..."In theory, there is no difference between theory and practice. In practice, there is."

Well, he was probably talking about baseball, not c900 SAAB mods, but no matter: adding a relief valve between the turbo and APC solenoid doesn't work, though, in theory, it should.

Having read lots on using a relief valve to help spool-up, and even parroting back what I'd learned (doubt I'm the first to do that ;-), I tried it. Set the valve to ~10 lbs, installed between turbo & solenoid, test drove and watched the boost go higher than ever before. Adjusted the valve, tried again. More boost overshoot. Re-adjust even lower. Overshoot. Adjusted to nearly 0 compression on the relief valve's spring. Overshoot. Yes, I had the valve facing the in the proper direction.

Valve inlet and outlet size is 4.5mm; hose is 6.0mm. Hole into solenoid valve is considerably smaller than hose - perhaps less than 3mm.

Dunno jack about flow, etc. but, somehow, the valve is too restrictive, even without any spring tension on the ball.

All of this is moot, however: I can't say I noticed much of an improvement in spool-up, though I did notice a more linear rise in boost.

YMMV

posted by 63.225.177...

• Yogi Berra once said of APCs & relief valves..., gorper, Mon, 3 Jun 2002 02:54:35 <-- Viewing This Message
  • How did you install this relief valve?, SteveW, Tue, 4 Jun 2002 00:17:45
    • It's installed in-line..., gorper, Tue, 4 Jun 2002 14:17:51
      • Re: It's installed in-line...And thanks Kevin..., SteveW, Wed, 5 Jun 2002 09:51:27
        • I'll double check, but..., gorper, Wed, 5 Jun 2002 16:37:38
  • Re: Yogi Berra once said of APCs & relief valves..., Kevin K , Mon, 3 Jun 2002 13:37:10
    • vent..., gorper, Mon, 3 Jun 2002 14:26:00
      • did u reverse ball position? nm, Kevin K , Tue, 4 Jun 2002 00:34:30
        • yup..., gorper, Tue, 4 Jun 2002 20:15:48
          • sure?, Kevin K , Wed, 5 Jun 2002 00:01:56
            • yup..., gorper, Wed, 5 Jun 2002 16:42:03
  • Re: Yogi Berra once said of APCs & relief valves..., Tim S., Mon, 3 Jun 2002 11:09:18
    • Re: Yogi Berra once said of APCs & relief valves..., gorper, Mon, 3 Jun 2002 12:03:48
      • I'm placing the valve between the compressor & sol. >>, Tim S., Mon, 3 Jun 2002 14:21:24
  • should be installed between wastegate and APC sol. nm, sab, Mon, 3 Jun 2002 04:30:09
    • hmm, don't see how it would matter -->, gorper, Mon, 3 Jun 2002 10:31:09

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