QLCC overshoot

["Graydon D. Stuckey" <graydon@apollo.gmi.edu>]

On Wed, 21 May 1997, Orin Eman wrote:

> It depends on the spring you have in the wastegate... a spring which
> allows slightly higher boost than the 'desired boost' table in the
> computer will produce an overshoot of boost before settling down to
> the desired boost level...  Both Scott Mockry and myself have plotted
> boost vs time and have demonstrated the overshoot.  A QLCC chip

I can follow that....

> with a stock spring however would be rather slow to get to the
> desired boost level and wouldn't overshoot.

I have seen this in Brian Vinson's car.  He had the stock spring, with my
ECU which has the QLCC chip.  It felt very good, but did indeed take a
little longer to get up to boost. 

On my car, the spring is set almost exactly at 14psi, and I do not get 
overshoot.   It rises very quickly up to 14 psi, and then gradually rises 
to 15psi (+/- 0.5psi), depending on ambient temperature mostly.

Later,
Graydon D. Stuckey 

"Cool name man!" - Jay Graydon   :-)