MyE28.com

say the engine is getting 14.7 PSI of air or oxygen or whatever the car needs and its a naturally asprirated engine....and say you are running 14.7 pounds of boost when you turbo
Would the car be getting twice the amount of air as normal or is that just a figure? I always wanted to know about this.
I dont understand too much about forced induction obviously.

Is the volumetric efficiency of a forced induction engine over 100%? sounds dumb but i just want to find out
cause i know a NA engine will never be 100 percent no matter how hard you try.

thanks

Yes,
at sea level or 14.7psi, if you push in 14.7psi more, your doubling air flow in a perfect model.

Yes, forced induction is more than 100% VE.

RussC

Super Eurobeat wrote:... i know a NA engine will never be 100 percent no matter how hard you try.

Maybe no matter hard you try, but there are normally-aspirated engines that can exceed 100% VE.

Ram air intake kinda thing, Shawn? Just wondering how >100%VE is accomplished on a naturally aspirated motor.

Matt, yes, you're pushing twice the amount of air at 1 bar of boost, but don't fool yourself into thinking that will result in twice the power. There are losses in various places that make that an impossibility.

Jeremy

Ram air would be "forced induction".
Through proper exhaust scavenging (along with really good intake design) you can acheve 100+ % VE.
Remember, air has mass and, therfore, inertia.

To add to what Sweeney said, harmonics in both the intake and exhaust are key to obtaining 100+ % VE. Consider that longer runners work better at lower RPM and vice-versa -- the longer runner will have a lower natural harmonic frequency than a shorter runner will. If you consider the way the intake and exhaust see engine speed, they don't see an RPM in that they don't know anything is rotating -- they only see a number of suck-squeeze-bang-blow events over a given time period.

Those are the best "events" ever!

thanks, that cleared up a "assumption" if you wanna call it, that i had.
I always thought a engine could never reach 100 % VE because i was always told that its difficult for an engine to get air in, Anyway being N/A. But thats just what ive heard so i assumed the most you could get was like 85 percent of the potential of the motor.
So saying how you know longer runners vs short runners.
Would the engine be getting more VE at lower RPM if it had longer runners? Or does it not matter?

thanks

I guess a good example im trying to say is velocity stack style intake versus say a M30 intake manifold.