Yes, the T5 did not have an MAF, but was a speed density system that mapped fuel to the MAP pressure and RPMs. Some assumptions are made about voumentic effiiency, but I expect that these factors were trimmed by feedback from the O2 sensors when off boost. The ECU boosted to obtain a target pressure. But the charge air density was all over the map with weather changes etc, so power and torque could vary a lot. Otherwise, it worked very well.

The T7 has a MAF and MAP sensors. It boosts to a target of mass air flow as a function of RPMs to attempt to control torque instead of pressure. This works very well. However some then think that a lower restriction exhaust or intake can then have no value. That thinking ignores the HP losses created by the turbine back pressure * that the turbine needs to generate shaft HP for the compressor. There is no free lunch. That thinking also ignores the effect of restrictions on charge air temperature and the fact that the ECU will retard timing with these higher temperatures and also limit boost pressures to avoid knocking as well.

* At 20 PSI of boost, rarely needed, the back pressure could easily be over 40 PSI in the exhaust manifold. 30 at 15 etc. When you see folks claim that the turbo gets free energy from the exhaust gases, find someone else to listen too.

The T7 has less boost lag. But a SMBC on a T7 is more responsive again... by a long shot. A MBC or a SMBC on a T5 make boost come on very fast. The T5 can be overboosted with a MBC, the T7 will give you a cel for your troubles unless you install in series as a SMBC.

posted by 208.24.17...

• Empirical vs. theoretical Viggen boost measurement, Nathan Work, Wed, 3 Sep 2003 14:55:54
  • Re: Empirical vs. theoretical Viggen boost measurement, E SMITH, Wed, 3 Sep 2003 20:39:41
    • Re: Empirical vs. theoretical Viggen boost measurement, Vigge, Fri, 5 Sep 2003 00:37:21
    • Re: Hey ESmith, please clarify..., STICKMAN, Thu, 4 Sep 2003 06:05:30
      • Re: Hey ESmith, please clarify..., e smith, Sun, 7 Sep 2003 16:06:37
  • Found it..., Nathan Work, Wed, 3 Sep 2003 14:58:38
    • Well, one more question, Nathan Work, Wed, 3 Sep 2003 15:07:01
      • Re: Well, one more question, Neil, Wed, 3 Sep 2003 18:05:37
        • Re: Well, one more question, Nathan Work, Wed, 3 Sep 2003 19:43:45
          • Re: Well, one more question, Neil, Wed, 3 Sep 2003 22:52:03
            • Re: Well, one more question, Nathan Work, Thu, 4 Sep 2003 16:58:53
            • Re: Well, one more question, Dean, Thu, 4 Sep 2003 09:15:47 <-- Viewing This Message
              • Re: Well, one more question, Vigge, Thu, 4 Sep 2003 12:57:51
                • correction to my last comment, Vigge, Fri, 5 Sep 2003 00:41:06
                • Re: Well, one more question, Dean, Thu, 4 Sep 2003 15:32:34

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