Welcome to the North American Subaru Impreza Owners Club Sunday May 31, 2020
Home Forums Images WikiNASIOC Products Store Modifications Upgrade Garage
NASIOC
Go Back   NASIOC > NASIOC Technical > Factory 2.5L Turbo Powertrain (EJ Series Factory 2.5L Turbo)

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.







* As an Amazon Associate I earn from qualifying purchases. 
* Registered users of the site do not see these ads. 
Reply
 
Thread Tools Display Modes
Old 07-13-2005, 08:26 AM   #1
singsing
Scooby Newbie
 
Member#: 36991
Join Date: May 2003
Vehicle:
2003 Liberty B4
blue

Default what is turbine clipping and what does it do?

as per the subject...

im seriously itching to get a sz55 with the fatboy turbine... but it costs a little more to get the turbine wheel clipped

what does this mean exactly and what does it provide in terms of power/spool etc...

thanks
* Registered users of the site do not see these ads.
singsing is offline   Reply With Quote
Sponsored Links
* Registered users of the site do not see these ads.
Old 07-13-2005, 08:49 AM   #2
serendipity
Scooby Specialist
 
Member#: 54597
Join Date: Feb 2004
Chapter/Region: MAIC
Location: Gaithersburg, MD
Vehicle:
08 'Busa, 08 ML63
10 Multistrada, 996 Targa

Default

Don't get it clipped. Clipping is a poor man's way of increasing the flow through the turbine by actually clipping the exhaust wheel's blades. This reduces drag, but it ruins the aerodynamics of the wheel and kills spool, all for a little better top-end potential.

Garrett strongly recommends never clipping a wheel - just buy an appropriately sized turbo for your needs, don't screw with the turbo designer's millions of dollars in R&D that came up with the ideal wheel shape.
serendipity is offline   Reply With Quote
Old 07-13-2005, 08:52 AM   #3
Project Rex STi
Scooby Newbie
 
Member#: 77249
Join Date: Dec 2004
Vehicle:
04 STi
WRB

Default

Quote:
Originally Posted by serendipity
Don't get it clipped. Clipping is a poor man's way of increasing the flow through the turbine by actually clipping the exhaust wheel's blades. This reduces drag, but it ruins the aerodynamics of the wheel and kills spool, all for a little better top-end potential.

Garrett strongly recommends never clipping a wheel - just buy an appropriately sized turbo for your needs, don't screw with the turbo designer's millions of dollars in R&D that came up with the ideal wheel shape.

Agreed.
Project Rex STi is offline   Reply With Quote
Old 07-13-2005, 12:10 PM   #4
pux888
Scooby Specialist
 
Member#: 8356
Join Date: Jul 2001
Chapter/Region: MAIC
Vehicle:
02 STi swap
12 WRX limited

Default

most of DB's 20g come w/ a 10 degree clip now, do you guys feel thats a bad thing? if you running a stock location turbo you can deal w/ so much backpressure before it becomes a problem, especially on the 2.5.
pux888 is offline   Reply With Quote
Old 07-13-2005, 04:03 PM   #5
AZScoobie
Scooby Guru
 
Member#: 8785
Join Date: Jul 2001
Chapter/Region: SWIC
Vehicle:
02 [email protected]
netcom.com

Default

Its internet fokelore that clipping is bad no matter the circumstance. Garretts position is that you no longer need/have to do this as they have newer GT wheels. If you choose the right product you no longer have to make a compromise. Garrett does offer factory clipped wheels right in the catalog.

Most Mitsu hybrid turbos use a clipped 5H or 6H turbine wheel. This is done as the 7cm housing is far to small. The solution was to clip the wheel to increase flow. Its been done for years and years. while it can reduce the effectiveness of the turbine and lowers Shaft trq, it does increase flow. In this case the flow increase FAR outweighs the loss in power to the shaft.

It is also internet fokelore that clipping a wheel increases lag or slows spool as a rule. In our application it actualy helps spool producing more power every where in the RPM band. While its generaly known that clipping a wheel helps top end (which it can do), clipping can many times help spool. This has been tested back to back with a Td05/50trim turbo (green) when run on our EJ motors. The clipped wheel produced 40ft lbs more in the middle(from memory) and had more power everywhere. Top end power stayed the same. Jarrad from PDX Did alot of testing last year and might even have those charts still.

Clark
AZScoobie is offline   Reply With Quote
Old 07-13-2005, 04:21 PM   #6
pux888
Scooby Specialist
 
Member#: 8356
Join Date: Jul 2001
Chapter/Region: MAIC
Vehicle:
02 STi swap
12 WRX limited

Default

thanks for the info thats just what I was waiting to hear, as my turbo is about to be shipped out for a nice clip! How much did you guys go w/ on the green 10-15 deg?
pux888 is offline   Reply With Quote
Old 07-14-2005, 04:20 AM   #7
singsing
Scooby Newbie
 
Member#: 36991
Join Date: May 2003
Vehicle:
2003 Liberty B4
blue

Default

ooook... so a clipped sz55 is better than an unclipped sz55?

singsing is offline   Reply With Quote
Old 07-14-2005, 11:06 AM   #8
pux888
Scooby Specialist
 
Member#: 8356
Join Date: Jul 2001
Chapter/Region: MAIC
Vehicle:
02 STi swap
12 WRX limited

Default

i would think it would require a clip if your using the 6h. with the fatboy trubine its fine.
pux888 is offline   Reply With Quote
Old 07-14-2005, 01:46 PM   #9
DISCOPOPE
Scooby Specialist
 
Member#: 43339
Join Date: Sep 2003
Location: mpls, mn
Vehicle:
2oo4 STi
URgt35r w/t3hM3finj3cki0n

Default

the turbine on my deadbolt 20g wes very subtle.
more of a shear than a clip... i'm sure if you ask jerry about it he will give you the lowdown.

i have no problems with spool...... whatsoever...
DISCOPOPE is offline   Reply With Quote
Old 07-14-2005, 02:23 PM   #10
SilverSurfer04STi
Scooby Specialist
 
Member#: 71542
Join Date: Sep 2004
Chapter/Region: MWSOC
Location: Midwest
Vehicle:
2013 WRB BRZ

Default

Quote:
Originally Posted by DISCOPOPE
the turbine on my deadbolt 20g wes very subtle.
more of a shear than a clip... i'm sure if you ask jerry about it he will give you the lowdown.

i have no problems with spool...... whatsoever...
+1
That makes two of us. When I inspected the turbine wheel prior to installation you could barely even tell it was clipped. Spooling and boost response in partial throttle situations are both excellent with my 20G.
SilverSurfer04STi is offline   Reply With Quote
Old 05-20-2020, 11:41 AM   #11
Jedi03
Scooby Newbie
 
Member#: 491095
Join Date: Sep 2018
Chapter/Region: SWIC
Location: New Mexico
Vehicle:
2009 STi Blue
Blue

Default

how does this improve vs porting the housing?
Jedi03 is online now   Reply With Quote
Old 05-22-2020, 06:45 AM   #12
bp05obxt
Scooby Specialist
 
Member#: 459799
Join Date: Dec 2016
Default

Quote:
Originally Posted by Jedi03 View Post
how does this improve vs porting the housing?


Porting a housing only improves inlet flow or how the exhaust pressure is introduced to the turbine wheel. Clipping is about flow though the turbo. Essentially the turbine wheel and housing A/R become a choke point and prevent the turbo from making power at some point. Clipping the wheel removes part of that choke allowing the turbo to potentially generate more efficient flow and boost at a higher rpm; generally.

In aftermarket turbos there are various different size A/R options for turbine housings. These housings will fit the same turbo, but allow the turbo to be tuned to a specific need. Garrett is a perfect example; just in TiAl housings alone there are .63/.82/1.03 A/R. V-band housings for a 35r. Each of which are interchangeable to I crease or decrease flow through the A/R of the turbo and past the turbine wheel.

In short porting can gain you spool and response, but increased flow through the turbo via clipping or increased A/R will decrease choke and increase efficiency into high rpm.

Ill always go for increased A/R over clipping. Most aftermarket turbo options available today have largely improved aero and housing designs that factory turbos cant compete with. The idea of clipping a turbine wheel and potentially compromising overall performance for a little gain up top just isnt my preferred method. 9/10 times Id go aftermarket even with the increased costs.
bp05obxt 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
What is Variable Turbine Geometry and how does it work? ka mano Factory 2.5L Turbo Powertrain (EJ Series Factory 2.5L Turbo) 26 10-22-2011 04:16 AM
What is this hose and where does it go? Sputt Factory 2.0L Turbo Powertrain (EJ Series Factory 2.0L Turbo) 4 03-08-2009 09:31 PM
STi: What is this part and where does it go? benyl Factory 2.5L Turbo Powertrain (EJ Series Factory 2.5L Turbo) 5 09-18-2006 02:58 AM
what the hell is SBF 5 and why does it keep blowing? jared nelson Electrical & Lighting 3 05-04-2005 07:52 AM
Isnt this arik's car and why does it do that? STi Sev General Forum Archive 8 05-15-2000 08:25 PM

All times are GMT -4. The time now is 03:28 PM.


Powered by vBulletin® Version 3.7.0
Copyright ©2000 - 2020, Jelsoft Enterprises Ltd.
Powered by Searchlight © 2020 Axivo Inc.
Copyright ©1999 - 2019, North American Subaru Impreza Owners Club, Inc.

As an Amazon Associate I earn from qualifying purchases.