so apparently volumetric efficiency is calculated on a rotary as a 2.6 liter engine
and something about a 13 b being at 90percent ve... i dont really remember as i have a killer head ache today.

but my question is .. if the engine is street ported how will the ve change? and how will i be able to calculate it ?

the reason why im asking is because im building a turbo and i want to figure out a turbo that will get me as close to the best of both worlds as possible...
short lag and not so restrictive up top

 

when porting an engine, all ur doing is changing the intake and exhaust timing like lift and duration in a cam. sure u increase the amount of air in and out but not the actual size of the combustion chamber. so i'd suspect the formula is the same regardless weather stock or streetport.

 

Any time you change intake or exhaust, you're changing the engine's volumetric efficiency. Calculating it would not be so simple, especially considering every port job is a little different. I'd say the best you could do is make an estimate.