TURBO 101 and How to read COMPRESSOR MAPS
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BOOST JUNKY
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TURBO 101 and How to read COMPRESSOR MAPS
Perhaps a good sticky??
"Turbo 101 - some info about GARRETT turbos"
Disclaimer: All of the following is correct to my knowledge. Please feel free to jump in and correct anything that is wrong or feel free to add anything. This post is pretty long, but hopefully it will help out some newbies that are getting into turbochargers.
There seems to be some confusion about there about what all of the numbers mean when looking at a turbochargers specs. Awhile back, BlueShadow wrote an excellent post on how to read a compressor map. Find that post, read it, and combine it with this one...voila, you'r a guru! (not really)
Garrett makes several "families" of turbochargers that are targeted for different sized engines, HP goals, and drivability characteristics. Crafty tuners, manufacturers, etc, have mixed and matched these components to produce hybrid turbos that can provide the benefits of several turbo families. The possibilities really are endless, but I'm just gonna list some common ones or else this post would be reeeeeeallly long.
Turbocharger families
The T25 family = super fast spooling "small" turbo that makes good low rpm torque, but lacks top end power. This turbocharger is commonly used where throttle response and low rpm torque are desired without much regard to high rpm power.
The T3 family = "intermediate turbo" that spools slower, but has the ability to make substantially more power than the T25 family. This turbocharger has been used on A LOT of production vehicles (Ford, Nissan, Volvo, Saab). They can make impressive power, but were known to be laggy.
The T04 family = "big turbo" that makes huge power, but is very very laggy. Without the beauty of being able to make a hybrid turbo, a T04 would probably not even be an option.
The 3 main components that have the biggest impact on performance are the a/r of the turbine housing, the size (aka trim) of the tubine wheel, and the size (aka trim) of the compressor housing.
Common turbine housing a/r "sizes"
T25: .64 a/r, .86 a/r
T3: .36 a/r, .48 a/r, .63 a/r, .82 a/r
T4: not listed...see why later
(CivicRyda2K's addition)
Common compressor housing a/r "sizes"
T3: .42 a/r, .50 a/r, .60 a/r, .82 a/r
T4: .50 a/r, .60 a/r, .70 a/r
In a nutshell, the larger the a/r, the later the power comes. A small a/r gives you a fast spooling turbo but limits top-end power. A large a/r gives you a laggy turbo with big top-end power.
Common T25 turbines:
DSM trim (?? not sure how big it is, but it's quite small)
60 trim (small)
76 trim (medium)
Common T3 turbines:
Stage 1 (small -- most common turbine on junkyard turbos)
Stage 2 (med)
Stage 3 (large -- most common turbine on new T3/T04 hybrids)
Stage 5 (very large)
Common T04 turbines:
I'm not gonna list any because I don't have info on them and the T4 turbines require so much exhaust energy to spin that they are practically unusable in our application unless you want insane lag and have got a motor that will spin to 10k every day.
Common T25 compressors:
I'm not gonna list any. I do have some info on them, but for the most part, a T25 compressor will struggle to stay in its efficiency range on a boosted Honda.
Common T3 compressors:
40 trim (20lb/min -- haha...don't even think about it)
45 trim (21lb/min)
50 trim (30lb/min -- probably one of the most common on junkyard turbos, works well for SOHC and LS engines)
60 trim (34lb/min -- biggest "production" T3 compressor, excellent power on D series/LS) <=== my old turbo
"Super 60" (36lb/min -- note: this is NOT the "60-1" compressor)
Common T04B compressors:
S trim (37 lb/min)
V trim (48 lb/min)
H trim (49 lb/min)
Common T04E compressors:
40 trim (36 lbs/min)
46 trim (41 lbs/min) <=== my new turbo
50 trim (47 lbs/min)
54 trim (45 lbs/min -- note that the 54 trim flows less than the 50 trim)
57 trim (49 lbs/min)
60 trim (50 lbs/min)
Common T04S compressors:
60-1 (flows a shitload, never seen a compressor map for it)
62-1 (bigger yet -- I believe this is a T04S compressor...correct this if it is wrong)
Performance (listed in order of increasing performance):
A T25 is a straight T25 turbo --> T25 turbine + T25 compressor
A T28 is a hybrid T25/T3 turbo --> T25 turbine + T3 compressor
A T3 is a straight T3 turbo --> T3 turbine + T3 compressor
A T3/T04B is a T3/T04B hybrid turbo --> T3 turbine + T04B compressor (used in Drag kits)
A T3/T04E is a T3/T04E hybrid turbo --> T3 turbine + T04E compressor (more performance than T3/T04B
A T3/60-1 is a T3/T04S hybrid turbo --> T3 turbine + T04S (60-1) compressor
Credit goes to Sonny and CivicRyda2k from Honda-Tech
Donated to 7thgen By SpdRcrChk
"Turbo 101 - some info about GARRETT turbos"
Disclaimer: All of the following is correct to my knowledge. Please feel free to jump in and correct anything that is wrong or feel free to add anything. This post is pretty long, but hopefully it will help out some newbies that are getting into turbochargers.
There seems to be some confusion about there about what all of the numbers mean when looking at a turbochargers specs. Awhile back, BlueShadow wrote an excellent post on how to read a compressor map. Find that post, read it, and combine it with this one...voila, you'r a guru! (not really)
Garrett makes several "families" of turbochargers that are targeted for different sized engines, HP goals, and drivability characteristics. Crafty tuners, manufacturers, etc, have mixed and matched these components to produce hybrid turbos that can provide the benefits of several turbo families. The possibilities really are endless, but I'm just gonna list some common ones or else this post would be reeeeeeallly long.
Turbocharger families
The T25 family = super fast spooling "small" turbo that makes good low rpm torque, but lacks top end power. This turbocharger is commonly used where throttle response and low rpm torque are desired without much regard to high rpm power.
The T3 family = "intermediate turbo" that spools slower, but has the ability to make substantially more power than the T25 family. This turbocharger has been used on A LOT of production vehicles (Ford, Nissan, Volvo, Saab). They can make impressive power, but were known to be laggy.
The T04 family = "big turbo" that makes huge power, but is very very laggy. Without the beauty of being able to make a hybrid turbo, a T04 would probably not even be an option.
The 3 main components that have the biggest impact on performance are the a/r of the turbine housing, the size (aka trim) of the tubine wheel, and the size (aka trim) of the compressor housing.
Common turbine housing a/r "sizes"
T25: .64 a/r, .86 a/r
T3: .36 a/r, .48 a/r, .63 a/r, .82 a/r
T4: not listed...see why later
(CivicRyda2K's addition)
Common compressor housing a/r "sizes"
T3: .42 a/r, .50 a/r, .60 a/r, .82 a/r
T4: .50 a/r, .60 a/r, .70 a/r
In a nutshell, the larger the a/r, the later the power comes. A small a/r gives you a fast spooling turbo but limits top-end power. A large a/r gives you a laggy turbo with big top-end power.
Common T25 turbines:
DSM trim (?? not sure how big it is, but it's quite small)
60 trim (small)
76 trim (medium)
Common T3 turbines:
Stage 1 (small -- most common turbine on junkyard turbos)
Stage 2 (med)
Stage 3 (large -- most common turbine on new T3/T04 hybrids)
Stage 5 (very large)
Common T04 turbines:
I'm not gonna list any because I don't have info on them and the T4 turbines require so much exhaust energy to spin that they are practically unusable in our application unless you want insane lag and have got a motor that will spin to 10k every day.
Common T25 compressors:
I'm not gonna list any. I do have some info on them, but for the most part, a T25 compressor will struggle to stay in its efficiency range on a boosted Honda.
Common T3 compressors:
40 trim (20lb/min -- haha...don't even think about it)
45 trim (21lb/min)
50 trim (30lb/min -- probably one of the most common on junkyard turbos, works well for SOHC and LS engines)
60 trim (34lb/min -- biggest "production" T3 compressor, excellent power on D series/LS) <=== my old turbo
"Super 60" (36lb/min -- note: this is NOT the "60-1" compressor)
Common T04B compressors:
S trim (37 lb/min)
V trim (48 lb/min)
H trim (49 lb/min)
Common T04E compressors:
40 trim (36 lbs/min)
46 trim (41 lbs/min) <=== my new turbo
50 trim (47 lbs/min)
54 trim (45 lbs/min -- note that the 54 trim flows less than the 50 trim)
57 trim (49 lbs/min)
60 trim (50 lbs/min)
Common T04S compressors:
60-1 (flows a shitload, never seen a compressor map for it)
62-1 (bigger yet -- I believe this is a T04S compressor...correct this if it is wrong)
Performance (listed in order of increasing performance):
A T25 is a straight T25 turbo --> T25 turbine + T25 compressor
A T28 is a hybrid T25/T3 turbo --> T25 turbine + T3 compressor
A T3 is a straight T3 turbo --> T3 turbine + T3 compressor
A T3/T04B is a T3/T04B hybrid turbo --> T3 turbine + T04B compressor (used in Drag kits)
A T3/T04E is a T3/T04E hybrid turbo --> T3 turbine + T04E compressor (more performance than T3/T04B
A T3/60-1 is a T3/T04S hybrid turbo --> T3 turbine + T04S (60-1) compressor
Credit goes to Sonny and CivicRyda2k from Honda-Tech
Donated to 7thgen By SpdRcrChk
Last edited by SpdRcrChk; Mar 5, 2004 at 05:07 PM.
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BOOST JUNKY
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Rep Power: 0 Oh yeah...and I looked up the "How to Read a Compressor Map" thread on honda-tech and found it. Here it is......
HOW-TO-READ A COMPRESSOR MAP
using a map of a T04E 60 trim I will explain all the numbers on the map
1-left side, PRESSURE RATIO
(14.7 + amount of boost) / 14.7 = PR
so to figure out the PR for 8 PSI
(14.7 + 8) / 14.7 = 1.54 PR
2-bottom side, AIRFLOW RATE UNDER BOOST (LB/MIN on this map)
Most methods of calculation your engine's airflow rate will give you the answer in cubic feet per minute (CFM). However most compressor maps measure airflow rate in pounds per minute (LB/MIN). As some of you may know the weight of air varies with the temperature. To convert CFM to LB/MIN use the following numbers.
@ 48 degrees F : (CFM * 0.078125) = LB/MIN
@112 degrees F : (CFM * 0.070318) = LB/MIN
@175 degrees F : (CFM * 0.06251) = LB/MIN
Say for example our airflow rate is 500 CFM , and the temperature is 112 degrees F.
(500 * 0.070318) = 35.16 LB/MIN
*For those of you that know anything about ideal gas law, if you know a better way of explaining how to convert CFM to LB/MIN, your input would be appreciated. But please explain it in "laymans" terms, so that everyone can get a grasp on it.
3-dotted line on far left side of "ovals", SURGE LIMIT
It is important to try and keep yourself on the right side of this dotted line whenever possible. If you fall to the left of this dotted line you will experience compressor surge. This type of compressor surge will occur when there is too much boost, but not enough airflow through the system, usually this is between idle and the point at which full boost is reached. The chirping sound that can be heard is a result of the oscillating air. This sound is often described as a "Snakelike" sound or a che-che-che sound.
*staying in the "surge limit" area for too long could possibly damage your turbo.
4-numbers on far right, 46,020, 69,640, 83,972 etc, COMPRESSOR RPM
This is RPM at which the compressor fans will be turning. an average RPM is between 90,000 and 130,000. The line that branches out from each of these numbers that goes towards the surge limit line shows you the RPM range of the compressor fan across the entire compressor map.
5-78%,75%, 74%, COMPRESSOR EFFICIENCY
This is related to the temp of air and how much it is being heated up as it is being compressed by the compressor. A low number (60%) means that the compressor is heating the air more a high number (78%) means the air is not heated as much when it is compressed.
6-"Ovals"
I you look closely you will see that the compressor efficiency numbers usually sit right on top of one of these Oval lines. These Ovals show you the boundaries of the compressor efficiency at the different percentiles. Think of it as a topography map that shows you different elevations or changes in elevations. The innermost Oval on the sample T04 E 60" is not labeleb but it is probably 79% or 80%, so any where inside that Oval and you would be operating in the 80% range of that compressor.
--changed # 1 (pressure ratios) 29 Mar 02
--changed # 2 (airflow rate) 29 Mar 02
--added # 2 (airflow rate) 13 Apr 02
--added # 3 (surge limit line) 13 Apr 02
--changed # 5 (compressor efficiency) 08 Jan 03
Credit goes to BlueShadow from Honda-tech
Donated to 7thgen by SpdRcrChk
HOW-TO-READ A COMPRESSOR MAP
using a map of a T04E 60 trim I will explain all the numbers on the map
1-left side, PRESSURE RATIO
(14.7 + amount of boost) / 14.7 = PR
so to figure out the PR for 8 PSI
(14.7 + 8) / 14.7 = 1.54 PR
2-bottom side, AIRFLOW RATE UNDER BOOST (LB/MIN on this map)
Most methods of calculation your engine's airflow rate will give you the answer in cubic feet per minute (CFM). However most compressor maps measure airflow rate in pounds per minute (LB/MIN). As some of you may know the weight of air varies with the temperature. To convert CFM to LB/MIN use the following numbers.
@ 48 degrees F : (CFM * 0.078125) = LB/MIN
@112 degrees F : (CFM * 0.070318) = LB/MIN
@175 degrees F : (CFM * 0.06251) = LB/MIN
Say for example our airflow rate is 500 CFM , and the temperature is 112 degrees F.
(500 * 0.070318) = 35.16 LB/MIN
*For those of you that know anything about ideal gas law, if you know a better way of explaining how to convert CFM to LB/MIN, your input would be appreciated. But please explain it in "laymans" terms, so that everyone can get a grasp on it.
3-dotted line on far left side of "ovals", SURGE LIMIT
It is important to try and keep yourself on the right side of this dotted line whenever possible. If you fall to the left of this dotted line you will experience compressor surge. This type of compressor surge will occur when there is too much boost, but not enough airflow through the system, usually this is between idle and the point at which full boost is reached. The chirping sound that can be heard is a result of the oscillating air. This sound is often described as a "Snakelike" sound or a che-che-che sound.
*staying in the "surge limit" area for too long could possibly damage your turbo.
4-numbers on far right, 46,020, 69,640, 83,972 etc, COMPRESSOR RPM
This is RPM at which the compressor fans will be turning. an average RPM is between 90,000 and 130,000. The line that branches out from each of these numbers that goes towards the surge limit line shows you the RPM range of the compressor fan across the entire compressor map.
5-78%,75%, 74%, COMPRESSOR EFFICIENCY
This is related to the temp of air and how much it is being heated up as it is being compressed by the compressor. A low number (60%) means that the compressor is heating the air more a high number (78%) means the air is not heated as much when it is compressed.
6-"Ovals"
I you look closely you will see that the compressor efficiency numbers usually sit right on top of one of these Oval lines. These Ovals show you the boundaries of the compressor efficiency at the different percentiles. Think of it as a topography map that shows you different elevations or changes in elevations. The innermost Oval on the sample T04 E 60" is not labeleb but it is probably 79% or 80%, so any where inside that Oval and you would be operating in the 80% range of that compressor.
--changed # 1 (pressure ratios) 29 Mar 02
--changed # 2 (airflow rate) 29 Mar 02
--added # 2 (airflow rate) 13 Apr 02
--added # 3 (surge limit line) 13 Apr 02
--changed # 5 (compressor efficiency) 08 Jan 03
Credit goes to BlueShadow from Honda-tech
Donated to 7thgen by SpdRcrChk
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BOOST JUNKY
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From: Wide Open Throttle
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3-dotted line on far left side of "ovals", SURGE LIMIT
It is important to try and keep yourself on the right side of this dotted line whenever possible. If you fall to the left of this dotted line you will experience compressor surge. This type of compressor surge will occur when there is too much boost, but not enough airflow through the system, usually this is between idle and the point at which full boost is reached. The chirping sound that can be heard is a result of the oscillating air. This sound is often described as a "Snakelike" sound or a che-che-che sound.
*staying in the "surge limit" area for too long could possibly damage your turbo.
It is important to try and keep yourself on the right side of this dotted line whenever possible. If you fall to the left of this dotted line you will experience compressor surge. This type of compressor surge will occur when there is too much boost, but not enough airflow through the system, usually this is between idle and the point at which full boost is reached. The chirping sound that can be heard is a result of the oscillating air. This sound is often described as a "Snakelike" sound or a che-che-che sound.
*staying in the "surge limit" area for too long could possibly damage your turbo.
Last edited by SpdRcrChk; Mar 5, 2004 at 05:15 PM.
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BOOST JUNKY
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From: Wide Open Throttle
Rep Power: 0 Your friend has a DSM right? Here's a link that might help. It's kinda technical....but if he really wants to understand it might be helpful, especially since it was written by somone that owns a DSM and in terms of a 14b and 16g turbo.....
http://www.honda-tech.com/zerothread?id=567398
more direct link here: http://home.comcast.net/~tarryo/kyle...fficiency.html
and this can most certainly help as well:
http://www.turbofast.com.au/tfcalc.html (turbo power calculator)
http://www.honda-tech.com/zerothread?id=567398
more direct link here: http://home.comcast.net/~tarryo/kyle...fficiency.html
and this can most certainly help as well:
http://www.turbofast.com.au/tfcalc.html (turbo power calculator)
Last edited by SpdRcrChk; Mar 5, 2004 at 05:49 PM.
wut up wut up!?!?!?! lmao 
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Originally posted by SpdRcrChk
Oh yeah...and I looked up the "How to Read a Compressor Map" thread on honda-tech and found it. Here it is......
HOW-TO-READ A COMPRESSOR MAP
using a map of a T04E 60 trim I will explain all the numbers on the map
1-left side, PRESSURE RATIO
(14.7 + amount of boost) / 14.7 = PR
so to figure out the PR for 8 PSI
(14.7 + 8) / 14.7 = 1.54 PR
2-bottom side, AIRFLOW RATE UNDER BOOST (LB/MIN on this map)
Most methods of calculation your engine's airflow rate will give you the answer in cubic feet per minute (CFM). However most compressor maps measure airflow rate in pounds per minute (LB/MIN). As some of you may know the weight of air varies with the temperature. To convert CFM to LB/MIN use the following numbers.
@ 48 degrees F : (CFM * 0.078125) = LB/MIN
@112 degrees F : (CFM * 0.070318) = LB/MIN
@175 degrees F : (CFM * 0.06251) = LB/MIN
Say for example our airflow rate is 500 CFM , and the temperature is 112 degrees F.
(500 * 0.070318) = 35.16 LB/MIN
*For those of you that know anything about ideal gas law, if you know a better way of explaining how to convert CFM to LB/MIN, your input would be appreciated. But please explain it in "laymans" terms, so that everyone can get a grasp on it.
Credit goes to BlueShadow from Honda-tech
Donated to 7thgen by SpdRcrChk
Oh yeah...and I looked up the "How to Read a Compressor Map" thread on honda-tech and found it. Here it is......
HOW-TO-READ A COMPRESSOR MAP
using a map of a T04E 60 trim I will explain all the numbers on the map
1-left side, PRESSURE RATIO
(14.7 + amount of boost) / 14.7 = PR
so to figure out the PR for 8 PSI
(14.7 + 8) / 14.7 = 1.54 PR
2-bottom side, AIRFLOW RATE UNDER BOOST (LB/MIN on this map)
Most methods of calculation your engine's airflow rate will give you the answer in cubic feet per minute (CFM). However most compressor maps measure airflow rate in pounds per minute (LB/MIN). As some of you may know the weight of air varies with the temperature. To convert CFM to LB/MIN use the following numbers.
@ 48 degrees F : (CFM * 0.078125) = LB/MIN
@112 degrees F : (CFM * 0.070318) = LB/MIN
@175 degrees F : (CFM * 0.06251) = LB/MIN
Say for example our airflow rate is 500 CFM , and the temperature is 112 degrees F.
(500 * 0.070318) = 35.16 LB/MIN
*For those of you that know anything about ideal gas law, if you know a better way of explaining how to convert CFM to LB/MIN, your input would be appreciated. But please explain it in "laymans" terms, so that everyone can get a grasp on it.
Credit goes to BlueShadow from Honda-tech
Donated to 7thgen by SpdRcrChk
First off, it's not really the Ideal Gas Law that's used. It's the basically a form of the Real Gas Law. The constant R being 10.73 and the Temperature is Rankine. Not to mention the units at psi, cubic feet, and pounds. But they're alike, so you can just get away with using the PV=nRT.... just because I can't type "rho" with a keyboard lol, but really because that's what most people know.PV=nRT
P = absolute pressure (in psi)
V = Volume of air (in cubic feet)
n = amount of air (in lbs)
R = constant (10.73)
T = Absolute Temperature (Rankine) = Degree F + 460
P (Absolute Pressure) is atmospheric pressure. That would be 14.7psi at sea level. But we're talking about boost here and this equation is calling for manifold pressure. Without boost, it's 14.7psi. With boost, it's 14.7psi + Xpsi.
So, P(abs) = P(atm) + P(boost)
V (Cu.Ft./Min): It's really cubic feet, but because we have to find lbs./minute for the amount, we have to convert this to cu.ft/min.
You need to first find the engines displacement. Displacement = bore X stroke X #cylinders. The engine displacement should be CID to keep it simple. To find CFM, use:
CFM = RPM * CID/(1728 x 2)
1728 X 2 (or 3456) accounts for conversions and valves/revolution. It works for 4 valves/cylinder, 4 stroke engines. It changes depending on engines though. Like the KA24E (the OLD Nissan 240SX, not to be confused with the KA24DE) had 3 valves for cylinder. So depending on how the engine works, the number changes.
R is a constant of 10.73
T is absolute temperature in Rankine. It's just another temperature scale like Kelvin. But Rankine is ambient temperature (in Farenheit) + 460.
T = degreesF + 460
So, to find n (lbs/min), you look at PV=nRT
Isolate n:
n=PV/RT
EXAMPLE:
(What you know):
2001+ HONDA CIVIC D17
BORE: 75.0mm
STROKE: 94.4mm
(Displacement = 1668cc = 101.7 Cu. In.)
CYLINDERS: 4
TARGET RPM: 6700rpm
BOOST: 8psi
Ambient Temp: 85 degrees Farenheit
P(abs) = 14.7psi(atm) + 8psi(boost)
P = 22.7psi
V = 6700(rpm) *101.7(cid)/(3456)
V = 197.1cu in/min
R = 10.73 (constant) and 28.4
T = 85 + 460
T = 545
Airflow(lbs/min) = (22.7psi*197.1cuin/min*28.4) / (10.73*545)
**** If you want to add the Volumetric efficiency to the equation... multiply the result by about 0.93-0.95 (93-95%VE)****
Airflow = 22.2lbs/min (compressor x axis)
P2/P1 (compressor y axis) = 1.51
There is a problem between the simple way posted earlier, and the way I just posted. The simple way really only accounts for an engine with a turbocharger that is charging nothing really. It's not accounting for the recirculation of the charge to the manifold, into the cylinders and out through the exhaust. It raises airflow. This way, accounts for that. The simple way is good enough to give you a rough idea, but it could be off by a good amount. The higher the boost pressure, the greater the innacuracy. In the above example, the simple way would be lower by about 5-6lbs/min.
If I messed up on anything, I'll pick it up later. It's 4AM so give me a break.
***Note: The general idea of these equations carries across... however, different companies use different standards and units in their maps. This was all done with Turbonetics maps in mind, so I used the standards accordingly. ****
Last edited by Boosted2k2; May 14, 2004 at 12:45 AM.
Some questions about finding volume (cfm) and mass (lb/min) of airflow:
To account for volumetric efficiency of the engine multiply by formula by the percentage:
cfm = (cid * rpm * VE%) / (1728 * 2)
What is the VE of the D17, is it 90%?
Where does the 29 come from? The units for constant R are:
(cfm * psia) / (lb * mole * deg. Rankine), right?
CFM = RPM * CID/(1728 x 2)
cfm = (cid * rpm * VE%) / (1728 * 2)
What is the VE of the D17, is it 90%?
R = 10.73 (constant) and 29 for conversions
(cfm * psia) / (lb * mole * deg. Rankine), right?
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Rep Power: 0 Originally posted by sitinduk
Some questions about finding volume (cfm) and mass (lb/min) of airflow:
To account for volumetric efficiency of the engine multiply by formula by the percentage:
cfm = (cid * rpm * VE%) / (1728 * 2)
What is the VE of the D17, is it 90%?
Where does the 29 come from? The units for constant R are:
(cfm * psia) / (lb * mole * deg. Rankine), right?
Some questions about finding volume (cfm) and mass (lb/min) of airflow:
To account for volumetric efficiency of the engine multiply by formula by the percentage:
cfm = (cid * rpm * VE%) / (1728 * 2)
What is the VE of the D17, is it 90%?
Where does the 29 come from? The units for constant R are:
(cfm * psia) / (lb * mole * deg. Rankine), right?
The units for R is Cubic Feet... not CFM. If it were CFM, then using the equation wouldn't give you a flow value.
It's not really 29, it's 28.4 It's the standard pressure used on compressor maps for the ratio in airflow. 28.4inHg. Give me a break, it was late
Anyway, maybe I'll go make some corrections. The general idea of this all applies to all compressor maps, but this specific way applies to Turbonetics. Different companies use different units and standards. 
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Re: TURBO 101 and How to read COMPRESSOR MAPS
Hey man i have this question im trying to use the borg warner k16 model r2s into my d17 trying to run only 5 or 6 psi do i really need a vafc or a aem ecu???
This is the compressor map for the k16 please send me a pm for the info, this turbo is to big to spool with my d17 i will throw it into sells,
if anybody is interested ill ship it to any where
this is the page
those ARE SOME PICS OF MY ACTUAL TURBO WITH THE COMPRESSOR MAP FROM AIRWERKS
THANK YOU BRO FOR READING!!!
This is the compressor map for the k16 please send me a pm for the info, this turbo is to big to spool with my d17 i will throw it into sells,
if anybody is interested ill ship it to any where
this is the page
those ARE SOME PICS OF MY ACTUAL TURBO WITH THE COMPRESSOR MAP FROM AIRWERKS
THANK YOU BRO FOR READING!!!
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