If you wanted to run aux powered supercharging in a streamliner, you could run two drive engines. One engine (AUX) would supply electric power, pump fuel, water pumping, supercharging, then be connected to an electric drive motor to apply any surplus power to the wheels. There is no rule concerning how much drive output an engine has to have. The aux motor would be a small, cheap, reliable, stable motor. Like an LS1, SBC, or I4 on gas. Since you would be most likely running AA with it, it would not have to be accessible to teardown, and should last the life of the car.
Why would you do this? Possible advantages:
Safety - The "hair on fire" engine would not have a blower or turbo mounted on it. No risk of blower backfire and less fire risk. In case of emergency, the fly-by-wire engine can be killed instantly (even automatically with fire sensors) and more reliably than the HOF engine. Suddenly all fuel is cut, all air is cut, all power is cut. Killing the aux, can be done very easy, and with various switches.
Accessibility - You should never have to play with the aux engine, and the HOFE would be naked.
Turnaround - For FIA events, you only have to look at one engine that is more accessible.
Constant blower speed, pressure - No belt worries, pulley hassle, easier jetting, and programmable boost changes simply.
Form factor - Both engines forward profile could be smaller than a dressed supercharged engine.
Easier plumbing - the aux motor is pretty much a stand-alone family car engine, electric fly-by-wire. The plumbing you need to worry about would be simplier.
Cost? - Let's say you want 2000rwhp. Assume 30% parasitic and drive losses. You would either need two 1300HP engines, one 2600HP, or an aux setup, plus a 2000HP or less HOF engine. The aux engine should also contribute enough power to make up for any driveline losses, and then some. You would also need only one supercharger. When it's time to rebuild or replace, you are only concerned with the single HOF engine. There are off the shelf, 100,000mi warranty engines, with outputs up to 630+ HP and a form factor of a N/A SBC. But you probably wouldn't need that much. A 430HP engine is much cheaper, and would probably get it done.
Crankshaft - Driving large amounts of accessory power on the front of a crank while pushing huge power on the back needs a crank that is far stronger than one that just drives out the back.
Driveline - Single engine driveline with no accessory considerations. The aux engine can be mounted anywhere with no concern for driveline issues.
Testing - You can test the aux engine separately (although little would needed), and the single HOE would be lower output for testing.
Starting - Fire up the AUX motor, use it's electric to assist forward motion, then the supercharged air would start the HOF engine. Shouldn't need a push start.
Braking - Assuming a RWD HOF setup for low drive losses, put the AUX electric motor(s) on the front wheels. Reversing the field on the motors will gently retard wheel motion without risk of brake overheating.
