Truckers, lets see your rigs!

1:1 has no basis in thrust values, unless you want to get all engineer level and calculate surface area acted upon on.

Opinion: 1:1 ratio has no basis in fact. The mass having work imparted to it and the mass imparting the work are only loosely connected by the turbine shaft. You would have to calculate enthalpy of the exhaust gas stream across the turbine, and calculate the power needed to flow/pump inlet air at any given point of operation. Pressure alone is far from an indicator of the efficiency of the turbocharger as a system. Calculate power in vs power out.

I would like to read if someone has published information to contradict my opinion. I've never had a reason to look in to it either way. I just (think I know) the energy available to the turbine and what's being imparted into the inlet air mass are so wildly different that it's not reliable to use pressure.

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biggy238 said:
1:1 has no basis in thrust values, unless you want to get all engineer level and calculate surface area acted upon on.

Opinion: 1:1 ratio has no basis in fact. The mass having work imparted to it and the mass imparting the work are only loosely connected by the turbine shaft. You would have to calculate enthalpy of the exhaust gas stream across the turbine, and calculate the power needed to flow/pump inlet air at any given point of operation. Pressure alone is far from an indicator of the efficiency of the turbocharger as a system. Calculate power in vs power out.

I would like to read if someone has published information to contradict my opinion. I've never had a reason to look in to it either way. I just (think I know) the energy available to the turbine and what's being imparted into the inlet air mass are so wildly different that it's not reliable to use pressure.

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A lot of that is over my head, however, wouldn't the 1:1 ratio lead you to believe that the forces are close to balanced? If the turbine housing is too tight or the wheel is too small, you'll see a much higher drive pressure number vs boost, the same if there's an intake restriction. When it gets a higher than 1:1 ratio you're seeing an inefficiency on one side or the other of the turbo, it's taking way more power than its producing.

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chevota84 said:
Thrust is axial, not radial. 1:1 will be near equal force towards the center of the turbo no matter what the pressure is.

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Yes so we can ignore the exhaust inlet and air outlet. The air inlet wants to climb the air, think of it as a propeller. If it was spun right up and let loose at high rpm (no housing or cover) it would launch forward at a high rate of speed.

Wouldn't the turbine do the same? It is expelling mass out the rear. That means the opposite force is forwards. So IF this is true, that means 1:1 drive to boost is irrelevant when it comes to axial thrust.
 
chevota84 said:
A lot of that is over my head, however, wouldn't the 1:1 ratio lead you to believe that the forces are close to balanced? If the turbine housing is too tight or the wheel is too small, you'll see a much higher drive pressure number vs boost, the same if there's an intake restriction. When it gets a higher than 1:1 ratio you're seeing an inefficiency on one side or the other of the turbo, it's taking way more power than its producing.

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Two scenarios I see:

1) VE of the engine is affected by the rise in back pressure. This causes the compressor map to shift to the left for the same pressure ratio. Not good.

2) VE of the engine is NOT affected by the rise in back pressure. This means the compressor side is not affected, it is exactly as efficient as 1:1 which means the TURBINE side has lost efficiency. This can probably measured by the temperature difference pre and post turbo.

Again these are just thoughts, I have no empirical data.
 
chevota84 said:
A lot of that is over my head, however, wouldn't the 1:1 ratio lead you to believe that the forces are close to balanced? If the turbine housing is too tight or the wheel is too small, you'll see a much higher drive pressure number vs boost, the same if there's an intake restriction. When it gets a higher than 1:1 ratio you're seeing an inefficiency on one side or the other of the turbo, it's taking way more power than its producing.

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It would appear that way on the surface but as kyle was getting at it is an arbitrary number when comparing a given turbine and compressor. Two entirely different designs. Different blade count, architecture, conditions (temperature), etc. More times than not bearings aren't the issue. It is overspeed and/or lack of oil supply. That doesn't necessarily mean the engine isn't keeping up so much as orifices and internal metering isn't supplying enough.
 
You guys know where I can get a chrome stamped peanut cover? Got a good customer asking for one

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zfaylor said:
It would appear that way on the surface but as kyle was getting at it is an arbitrary number when comparing a given turbine and compressor. Two entirely different designs. Different blade count, architecture, conditions (temperature), etc. More times than not bearings aren't the issue. It is overspeed and/or lack of oil supply. That doesn't necessarily mean the engine isn't keeping up so much as orifices and internal metering isn't supplying enough.
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I get that, but we're using it to monitor a setup that's in use, not engineering a turbo from scratch. Since you rarely see under 1:1 at wot we should able to use that number as an estimate of overall effeciency even though it won't cover every eventuality. You've seen a lot more turbos than I ever will; when would a 2:1 setup be efficient and a 1:1 wouldn't be?

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chevota84 said:
I get that, but we're using it to monitor a setup that's in use, not engineering a turbo from scratch. Since you rarely see under 1:1 at wot we should able to use that number as an estimate of overall effeciency even though it won't cover every eventuality. You've seen a lot more turbos than I ever will; when would a 2:1 setup be efficient and a 1:1 wouldn't be?

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That sounds dickish after I reread it and that's not what I intended lol.

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chevota84 said:
I get that, but we're using it to monitor a setup that's in use, not engineering a turbo from scratch. Since you rarely see under 1:1 at wot we should able to use that number as an estimate of overall effeciency even though it won't cover every eventuality. You've seen a lot more turbos than I ever will; when would a 2:1 setup be efficient and a 1:1 wouldn't be?

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All I'm saying is who is actually doing to show that X setup is in peak efficiency at 1:1? It is (very well put) arbitrary.

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