FAO TURBO Experts: Understanding Compressor Maps
06-12-2005, 09:27 AM
#1
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FAO TURBO Experts: Understanding Compressor Maps
Can somebody in the know explain a compressor map?
Here is an example of a compressor map (Turbonetics T76)
Here is an example of a compressor map (Turbonetics T76)
06-12-2005, 09:43 AM
#2
Basically the pounds of air per minute can be converted into bhp (x10 + 30-40), which will be about it's absolute limit (with the turbo on it's knees).
So for example, a T4 flows 48lb x 10 = 480 + 40 = 520bhp, which is about the most you'd get from a T4 on today's crap fuel.
That turbo looks to me to be around 850-900bhp worth at 2.2 bar...
So for example, a T4 flows 48lb x 10 = 480 + 40 = 520bhp, which is about the most you'd get from a T4 on today's crap fuel.
That turbo looks to me to be around 850-900bhp worth at 2.2 bar...
06-12-2005, 09:49 AM
#4
Yep, as Mike says its about 10* airflow for BHP you will get, although obviously its dependant on the car in question as some engines are more effiencent that others.
With regards to the rest of the map, the line on the left is the point at which the turbo will start to surge, so if you tried to flwo for example 200bhp worth of air but needed a bar to so on your engine then it wouldnt be able to do it as that point is above that line.
The islands represent effiency levels of the turbo, so the inner one is the point the turbo "works best" at, and will generate small amounts of heat etc.
On the right handside its not as clear cut as the surge limit on the left, its possible to run a turbo right off its map, but doing so will produce a lot of heat and will also shorten the life of the turbo, although things like precompressor water injection can help obviously.
That probably covers most things, but let me know if there is anything else you want to know mate
With regards to the rest of the map, the line on the left is the point at which the turbo will start to surge, so if you tried to flwo for example 200bhp worth of air but needed a bar to so on your engine then it wouldnt be able to do it as that point is above that line.
The islands represent effiency levels of the turbo, so the inner one is the point the turbo "works best" at, and will generate small amounts of heat etc.
On the right handside its not as clear cut as the surge limit on the left, its possible to run a turbo right off its map, but doing so will produce a lot of heat and will also shorten the life of the turbo, although things like precompressor water injection can help obviously.
That probably covers most things, but let me know if there is anything else you want to know mate
06-12-2005, 09:50 AM
#5
This could be a good topic and lead to one about surge...
Basically Cam, if you look at the left hand side of the map you can see the pressure ratio, for teh purpose of this brief description, 1 bar of boost plus one atmosphere is a Pressure ratio of 2.00.
Now, if you follow the line from right to left of the map on the 2.00 line, you will see there are "Efficiency" islands and you will note there are now vertical lines from each efficiency island dropping down to an airflow scale.
For this example:
If we have an engine that will make 1bar of boost at 3000rpm but can only consume 20lbhr of air at 3000rpm, it will surge.
If we modify the engine so that it will make 1bar of boost at 3000rpm but can now consume 50lbhr of air at 3000rpm, it will not surge and it will make great power with great efficiency.
If our same engine goes on to make 1.8 bar of boost and can consume 80lbhr of air, it will make a lot of heat as well as around 850bhp.
Its all about choosing a turbo that suits the engine and its expected horsepower output without having a monster that will surge until high RPM when it becomes efficient.
Hope this helps as i admit its not worded the best way possible but im a tad busy at teh moment...
Basically Cam, if you look at the left hand side of the map you can see the pressure ratio, for teh purpose of this brief description, 1 bar of boost plus one atmosphere is a Pressure ratio of 2.00.
Now, if you follow the line from right to left of the map on the 2.00 line, you will see there are "Efficiency" islands and you will note there are now vertical lines from each efficiency island dropping down to an airflow scale.
For this example:
If we have an engine that will make 1bar of boost at 3000rpm but can only consume 20lbhr of air at 3000rpm, it will surge.
If we modify the engine so that it will make 1bar of boost at 3000rpm but can now consume 50lbhr of air at 3000rpm, it will not surge and it will make great power with great efficiency.
If our same engine goes on to make 1.8 bar of boost and can consume 80lbhr of air, it will make a lot of heat as well as around 850bhp.
Its all about choosing a turbo that suits the engine and its expected horsepower output without having a monster that will surge until high RPM when it becomes efficient.
Hope this helps as i admit its not worded the best way possible but im a tad busy at teh moment...
06-12-2005, 09:50 AM
#6
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Very quickly - sure somone else can elaborate...
You have 2 axis - the x axis is the volume of air that the turbo is moving, ie ur engine will be consuming, and the y axis - the pressure/boost the turbo is developing.
The x axis is in ib/min - which is roughly translates to 10lb=100hp.
The Y axis is pressure ratio - a pressure ratio of one is atmosphere ie 0psi of boost. Pressure ratio 2, is 1 bar of boost or 2 bar absoloute, pressure ratio of 3 is 2bar boost etc....
In the middle u have efficience islands. basically, they detemine how much heat is put into the compressed air. That particular turbo, working it quite hard at 2 bar of boost and 800hp would be in the second to last efficeincy island.
You have 2 axis - the x axis is the volume of air that the turbo is moving, ie ur engine will be consuming, and the y axis - the pressure/boost the turbo is developing.
The x axis is in ib/min - which is roughly translates to 10lb=100hp.
The Y axis is pressure ratio - a pressure ratio of one is atmosphere ie 0psi of boost. Pressure ratio 2, is 1 bar of boost or 2 bar absoloute, pressure ratio of 3 is 2bar boost etc....
In the middle u have efficience islands. basically, they detemine how much heat is put into the compressed air. That particular turbo, working it quite hard at 2 bar of boost and 800hp would be in the second to last efficeincy island.
06-12-2005, 09:51 AM
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Originally Posted by Mike Rainbird
Basically the pounds of air per minute can be converted into bhp (x10 + 30-40), which will be about it's absolute limit (with the turbo on it's knees).
So for example, a T4 flows 48lb x 10 = 480 + 40 = 520bhp, which is about the most you'd get from a T4 on today's crap fuel.
That turbo looks to me to be around 850-900bhp worth at 2.2 bar...
So for example, a T4 flows 48lb x 10 = 480 + 40 = 520bhp, which is about the most you'd get from a T4 on today's crap fuel.
That turbo looks to me to be around 850-900bhp worth at 2.2 bar...
Thats about the only bit I understand but what other info can be gleened from a compressor map?
The T76 is rated at 900hp max btw
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06-12-2005, 09:51 AM
#8
Originally Posted by Ryan
is it best to make the turbo work within the first ring? i.e highest effieceincy? 76%?
The problem is, if you specced a car for peak power in that island, it would be a lot laggier than another car which is using a smaller turbo and is on a further out island.
06-12-2005, 09:53 AM
#11
Originally Posted by Stu @ M Developments
Bugger.. i didnt expect anyone to answer 
likewise, i just thought i would whack a quick explanation up so he didnt get left with no replies, but im a bit busy for writing a full on article at the moment.
06-12-2005, 09:55 AM
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so which way round do you do it?
spec the turbo to the engine or spec the engine to the turbo?
I.e you get a compressor map, work out the max bhp and then build and engine that will be effeicent in all the right area so that effiecent is at its highest troughout the rev range?
or is that expecting to much?
spec the turbo to the engine or spec the engine to the turbo?
I.e you get a compressor map, work out the max bhp and then build and engine that will be effeicent in all the right area so that effiecent is at its highest troughout the rev range?
or is that expecting to much?
06-12-2005, 09:59 AM
#14
Originally Posted by Ryan
so which way round do you do it?
spec the turbo to the engine or spec the engine to the turbo?
I.e you get a compressor map, work out the max bhp and then build and engine that will be effeicent in all the right area so that effiecent is at its highest troughout the rev range?
or is that expecting to much?
spec the turbo to the engine or spec the engine to the turbo?
I.e you get a compressor map, work out the max bhp and then build and engine that will be effeicent in all the right area so that effiecent is at its highest troughout the rev range?
or is that expecting to much?
Both together mate.
Its no good saying "right i want a gt40r with the smallest exhaust housing on my cossie" then trying to build an engine that manages to stay under the surge limit as you will really struggle to do so.
You need to think of what you want from your engine, look at potential turbos and see which one will best suit an engine that you can realistically build.
This is where experience comes in of course, as until you've tried it on a particular engine, you are only guessing really!
06-12-2005, 12:58 PM
#16
Originally Posted by Mike Rainbird
Ryan,
The way to do it is decide on the power you want FIRST, and THEN spec the whole engine around achieving that
.
The idea then is to have the smallest of everything to achieve your goal, so that you retain as much response as possible.
The way to do it is decide on the power you want FIRST, and THEN spec the whole engine around achieving that
.The idea then is to have the smallest of everything to achieve your goal, so that you retain as much response as possible.
06-12-2005, 01:56 PM
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Will this interesting tread also be removed from public access? Or can i get involved in this tread without beeing afraid of it getting moved as soon as i get into the discussion?
L.
L.
06-12-2005, 02:05 PM
#19
Professional Waffler
cool topic
someone posted the same question a few weeks ago,, but i was left all on my own
https://passionford.com/forum/viewto...ght=compressor
someone posted the same question a few weeks ago,, but i was left all on my own
https://passionford.com/forum/viewto...ght=compressor
06-12-2005, 02:09 PM
#20
Originally Posted by YBP
Will this interesting tread also be removed from public access? Or can i get involved in this tread without beeing afraid of it getting moved as soon as i get into the discussion?
L.
L.
Im sure as you have mentioned it, they will leave it here for a few days at least
If not, i will email you a copy of what gets said
06-12-2005, 02:53 PM
#24
Originally Posted by DaveEscos
can anyone get a compressor map for a T38?
You won't get a compressor map for your turbo, as it is unique to Harvey. It was developed on the engine dyno and lots of different configurations tried before settling on the final design. Your particular variation of the T38 can only be purchased through Harvey as UT have signed up to a licensing agreement in view of the development work that Harvey carried out....
06-12-2005, 02:55 PM
#25
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Ok. Makin´ a couple of statements I hope people can comment on. (true, false, yes, but... , no, but... etc. )
- If we could live in a dreamworld and get 100% efficency from the compressor, then the temperature of the air entering the turbo would be the same as the air leaving the turbo.
- Surge is the compressor not spinning fast enough to maintain a given pressureratio because the airflow/mass not beeing high enough.
L.
- If we could live in a dreamworld and get 100% efficency from the compressor, then the temperature of the air entering the turbo would be the same as the air leaving the turbo.
- Surge is the compressor not spinning fast enough to maintain a given pressureratio because the airflow/mass not beeing high enough.
L.
06-12-2005, 03:01 PM
#27
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Originally Posted by Mike Rainbird
Originally Posted by DaveEscos
can anyone get a compressor map for a T38?
You won't get a compressor map for your turbo, as it is unique to Harvey. It was developed on the engine dyno and lots of different configurations tried before settling on the final design. Your particular variation of the T38 can only be purchased through Harvey as UT have signed up to a licensing agreement in view of the development work that Harvey carried out....
oooh... moist!
would be nice to actually know WHAT is in the turbo
06-12-2005, 03:12 PM
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Originally Posted by DaveEscos
can anyone get a compressor map for a T38?
L.
06-12-2005, 03:16 PM
#32
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Originally Posted by YBP
Originally Posted by DaveEscos
can anyone get a compressor map for a T38?
L.
Mike??
pmsl
06-12-2005, 03:35 PM
#39
Originally Posted by DaveEscos
Originally Posted by YBP
Originally Posted by DaveEscos
can anyone get a compressor map for a T38?
L.
Mike??
pmsl
.Seems like a lot of aggro just to get a compressor map
. If you want to know the limit of the turbo, it's around the 460 area (maybe 470).
06-12-2005, 03:35 PM
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Originally Posted by DaveEscos
Originally Posted by YBP
Originally Posted by DaveEscos
can anyone get a compressor map for a T38?
L.
Mike??
pmsl
Sorry, I don´t understand.
