back from Canada....

The MBC's control the boost pressure at the point where the MBC gets pressure. So if you use the turbo compressor hose barb, then the pressure at that location is being controlled to the set point. At higher RPM's and high CFM's the pressure drops across the IC and other plumbing will cause what you are seeing.

The spiking is what you will get in cold weather. I went to the turbo XS after getting frustrated with the HMC in cold weather. My main issue was that I had the HBC pressured from the manifold. I did not get boost taper. But the time delay from that set up made the system nasty in cold weather. I can't say if the Turbo XS or Dawes would be better than the HMC, but I did try the pressure from the compressor housing and that sucked. So I did create a pressure tap 1/2 across the old style IC's return pipe. That is a much better compromise. Someone else created at tap near the BPV and was haappy with that.

The taper and pressure overshoots are somewhat unrealated. A pressure tap at the manifold will provide great boost control, no - or little taper. But that location makes the pressure overshoots worse. I was using the HBC at the manifold in the warm and summer seasons and it was very strong at high RPM's.

I am considering a mechanical pop-off valve at the manfold and or a electronic mod to the MAP sensor to leak off the spike or make the ECU ignore it. Then I could get back to a manifold pressure tap.

posted by 207.43.195.2...

• What kind of boost taper are you getting?, Mike W, Mon, 26 Nov 2001 00:04:41
  • Using Greddy Profec B, MTAERO , Wed, 28 Nov 2001 20:37:13
  • Re: What kind of boost taper are you getting?, ckpaden, Mon, 26 Nov 2001 01:12:25
    • Hmm..., Mike W., Mon, 26 Nov 2001 02:04:21
      • Re: Dean we need your help about boost taper., ckpaden, Mon, 26 Nov 2001 16:00:11
        • Re: Dean we need your help about boost taper., Dean, Tue, 27 Nov 2001 09:22:18 <-- Viewing This Message
          • I think I understand what you are saying..., Mike W., Tue, 27 Nov 2001 14:59:57
            • Re: I think I understand what you are saying..., Dean, Wed, 28 Nov 2001 14:59:55
        • Re: Dean we need your help about boost taper., LDH, Tue, 27 Nov 2001 01:00:50
        • I will be going with a Maptun ECU..., Mike W., Mon, 26 Nov 2001 16:10:48
      • hollowed cat, $$$$$$, nickR, Mon, 26 Nov 2001 11:21:04
        • Summit racing has cats for $50 n/m, ckpaden, Mon, 26 Nov 2001 15:49:25
          • Yep, I have an extra high-flow cat laying around, Mike W., Mon, 26 Nov 2001 16:00:31

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