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Re: Re[2]: Improved S-Knob

On 19 Jun 1997, Russell S Southerlin wrote:

> Maybe I didn't explain my setup well enough. I have the same pressure 
> regulator to the top of the W/G (standard S-Knob) set for 15 psi boost 
> pressure. While installing the pressure reg I noticed that when the 
> engine was in a vacuum condition ie. between gear shifts there would be 
> vacuum on top of the W/G which I initially thought would be working 
> against the W/G spring and possibly even opening the W/G between gear 
> shifts. After thinking about it more I think the vacuum is on both sides 
> of the W/G which gives the net effect of only the spring keeping the W/G 
> closed.

	OK, now I got you.

> and then as I get back into the throttle it jumps to about 6 psi (2 psi 
> without the check valve) and hesitates for a second or two before 
> continuing up to the 15 psi set point. I have always assumed that this 
> was normal turbo lag. You can't feel any noticable hesitation by the seat 

Are you talking about a leisurely shift?    When I'm talking performance, 
I typically try to shift in a half second or less.   My 016 transaxle, 
with Redline MTL seems to shift veyr well, so I snap off shifts pretty 

> Mine acts similar. How fast does yours get to the set point when 
> shifting? Mine goes to 6 psi real fast and the climbs to the set point.

Apples to oranges here.   My EFI system makes the turbo respond much 
faster, so its not really a valid comparison to your turbo setup.   I can 
almost get wheelspin in 2nd, although I haven't abused it enough to see 
for sure.   I tihnk another 50 hp would do it.   This correlates with 
Ross' experience also, since he's probably running 310+hp, where mine is 
probably around 270.  (less lately - its been warm)

> The pin hole is between the check valve and the W/G. I put a temporary 
> pressure gauge between the check valve and the W/G just so I could see 
> what pressures were on top of the W/G. You don't need very much 
> pressure from the regulator for 15 psi of boost, I was seeing 6 psi 
> from the regulator for 14 psi of boost. Since the check valve only 

RIght, I found the same thing.   I actually had to put a lighter spring 
in the regulator to get the required boost pressure.

> alows pressure to be applied to the W/G and not vacuum you would have 
> no vacuum leaks (proved this with the gauge) only a small leak when the 

You're right, only pressure leaks.

> pressure is being applied to the W/G. Since this pressure is small ~6 
> psi I don't think it affects the system. As evidence I have run with 
> and without the check valve and have gotten essentially the same boost 
> set point (15 psi) without adjusting the Knob.

Probably not.

Graydon D. Stuckey 

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