RL Volumetric Efficiency

[Bogie]

Does anyone know, or can point me to a URL, that covers the actual volumetric efficiency of Ecotec 2.0 with our stock Turbo. I've calculated cfm at 100%VE:

2500 RPM: 88 cfm
5300 RPM: 187 cfm
6200 RPM: 218 cfm

I'm looking at the stock turbo envelope, and it's pretty obvious the cfm needs to move up to hit the efficient operating band of our turbo. Not only should the efficiency go up due to the turbo, but we also have VVT overlap which will add even more flow.

It would be nice to know the actual numbers, but if anyone has a range of percentages for four cylinder turbos with VVT in general, that would help me at least get a feeling for the magnitude of the flow.

[MataguaySky]

Here is a link that may help?

Turbo Modifications - Volumetric Efficiency - Turbo Sizing 101 - European Car Magazine

[MataguaySky]

Looks like mostly they use .90 for calc.

Found a good read.
This site just screams Bogie!

Compressor Maps

Enjoy!

[LeadSled1]

[Bogie]

All good stuff folks, but it appears none of the current web fare on volumentric flow and turbos takes into account VVT the way our Ecotec is engineered.

The turbo sizing article says to assume a VE of .85 or .9. This can't be the proper assumption for our design. We have to be in the 100+ range. And for low end RPM perhaps in the 100++ range.


The compressor maps article is also a good read. This analysis is actually what I'm trying to do with our Ecotec. But instead of trying to design a solution, I'm trying to back out the designed solution and figure out where the Ecotec/GM guys put us in our RPM band. For example, the rule of thumb is to design the turbo for peak efficiency at the torque peak. But our engine is designed for peak torque from 2500 to 5300! The presumpition is the VE changes lineraly with RPM, but that is NOT the case if you can change the valve timing...which is what our Ectotec does....so that design approach won't work without a better handle on how VE changes over the RPM, which is dictated by VVT.

The last map is the compressor map for our turbo. It's the one I'm using now. But I can't establish our operating band without a good number for VE. I put our 100% VE numbers on the compressor map, and it strongly suggests we need to be well over 100% VE (which makes sense considering the GM engineer coments on the liberal valve overlap at low RPM...but how much is the question).

Again, thanks for the input. That's very good info. Good reads. But I still need the VE for our Ecotec...or at least a 4 banger with turbo AND VVT.

[MataguaySky]

Ray Hall Turbocharging has a VE calculator. Used parameters as follows:

CI 122, HP RPM peak 5200, HP Peak 260 = VE 184%

a place to start?

[Bogie]

Originally Posted by MataguaySky

Ray Hall Turbocharging has a VE calculator. Used parameters as follows:

CI 122, HP RPM peak 5200, HP Peak 260 = VE 184%

a place to start?

Thanks, the 184% number looks very reasonable.