Turbo exhaust theory discussion
#29
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The turbine on the turbo is extracting energy from the exhaust to drive the compressor. The total amount of thermal energy in the exhaust is called enthalpy. The amount of energy at any given point is the mass flow times the enthalpy. Energy = mass flow x Enthalpy
The change in enthalpy across the turbine is how much energy the turbine extracted from the exhaust. You want to maximize this to make it spool faster. It takes a certain mass flow to spool the turbo, the quicker you get that mass flow, the sooner you get boost.
A larger exhaust pipe after the turbine lowers the pressure on that side of the turbine. The bigger the pipe, the lower the pressure will be. This improves the flow in the system, so mass flow goes up at any given boost pressure. So more mass flow everywhere from spooling to redline.
This has two big benefits. Time to boost is shorter, and power at a given boost level will be higher. Smaller benefit would be reduced turbine inlet pressure, which will make the motor slightly more knock resistant too due to less internal EGR.
The change in enthalpy across the turbine is how much energy the turbine extracted from the exhaust. You want to maximize this to make it spool faster. It takes a certain mass flow to spool the turbo, the quicker you get that mass flow, the sooner you get boost.
A larger exhaust pipe after the turbine lowers the pressure on that side of the turbine. The bigger the pipe, the lower the pressure will be. This improves the flow in the system, so mass flow goes up at any given boost pressure. So more mass flow everywhere from spooling to redline.
This has two big benefits. Time to boost is shorter, and power at a given boost level will be higher. Smaller benefit would be reduced turbine inlet pressure, which will make the motor slightly more knock resistant too due to less internal EGR.
#30
![Default](https://www.miataturbo.net/images/icons/icon1.gif)
The turbine on the turbo is extracting energy from the exhaust to drive the compressor. The total amount of thermal energy in the exhaust is called enthalpy. The amount of energy at any given point is the mass flow times the enthalpy. Energy = mass flow x Enthalpy
The change in enthalpy across the turbine is how much energy the turbine extracted from the exhaust. You want to maximize this to make it spool faster. It takes a certain mass flow to spool the turbo, the quicker you get that mass flow, the sooner you get boost.
.
The change in enthalpy across the turbine is how much energy the turbine extracted from the exhaust. You want to maximize this to make it spool faster. It takes a certain mass flow to spool the turbo, the quicker you get that mass flow, the sooner you get boost.
.
You also want to minimize the work that the compressor has to do, it is a small amount but if you can optimize this there are gainz to be had. Also the pressure ratio of the turbine is directly related to the temperature, if you can increase the temp prior to the turbine you can increase the delta of the enthalpy which will give you more power. Yet we are a bit limited on a metallurgical level here as melting pistons and such is no fun.
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