what is the Volumetric Efficiency on our VQ's?

 

I know the VE on the 350Z is supposed to be 105%.

I do not know whet the others are. Supposedly less.

 

damn, i guess im gonna go with the default 85%

 

VE is a strong function of RPM. Peak Torque occurs at peak VE.

Using MAF data and the calculated air density at the conditions I tested at, I came up with an approximate VE of .98 @4400rpm. VE was above 0.9 between 3200 and 5200.

This is for a VQ30DE. If you have VI or MEVI, the curves are significantly different. I can post the curves if you are interested.

 

Based off these STOCK chasis dynos(withOUT drag):


VQ30 5th gen:
RPM--VE%
2500-78.86%
3000-84.61%
3500-88.02%
4000-86.26%
4500-85.44%
5000-81.33%
5500-78.42%
6000-75.58%
6500-69.2%

4th gen:
RPM--VE%
2500-77.88%
3000-75.58%
3500-81.68%
4000-80.10%
4500-79.96%
5000-78.86%
5500-71.69%
6000-59.97%
6500-47.77%

3rd gen:
RPM--VE%
2500-72.95%
3000-73.11%
3500-74.64%
4000-78.25%
4500-76.67%
5000-78.37%
5500-71.69%
6000-65.72%
6500-53.08%

 

True...from 4000-6400rpm, the 350Z exceeds 100% VE, and at 5600rpm acheives 105%, thanks to CVTC, high angle intake ports, straightened intake system, and a focus on CAE modeling/airflow analysis of the intake plenum.

Pretty impressive for a street car to achieve >100% VE, since that's typically only seen on high RPM race engines.

 

since i will be using the vi from the dek, i should use the VE% from the 5th to caluculate the desired cfm for my new hp goal?

 

I'd put it on and get a dyno with all your mods, then you can accurately calculate YOUR engines VE at varying RPM.

 

What is the calculation to determine VE?

 

here is a link
http://www.installuniversity.com/ins...n_9.012000.htm

 

That's a better way of calculating ACTUAL VE, since it takes into account air density, ie pressure/humidity/temperature.

What I posted it was approximations based off sea level and standard temp, since I was using SAE correced numbers, using the RayHall calculator: http://www.turbofast.com.au/freesoftware.html

Although, I'm not sure how RayHalls' calculator is 100% working, since it seems to assume a few things, I think, like Compression Ratio = 12:1.

Someone should use their OBD scanner and log a few WOT 3rd gear runs and dump them into Excel to get ACTUAL VE. Then it's just: VE=Actual/Theoretical * 100

 

who has a obd scanner? i dont....can someone help us out?

 

I tried this past Friday to get a scan of a 5th gen. while on the dyno, which would have been ideal for comparison, ie theoretical vs. actual with both on the dyno. However, my POS laptop battery was dead and my car DC/AC convertor blew and took out my fuses before I even left to the dyno shop, so no luck.

I have some stock and stock+POP OBD runs somewhere that I'll dig up and crunch in Excel.

 

thanks man

 

Still looking, all I found were second gear runs so far.

 

cool...no rush. motor wont be in until july