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copbait73 copbait73 is offline
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Join Date: Nov 2003
Location: Chesterfield IN
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Quote:
Originally Posted by turboteener View Post
Here is the map for the Garrett GT25R:


I am looking for a map of that Chrysler VNT.

I would never consider a single GT25 for anything bigger than about 1.3 litres. What would possess anyone to try a single GT25 on 3.2 Six (Porsche?)? That turbo is tiny. I think a GT28 is a good turbo for a 1.6-1.8litre engine. Maybe a 2.0 if it has head flow like a VW four cylinder. I would be tempted to try two of them on a 3.5. Maybe a pair of GT2871s for good drivability, not ultimate top end power, but it would work great on a daily driver level.

I got the GT15 from Garrett. It may have been a GT12, it has been awhile since I looked at it.
No, no I didn't suggest a T25 SINGLE on a 3.2 Porsche. Second, this GT25 may not be the compressor on the T25VNT.
Finally, I said I recall T25 singles used on 3.2L DET cars with full restrictive CATs and low power settings. Mainly torquers meant for bottom end power ending around 4000RPM. I think they were GrandAms roughly 88-90 timeframe.
But, using this map, If you look at a Porsche 3.3L with twins you look at say, 3000 RPM, 20#/min at 2.0P.R.(1 bar) and 6000, 48#/min, 2.0P.R. Taking these flow readings at half you are centered on the map.
Actually the VNT can drive you right up the surge line. In this example it's at a full 1 bar at 3000RPM. Obviously this is a problem and the reason why most modern turbos use recirculating inlets and broad range impeller designs to improve the surge line so you can use your more desirable higher flowing turbos.

Last edited by copbait73; 03-03-2008 at 06:44 PM..
Old 03-03-2008, 06:32 PM
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