Exactly. As soon as you turn off the air (compressor side), the wheel will stall immediately; there is still no pressure, and suddenly ALSO no velocity.

There is no theory, the air would go out of the airbox lol.

It wouldn't.
Not "better" your idea has no merit whatsoever. Nitrous works.
If you want to use an air reservoir, you can use a Y pipe with an electronically controlled flap - provide boost from the air reservoir, and once the turbo spools up switch over gradually.
Though if you calculate the volume of air required it probably can't be done.

I think the air would aid the turbo in the way of reducing effort on the compressor side. If you  want to spool the turbo with the compresor, the turbine wheel would create a vacuum because it has no free resource of air(gas) thus in an extreme situation it would create a vacuum in the exhaust manifold between firing cilinders and possibly open up a black hole in space.

I still have several more months before I can start up this allroad build.  In all likelihood, I won't be adding anything to aid spool beyond good manifold and up-pipe design/diameter, but it has been interesting to think through this idea and its execution.


PRJ, I hear you regarding N2O; my thoughts are that if compressed air is viable then I'd be looking at ~$100 to build plus no bottles taking up space or getting refilled.


It seems like several people are describing a scenario that would only occur if the system was used indiscriminately.   

The idea is to trigger the compressed air at/above xxxx rpm under wide open throttle, thereby dropping maybe 500 rpm to reach full boost. Who would just press the button at random times while driving?  If that were to happen, the bypass valve and internal wastegate do still function as normal just as when using anti-lag.


Here are a couple more interesting related things:

Turbo Charger Pre-Spooler:  https://www.google.com/patents/US20140026538


I'd have a nozzle like this, except it would enter the turbine housing through the up-pipe





New-ish (2014) Volvo 450hp 2.0L making use of air pressure and electric motor driven compressors:  http://autoweek.com/article/car-news/volvos-new-electric-supercharger-explained


After reading the Auto Week article, makes me wonder about running a twin charger setup using an electric supercharger....

In theory it would not shut off till the exhaust gas had taken over.
I understand what your saying and I cant say i'm sure it would work...

The normal flow of exhaust gas.   This is a parameter that will need to be determined.  I can see your point, if the air was shut off too soon.

 I expect parameters of operation to be something like:
1) 90% throttle or greater
2) Turn on @ around 2k to 2500 rpm
3) Shut off when requested boost is reached or just under (or whatever testing shows to perform best/smoothest)

I wish I had the skills to build this simple function into ME7.1.  output could just be a single 12v +.  This would then be the trigger wire for relay controlling an air valve.    Since I don't have those kinds of skills, I'll probably use a 12v timer relay... or something in between.