Compressor Map Reading made simple!

[goofynick6]

UPDATE: ADDED A LOT OF NEW FEATURES!!

I know a lot of people are usually quite put-off by reading a compressor map and trying to figure out how their engine will plot out properly, so today I decided to make a spreadsheet to make it easier.

Although I'm sure something like this has been made before, I think this one is fairly simple to use. I put in a T04E 50 trim compressor map as an example, but you can still use the calculated values and plot them on any other compressor map of course (I included a link to many popular Garret maps).

Just plug in the proper values and it will give you the numbers you need and even plot them on the example map up to 50lbs/min.

Right-click and save as

EDIT: I added a LOT of compressor maps, and added 5 data points instead of one, and also included elevation and pressure drop calculations!!

That is the link, enjoy! If you find any errors let me know and I'll fix it, or if you have a better idea of how to do things let me know. This was just done out of boredom today to save myself some time of doing all the math involved.

Nick

 

[definitiveno]

There is no coralation between compressor efficiencies. It said at 100 psi and 7000rpm my 50 trim will flow 122 lbs/min


theres a glitch too, 7000rpms plots the same as 2750rpm's

 

[rsunahar]

There is no coralation between compressor efficiencies. It said at 100 psi and 7000rpm my 50 trim will flow 122 lbs/min

I don't understand how to change to a different compressor map.
It's cool, though

 

[goofynick6]

There is no coralation between compressor efficiencies. It said at 100 psi and 7000rpm my 50 trim will flow 122 lbs/min


theres a glitch too, 7000rpms plots the same as 2750rpm's

Ok,
It does change at 2750, there's no glitch, you just have to click off the cell you're typing in for it to take effect. So type in the rpms, then click anywhere else and it will change the values.

The 50 trim map as stated, was just an example I included in this spreadsheet to show how you would plot the point (pressure ratio vs. Lbs/min) on a normal map. If I wanted to make all the maps selectable on that spreadsheet it would take days to finish.

So, if you want to do another turbo, just take the pressure ratio and the Lbs/min and plot them on that map (takes 2 seconds) and that will show how that compressor size works with the specs of the engine you typed in.

 

[goofynick6]

I don't understand how to change to a different compressor map.
It's cool, though

As I said in the previous post, you can't select different maps in this spreadsheet as it would take me days to input them all (we'll see, I might do it later).

So, just click on the link provided to check the other maps and plot the pressure ratio vs the Lbs/min.

Nick

 

[kmartind]

Good idea, just a couple corrections.
First: You're off by 1 on the pressure ratio plot example, the pressure ratio is correct but the graph plots it one unit too high because it starts at 0 instead of 1 like it should. A pressure ratio less than one would be vacuum...
Second: It would be useful to be able to adjust altitude as well as temperature. I had to unlock the spreadsheet to adjust it for 5860ft.

 

[goofynick6]

Thanks! Fixed the chart info...just trying to figure out how to compensate for elevation..

NIck

 

[kmartind]

I usually approximate with something like:
14.7*(1-((altitude_in_feet/1000)*.03))
I could be off though, it's been years since my last math class, but it seems you lose about 2.9-3% air density per 1000 ft on average.

 

[goofynick6]

Awesome, thanks for the formula; I added that to the program and updated it.

Nick

 

[90AWDTalon]

There seems to be some problems with your formulas. I made a calculator a year or so ago and get different results. Using the numbers you have inputed at 22 psi the pr should be 2.598639456 not 2.5. Ib/min on my calculator is 20.57832 you have 21.41. You have everything locked except for inputs so I can't see what your doing with your formula's.

EDIT: I think I just figured out why your pr is different, are you figuring in any pressure loss do to intercooler and piping?

 

[goofynick6]

If you want it unlocked, just goto "tools", then "unprotect sheet"

As far as pressure loss, no, I'm not accounting for that. These are just basic formulas to get an idea of things, a difference in pressure of 1psi won't make a huge difference for most people getting a rough idea.

Nick

 

[fiveiron]

maybe im a retard..which i probably am..but i dont really understand how to use the spreadsheet

 

[goofynick6]

maybe im a retard..which i probably am..but i dont really understand how to use the spreadsheet

Haha, no problem, the directions are near the bottom in the orange section.

Basically you fill in the boxes that are blue with the values corresponding to your car and rpm levels, boost levels, etc and then it calculates two main numbers. One is pressure ratio, that is the number found on the vertical (y) axis of compressor maps, and the other, Lbs/min is the x axis or horizontal axis on compressor maps.

You can calculate different flow levels at different rpms and plot out these points on any compressor map to see how its efficiency levels are at that level of pressure. In the spreadsheet I have put in a to4E 50 trim graph as an example of where the point will fall if plotted. You can instead take those two numbers and plot them on any compressor map and it will show you the efficiency level. Plot 4 or 5 points corresponding to different rpm or boost levels to see how your turbo will be when spooling.

Nick

 

[fiveiron]

boy do i feel dumb..that clears everything up..thanks

edit: so then that point that you plot will go into a certain section that shows the efficiency, right?

 

[goofynick6]

boy do i feel dumb..that clears everything up..thanks

edit: so then that point that you plot will go into a certain section that shows the efficiency, right?

That point shows the amount of flow your engine will have at that rpm and boost psi, the map shows where in the compressor's efficiency range that point will fall...ie, the 70% ring or 65%

Nick

 

[goofynick6]

I think I'll work on this in the future, making maps selectable, but that'll take some time. I might also make it so you can plot several points, instead of just one.

Nick

 

[fiveiron]

keep us informed with the newer versions when you get them done..i am trying to learn how to read the maps and this is helping me out

 

[goofynick6]

UPDATED:

Lots and lots of maps, 5 data points, pressure drop calculations, elevation, etc!

Much more fun to use.

New Version 2.1

Nick

 

[thegreatms]

awesome spreadsheet. Thanks alot

 

[blcknspo0ln]

thanks !

 

[fiveiron]

man this is awesome...really helps when you are trying to learn how to read the maps..especially giving us multiple points..thanks

 

[goofynick6]

man this is awesome...really helps when you are trying to learn how to read the maps..especially giving us multiple points..thanks

Glad I could help someone out. If anyone else thinks of a turbo they'd like on there, or can see a way to improve things, just let me know.

Nick

 

[definitiveno]

The gt35 maps don't look right to me. Only 50 lbs/min?

 

[goofynick6]

The gt35 maps don't look right to me. Only 50 lbs/min?

Are you referring to the webpage with the compressor maps? If so, those are manufacturer-spec maps made by Garrett, the GT35R flows about 60lbs/min if that's what you're thinking of.

Nick

 

[definitiveno]

Are you referring to the webpage with the compressor maps? If so, those are manufacturer-spec maps made by Garrett, the GT35R flows about 60lbs/min if that's what you're thinking of.

Nick

alright