Has the March superurbo got it wrong?

[pumpngo]

Hi , some would say it's been discussed before , But i've read most of the Twincharging forum posts. The general consensus seems to be that the Nissan March Superturbo is plumbed backwards. It won many awards , is seen as powerfull and ecconomical. Did they really get it so wrong?
From what i've read the consenses seems to be constant compounding is better ,why?
If you only want 20 to 30lb boost, the turbo alone can easily produce this without compounding and with less heat.
I have read a heap of stories about pure racing cars using the compound system with great success, but i have yet to find a good one using the SC first. None of these people were interested in economy, as they were race cars.
I'm looking at doing my sons car as a daily driver, so fuel is of some concern on light throttle, of course not so much when using the power.
I'm not claiming either to be better as i have no personal experience with either, but i would like to have the debate by those of you with far better knowledge on the subject.

 

[patprimmer]

I'm not exactly sure what your question really is.

It seems you have a few misconceptions at least to some degree.

1) A twincharger really only offers any real benefit if the belt driven supercharger is positive displacement like a roots type as they produce real boost at idle speed and do most to overcome lag as seen in centrifugal types or turbos.

2) To configure a twincharger with a roots type and a turbo in series with the roots first is totally useless as the roots would severely throttle the turbo as the turbo spooled up.

3)In parallel systems are possible, but waste the extra advantage of the roots after having paid for it to be installed and having to carry the weight and space it takes at all times. You still have to establish effective valves to control where the boost comes from and that it can't escape. These valves need to coordinate effectively with the throttle valve.

4) If Nissan did it that way, they have much greater access to resources to sort the valves out than you are likely to have.

5) fuel consumption is important to race cars and is still a compromise they even adjust during a race in some classes. This is with regard to compromises with the weight of fuel carried at the start and time taken for refueling stops.

Regards
Pat
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[140Airpower]

Pat, it appears the Nissan is configured like your #3) description with the Roots blower there just for the low rpm response, switching off and bypassed once the turbo has spooled up.