I know there are few of these little programs around but I thought I'd post the one I wrote using the formulas Garrett uses on their selection guides. Makes it easy to change around conditions and see the results instantly without having to recalculate everything. Let me know if you have any questions on using it. I think it's pretty self explanatory tho. Here's the link to it as well as a couple screenshots. Many of you guys are using used turbo's from other vehicles so you'd have to find the specs for the turbo for this to be used very accurately. Read a post from someone wanting a turbo for a 454 so I thought I'd post as it might help.

http://c4caraudio.com/tech/forced_in...rbocalc_v2.xls

 

Very nice. I filled out all the info on the first table (User Variable Data). It gives me figures in all 3 Calculated Data tables, but no Example Plots on the table below. Am I missing something? :1

EDIT: Nevermind, figured it out. My pressure ratio's are way under 1.00 so that's why it's not showing up. But they look low, only around .18 to .19 for all series. That doesn't seem right.

 

Hard to say without knowing what info you input. If your ratios are under 1 then some data is wrong. Make sure you input the correct engine displacement in cubic inches, not cubic centimeters or the ratios will be low. If your horsepower number is less then the engine will do NA then it will be low as well. Post your data or a screenshot if you want and I can help figure it out.

 

Make sure there is a decimal point in front of your VE.

That is what I was doing wrong.

 

And thats what I was doing wrong too. :1 Thanks!

 

Thanks for this, I've been trying to settle down on one turbo and haven't been able to figure out what I'm going to use until now.

 

very useful tool thanks

 

You can also put a % symbol after the number too if you don't have the decimal. VE = .92 or 92% (or whatever you use)

 

kick ***! thanks man

 

so how does this factor in compression ratio, rod/stroke and the increase or decrease flow from manifold/dp combinations?