How do you read/use this?
07-21-2005, 08:55 AM
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07-21-2005, 09:23 AM
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Re: How do you read/use this? (0x64)
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by 0x64 »</TD></TR><TR><TD CLASS="quote">https://honda-tech.com/zerothread?id=142398</TD></TR></TABLE>
That's something else...the chart he posted relates to turbines or the hot side of a turbo. That thread is about compressors or the cold side of the turbo.
EDIT: if you have a copy of Maximum Boost turn it to page 33. Halfway through the 2nd para. "Judging by the numbers (A/R ratios) requires measurements of the exhaust manifold pressure, or turbine inlet pressure with boost pressure".
I think what that chart is telling us that the smaller a/r (the lower line) will create more boost pressure through the compressor at the same turbine inlet pressure as the bigger a/r. If I'm reading it right, the numbers on the left tells us the pressure of the exhaust gas entering the turbine, and the numbers on the bottom tells us how much boost pressure it would generate through the compressor. I'm not sure if the bottom number deals with pressure from the compressor or if it's the pressure of the exhaust gas after the turbine like civicross said.
DOUBLE EDIT: after looking at it again, the bottom number might be related to the turbine too. A PR of 3 is roughly 30 psi, and a GT28RS compressor at 30 psi is way out of it's effieciency rating. So I dont thing that PR or pressure has to do with the compressor, but the turbine.
But still to be able to make use of this chart I think you would have to know your engines specific exhaust manifold pressure/turbine inlet pressure, so you can see where you would fall on this chart.
Modified by BlueShadow at 10:45 AM 7/21/2005
Modified by BlueShadow at 10:47 AM 7/21/2005
That's something else...the chart he posted relates to turbines or the hot side of a turbo. That thread is about compressors or the cold side of the turbo.
EDIT: if you have a copy of Maximum Boost turn it to page 33. Halfway through the 2nd para. "Judging by the numbers (A/R ratios) requires measurements of the exhaust manifold pressure, or turbine inlet pressure with boost pressure".
I think what that chart is telling us that the smaller a/r (the lower line) will create more boost pressure through the compressor at the same turbine inlet pressure as the bigger a/r. If I'm reading it right, the numbers on the left tells us the pressure of the exhaust gas entering the turbine, and the numbers on the bottom tells us how much boost pressure it would generate through the compressor. I'm not sure if the bottom number deals with pressure from the compressor or if it's the pressure of the exhaust gas after the turbine like civicross said.
DOUBLE EDIT: after looking at it again, the bottom number might be related to the turbine too. A PR of 3 is roughly 30 psi, and a GT28RS compressor at 30 psi is way out of it's effieciency rating. So I dont thing that PR or pressure has to do with the compressor, but the turbine.
But still to be able to make use of this chart I think you would have to know your engines specific exhaust manifold pressure/turbine inlet pressure, so you can see where you would fall on this chart.
Modified by BlueShadow at 10:45 AM 7/21/2005
Modified by BlueShadow at 10:47 AM 7/21/2005
07-21-2005, 09:38 AM
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Re: How do you read/use this? (0x64)
The above thread does not address reading turbine maps. I have searched and searched and not found good information on the subject.
What I have come to understand is this. The X axis or Pressure Ratio is the pressure ratio inside the exhaust manifold relative to atmosphere, similar to how you calculate the pressure ratio for a compressor map. The problem is there is no easy way to read your exhaust manifold pressure. We have a boost gauge for the intake but seldom if ever have I seen a guage used on the exhaust. On the Y axis is plotted exhaust flow in lb/min. You can see it is roughly half the flow you see on the compressor side. It is a smaller amout of flow since you have converted flow to power. But how do we know exactly how much we are flowing in the exhaust side? We would need a means by which to measure it. I think this is much easier done on an engine dyno under controlled conditions than what "we" have in our street cars or garage. Again, I am not swearing on this, it is just what I have been able to piece together from various sources.
The take away I get from all of this is it is MUCH more important to match the compressor side as it will have the biggest impact on efficiency which we call power. On the turbine side we can trust that smaller turbine housing provides quicker spool along with more resistance to flow limiting TE power. Other way round for a larger turbine housing. Larger housing equals decreased spool but greater TE. I think it is pretty common knowledge what turbine housing to use on which size engine for your driving goals. We just need to remember that until Garrett makes a wider variety of VNT turbos or the electric assist turbo comes to market we will ALWAYS have a trade off to consider.
Hope this is useful to you.
-Brian
What I have come to understand is this. The X axis or Pressure Ratio is the pressure ratio inside the exhaust manifold relative to atmosphere, similar to how you calculate the pressure ratio for a compressor map. The problem is there is no easy way to read your exhaust manifold pressure. We have a boost gauge for the intake but seldom if ever have I seen a guage used on the exhaust. On the Y axis is plotted exhaust flow in lb/min. You can see it is roughly half the flow you see on the compressor side. It is a smaller amout of flow since you have converted flow to power. But how do we know exactly how much we are flowing in the exhaust side? We would need a means by which to measure it. I think this is much easier done on an engine dyno under controlled conditions than what "we" have in our street cars or garage. Again, I am not swearing on this, it is just what I have been able to piece together from various sources.
The take away I get from all of this is it is MUCH more important to match the compressor side as it will have the biggest impact on efficiency which we call power. On the turbine side we can trust that smaller turbine housing provides quicker spool along with more resistance to flow limiting TE power. Other way round for a larger turbine housing. Larger housing equals decreased spool but greater TE. I think it is pretty common knowledge what turbine housing to use on which size engine for your driving goals. We just need to remember that until Garrett makes a wider variety of VNT turbos or the electric assist turbo comes to market we will ALWAYS have a trade off to consider.
Hope this is useful to you.
-Brian
07-21-2005, 11:05 AM
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07-21-2005, 11:33 AM
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Re: How do you read/use this? (legendboy)
Great article, thanks for posting. I would still like to see a basic breakdown for how to match the turbine wheel and housing size to the compressor side and ultimately our power/usage goals... as we have seen for the compressor side.
07-21-2005, 12:02 PM
#9
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Re: How do you read/use this? (Alfa Turbo)
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Alfa Turbo »</TD></TR><TR><TD CLASS="quote">Great article, thanks for posting. I would still like to see a basic breakdown for how to match the turbine wheel and housing size to the compressor side and ultimately our power/usage goals... as we have seen for the compressor side.</TD></TR></TABLE>
you won't find that information anywhere. i don't even think garrett performance dealers get that information lol
you won't find that information anywhere. i don't even think garrett performance dealers get that information lol
07-22-2005, 07:59 AM
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Re: How do you read/use this? (Benjithx)
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Benjithx »</TD></TR><TR><TD CLASS="quote">pick up the latest "Super Street" magazine
Has a great multi-page article on turbo selection
</TD></TR></TABLE>
Cool, I'll take a look and let eveyone know what I find.
Has a great multi-page article on turbo selection
</TD></TR></TABLE>Cool, I'll take a look and let eveyone know what I find.
07-22-2005, 08:29 AM
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Re: How do you read/use this? (vwandhondaboy)
It is another good article... still does not go directly to the topic of this thread. 
Anyone got Garretts direct line?
Anyone got Garretts direct line?
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