Volumetric Efficiency

[oldtimerookie]

I'm currently studying for my mechanical PE, so been spending a lot of time in my engineering books and looking up stuff online. I came across this online and found it pretty interesting:

"The actual amount of air the engine ingests compared to the theoretical maximum is called volumetric efficiency (VE). An engine operating at 100% VE is ingesting its total displacement every two crankshaft revolutions."

[COLOR=rgb(0, 0, 153)]VE = ( 9411 x HP x BSFC ) / (DISPLACEMENT x RPM)

For the RX assuming it makes 185 at the crank at around 10K

= (9411 x 185 x 0.45) / (73 x10,000) = 107%

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"For contemporary naturally-aspirated, two-valve-per-cylinder, pushrod-engine technology, a VE over 95% is excellent, and 100% is achievable, but quite difficult. Only the best of the best can reach 110%, and that is by means of extremely specialized development of the complex system comprised of the intake passages, combustion chambers, exhaust passages and valve system components. The practical limit for normally-aspirated engines, typically DOHC layout with four or more valves per cylinder, is about 115%, which can only be achieved under the most highly-developed conditions, with precise intake and exhaust passage tuning."

[COLOR=rgb(0, 0, 153)]Pretty cool, at least I think so!


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[buell-fan]

That is pretty cool! Thanks for sharing.

[d_adams]

So bumping that output up by 14 hp at the wheel nets you what?

[oldtimerookie]

So bumping that output up by 14 hp at the wheel nets you what?

Assuming 185HP Crank & 160HP RW thats about 14% loss
Therefore 14HP RW asuming same loss should yield about 16HP Crank Gain or 201HP at crank (Very cool, breaking the two century marker!!!)

9411x201HPx0.45/73/10000rpm = 116%

Very nice, obviously my numbers are not exact but close enough to illustrate your point Dean. I think you made the comment in one of the post that it would be very difficult to get anything else out of the bike past your exhaust / pc-v for top end power without extensive motor work.

One question I do have for your slip on / pc-v, how does it work on partial throttle, low end, mid range. For the guys who have purchased the pc-v do you think they've done a good job tuning?

I'm sold gonna purchase your exhaust very shortly as soon as I have enough $.

[d_adams]

It does well enough, I didn't have any issues with it. I ran it for a few months until I had someone that just didn't want to wait for me to build an exhaust for him. Sold the prototype and PC-V as a package. Bought the full programmable ecm and widebands for mine since I'm always changing stuff anyway and needed to be able to swap tunes or tweak stuff as I see fit. There's certainly nothing wrong with the PC-V.

Btw, lead time is out past 4-5 weeks right now.

[zviadi]

Any internal combustion engine having an inlet pressure greater than atmospheric, will be greater than 100% VE.
EBR have ram-air for this, like all modern motorcycles. I do not see anything surprising.
If you put the turbo charger, you can VE increase to 137% in theory.

[d_adams]

Sure, but to do that on a dyno without pressurizing the airbox? Wonder what it _really_ makes.

[zviadi]

Maybe due to the good ventilation of the combustion chamber and correct phase overlaps.

[zviadi]

What is "BSFC" from first post?

[Hughlysses]

I believe it's Brake Specific Fuel Consumption: https://en.wikipedia.org/wiki/Brake_...el_consumption