compressor maps help
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compressor maps help
i hate to sound like a nwbie, but i really don't understand how exactly to use one of these things. i was hoping i could get some help, i was told a compressor map would show me which turbo to use on my car.... i have a 97 prelude and i am trying to find out what size to use, i would appreciate any help 
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From: All around, De/Pa
Re: compressor maps help (LUDE-a-cris)
You can thank Blueshadow for this informative post! Put it in your notepad for future reference--thats what I did.
Hey everybody, I was bored so I though I would type up a brief Topic on how to read a compressor map. I know this has been covered before but the threads have already been archived and some people (my self included) are unable to go back and add/change some of the info. so here it is, hopefully I remembered to add all the inportant information.
HOW-TO-READ A COMPRESSOR MAP
using a map of a T04E 60 trim I will explain all the numbers on the map
<u>1-left side, PRESSURE RATIO</u>
(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
<U>2-bottom side, AIRFLOW RATE (LB/MIN on this map)</u>
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
<U>3-dotted line on far left side of "ovals", SURGE LIMIT</U>
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.
<U>4-numbers on far right, 46,020, 69,640, 83,972 etc, COMPRESSOR RPM</U>
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 across the entire compressor map.
<U>5-78%,75%, 74%, COMPRESSOR EFFICIENCY</U>
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. If there was such a thing as a compressor with 100% efficiency then the air would not be heated up at all.
<U>6-"Ovals"</U>
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.
HOW-TO-READ A COMPRESSOR MAP
using a map of a T04E 60 trim I will explain all the numbers on the map
<u>1-left side, PRESSURE RATIO</u>
(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
<U>2-bottom side, AIRFLOW RATE (LB/MIN on this map)</u>
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
<U>3-dotted line on far left side of "ovals", SURGE LIMIT</U>
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.
<U>4-numbers on far right, 46,020, 69,640, 83,972 etc, COMPRESSOR RPM</U>
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 across the entire compressor map.
<U>5-78%,75%, 74%, COMPRESSOR EFFICIENCY</U>
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. If there was such a thing as a compressor with 100% efficiency then the air would not be heated up at all.
<U>6-"Ovals"</U>
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.
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Joined: Jun 2002
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From: NE Of Metro Area, MN, US
Re: compressor maps help (93LSivic)
if u do a search on recent posts.. there is a nice long back-and-forth conversation me and blue had on figuring it all out.. he goes a little more in-depth into it in that post.
EDIT: Here is the post I am talking about: https://honda-tech.com/zerothread?id=208032
[Modified by CustomCockpits, 9:25 PM 6/17/2002]
EDIT: Here is the post I am talking about: https://honda-tech.com/zerothread?id=208032
[Modified by CustomCockpits, 9:25 PM 6/17/2002]
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Re: compressor maps help (CustomCockpits)
i did a search for "compressor map" and couldn't find anything recent, then i did archives and couldn't really find what i was looking for... the onlt thing that sucks about compressor maps is that they're just about as hard to figure out as those damn V-AFC directions... if you have one, you know what i mean 
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Joined: Mar 2001
Posts: 4,408
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From: Somewhere in California
Re: compressor maps help (93LSivic)
93LSivic,
that looks like the original post that i did, I went in several times to add some other bits of info and also to make some changes. One for example, I mistakenly put the wrong formula on how to figure the pressure ratio (put multiply when i meant divide)
here is the link to the archived post with all the changes and updates in them.
https://honda-tech.com/zerothread?id=142398
that looks like the original post that i did, I went in several times to add some other bits of info and also to make some changes. One for example, I mistakenly put the wrong formula on how to figure the pressure ratio (put multiply when i meant divide)
here is the link to the archived post with all the changes and updates in them.
https://honda-tech.com/zerothread?id=142398
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Re: compressor maps help (BlueShadow)
BlueShadow, i talked to you a while back on HondaPrelude.com... i decided to build my own setup rather than buy a kit, your advice then was very helpful and persuasive to doing it myself. thanks for all the information
Honda-Tech Member
Joined: Mar 2001
Posts: 4,408
Likes: 4
From: Somewhere in California
Re: compressor maps help (LUDE-a-cris)
BlueShadow, i talked to you a while back on HondaPrelude.com... i decided to build my own setup rather than buy a kit, your advice then was very helpful and persuasive to doing it myself. thanks for all the information
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Smarter than you
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Re: compressor maps help (LUDE-a-cris)
compressor maps are only a rough guesstimate. they can get u an idea of what turbo will work well, but the only way to really find out which turbo has better characteristics this and that is to actually experiment with it in real life.
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