Calculating power of a Turbocharger

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Discussion Overview

The discussion revolves around calculating the power output of a turbocharger based on changes in pressure and temperature within the intake manifold. Participants explore the relationship between these variables and the implications for engine performance, focusing on theoretical calculations rather than empirical results.

Discussion Character

  • Exploratory, Technical explanation, Debate/contested

Main Points Raised

  • One participant inquires about calculating turbocharger power using changes in pressure and temperature, providing specific values for atmospheric and intake manifold conditions.
  • Another participant questions the assumption of constant volume during compression, suggesting that this may not hold true.
  • A different participant proposes that the air intake system should be considered as having a constant volume throughout the process, excluding outside volume from the calculations.
  • One participant estimates the air displacement of a 2L engine at 5000rpm, suggesting that the energy stored in the compressed air could yield a power output around 50kW, although they do not provide a specific equation to support this claim.

Areas of Agreement / Disagreement

Participants express differing views on the assumption of constant volume during compression, indicating a lack of consensus on this point. The discussion remains unresolved regarding the exact calculations and implications for turbocharger power output.

Contextual Notes

Participants do not provide a definitive equation for calculating power, and the discussion includes assumptions about the system boundaries and conditions that may affect the calculations.

Who May Find This Useful

Individuals interested in automotive engineering, turbocharging technology, and thermodynamics may find this discussion relevant.

b_dobro
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Hi. My question is about the turbocharger itself and not about the resulting power increase from the added air in the combustion chamber.

Can you calculate the power of a turbo if you have the change in pressure (atmospheric VS. Intake Manifold), and the change in temperature (outside air to intake manifold temp).?

For example, you know the outside temperature is 25 C, the temperature after compression is 120 C. The initial pressure is atmospheric 14.7Psi, and after compression it is 24.7Psi. Volume is constant. Is there a way to find the power of the turbo if it is able to deliver this pressure change at a constant rate?

I'm just looking for a ballpark number, no need to be exact.
 
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I'm sure there's a way to do it although I'm not in a position to figure it out right now, but, are you sure the volume is constant...during compression?
 
I'm guessing the system would be the air intake side of the engine, so volume should remain the same throughout. I don't think the outside volume should be part of the system.
 
Every revolution of a 4 stroke engine, it displaces half of it's displacement. So, a 2L engine moves 1L of air every revolution.

Say you're boosting 15psi at 5000rpm, that's 83L of air at 15psi every second.

I don't know the equation off hand, but however many joules of energy are stored in 83L of air at 15psi above atmospheric should approximately be the wattage the turbo is putting out. It'll probably be some stupid high number around 50kW; Those things pump some serious amounts of air.
 

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