Go Back   FloridaStreetScene > Community Forums > General Automotive Discusions


General Automotive Discusions Discuss your problems, solutions or any other automotive topic, give and get technical help here also. Import or Domestic, it doesn't matter.

Thread Tools Display Modes
Old 11-04-2005, 01:11 PM   #1
Senior Member
SpdRcrChk's Avatar
Join Date: Oct 2005
Location: W.O.T.
Age: 38
Posts: 1,790
SpdRcrChk Has the base repuation (you start with 5 points just for registereing), 5 rep points.
Default How To Read Compressor Maps


I found this information on Honda-Tech once. Thought it was some interesting material to read, especially for those always in search for more info. / knowledge.

by BlueShadow from Honda-tech

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.

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.

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

FSS-T - member # 2
SpdRcrChk is offline   Reply With Quote
Old 11-04-2005, 02:11 PM   #2
Admin & Student

Bone's Avatar
Join Date: Sep 2005
Location: South West Florida
Posts: 27,939
Bone has a brilliant future 100-124Bone has a brilliant future 100-124

I was saing all the pickture that you used and forgot to sticky this one. I saved them all because i'm sure that soon enough they will block this site from useing them. but this one is stuck now.
Bone is offline   Reply With Quote
Old 11-04-2005, 02:18 PM   #3
Senior Member
SpdRcrChk's Avatar
Join Date: Oct 2005
Location: W.O.T.
Age: 38
Posts: 1,790
SpdRcrChk Has the base repuation (you start with 5 points just for registereing), 5 rep points.

yah if anythin' ever gets taken down...least u have the pics and we can (or i can...no biggie bout that) host the pics. honestly they're all good info that i wouldn't mind keepin.

FSS-T - member # 2
SpdRcrChk is offline   Reply With Quote
Old 12-27-2005, 02:42 PM   #4
Senior Member
Join Date: Dec 2005
Age: 31
Posts: 199
92redhatch has much to be proud of, 50-99

92redhatch is offline   Reply With Quote


Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Similar Threads
Thread Thread Starter Forum Replies Last Post
WTB: A/C compressor for b16 sportyrob Want to buy (WTB) 0 07-09-2010 01:06 AM
WTB: compressor Rez146 Want to buy (WTB) 0 11-12-2009 11:24 AM
b16 a/c compressor OsoTarzan HONDA/ACURA parts for sale 0 07-09-2009 03:37 PM
Halo 3: new maps released Bone Computer, Electronics, and Gaming 4 04-21-2008 03:11 PM
If you can read spanish please step in and read this Robi OFF TOPIC 10 05-28-2006 06:03 PM

All times are GMT -4. The time now is 08:10 PM.

Powered by vBulletin® Version 3.7.0
Copyright ©2000 - 2018, Jelsoft Enterprises Ltd.
The forum is protected by expressed copyright and the information contained within this forum is intended for its members to be used here and is privileged to the valued users of this forum. You are notified that any use, dissemination, or coping of the information here is not permitted without the permission of the administration.