Originally Posted by
Stu @ M Developments
Sounds like it will work in theory mate... may have to be carefull with switch over points to ensure the switch takes place prior to any large inlet depression otherwise you are likely to have a very sudden and high overspeed condition on the turbos compressor / turbine.
Done this way I wont have any ECU control over it, it will be entirely mechanical.
But I think that the switchover should hopefully happen by the time inlet to the turbo sees even moderate vacuum.
I'll have to install a few boost gauges though so that I can watch it happen with the turbo set for moderate boost still to try and avoid that happening.
Might even set a boost cut at 5psi of vacuum for example so that if the inlet before the turbo sees that vacuum or greater (ie less absolute pressure) it simply turns off the solenoid control the turbo wastegate (the one in the exhaust) so stop the turbo trying to make big boost under that circumstance.
A weaker spring in the wastegate on the inlet would make it less likely to be a problem with the turbooverspeeding, but obviously it could end up fluttering like mad if its too weak.
Additionally I would be interested to see if you could find a way to maintain some supercharger input into the compressor at all times to keep the efficiency high... that however, is likely to be a total mindfuck of a convertion requiring complex one way sealed valves, and the more I think about it, the less interested I would be in trying to do it. LOL
For this project, I dont think that will be particuarly useful TBH mate, I am trying to only solve the problems I need to in order to get it to work "fairly well" rather than looking for a perfect solution which with my lack of budget and funds (ie I dont have a team of 100 and 50 million euros to spend) is never going to happen anyway.
Was racking my brains all last night trying to think why this wastegate idea WONT work, but cant come up with anything so far, which surprises me as if its that simple I just cant understand why its not quite commonly done!