I think I understand what you are saying... - Saab Performance Bulletin Board - Saabnet.com
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I think I understand what you are saying...
Posted by Mike W. [Email] (more from Mike W.) on Tue, 27 Nov 2001 14:59:57
In Reply to: Re: Dean we need your help about boost taper., Dean, Tue, 27 Nov 2001 09:22:18
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When you set the MBC between the wastegate and the turbo compressor, it is operating farter downstream of the intake manifold. The problem is that in higher RPMS the pressure drops across the plumbing and intercooler and without an ECU to compensate for it, the essentially tricked wastegate is now being further deceived by the drop in pressure. Moving the MBC to the manifold solves the problem with boost pressure drop in higher RPMS because while there is still a loss across the plumbing, it is accounted for in the manifold andessure drop is irrelevant. The problem is that because it's so far upstream, by the time the pressure builds in the manifold there isn't enough time for the wastegate to react.
Exactly how did you connect the MBC to the manifold? Did you splice a T into one of the hoses? I would be curious to see how much of a change it makes, but I live in Seattle and the average temp here is in the mid 40's. Now, wouldn't it be possible to set up the MBC while in the cold so that's already accounted for, basically just a lower boost setting. Or would that still be pointless because the problem is still lag from turbo through plumbing to the manifold then back to the wastegate. Wouldn't it be possible to set up a bleed valve so the if it does overshoot, it will let off pressure?
And lastly, an upgraded ECU that would solve the problems because it can continually adjust the flow between the compressor and wastegate.
Mike
posted by 158.252.226.1...
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