Click to go to Forum Home Click to go to maXbimmer Home

Go Back   maXbimmer Forums > maXimum Tech > Forced Induction
User Name
Password


Welcome to Maxbimmer.com!

You are currently viewing our boards as a guest which gives you limited access to view most discussions and access our other features. By joining our free community you will have access to post topics, communicate privately with other members (PM), respond to polls, upload content and access many other special features. Registration is fast, simple and absolutely free so please, join our community today!

Reply
 
Thread Tools Rate Thread Display Modes
Old 03-18-2009, 01:58 AM   #16
///tyron
4th Gear Member
 
///tyron's Avatar
 
Join Date: Jun 2006
Location: whitby
Posts: 690
Quote:
Originally Posted by e30_kid89 View Post
.82ar will be good. size for a s52.

///tyron, I'd bet they use that t3/t4 for the m50 and maybe m52...I dunno if its me but a .63 seems on the small side for an s52 (3.2L)

Too much backpressure from small sizing = EGT's go through the roof.
It is small. I was just comparing the t3/t4 to the gt30r 1.06 a/r. If that turbo can make 325rwhp with a .63a/r on a 2.5L the gt30 with a 1.06a/r will flow well .

Big D If you look at the compressor map, you should require around 44lb/min of air. At your boost level of 10psi to make your power goal. that should indicate a 1.6 pressure ratio.

The Garrett turbo tech site says "this means that for any engine, in order to make 400 Hp, it needs to flow about 44 lb/min"

If you look at the map you're completely off the efficiency island. I'd say you'd have to run at least 15psi to be with in both the 30r and 35r's efficiency


heres a thread for you. S52 t3/t4 Pump gas 12 psi 360rwhp
http://forums.bimmerforums.com/forum...d.php?t=578916.
__________________
///tyron is offline   Reply With Quote
Old 03-18-2009, 02:06 AM   #17
e30_kid89
The Afro-stig
 
e30_kid89's Avatar
 
Join Date: Nov 2005
Location: TDot West End
Posts: 4,598
Send a message via MSN to e30_kid89
I see what you're saying now... If the pressure ratio is 1.6 then yea he'll be off the map.
In that case I'd agree with you on a GT30r with a 1.06 a/r housing being a better match.
__________________
e30_kid89 is offline   Reply With Quote
Old 03-18-2009, 12:17 PM   #18
BigD
the misanthropist
 
BigD's Avatar
 
Join Date: May 2002
Location: a house
Posts: 6,168
Again please provide the math. I think my estimates were all pretty reasonable and I end up at a pressure ratio of over 1.9. You can't just pull out boost numbers out of thin air. 15PSI in an efficient DOHC head (if I remember correctly, I assumed .97 volumetric efficiency, which is pretty conservative) of a 3.2 at 7000 rpm at sea level is going to make a hell of a lot more than 400hp.
__________________
BigD is online now   Reply With Quote
Old 03-18-2009, 01:56 PM   #19
///tyron
4th Gear Member
 
///tyron's Avatar
 
Join Date: Jun 2006
Location: whitby
Posts: 690
Quote:
Originally Posted by BigD View Post
Again please provide the math. I think my estimates were all pretty reasonable and I end up at a pressure ratio of over 1.9. You can't just pull out boost numbers out of thin air. 15PSI in an efficient DOHC head (if I remember correctly, I assumed .97 volumetric efficiency, which is pretty conservative) of a 3.2 at 7000 rpm at sea level is going to make a hell of a lot more than 400hp.
I used a basic equation with your numbers in the equation, i didnt just make up the numbers.

10 psia + 14.7 psia = 24.7 psi absolute pressure in the manifold

24.7psi/14.7 = 1.68 pressure ratio
__________________

Last edited by ///tyron; 03-18-2009 at 02:08 PM.
///tyron is offline   Reply With Quote
Old 03-18-2009, 04:10 PM   #20
BigD
the misanthropist
 
BigD's Avatar
 
Join Date: May 2002
Location: a house
Posts: 6,168
Only according to Garrett, you have to use 1psi pressure loss through inlet depression and 2 psi for a typical pressure loss through piping etc (which, since I'm no expert, is probably even optimistic) for calculating the ratio, so it's 26.7/13.7 = 1.95
__________________
BigD is online now   Reply With Quote
Old 03-20-2009, 11:26 AM   #21
everlast
if I lived . I would be ~
 
everlast's Avatar
 
Join Date: Mar 2004
Location: Ottawa
Posts: 5,847
Try this out:

http://www.not2fast.com/turbo/glossary/turbo_calc.shtml

Remember that calculations and math will only approximate things; experience is the only true measure. I'm sure there are guys running different turbos on the S52 that have posted numbers. Ask the Google.

Edit - where did you get this info: ".97 volumetric efficiency, which is pretty conservative"? Race motors can go above 1 at the right RPM range, but most street motors don't approach 1 from what I understand.
__________________
everlast is offline   Reply With Quote
Old 03-20-2009, 11:46 AM   #22
BigD
the misanthropist
 
BigD's Avatar
 
Join Date: May 2002
Location: a house
Posts: 6,168
Quote:
Originally Posted by everlast View Post
Edit - where did you get this info: ".97 volumetric efficiency, which is pretty conservative"? Race motors can go above 1 at the right RPM range, but most street motors don't approach 1 from what I understand.
From Garrett - they say figure 96-99 for a good DOHC head.
__________________
BigD is online now   Reply With Quote
Old 03-20-2009, 12:06 PM   #23
everlast
if I lived . I would be ~
 
everlast's Avatar
 
Join Date: Mar 2004
Location: Ottawa
Posts: 5,847
Wow!
__________________
everlast is offline   Reply With Quote
Old 03-28-2009, 10:34 PM   #24
90E30i
3rd Gear Member
 
90E30i's Avatar
 
Join Date: Jan 2004
Location: Mississauga
Posts: 493
Choosing the right turbo is half the battle. Manifold design and intercooler size and design also play a major role. For example a twin entry exhaust housing with a split pulse manifold will give you huge improvement over the same turbo with a single entry manifold. I suppose being a track car you want to have good mid range power to pull you out of the turns.
90E30i is offline   Reply With Quote
Reply

Thread Tools
Display Modes Rate This Thread
Rate This Thread:

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 On

Forum Jump


All times are GMT -4. The time now is 04:49 PM.


Powered by vBulletin® Version 3.8.1
Copyright ©2000 - 2014, Jelsoft Enterprises Ltd.
Maxbimmer Copyright 2001 - 2014