Volumetric Efficiency

[Max Headroom]

With air being a fluid, another aspect is density. You're not going to change the actual volume an engine has in it unless you open up cylinders and ports. The denser the air the more friction you'll have as it's moving through an engine. Probably a minimal effect when you factor in heat soak and dwell, but it's a factor as altitude changes.

What you say is true and I have to give that some consideration. However, my immediate reaction is that increased density of inlet charge should create some kind of pressure differential over or under atmospheric (14.7 psi) especially if you add fuel to the intake charge.
Would appreciate any more thoughts about this.

 

[joesregalproject]

What you say is true and I have to give that some consideration. However, my immediate reaction is that increased density of inlet charge should create some kind of pressure differential over or under atmospheric (14.7 psi) especially if you add fuel to the intake charge.
Would appreciate any more thoughts about this.

The formula I gave accounts for this. k= mass flow rate, in kilograms per second, measuring air in kilograms, not volume.

 

[Max Headroom]

The formula I gave accounts for this. k= mass flow rate, in kilograms per second, measuring air in kilograms, not volume.

Cool, Thanks

 

[64nailhead]

My testing has given me a couple of known numbers that I trust. Of course I’m relying on an ECM to calculate the 1st one - lbs of fuel hour. This could be calculated the old fashion way of evacuating the tank and measuring how much was used, but that’s too much work for me lol. Holley
Gives a relatively accurate lb/hr number based on my testing.

My testing is with E85 and boost. 1lb:hr is very close to hp. So 1100lbs/hr of e85 is very close to 1100whp. When the motor or turbo run out of efficiency the lb/hr to boost ratio starts to tail off.

 

[Clone TIE Pilot]

This page may be of some help for you. http://www.epi-eng.com/piston_engine_technology/volumetric_efficiency.htm

Remember that peak VE occurs at a certain RPM and that peak torque RPM is about the same RPM for peak VE. As I understand it intake and exhaust manifold runner cross sectional areas are major factors that determine the RPM for peak torque and VE. Moreover, intake and exhaust runner length rock torque above or below peak torque RPM.