Those who can read compressor maps... this any good?

[DCsGST]

I found this turbo on Ebay, but all the description says is "T3/T4 that supports 350-450 whp"

Here is the compressor map, I emailed the guy asking what trims this turbo is, but I can't really read these maps:

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[IceClaw]

I don't know if this will help but here are a few links to some articles regarding compressor maps and calculations...

http://www.vfaq.com/mods/Turbo-compressor-maps.html

http://www.lovehorsepower.com/MR2_Docs/compressor_flow_maps.htm

If I get a chance later today I'll check my oldschool turbo book that has a pretty detailed write up on compressor maps for you.

 

[Talonman]

I heard the TO4b is weak sauce :laugh:

 

[DCsGST]

Compressor is a T04B-V1/V2, but what the heck is that in normal person language?

 

[DCsGST]

Compared to a TO4E 50trim it does look like a POS, but I don't know. I'm just looking at the surge line.



50 trim

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V-1/V-2

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[IceClaw]

You need to figure out what boost pressure you are planning on operating it at as well as the rpm you want to make peak power at, do some calculating with various rpm points in order to see where on the map you fall. Ideally the closer to the center of the map the better.

For example you need to know the pressure ratio, volumetric efficiency, and flow rate for a few different rpm ranges like max hp, max boost and where boost starts.

To find the engine flow rate use this formula:

CFM = L x RPM x VE x Pr
5660

L is engine displacement in liters
VE is volumetric efficiency (turbo vehicles tend toward VE of >100% but we'll use 90%
Pr is pressure ratio

Pr =
(atmospheric + Boost)
atmospheric

Atmospheric is 14.7 psi (or lower at higher elevations) and we'll use 17 psi for our max boost.

So Pr is:
14.7 + 17 = 2.1564 ( 2.16)
14.7


So to use our formula for finding our flow rate at max Hp (we'll say 7000 rpm):

2 X 7000 X 90 X 2.16 = 480.84 cfm (481 cfm)
5660

We now know that our engine will flow about 481 cfm at 7000 rpm, to convert to lbs/min divide by 14.27 so 481 cfm = 33.71 lbs/min

Take the flow rate (33.71 lbs/min) and the pressure ratio (2.16) and find where they cross on the map.

Do they same calculation for the other rpm's and plot them as well. After that you should have a better idea if it will work for you.

Remember when calculating for initial onset of boost to use 1 psi for the boost pressure.

All of the information for these calculations are from www.lovehorsepower.com and from Hugh MacInnes book: Turbochargers.

As well any errors in grammer, punctuation or spelling (and even possibly some of the technical information) are a result of my stomach growling and my mouth watering as my wife is cooking what smells like an AMAZING roast beef dinner for me!

Hope this helps!

 

[gasguzzler]

Doesn't look very efficient to me. Peak of 73%, I know there are turbos out there more in the 75-77% neighborhood with a much larger island in that area.