Wastegate mod.....

[avos at cochlear.com.au]

     Simon,
     
     Unfortunately its not (quite) a perfect world, and if you do not let 
     the pressure get to the wastegate a few psi before the set boost 
     level, you will find that boost may fluctuate (oscillate), and you 
     will get a lot of overshoot ( jumps to a few psi above the set level 
     initially before backing off), as the wastegate response is not that 
     quick. Your engine may be capable of handling this over-boost, and 
     overshoot in the boost feels good in a straight line, but it is not 
     that drivable through a corner, as it become difficult to balance the 
     car with the throttle.
     
     Still I would be interested to find out what you find when you try it!
     
     Regards,
     
     Adrian 


______________________________ Reply Separator _________________________________
Subject: Re: Wastegate mod.....
Author:  diy_efi at coulomb.eng.ohio-state.edu at INTERNET
Date:    13/10/97 9:57


Hi Adrian and All the rest of the Petrolheads ;-)
     
>      Sounds good. I am curious how much before full boost you would need to 
>      open the solenoid. 
     
A good question ;-) I'll be giving trial and error a go !
     
>      Personally, I am building a boost controller that 
>      implements a PID algorithm to allow the control parameters to be 
>      optimised for a particular turbo response. 
     
Could someone please enlighten me...... why would you want the waste gate to 
crack before the boost set point ( just for the moment we are living in a 
perfect world 
where the waste gate stabilises the boost instantly ) wouldn't it be ideal ( 
quickest 
spool up time ) if the tubo got all the exhaust gas untill it didn't need more? 
Is the PID used as some form of traction control ie: it's programed so that the 
power 
going down doesn't make the wheels loose traction?   
     
>      The idea is similar to 
>      yours, but instead of using comparators (opamps) it uses a 
>      microcontroller to calculate the optimum duty cycle ..... 
     
Sounds cool ......I've been looking at doing a couse at the polytech on micros 
as it 
looks like most of the stuff I want to build would be easyer to do using micros.
     
     
>      Please let me know how this system you have planned goes if 
>      you decide to do it.....
     
I'll keep you posted....
     
Cheers
     
Simon
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  Simon Quested (E-mail questeds at lincoln.ac.nz)
  Computer Technician, Silicon Graphics & Windows NT Support 
  Centre for Computing and Biometrics
  LINCOLN UNIVERSITY OF NEW ZEALAND
  Phone (64)(03) 3252811 Ext. 8087
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http://www.lincoln.ac.nz/ccb/techs/simon/default.htm 
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Albert Einstein: "Only two things are infinite, the universe and
human stupidity, and I'm not sure about the former." 
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