Doesn't change direction???!!!! You have got to be kidding.

The engine is sideways. The trani has a chain drive that makes a 180 degree turn.

It is much more direct but not much more efficient.

Changing directions doesn't play as much a role in the efficiency as does the design of the transmission in the first place. The aforementioned Chrysler transmissions are longitudinally mounted and extend backward just as a RWD transmission would. They then have a gear set and chain that transmits the power back forward to a standard differential between the engine and the transmission (albeit part of the transmission housing). This design coupled with the weakness of the internals inside this transmission make for a highly inefficient transmission.

Automatics will always be less efficient than a manual gearbox because automatics have to use some of the engine power to run the pump in the transmission. How much of a difference depends on the design of the transmission. You will never have an conventional automatic match the efficiency of a manual gearbox because of the pumping losses.

Arent there torque converter losses as well? what exactly does the B in BHP stand for?

It stands for Brake horsepower. It'* a term commonly used in the UK to describe what we know as the SAE HP, or just the true engine horsepower.

Is there a standard conversion factor to change from bhp to hp and back?

It is the same thing. We just call it HP, while others may call it BHP. It'* just another name.

The Brake was a tool used to measure engine HP.

Net HP and Brake HP.

Centrifugal pump formula:
BHP = Flow(GPM) X TDH(FT) x SG /3960xEFFICIENCY(%)

Net horsepower used to be used to rate auto engines and it is always higher than the actual brake horsepower which takes into account all the accessories including the exhaust and intake systems.
They are both measured at the flywheel before any losses caused by the rest of the drivetrain.