting calculator to do all the calculations almost instantly. www.dragonfly75.com/moto/PCalcInstr.html
Hi, great videos. Can you please make a video about expansion chamber variables. Carburatour size, port durations, compression... Which sections changes based on variable. Thanks
Carburetor size affects the burn time so the bigger the carb, the faster the burn and the lower the EGT. The higher the EGT the quicker the pipes return waves reach the cylinder. Jetting and compression affect exhaust gas temperature and its near impossible to calculate for that so it's best to measure the EGT which you can do with a $70 gauge (listed on my site). Rich jetting causes a slower burn which extends closer to the time of port opening so the EGT is hotter. More compression causes a faster burn and so makes the EGT less. Port durations interplay with the timing of the pipes return waves and that is best analyzed with a pipe calculator with return wave simulator (like mine that I sell at www.dragonfly75.com/motorbike/portsMS.html ).
thanks Mick
hi, a question, the mean area is in question, the degrees of crankshaft rotation, not the piston, so lets say a engine port open at 89* atdc, the "mean area, gonna be 133.5* in crank degrees,
it is right?
(89/2):44,5 (89+44,5):133,5*
Port open degrees and port open area are two different things and should not be confused together although they do have a light relationship. Go to this page to see how I measure the port area which is constantly changing as the piston lowers. The old method was brutally crude and inaccurate by only considering the whole area instead of doing it the meticulous and time consuming way which then could be input into mathematical formulas but you're talking maybe 2 to 3 hours of work which is why I created my porting calculator to do all the calculations almost instantly. www.dragonfly75.com/moto/PCalcInstr.html
Hi, great videos. Can you please make a video about expansion chamber variables. Carburatour size, port durations, compression... Which sections changes based on variable.
Thanks
Carburetor size affects the burn time so the bigger the carb, the faster the burn and the lower the EGT. The higher the EGT the quicker the pipes return waves reach the cylinder. Jetting and compression affect exhaust gas temperature and its near impossible to calculate for that so it's best to measure the EGT which you can do with a $70 gauge (listed on my site). Rich jetting causes a slower burn which extends closer to the time of port opening so the EGT is hotter. More compression causes a faster burn and so makes the EGT less. Port durations interplay with the timing of the pipes return waves and that is best analyzed with a pipe calculator with return wave simulator (like mine that I sell at www.dragonfly75.com/motorbike/portsMS.html ).
@@MichaelForrestChnl thank you. I might buy it.