Thanks Mike. That number sounds like a good average for these beasts.

 

What I meant was that an early statement said that for non turbo cars, that max VE would be say 130. So take any non turbo car that has the same performance as say a 996tt or 997tt (standard), then would that same car have a similar VE e.g. 185?

 

Can you explain that in English for me - the formula

 

Sorry guys, I have a question on Ve: in A. Graham Bell's forced induction book I found some suggested Ve values for 4 valve engines: 90% through 105% depending on the level of modifications operated on the engine...And he uses these values to calculate the necessary compressor CFM when trying to match engine/turbo.

How can I relate the values you are calculating to those suggested in the book?

 

Try this link. You should have all the values to populate.

 

wa = actual engine airflow (lb/min)
hp = horsepower at the crank
AFR = air fuel ratio
BSFC = brake specific fuel consumption which you divide by 60 to convert to min. (typical turbo engine is .45 to .60)

 

depends on the fuel used, but figure an aggressive tune and race fuel .45 to .50

 

Why cant i see the graph!

 

lol!

 

Hi, I think what you're asking is described nicely on the Garret turbo site with examples. Click here. As far as my understanding goes, you can't really relate the VEs calculated here with what you are asking. Basically, you have to match the turbo with what your motor can flow. Obviously, if you slap on a big honking turbo and your motor can't flow enough air to spin the turbine adequately, it will do you no good. So those equations are meant to be used to put you in the right ballpark in choosing a turbo if you were starting from scratch. Fortunately, we have a ton of real-world data to rely on.

After you add the turbo's, the VEs obviously go up. We're are measuring VEs for different set-ups, post-mod. The goal, of course, is to maximize VEs across the rpm power range. You could measure VEs after installing different supporting mods like ICs to see which might be more effective under different conditions. Just because an IC may be controlling IATs better at X hp does not mean that it will be suitable at higher hp due to flow restrictions. VEs will tell you this.

 

Sorry, dunno. Try a different computer? Attached is a PDF of that graph. Hope that helps.

 

This is exactly why we stopped using the modded VTG's after 750hp, we can make "better" power running the custom A28's...

 

Have you guys gotten over 700whp out of VTG's?

 

From the looks of it, it seems that you get better power even well below 750--lol.

 

How do you work out BSFC

Given that


Where:
r is the fuel consumption rate in grams per second (g·s-1) P is the power produced in watts where P = τω How do you know what the fuel consumption of your engine is ie r

Frank