Welcome to the North American Subaru Impreza Owners Club Wednesday July 30, 2014
Home Forums WikiNASIOC Products Store Modifications Upgrade Garage
NASIOC
Here you can view your subscribed threads, work with private messages and edit your profile and preferences Home Registration is free! Visit the NASIOC Store NASIOC Rules Search Find other members Frequently Asked Questions Calendar Archive NASIOC Upgrade Garage Logout
Go Back   NASIOC > NASIOC Technical > Normally Aspirated with bolt-on Forced Induction Powertrain

Welcome to NASIOC - The world's largest online community for Subaru enthusiasts!
Welcome to the NASIOC.com Subaru forum.

You are currently viewing our forum as a guest, which gives you limited access to view most discussions and access our other features. By joining our community, free of charge, 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 free, fast and simple, so please join our community today!

If you have any problems with the registration process or your account login, please contact us.
* Registered users of the site do not see these ads.
Reply
 
Thread Tools Display Modes
Old 09-09-2005, 08:52 PM   #1
GregBolby
Scooby Specialist
 
Member#: 498
Join Date: Nov 1999
Chapter/Region: South East
Location: Charleston, SC
Vehicle:
1981 jdm swapped gc
sniklfritz

Default so is 5psi well...5psi?

i have a rhb5 turbo, running 5psi, if i swapped to a bigger turbo and ran the same boost will it be the same hp wise? or will the bigger volume of air matter?

G
* Registered users of the site do not see these ads.
GregBolby is offline   Reply With Quote
Old 09-09-2005, 08:57 PM   #2
Soon2Bgreat
Scooby Specialist
 
Member#: 2258
Join Date: Sep 2000
Chapter/Region: Tri-State
Location: Irvington, New York, USA
Vehicle:
1999 gc8 ver7 6mt
GT35R 504.7whp;)

Default

Yes it will still be 5psi technically. You are right in assuming more air will be flowed though...but that depends. If the smaller turbo is inefficient at 5psi and the bigger turbo is more efficient that holds true. BUT if it's a gt42 then at 5psi it would probably be less air. At least that's my understanding of it, hope that's somewhat clear.
Soon2Bgreat is offline   Reply With Quote
Old 09-09-2005, 09:39 PM   #3
Matth3w
Scooby Specialist
 
Member#: 94597
Join Date: Aug 2005
Chapter/Region: TXIC
Location: Fort Huachuca, AZ
Vehicle:
2003 Corvette Z06
Black/Black

Default

5psi on a GT28 turbo is less power than 5psi on a T3 for example. its still 5psi but you cant switch turbo sizes and expect to run the same psi. you might BE able to, but say on a T3/T4 hybrid youll be making more hp at 5psi than on a GT25.

so the moral of the story is, if you have a smaller turbo and go to a bigger, you should probably decrease the psi unless youre tuned for it. either way though, if youre buying a new turbo that is either bigger or smaller and youre not tunning the car to go with it, if not for motor safety than for efficiency and power, there is something wrong.
Matth3w is offline   Reply With Quote
Old 09-09-2005, 10:30 PM   #4
Barge
Scooby Newbie
 
Member#: 62941
Join Date: May 2004
Chapter/Region: RMIC
Location: Denver, CO
Vehicle:
2004 WRX
Rally Blue

Default

Yes.. 5 psi is 5 psi. The only way you would have a difference in power was if the bigger turbo was more efficient at that flow and that pressure ratio since you would then have a higher density ratio. The density ratio is what's actually determing how much more air you are using over an NA engine.

Bigger turbo are an advantage because they usually flow more air.. not necessarily support that much more boost but they will be able to hold a certain pressure ratio into higher rpm's (more air) and at a decent efficiency.
Barge is offline   Reply With Quote
Old 09-10-2005, 01:44 AM   #5
no-coast-punk
Scooby Specialist
 
Member#: 49087
Join Date: Nov 2003
Chapter/Region: RMIC
Location: Inside your carnot cycle
Vehicle:
1998 RST V8 STi swap
'05 R6 '95 BMW V8 hotness

Default

If you are running a MAF style ECU things may change a bit. If you are running a speed density system all you have to do is make sure your IAT sensor is between the IC and TB.... of course you should have done this from the beginning right? If the IAT sensor is right before the TB your fuel/timing maps should change not a wink.
no-coast-punk is offline   Reply With Quote
Old 09-10-2005, 11:41 AM   #6
kgb
Scooby Specialist
 
Member#: 1366
Join Date: Apr 2000
Chapter/Region: VIC
Location: Delta, BC, Canada
Vehicle:
2000 RS-T -> RSTi-8
Blue Ridge Pearl

Default

5psi on a bigger turbo will generally push more air than 5psi on a smaller turbo, so that means more power and requires more fuel. Depends on how your EM does fueling - if your EM uses MAF, or MAP and compensates for IAT, extra fueling should be accounted for already. But if you're like me who is running MAP without IAT, you will need to add more fuel across the board.
kgb is offline   Reply With Quote
Reply

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
Forum Jump

Similar Threads
Thread Thread Starter Forum Replies Last Post
So im promoting wellness.. Skell Off-Topic 13 10-16-2007 09:57 PM
Well at Least the War is Going Well and We Caught Bin Laden proletariandan Political Playground 8 02-26-2007 12:37 PM
So my wheel-well cover got ripped out on the highway last weekend... perret318 Off-Topic 12 11-28-2005 01:23 PM
So my ladyfriend is very well likely an idiot. In related news, so am I. scaryfastskier Off-Topic 27 10-27-2004 04:06 PM
well the ej22t swap is going......well , it's going wrxtuner02 Subaru Conversions 1 06-21-2004 12:17 AM


All times are GMT -4. The time now is 08:47 PM.


Powered by vBulletin® Version 3.7.0
Copyright ©2000 - 2014, Jelsoft Enterprises Ltd.
Powered by Searchlight © 2014 Axivo Inc.
Copyright ©1999 - 2014, North American Subaru Impreza Owners Club, Inc.