Pelican Parts
Parts Catalog Accessories Catalog How To Articles Tech Forums
Call Pelican Parts at 888-280-7799
Shopping Cart Cart | Project List | Order Status | Help



Go Back   Pelican Parts Technical BBS > 1- Porsche Technical Forums > 911 / 930 Turbo & Super Charging Forum

Reply
 
LinkBack Thread Tools Rate Thread
Author
Thread Post New Thread    Reply
3 restos WIP = psycho
 
kenikh's Avatar
 
Join Date: Feb 2005
Location: North of Exit 17
Posts: 7,708
Running divided turbo on stock (open) flange?

Is there any downside divided turbo on stock (open) flange? The reasoning being one can run the divided turbo on a factory exhaust until one can afford to fabricate a divided exhaust to suit.

Sent from my Nexus 6P using Tapatalk
__________________

- 1965 911
- 1969 911S
- 1980 911SC Targa
- 1979 930
Old 06-08-2017, 09:41 AM
  Pelican Parts Technical Article Directory    Reply With Quote #1 (permalink)
Chain fence eating turbo
 
Join Date: Dec 2008
Location: Austin, TX
Posts: 7,889
I did it. Honestly, when I finally divided the header, it didn't make a lot of difference.

But, I did make the divider about 3/8" tick instead of the 1/4" of the turbine housing possibly choking a little and causing turbulence. It's on my list of things to address while I have the motor down.
Old 06-08-2017, 11:09 AM
  Pelican Parts Technical Article Directory    Reply With Quote #2 (permalink)
Registered User
 
copbait73's Avatar
 
Join Date: Nov 2003
Location: Chesterfield IN
Posts: 1,310
Garage
Quote:
Originally Posted by kenikh View Post
Is there any downside divided turbo on stock (open) flange? The reasoning being one can run the divided turbo on a factory exhaust until one can afford to fabricate a divided exhaust to suit.

Sent from my Nexus 6P using Tapatalk
No problems. Now, if you ran the full 24 hrs of Le mans you may have heat checking/erosion at the flange surface.
Old 06-08-2017, 12:32 PM
  Pelican Parts Technical Article Directory    Reply With Quote #3 (permalink)
3 restos WIP = psycho
 
kenikh's Avatar
 
Join Date: Feb 2005
Location: North of Exit 17
Posts: 7,708
Thanks guys!

Sent from my Nexus 6P using Tapatalk
__________________

- 1965 911
- 1969 911S
- 1980 911SC Targa
- 1979 930
Old 06-08-2017, 01:58 PM
  Pelican Parts Technical Article Directory    Reply With Quote #4 (permalink)
Registered User
 
MikeD930's Avatar
 
Join Date: Apr 2008
Location: missouri
Posts: 1,502
Garage
My 930 is set up that way using divided turbo with custom headers that are not divided. It was already that way when I bought this car. I don't know why whoever did this mod did not divide the headers. Anyway the divided housing will be fine as mine were good shape when I removed the turbo to add new compressor seal.
__________________
MikeD
'87 930
Old 06-08-2017, 02:54 PM
  Pelican Parts Technical Article Directory    Reply With Quote #5 (permalink)
Crotchety Old Bastard
 
RarlyL8's Avatar
 
Join Date: Jan 2000
Location: Huntsville, AL
Posts: 13,257
Garage
If you were going to leave it that way (divided turbo only) I would file the turbo plenum to a sharp edge to improve flow. When you get your split plenum headers (all of ours are split by the way) you should match the dividers so flow is smooth. Every little bit helps.
__________________
RarlyL8 Motorsports / M&K Exhaust - 911/930 Exhaust Systems, Turbos, TiAL, CIS Mods/Rebuilds
'78 911SC Widebody, 930 engine, 915 Tranny, K27, SC Cams, RL8 Headers & GT3 Muffler. 350whp @ 0.75bar
Brian B. (256)536-9977 Service@MKExhaust Brian@RarlyL8
Old 06-09-2017, 04:19 AM
  Pelican Parts Technical Article Directory    Reply With Quote #6 (permalink)
 
Now Available for Ordering:   101 Projects For Your BMW 3 Series 1982-2000  [more info]
Metal Guru
 
911nut's Avatar
 
Join Date: May 2001
Location: Michigan
Posts: 2,502
Garage
Quote:
Originally Posted by kenikh View Post
Is there any downside divided turbo on stock (open) flange? The reasoning being one can run the divided turbo on a factory exhaust until one can afford to fabricate a divided exhaust to suit.
As it was explained to me by the exhaust guys I work with, when an exhaust pulse from one bank flows to the turbo, there's low pressure in the opposite bank. The divider forces flow into the turbo instead of having the exhasut flow into the low pressure area. Without the divider, you lose some low speed response in the form of backflow into the low pressure in the opposite bank.
I'm in the opposite situation; I added the divider to my collector to stop the backflow and improve boost onset but I don't have a twin scroll turbo. I did gain a small improvement in boost onset.
__________________
Paul B.
'91 964 Turbo
Port matched, SC cams, K27/K29 turbo, Roush Performance custom headers w/Tial MV-S dual wastegates, Rarlyl8 muffler, LWFW, GT2 clutch & PP, BL wur, factory RS shifter, RS mounts, FVD timing mod, Big Reds, - 210 lb
Old 06-16-2017, 07:12 AM
  Pelican Parts Technical Article Directory    Reply With Quote #7 (permalink)
Registered User
 
Ken911's Avatar
 
Join Date: May 2005
Location: Loxahatchee, florida
Posts: 2,480
So with a twin scroll equal length primaries are supposed to help a lot. Does the Secondary need to be equal length also? Or is the fact that they are divided enough?
__________________
88 turbo Guards red Targa slant nose, and yes I am a horsepower junkie, 3.4liter,7.5 to 1 JE pistons, Adjustable WUR, Imagine fuel head, 1 bar waste gate headers,allthe cis toys. Now apart to become the next EFI monster. fabbing my own intake, headers Individual throttle bodies, MS-3, pauter rods, Xtreme twin plugged heads, gt-2 evo cams cop's.
05 Cayenne S lapis blue
Old 06-16-2017, 07:59 PM
  Pelican Parts Technical Article Directory    Reply With Quote #8 (permalink)
3 restos WIP = psycho
 
kenikh's Avatar
 
Join Date: Feb 2005
Location: North of Exit 17
Posts: 7,708
Everything should be equal length. There's some debate that you can essentially get the same effect in unequal exhausts by timing the length of one set of headers to be in phase, but one cycle off, but the maths hurt my head.

Sent from my Nexus 6P using Tapatalk
__________________

- 1965 911
- 1969 911S
- 1980 911SC Targa
- 1979 930
Old 06-16-2017, 08:16 PM
  Pelican Parts Technical Article Directory    Reply With Quote #9 (permalink)
Crotchety Old Bastard
 
RarlyL8's Avatar
 
Join Date: Jan 2000
Location: Huntsville, AL
Posts: 13,257
Garage
Everything needs to be equal length for a divided plenum to be optimized. Each pulse needs to hit the turbine at the same unique time and sequence as the exhaust valves open. The complexity to do this in an unequal system based on individual tube length would not only be a mathematical challenge but a packaging nightmare. Any compromise would ruin the effect. Our headers are equal length both on the primaries and secondaries with a divided plenum. Each bank gets a smooth transition bend waste gate outlet. The result is a minimum of back fill when using a single waste gate and open plenum turbo such as the K27. The tuned sound is completely different than short tube systems, off boost torque is greater, turbo lag is essentially the same as the short tube systems and HP is greater once on boost. All of this is enhanced further when using twin waste gates and a twin scroll turbo. Very quick response, big off-boost torque and big HP capacity. Tubing sizing can be kept conservative as well which enhances velocity for quick response without reducing power capacity at full boost redline.
__________________
RarlyL8 Motorsports / M&K Exhaust - 911/930 Exhaust Systems, Turbos, TiAL, CIS Mods/Rebuilds
'78 911SC Widebody, 930 engine, 915 Tranny, K27, SC Cams, RL8 Headers & GT3 Muffler. 350whp @ 0.75bar
Brian B. (256)536-9977 Service@MKExhaust Brian@RarlyL8
Old 06-17-2017, 06:53 AM
  Pelican Parts Technical Article Directory    Reply With Quote #10 (permalink)
Reply

Thread Tools
Rate This Thread
Rate This Thread:

 


All times are GMT -8. The time now is 02:36 PM.


 
Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2017, vBulletin Solutions, Inc.
Search Engine Optimization by vBSEO 3.6.0
Copyright 2016 Pelican Parts - Posts may be archived for display on the Pelican Parts Website -    DMCA Registered Agent Contact Page
 

DTO Garage Plus vBulletin Plugins by Drive Thru Online, Inc.