servo controlled wastegate

[brett_celicacoupe]

peak power probably wont change but you should be able to improve arear under the power curve

[Mos]

Its not...
Well, direct control may be a little faster acting, but thats the only difference.

In a pressure controlled wastegate the servo loop will need to account for changes in air pressure, with electronic you get to control the current supply to the actuator rather than having to deal with the supply constantly changing.

Mos.

[Kyosho]

You'll have to vary your signal all the time with a servo control to account spiking etc.
It'll need a bloody damn fast acting processor behind it in a closed loop mode to be able to control the boost as easily.

If you get a boost spike, you need it to open quickly, and then settle back down. (All done electronically via that servo) if you don't open the servo up on a spike, it'll just most likely continue to snow ball as now even more gasses are going through the turbo (on your spike) and you haven't accounted for it.

Its not as easy as just building a simple micro and wacking a servo on it.

[kewp]

the controller i've got planned is not digital at all, its completely analogue. As far as system response goes, the PID controller, once properly tuned will give very fast response and will not overshoot

[MWP]

In a pressure controlled wastegate the servo loop will need to account for changes in air pressure, with electronic you get to control the current supply to the actuator rather than having to deal with the supply constantly changing.

Yup, good point.

[MWP]

the controller i've got planned is not digital at all, its completely analogue. As far as system response goes, the PID controller, once properly tuned will give very fast response and will not overshoot

Will be interesting to see what control circuit you come up with.
Im a digital guy... ill always whip up something like this quicker with a uC than with analog parts.

[Mos]

Will be interesting to see what control circuit you come up with.
Im a digital guy... ill always whip up something like this quicker with a uC than with analog parts.

Then you have to tweak everything in software. Curious what would be easier in the long run
In commercial applications doing something the ugly way (ie discrete electronics) can mean you don't have to go through the process of software validation, making something easier to comply.
Obviously for your own stuff you will use whatever you're most comfortable with.

Mos.

[RObErT_RaTh]

I don't know if it's been said yet but if you go with a high torque RC servo (meaty one for the bigger scale cars) then don't cheap out on it and make sure it's one with metal gears.