CanBus output for wastegate control?

[clayb]

> Subject: CanBus output for wastegate control?
> 
> What commercially available ECU's will drive a stepper motor for
> wastegate control? I want a turbo system that enables me to have the
> w/gate opened fully at cruise to bypass the turbo, for better economy
> and cooler running. A friend has done this with a home brew ECU (well a
> very professional home brew ECU...) and he uses a CanBus output to drive
> the w/gate stepper motor. he doesn't use a pulsed solenoid as i don't
> think this could be used for this function, or could it?
> I was hoping to use a Motec M4 for this application (Mazda 13b rotary
> single turbo engine), but I don't know if it has a suitable output.
> 
> Thanks.
> 
> - -- 
> Best regards,
>            Chris Wilson     

The PWM'd solenoid relies on manifold pressure to pneumatically operate
the wastegate. You could not (easily) make it open both in vacuum, and
control maximum boost.

As Bruce said, there would be a neglibible if any increase in fuel
economy. Any decrease in volumetric efficiency caused by the slight
exhaust restriction, is returned in the form of increased volumetric
efficiency by the compressor on the intake side.

Also, you mentioned fuel efficiency and 13B rotary in the same sentence.
If you're concerned about fuel economy, build a different engine.

-  Clay
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