volumetric efficiency
Turbo Mini Forums

hello, i am supercharging my 1380 over the summer. I am trying to determine a suitible pulley size/ratio.

I have calculated volume flow rate but the only value i am unsure about is how much pressurized fuel/air mix fills the cylinder on each induction stroke. I know for a n/a engine this is about 85%, can you assume it will be similar amount of pressurized fuel/air entering on a forced induction engine????

cheers

in short no

"Turbo's make torque, and torque makes fun"

"did you know you can toast potato waffles?"

"volumetric efficiency" try that in a search nobby ,and tick the content box .

Medusa + injection = too much torque for the dyno ..https://youtu.be/qg5o0_tJxYM

A VE of 85-90% is about right.

However, the biggest mistake most people make in selecting blower pulleys is that they do not take account of the heating of the air due to inefficiency of the supercharger.

The blower pumps a relatively fixed mass flow of air per revolution. When that air gets heated it will want to take up more space as it tries to expand. Because it can't expand it creates pressure which is additional boost over and above that created by trying to cram the air into a smaller space.

This is whay an intercooled turbo engine will always make a lot more power than a superharged engine at the same boost.

You need to do similar air flow calcs as with a turbo, taking into account the adiabatic efficiency of the blower, then use the compressor map to work out the blower/engine ratio.

Saul Bellow - "A great deal of intelligence can be invested in ignorance when the need for illusion is deep."
Stephen Hawking - "The greatest enemy of knowledge is not ignorance, it is the illusion of knowledge."