Compressor Map

[CrazyM]

So tonight I was reading about compressor maps and stuff. and found a sweet excel spreadsheet to plot mine out. This is what it looks like with the specs I entered. Can anyone tell me If I entered anything wrong? And tell me what exactly it means.

MUCH appreciate!

Mike
http://www.dsmtuners.com/forums/attachment.php?attachmentid=79125&stc=1&d=1200302944
Compressor Map.jpg

 

[kenamond]

I don't have the actual spreadsheet, and I don't know if your VE is reasonable, nor if the Liter to cubic inches conversion is correct. I assume the spreadsheet is computing the lb/min values from all of this. If this is all correct, then the overlay on your compressor map tells you what efficiency the compressor will be compressing the intake charge at for those 5 points. If you look at the compressor map, it gives efficiency values for each contour line on the map. Lower efficiency means the outlet (compressed) temperatures will be higher than at higher efficiency. At higher temperatures, your intake temperatures will be higher, and you'll be more likely to knock. Also, you'll heat soak your intercooler if temps are too high.

It's just a way of evaluating a turbocharger's compressor given a target boost pressure (which is used to calculate the pressure ratio on the map) and motor (including VE, RPM, displacement, etc.). But the VE numbers are probably off for the high rpm range. And the turbine side also has to be able to handle the high flowrates at higher RPM in order to drive the compressor at the desired boost level.

 

[Artago]

Can you post the excel sheet?

 

[toofast82]

Try this one out, then plot it on the compressor map
CFM Calculations
it will give you your engine's cfm requirement at a given rpm/boost setting

 

[Artago]

^^ That's kinda cool but how does it work and does it work correctly?

 

[toofast82]

^^ That's kinda cool but how does it work and does it work correctly?

you plot your engine info(2.0l, max rpm, target high boost, 90%ve) then it will come up with figures of cfm/lbmin requirents at a given rpm/boost then you plot the lb/min on the compressor map at the appropriate pressure/boost to see how efficient the compressor is for a given application. you can also get an idea of spoolup on the low side as well. It seems decently accurate for what ive played around with it. There are variables that will effect ve though such as cams and intake manifold.
For example ill use a typical 2.0l, 7krpm, 20psi at 90%recommended ve for 4valve engines.
http://cybrina.mine.nu:8080/WebModule2/compcalc?size=2.0&ve=90&boost=20&maxrpm=7000&Submit=Submit
http://www.stealth316.com/images/td06h-20g-cfm.gif
At 7k rpm at 20psi it will require 36.82lbmin/525.4cfm. If you plot this on a 20g compressor map with a pressure ratio of 2.36 or 20psi you will see it maintains pretty good efficiency. For spoolup you could lets say plot 20psi at 4krpm(300cfm) and will notice its right on the edge of the surge line

 

[dsm-onster]

Can you post the excel sheet?

Yes. Post a download link.