Go Back   986 Forum - The Community for Porsche Boxster & Cayman Owners > Porsche Boxster & Cayman Forums > Performance and Technical Chat

Post Reply
 
LinkBack Thread Tools Display Modes
Old 09-27-2013, 03:53 PM   #1
edc
550 Anniversary
 
edc's Avatar
 
Join Date: Jul 2012
Location: Surrey, UK
Posts: 747
Garage
Has anyone fitted an OBX or similar throttle bodies kit?

If so I'd like to hear more - costs, unexpected problems, extra bits, gains, mapping etc.

__________________
Current: 550 Spyder Anniversary- Carnewal exhaust - 100 cell cats - stainless manifolds - 4" underdrive pulley - poly gearbox mounts - rear lower alu brace - adjustable rear toe links
Sold: 986S - Zenith Blue - 18" Sport Classics - Black Zunsport grilles - Stainless silencer and manifolds - K&N panel - shortshift - M030 suspension - 75mm throttle body - custom 83mm intake - SmartTop - custom remap - MDS underdrive pulley
edc is offline   Reply With Quote
Old 10-01-2013, 06:39 AM   #2
Registered User
 
The Radium King's Avatar
 
Join Date: Apr 2010
Location: Canada
Posts: 3,121
i'd looked into itb's for a 911 project before, but first i'd heard that they make them for the m96 engines. first concern would be fit in the boxster. geometry aside, in searching around I found some cool info on alpha-n tuning - running the car without a maf (required with itb's) and just using tps. the bosche ecu can do it (that's how it runs in 'limp' mode') so it's just a matter of tweaking it for performance and accuracy (and fining a place for your iat sensor, and rigging a cable throttle that also has a tps sensor that speaks to the ecu). apparently chip wizards in the uk has experience with this. so, with tuning addressed you just need vacuum. there's a variety of electric vacuum pumps on the market, but uncertain if they can handle the crap that comes out of the aos (you want to keep vacuum on the crankcase to seal the rings); if so you can just vent it to a catch-can that you drain occasionally.
The Radium King is offline   Reply With Quote
Old 10-01-2013, 07:08 AM   #3
Registered User
 
The Radium King's Avatar
 
Join Date: Apr 2010
Location: Canada
Posts: 3,121
not a lot of info out there on alpha-n tuning for Porsche. seems to be a lot of use on bmw's, due to the fact that the m-sport cars come with itbs so no maf. apparently some Porsche gt3 race teams run alpha-n, not because they have itb's, but because it gets the maf out of the intake for less restriction. seems like it could be a tuning option for any boxster owner - if you're gonna pay $1000 for a softronic tune, why not pay something similar and get the maf out of there altogether (less restriction, no fouling issues, etc.)? of course, you can't modify fuel trim for air density ...
The Radium King is offline   Reply With Quote
Old 10-01-2013, 07:36 AM   #4
Registered User
 
The Radium King's Avatar
 
Join Date: Apr 2010
Location: Canada
Posts: 3,121
another way to avoid ditching the current ecu would be to go wideband 02 and piggyback. disconnect the maf and let the car go into limp mode (disconnect the cel to avoid the pesky orange light) then use the piggyback to add fuel based on what the wideband sees. uncertain if limp mode messes with timing, however ...
The Radium King is offline   Reply With Quote
Old 10-02-2013, 04:11 AM   #5
Registered User
 
Join Date: May 2011
Location: weehawken nj
Posts: 240
Ditching the maf and tuning with a piggy back isnt as easy as you say it is.

Youll need a very good manifold pressure sensor to start, and then the rest is programming. Now, a few issues to running ITBs and alpha n...

Space for an air filter ( which is MANDATORY for a mid engine )
Length of the runners
Alpha N seems to only be good for idle and WOT, and nothing in between

Between this, some good camshafts and headwork, you should be able to pull close to 100hp/liter if done correctly.
Bigsmoothlee is offline   Reply With Quote
Old 10-02-2013, 05:47 AM   #6
Registered User
 
The Radium King's Avatar
 
Join Date: Apr 2010
Location: Canada
Posts: 3,121
i thought alpha n didnt need to know manifold pressure? i thought it was purely a tps thing ( the bosch ecu doesnt have a manifold pressure sensor and these guys are getting it done with just the oem ecu). if you are going stand-alone fueling then yeah run a pressure sensor in conjunction with tps. i could see how tuning from just tps could get very on/off (trying to use a 0 to 5v signal to calculate fueling over a 7000 rpm range - this is why the stand-alone units use the pressure signal as well) but ive driven my car in limp mode, which is presumably just running on tps, and it is quite responsive. but i could see a lot of finesse and tuning being required. and no idea how youd fit it in a boxster.
The Radium King is offline   Reply With Quote
Old 10-23-2013, 04:30 PM   #7
Registered User
 
The Radium King's Avatar
 
Join Date: Apr 2010
Location: Canada
Posts: 3,121
just found this:

cam tweak, early 996 cup - Rennlist Discussion Forums

the poster works (owns?) blitzkrieg autowerks in Vancouver; you could contact him for more info on itbs.
The Radium King is offline   Reply With Quote
Old 10-23-2013, 08:25 PM   #8
Moderator
 
Join Date: Feb 2012
Location: DFW
Posts: 782
Garage
It's been done before.



A British rally driver, Mr. Ian Jemison would probably be the person I would want to talk to. He did quite a bit of work to a boxster. I wonder what power he is making! I believe he also swapped to a 3.6 or 3.4 engine too.

Kenny Boxster is offline   Reply With Quote
Post 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 On
Trackbacks are On
Pingbacks are On
Refbacks are On




All times are GMT -8. The time now is 03:35 PM.


Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2024, vBulletin Solutions, Inc.
Content Relevant URLs by vBSEO 3.6.0
Copyright 2024 Pelican Parts, LLC - Posts may be archived for display on the Pelican Parts Website -    DMCA Registered Agent Contact Page