Homebrew guys : Need help calculating proper airflow in lb/min for a homebrew for turbomap...
03-24-2006, 11:37 AM
#1
AudiWorld Senior Member
Thread Starter
Join Date: Sep 2002
Posts: 1,698
Likes: 0
Received 0 Likes
on
0 Posts
Homebrew guys : Need help calculating proper airflow in lb/min for a homebrew for turbomap...
I have conflicting information and notes...
I currently hit 301 g/s MAF Reading and run 88mm ID MAF Housing. Since stock (correct me if I'm wrong) is 72mm, is it ok to start calculating this way?
Adjusted Mass Air Flow = MAF Reading * ((3.1415 x (88/2)^2) / (3.1415 x (72/2)^2)
Adjusted Mass Air Flow = MAF Reading * 1.494
AMAF = 449.7 g/s
??? Is this ok ???
Then convert to lb/min using 0.1323..
AMAF = (449.7 g/s x 0.1323) = 59.5 lb/min
AMAF per turbo side = 29.75 lb/min
I think it's the right way to calculate but want to be sure (I'm not the one doing this normally!).
I currently hit 301 g/s MAF Reading and run 88mm ID MAF Housing. Since stock (correct me if I'm wrong) is 72mm, is it ok to start calculating this way?
Adjusted Mass Air Flow = MAF Reading * ((3.1415 x (88/2)^2) / (3.1415 x (72/2)^2)
Adjusted Mass Air Flow = MAF Reading * 1.494
AMAF = 449.7 g/s
??? Is this ok ???
Then convert to lb/min using 0.1323..
AMAF = (449.7 g/s x 0.1323) = 59.5 lb/min
AMAF per turbo side = 29.75 lb/min
I think it's the right way to calculate but want to be sure (I'm not the one doing this normally!).
03-24-2006, 12:00 PM
#2
AudiWorld Super User
Join Date: Mar 2002
Posts: 17,933
Likes: 0
Received 0 Likes
on
0 Posts
So i've found this post so far in the archives
so if you go through using your calculations but plug in a 90mm MAF instead of 88mm.....the number doesn't match what number mike got. It comes out to 390 actual using your cals whereas mike said it was 380. Still trying to dig out his calcs, i thought they were in the archives somewhere.
Also, incase you were wondering for KKK maps, the theorectical 449.7g/sec is equal to .202 m(3)/sec<ul><li><a href="https://forums.audiworld.com/s4/msgs/2140751.phtml">https://forums.audiworld.com/s4/msgs/2140751.phtml</a</li></ul>
Also, incase you were wondering for KKK maps, the theorectical 449.7g/sec is equal to .202 m(3)/sec<ul><li><a href="https://forums.audiworld.com/s4/msgs/2140751.phtml">https://forums.audiworld.com/s4/msgs/2140751.phtml</a</li></ul>
03-24-2006, 12:52 PM
#5
Senior Member
Join Date: Mar 2000
Posts: 7,467
Likes: 0
Received 0 Likes
on
0 Posts
Thought stock was supposed to be 73mm, but since I've not personally measured it, either could be
right.
in that case:
301 * ((3.1415 x ((88 / 2)^2)) / (3.1415 x ((73 / 2)^2))) = 437.407394
(437.407394 * 0.1323) / 2 = 28.9344991
in that case:
301 * ((3.1415 x ((88 / 2)^2)) / (3.1415 x ((73 / 2)^2))) = 437.407394
(437.407394 * 0.1323) / 2 = 28.9344991
Trending Topics
03-24-2006, 06:01 PM
#9
AudiWorld Super User
Join Date: Dec 2002
Posts: 2,718
Likes: 0
Received 0 Likes
on
0 Posts
MAF info and Cal.
73mm maf= 36.5*36.5*3.1416=4185.39 = Stock
83mm maf= 41.5*41.5*3.1416=5410.62= 29% larger than stock
85mm maf= 42.5* 42.5*3.1416= 5674.5 = 35.5% larger than stock
88mm maf= 44*44*3.1416= 6082.1376= 45% larger than stock
90mm maf= 45*45*3.1416= 6361.74= 52% larger than stock<ul><li><a href="http://homepage.mac.com/edyjun1/S4/index.htm">EdyJun's S4 Directory (FAQ, DIY, Info, Tips and Help)</a></li></ul>
83mm maf= 41.5*41.5*3.1416=5410.62= 29% larger than stock
85mm maf= 42.5* 42.5*3.1416= 5674.5 = 35.5% larger than stock
88mm maf= 44*44*3.1416= 6082.1376= 45% larger than stock
90mm maf= 45*45*3.1416= 6361.74= 52% larger than stock<ul><li><a href="http://homepage.mac.com/edyjun1/S4/index.htm">EdyJun's S4 Directory (FAQ, DIY, Info, Tips and Help)</a></li></ul>
Thread
Thread Starter
Forum
Replies
Last Post
GeTT da NeTT
TT (Mk1) Discussion
5
05-09-2006 05:02 PM
wagongotya
Rocky Mountain Discussion
23
05-05-2006 06:10 PM
pattersom
S4 / RS4 (B5 Platform) Discussion
21
12-15-2002 11:24 AM
BigMouse
Audi 90 / 80 / Coupe quattro / Cabriolet
6
09-28-2002 05:32 PM
