#1  
Old 09-29-2019, 09:43 PM
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74SDformula 74SDformula is offline
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Default Tell Me About This Turbo

Have been thinking about a single turbo build for some time now. A friend of mine mentioned he has this turbo for sale. I am totally ignorant about these things so maybe someone can tell me something about this one. Garrett GTX4294R I believe he said it has a divided T4 flange and it has a 1.15a/r whatever that means. Thanks in advance.

  #2  
Old 09-29-2019, 11:25 PM
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Tom Vaught Tom Vaught is offline
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The following info is if you bought the Turbo right from Garrett NEW.

The turbo can make 850- 900 HP at 30 psi of boost pressure.


Super Core P/N 800269-50015
CHRA P/N 451888-0043

Compressor:
Inducer= 70mm
Exducer= 94mm
Trim = 56
A/R = 60

Turbine:

Exhaust Inducer= 82
Exducer = 75
Trim = 84

Two T-4 Turbine Housing sizes available:
Turbine Kit = 101 mm Turbine housing
or a
Turbine Kit = 115 mm Turbine housing

Tom V.

ps I have attached a compressor map (1st image) and a Turbine map (2nd image)
The 115 mm turbine housing allows greater exhaust flow vs the 101 mm turbine housing.
The 101 will spool up faster.
Attached Thumbnails
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Last edited by Tom Vaught; 09-29-2019 at 11:31 PM.
  #3  
Old 09-30-2019, 07:52 AM
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74SDformula 74SDformula is offline
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Thanks Tom.

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Old 09-30-2019, 09:53 AM
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74SDformula 74SDformula is offline
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So how do I go about calculating what this turbo is capable of making at lower boost pressures such as 8, 10 or 12 psi?

  #5  
Old 09-30-2019, 02:43 PM
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Tom Vaught Tom Vaught is offline
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One Pressure Ratio = Atmospheric Pressure
1.5 Pressure Ratio = 7.5 psi of boost pressure
2.0 Pressure Ratio = 15 psi of boost pressure
2.5 Pressure Ratio = 22.5 psi of boost pressure

Draw a line thru the map from say 1.5 Pressure Ratio and you get about 42 lbs/min of
air flow and that multiplied by 10 gives you 420 horsepower.

Draw a line thru the map from say 2.0 Pressure Ratio and you get about 62 lbs/min of
air flow and that multiplied by 10 gives you 620 horsepower.

This Turbo/Garrett Turbo Map shows a fairly sharp angle on the difference between pressure ratio and lbs per minute on the lower scale.

This means that it really wants a higher boost/pressure ratio dialed in to make the resultant horsepower.

Some turbos have a wide map and the hp goes up because the lbs/min goes up quite a bit for a small change in pressure ratio.

Tom V.

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