Newbie learning, answer: Whats the KA24DE volumetric efficiency??

[sanioll]

Yes, i'm gonna have couple weeks outta school, so i grabbed couple books etc, trying to learn and plan early for turbocharging my car properly and reliably.

As title says, Whats its Volumetric efficiency?? I need it to use couple formulas for airflow etc.. to see if i'm gonna need a headwork or not.

thanks, please dont flame, i didnt search at all.

[SSS]

Volumetric efficiency (VE) is the efficiency at which an engine can fill a cylinder with fresh intake charge each intake cycle.

So for a KA24, at 100% VE one cylinder will inhale 600cc's of fresh intake charge for combustion.At 80% VE, the cylinder will only fill with 480cc's of fresh intake charge.

Typical NA VE's are around 70-80% unmodified.

However, turbo'd engines experience VE's over 100%, depending on boost pressure.

[sanioll]

So anyone knows whats the actual Volumetric efficiency for our ka24de??

[Red coupe]

I have no Idea, but just wanted to add I belive it would change with rpm, so their isnt just a number for the ngine it would be like wats VEat 3.5k rpm...

[deezlins]

Im not gonna get into the whole VE over 100% thing with turbo again.

Yes, VE does change with rpm, it will actually follow the torque curve.

Im not sure what the VE of the KA is, but we can find out.

using the formula VE = (HP*792001.6) / (AP*CR*CID*RPM)

VE = volumetric efficiencyHP = horsepowerAP = atmospheric pressure in PSICR = compression ratioCID = cudbic inch displacementRPM = revolutions per minute

lets just use standard sea-level atmospheric pressure of 14.7

the ka is about 145.78 cubic inches from my calculations (2389cc's right?)

compression ratio is 9.5:1 right?

I found a baseline KA24DE (stock, 120,000 miles) dyno from importtuner on a google search and it made about 130hp peak at about 5500 rpm, so we'll use that.

so VE = (130*792001.6) / (14.7*9.5*145.78*5500)

so VE = 0.9195, so about 92% VE at 5500 rpm? that seems kinda high, but i guess thats right?
Modified by deezlins at 4:34 PM 4/24/2005

[TrunkMonkey]

So anyone knows whats the actual Volumetric efficiency for our ka24de??

do you mean VE, or do you want to know how much cfm it flows? 90% of the time VE is a guess at best if you don't have any actual tested data to go with. iirc, the KA flows around 250 cfm at redline. search for it. i know i've posted it before.

-demetrius

[madbouncy]

VE RPM TQ HP0.844 2000 114 430.881 2200 119 500.889 2400 120 550.896 2600 121 600.889 2800 120 640.881 3000 119 680.859 3200 116 710.896 3400 121 780.911 3600 123 840.933 3800 126 910.948 4000 128 970.963 4200 130 1040.956 4400 129 1080.941 4600 127 1110.918 4800 124 1130.889 5000 120 1140.874 5200 118 1170.837 5400 113 1160.793 5600 107 1140.748 5800 101 1120.704 6000 95 109

THat's what I got for it from that dyno, don't remember where i got the dyno but it seems a little low so it was probably and older car, i figured if I worked with the worst dyno my car could pull I wouldn't be suprised if my car ends up with low numbers.

[Drift Machine]

Yeah if I can remember from when I calculated it all out a long time ago when I was plotting compressor maps, it's roughly about 247CFM at redline. I also just assumed 85% VE, since that's generally what most cars run.

[sanioll]

so VE = 0.9195, so about 92% VE at 5500 rpm? that seems kinda high, but i guess thats right?

wow, that is high, i'd love it to be that much.

Guess i'm gonna have to assume 85% efficiency when deciding on a turbo.

p.s. i searched, but there was no threads about this. well this is the first one.

[deezlins]

also the dyno pull i used from the importtuner website was made on a dynojet dyno, so in reality it would probably be a little lower.I substituted in 125hp instead of 130 in the equation just to see what it would do, and it brought the VE to 88%Does anyone have any baseline dynos? especially on a Dyno Dynamics, Dyna Pack, or Mustang dyno?

[hannibal]

Peak VE should occur at the rpm of peak torque. (Apparently the tq peak is the tq peak because the motor is 'most effiecient' here.)

A method that Ive read on NICO before was to assume a certain peak VE% at the torque peak (say 85%).

Using a dyno chart, find the peak tq produced (135 lb-ft for example). If the motor was operating at 100% VE, torque output at this rpm would be 158.8 lb-ft (135 / 0.85).

Using a dyno chart and this theoretical torque at 100% VE, you can estimate VE at all rpm points. Just find the torque produced at that rpm (say 100 ft-lbs at 6000rpm) and divide this tq value by the 100% VE torque value. In this example, VE at 6000rpm would be 62.9% (100 / 158.8).

This idea agrees with the chart madbouncy posted, where VE peaks at the tq peak, and falls as torque declines (both at higher and lower rpms).