Turbo Compressor Maps

Who on here actually understands/knows how to read them?
I looked into this the other night as I wanted to know more and now understand what they mean, I think? Quite interesting just a lot of calculations involved.

I havent got a clue tbh never looked that close into it .... probably dave (watoga) seeing as he loves graphs   

I googled it as I didn't know what to do with the numbers on the graphs provided by the turbo suppliers. Might throw up some comparisons at some point between some of the garrett turbos?

Yeah that would be great pete ....is it relativley simple once you actually know what your looking at ?

This is where I found my info, have a read of this Leighton

http://hondaswap.com/forced-induction/compressor-map-reading-dummies-129194/

i opened a thread for this subject before buying my GT2860rs...

fred05 wrote:i opened a thread for this subject before buying my GT2860rs...

On here Fred? What did you find out?

I don´t understand compressor maps also, i wich i could, but generally for comparison sake you can look at the CFM rating...

That´s good for comparing turbos and horsepower capabilitys, not good for response/spool estimates... that varies on another factors, like exhaust, timing, cams, etc...

But if you want to compare lets say a GTIR that´s rated at 465CFM@14.7psi to a Subaru TD04 390CFM@14.7PSI you know that the gtir flows more volume of air, capable of making more horsepower...

Compressor maps are not easy to read, i tried...

The thing with compressor maps for me is you cant just look at one and know what info you can extract, knowing certain figures/info and doing a few calculations is firstly needed.

Right I finally got round to working out the calculations of my turbo as per my spec.
My GT2560R is rated on Garrett's website as 200-330hp. So below is the compressor map with an explanation.


Right so I planned to run turbo @ 1.2 bar which works out as 2.2 on the pressure ratio(red line). The blue line indicates where I would first achieve 1.2bar; approx. 13lb/min which equates to roughly 2450RPM. After discovering I currently make peak power around 6500rpm i wouldn't rev it much beyond this, say 6750rpm.
With the calculation of 2x6750x90x2.2=2,673,00/5660=472cfm(33.1lb/min), the yellow line.
So theoretically i could achieve approximately the stated 330hp.

This probably make no sense to most as it took me a while to understand. Ill do one on the GT2871 and maybe the GT3071 at some point.

Very intresting pete .... although its little bit beyond my knowledge of turbos i kind of understand the basics of the graph ... 

Yeah, all the theory is in the link in one of my above posts.

I understand what your saying I don't personally think it works like that in practise

Reckon your right Johnny as mine is making nowhere near the potential 330hp and don't think it would with a remap, maybe 290hp?

Yep I was thinking solid 280 same with my 2860R when I ran it I loved that turbo super fast spool but people claim 360 mine just produced heat after 320bhp it was brand new and on a solid engine slight restriction at the time on the elbow but doubt it was stopping it flow 30-40 bhp it really is a number of factors on each unit each car/engine in my experience and opinion mate

Yeah I get what your saying, just using this as a rough example to aid me in my next choice of turbo...if I get one.

Right this is a comparison for a GT2871R direct replacement.

The Pressure ratio(red line) is 2.5 which is just over 1.5bar. The blue line works out roughly that max boost would be achieved by around 3850rpm and the yellow line shows where the maximum flow is if revving to 7500rpm. The yellow is in the 71/71% island which according to the link anything over 70% is good?