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 Forums > Porsche Forums > 911 / 930 Turbo & Super Charging Forum


Reply
 
LinkBack Thread Tools Rating: Thread Rating: 1 votes, 5.00 average.
Author
Thread Post New Thread    Reply
Acceleration Junkie
 
Join Date: Aug 2007
Location: Laguna Beach, CA
Posts: 263
Garage
Quote:
Originally Posted by gogomobil View Post
what happens if the AFR sensor is installed before the turbo? wrong readings? or will the sensor be toasted?
Toast.
Old 11-20-2008, 12:46 PM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #41 (permalink)
Crotchety Old Bastard
 
RarlyL8's Avatar
 
Join Date: Jan 2000
Location: Huntsville, AL
Posts: 13,580
Garage
I think position sensitivity may depend on the equipment and the engine configuration.
I have my AFR O2 sensor located in the stock J-pipe Lambda location, before the turbo, and it has worked flawlessly for years. I check and tune using the bung right after the turbo and see similar numbers. The response when the throttle is lifted is different as you might expect. The dyno shop that I use runs the typical tube up the tailpipe and gets consistant readings above idle.
__________________
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 11-20-2008, 06:15 PM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #42 (permalink)
Registered User
 
rsrmike's Avatar
 
Join Date: Jan 2008
Location: Birmingham, AL
Posts: 538
Quote:
Originally Posted by Chuck Jones View Post
rsmike: It was the thin gauge of the 304 stainless that made me decide to go to the muffler pipe...but I was close to putting it on the end of the muffler itself...your post makes sense. However with a muffler, the leak is usually easy to spot either thru the sound of the leak or an exhaust stain where it's leaking. It seems to me that as long as the bung was installed correctly, and you check it every so often for leaks, it still might be a good place to put the sensor. I'm sure the experts will chime in...

I agree, that is a good idea I never thought of. I was just curious how a crack in the muffler would actually affect AFR readings, or if it would really matter.

FWIW, most of the mufflers I mentioned were so noisy, the cracks weren't really audible, it's was usually the floppy tail pipes of the borlas that got your attention. They did leave nice black trails though

The point I wanted to make was, if you go that route, and suddenly start getting lean AFR readings, before you freak out and suspect a fuel system issue or try to re-tune, check for cracks in the muffler, that's all

No worries
__________________
Professional Overcomplicator
Old 11-20-2008, 07:03 PM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #43 (permalink)
Registered User
 
hipdoc's Avatar
 
Join Date: Sep 2007
Location: Fresno, CA
Posts: 156
What happens if the O2 sensor is about 6" downstream from the turbo. One of my engines for the track has no muffler and the O2 sensor for my Electromotive just goes into a short exhaust tube. Do I have to make a longer tube?
Old 11-21-2008, 07:19 AM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #44 (permalink)
After the next project
 
x98boardwell's Avatar
 
Join Date: Sep 2006
Location: Central Valley, CA
Posts: 1,522
Garage
HipDoc

6" downstream from the turbo is a great location unless the pipe after the turbo is only 7" long. The worry would be that fresh air would enter the pipe and report false readings.

How long is your current pipe? If it is 12 inches long then you are probably ok.

I have heard that 6" after the turbo is ideal. Remember to have the sensor between the 10 and 2 positon from the top of the pipe facing down into the pipe.

Bryan
Old 11-21-2008, 07:33 AM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #45 (permalink)
A fellow Pelacanite
 
NathanUK's Avatar
 
Join Date: Nov 2006
Location: UK
Posts: 2,002
Garage
Certainly putting the sensor too near the end of the tailpipe can cause problems at idle and cruise.
Placing the sensor before the turbocharger could be disastrous if it broke up and damaged your expensive turbocharger.
__________________
1981 UK 930. G50/01 shortened, 964 3.8RS Fibreglass Body Kit, 18" Alloys 8.5" F & 10" R, 225's F & 285's R, Special Colour Metallic Blue Paint, FIA Sparco Evo's, A/C and Air Pump removed, Electronic Boost Controller, GHL Headers, Tial46 WG.
Fitting - New service kit.
Needs Fitting - Innovate XD-16 Kit, Kokeln IC. Stephen's K27 HFS, EVO Intake Assy & his Modded USA Fuel Head.

1983 UK 911 3.2 Carrera Sport Coupe. Black, Black Leather with Red Piping, Black Alloy Gear Knob, K&N Air Filter Element, Turbo Tie rods.
Needs Fitting - K&N CO Sensor, Round A/F Dial Gauge, Factory Short Shift Kit.

http://www.danasoft.com/sig/Iamnotanumber.jpg
Old 11-26-2008, 01:34 PM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #46 (permalink)
Registered User
 
beepbeep's Avatar
 
Join Date: Jun 2001
Location: Sweden
Posts: 5,565
Quote:
Originally Posted by gogomobil View Post
what happens if the AFR sensor is installed before the turbo?
wrong readings? or will the sensor be toasted?
Exhaust backpressure usually leads to wrong readings on-boost to tune of 1 AFR point or more. Sensor will also suffer from the heat and might fail sooner.
__________________
Thank you for your time,
Old 11-27-2008, 09:42 PM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #47 (permalink)
Reply

Thread Tools
Rate This Thread
Rate This Thread:

 


All times are GMT -8. The time now is 07:18 AM.


 
Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2018, vBulletin Solutions, Inc.
Search Engine Optimization by vBSEO 3.6.0
Copyright 2018 Pelican Parts, LLC - 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.