[s-cars] Turbo Compressor Maps

Cody Payne cpayne at bconnected.com
Wed Aug 6 12:05:49 EDT 2003

	I have Corky Bell's Maximum Boost on order but wanted to get some pre-knowledge on reading and planning on a turbo upgrade via Compressor Maps.  In looking at some Garrett Hybrids at I am trying to understand how a Garrett T04E at 54-57 trim is the turbo that most of the Hybrid users are using.

To calculate my Y Axis Pressure Ratio you take Target PSI + 1 Atmosphere (14.7) and divide by 1 BAR

So lets say we are shooting for 24 PSI that would give me a PR of 2.63
Or at 20 PSI 2.36

On the X axis we have Corrected Air Flow (Lbs/Min).
	Assuming that for every 1 PSI of boost is equal to roughly 10 HP (very rough google estimate..more accurate would be appreciated)
		(I understand there are MANY more factors but for the layman like me lets KISS (Keep it simple stupid)

Now if the 2.2L engine normally aspirated could say put out 130 HP then to get up to around 380 HP I would need around 25 lb/min right?

But now if you look at the above URL/Link and connect the two lines on the 54 trim puts me on the surge limit line and the 57 trim also puts me over the line.  Now perhaps my amateur calculations are WAY off as I know 3-4 guys running the 54 Trim that are very happy with it.  So perhaps it is more like 30 lbs/min at a lower boost?

Any insight while my book is being shipped would be greatly appreciated.


Cody Payne

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