Fourtitude.com - Audi S1 Evo 2 rally cars tech question
Username or Email Address
Do you already have an account?
Forgot your password?
  • Log in or Sign up

    Fourtitude.com


    Results 1 to 6 of 6
    1. 09-09-2009 09:14 AM #1
      Hi all, I'm new to this forum and have a question about the S1 evo2 versions of Audi's old Grp. B rally cars. The questions is regarding the chirping squeaking sound on the over-run or between shifts from the excess boost? In these cars what exactly causes this sound? I believe this to be the type of diverter valve used venting to atmosphere but am not convinced. I have also been told that they ran twin wastegates and this is the cause. Does anyone know this for sure? It can clearly be heard during much of the footage of this car in action although not all versions sounded this way. If anyone can help I would appreciate it. Thanks.

    2. Remove Advertisements

      Advertisements
       

    3. 10-21-2009 01:35 PM #2
      there are a number of noises, wastgates, anti leg systems, & blow off valves make most of the odd sounds.
      Thinking back anti leg was not around back then, Blow off valves have distinctive sounds.

    4. Member mikegilbert's Avatar
      Join Date
      Nov 29th, 2006
      Location
      Los Angeles
      Posts
      16,492
      Cars
      F80 / TDI / LWB
      11-07-2009 01:29 PM #3
      Quote, originally posted by dkbottles »
      Thinking back anti leg was not around back then

      Actually, Audi developed antilag or 'Umluft' as they called it for the S1, here's a great page to read through for more information.
      http://www.bufkinengineering.com/Umluft.htm
      And a wonderful video of it. [IMG]http://*****************.com/smile/emlove.gif[/IMG]
      http://www.youtube.com/watch?v...edded
      http://www.youtube.com/watch?v=IZskSMSsiPA&NR=1


      Modified by mikegilbert at 10:46 AM 11-7-2009
      flickr | Everything you need to know | » | Scratch-It™ | Vimeo | Instagram

      Quote Originally Posted by bzcat View Post
      BMW made the decision to chase tuhao money with questionable aesthetic and it can't expect more sophisticated markets to go along with the crassness of its current batsh1t crazy design.

    5. Remove Advertisements

      Advertisements
       

    6. 11-28-2009 01:19 AM #4
      Now that was a fascinating read. Given the short life span I would guess they did not use the system on rally cars, 12 min up pikes peak is a different game. I think I once read they tried electric motors to drive a turbo too., the cracking sound in the videos sounds more like current ALS where the ignition is retarded to fire with the exhaust valve open, crating no power but spooling the turbo. I know there are other systems out there now too.

    7. Member mikegilbert's Avatar
      Join Date
      Nov 29th, 2006
      Location
      Los Angeles
      Posts
      16,492
      Cars
      F80 / TDI / LWB
      12-25-2009 12:18 AM #5
      Quote, originally posted by dkbottles »
      Now that was a fascinating read. Given the short life span I would guess they did not use the system on rally cars, 12 min up pikes peak is a different game. I think I once read they tried electric motors to drive a turbo too., the cracking sound in the videos sounds more like current ALS where the ignition is retarded to fire with the exhaust valve open, crating no power but spooling the turbo. I know there are other systems out there now too.

      Oh, they used it on the Rally verions as well. [IMG]http://*****************.com/smile/emthup.gif[/IMG]
      Here's Röhrl testing an umluft setup on an S1.
      http://www.youtube.com/watch?v=XrhcSRktAs0


      Modified by mikegilbert at 9:20 PM 12-24-2009
      flickr | Everything you need to know | » | Scratch-It™ | Vimeo | Instagram

      Quote Originally Posted by bzcat View Post
      BMW made the decision to chase tuhao money with questionable aesthetic and it can't expect more sophisticated markets to go along with the crassness of its current batsh1t crazy design.

    8. 01-05-2010 02:58 PM #6
      The chirping sound is the compressor wheel on the turbo getting hit with pressure when the throttle is closed between shifts, they did not run a blow off valve or diverter valve on those cars.

    Posting Permissions

    • You may not post new threads
    • You may not post replies
    • You may not post attachments
    • You may not edit your posts
    •