Can a twin screw charger be adapted to be placed "before" the TB?

[bob8907]

In a custom application, we would prefer the instant performance that only a twin screw can offer. I have also not found much to support that a centrifugal type will really give any additional boost at peak rpm than the twin screw. (open to debate).

Problem is we really need something that can mount before the TB, not between the engine and TB as typically done. Is it possible to do this? Is there an air bypass or something that would be needed? it seems like it should work other than a possible runaway at idle due to trying to force open the TB?

 

[gruntguru]

Belgian1776. A turbo compressor has a very different characteristic to a twin screw. Depending on how far the operating point is from the surge line, closing a downstream throttle on a centrifugal compressor will produce a small pressure increase (or none at all) and a large flow decrease. Same situation on a twin screw will always produce a significant pressure increase because it is a positive displacement machine.

 

[flyinhigh2]

I think this is an interesting question and one that I wondered myself. The OP is specifically asking about using a pop off or similar bypassing valve to nil the concerns of over boost when the throttle is closed and reduce concerns of throttle plate damage. In theory, it could work. I want to say there is a could vehicles that have done just this.


I think the OP is probably fighting space constraints which would limit the addition of a compressor under the TB. I think additional piping could be employed BUT if a simple bypass valve could do it, that would be easier. You would just have to make sure you size the bypass big enough to completely drop the pressure of the manifold under closed throttle. I think a tuned spring system would work just fine for that.