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Old 04-22-2012, 02:14 AM   #1
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Default Turbo backpressure? What turbo backpressure?

I logged turbine inlet pressure and generated the plot below.

X axis is RPM
Y axis is TIP-MAP (kPa)
color is boost

The darn GT2560 operates in crossover (MAP > TIP) in most conditions below 4200 RPM, by over 1 psi. The sucker makes 5 psi of boost by like 2200 RPM BTW.

At 15 psi of boost, TIP-MAP is 5 psi at 5700 RPM and 10 psi at 6800, 12.5 psi at 7400.

BTW at 15 psi of boost, my intercooler has 1 psi of pressure drop at 5000 RPM and 2 psi at 7400.

My exhaust has 4.5 psi backpressure at peak power and probably 2 psi in the midrange (I will log this next)

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Old 04-22-2012, 05:31 AM   #2
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lol is there anything you haven't logged on your car yet?
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Old 04-22-2012, 11:37 AM   #3
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what are your EGTs that correlate to that scatter plot?

Enthalpy drives the turbo and includes heat, pressure, and dynamic energy effects. with a hot, high volume flow rate exhaust, you'll spin that turbine.

I'm sure with VVT and some spark retard you can get more time in crossover.
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Old 04-22-2012, 12:52 PM   #4
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Bauce.
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Old 04-22-2012, 01:20 PM   #5
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Very interesting.
Ive always heard that with a good turbo setup with a free flowing exhaust, that the pressure in the IM should be a bit higher than in the turbo manifold, I just never knew by how much.

Any idea what typical NA backpressure values would be?
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Old 04-22-2012, 02:52 PM   #6
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Typical NA backpressure will be 4-5 psi at peak power.

My turbo shows TIP-MAP < 5 psi to about 6000 RPM.

Food for thought.
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Old 04-22-2012, 02:56 PM   #7
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Quote:
Originally Posted by y8s View Post
what are your EGTs that correlate to that scatter plot?
EGT sensors have a very slow response time. The data will be worthless without sustained loading like on a dyno or very high speeds.
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Old 04-22-2012, 03:23 PM   #8
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which EGT sensors are you talking about, they very on what type of thermocouple you use, like shielded vs unshielded.
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Old 04-22-2012, 05:02 PM   #9
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Old 04-22-2012, 05:22 PM   #10
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Jason what exhaust mani are you running?
(sorry for off topic)
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Old 04-22-2012, 05:56 PM   #11
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looks like a shielded thermocouple.
http://www.omega.com/pptst/JTIN.html
exposed junction, k type, innconel
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Old 04-22-2012, 09:46 PM   #12
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The graph looks vaguely like a *****.
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Old 04-22-2012, 11:00 PM   #13
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U know how I know you're gay?
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Old 04-22-2012, 11:45 PM   #14
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Jacopb inwanna measure my studf too.

What sensor u use?
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Old 04-22-2012, 11:46 PM   #15
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Quote:
Originally Posted by 2ndGearRubber View Post
The graph looks vaguely like a *****.
No it do not. Let me show u what one llook like.
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Old 04-22-2012, 11:52 PM   #16
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