There's something wrong with Scarb's explanation of what is going inside an F1 engine and I'm not entirely sure that he's on the right track. I've got to give this a great deal more thought before I explain definitively what I think is wrong but if there's anyone on here with more current engineering knowledge than I've got I'd be really interested to hear their take on the following:
1) When did left foot braking become redundant?
The ability to brake with the left foot rather than taking the right foot off the accelerator allows the driver to manually control fuel flow into the engine, either smoothly or via staccato feathering of the throttle, whilst braking simultaneously. It is a technique long employed by racing drivers to control and balance engine braking, traction and the overall behaviour of the vehicle under braking. Motorcyclists learn to balance combined use of brakes and throttle for the same purpose. After initially braking hard and then "tipping" into a corner, road racers use this technique to "trail brake" to further decelerate through a corner before clipping the apex and getting back on the throttle to exit the corner. Rally drivers use the toe and heel method of balancing the throttle and brake with the right foot whilst using the clutch pedal with left for gear changes and indeed before the advent of automatic clutches and semi-auto gearboxes F1 drivers did this as well. Scarb's suggests that this is now controlled by the engine maps and I'm not sure that that is entirely the case as it would suggest that the accelerator pedal is just an on/off switch but it is actually a potentiometer the driver uses to input his demands into the “fly by wire” fuel induction system.
2) When a driver takes their foot off the throttle the inlet and exhaust valves in the engine continue to open and close mechanically synchronised with the revolutions of the crankshaft. The only difference is that less fuel is injected into the air being sucked through the air induction system, from the air box into the cylinders, during the induction strokes. This air is compressed on the compression stroke as usual but it is only ignited if there is sufficient fuel present in the mix, is less energetic and it is
ejected cold into the exhaust header pipe when the exhaust valves open.
The vacuum Scarb's referred to would only exist in true terms if the air intake and or inlet valves remained closed during the induction stroke. Designing something into an engine to make that happen makes no sense to me since one of the principles of sound engineering is the KISS principle. It would require more complex valve and air induction control mechanisms into the design. Not only that, the sucking of "clean" air through the system helps to clean the combustion chamber during deceleration of the engine.
One of the other things Scarb's appears to overlook is the oiling of the engine. The engine oil used in any engine is designed to have characteristics (viscosity, etc.) in order to lubricate the engine but at the same time, in concert with the oil pump, maintain pressure in the crankcase. The oil pressure in the crankcase prevents the leakage of gases from the combustion chamber past the piston rings enabling maximisation of the compression and ignition of the fuel air mix. Unless I've misunderstood what he's saying Scarb's suggests that a vacuum in the combustion chamber draws air past the piston rings into the crankcase causing problems in the drive train. Without going into everything that's wrong with that idea, where that air is coming from is a mystery to me and again makes no sense at all. Maybe someone else can explain that to me!
3) From everything I've read about the hot blown EBD this is my understanding of how that works and it is not that complex an idea. In a standard configuration the valve timing and timing of the ignition of the fuel/air mix in the combustion chamber is synchronised so that the mix is burnt in a single explosion forcing the piston
down the cylinder (i.e. the ignition stroke). On its return
up the cylinder the exhaust valves open and the burnt gases are forced out through the exhaust system (i.e. exhaust pipes). An exhaust becomes
hot blown when fuel is introduced into the air flow during the exhaust strokes and the ignition is momentarily retarded so that the mix is ignited whilst the exhaust valve is still open. This results in the gases in the exhaust pipe having been ignited and thus
hot exhaust gases are blown through the exhaust pipes onto the diffuser.
Under normal circumstances there is a minimum throttle setting to enable an engine to keep running (i.e. to idle) otherwise the engine would stall. The application of a higher minimum setting means that more fuel is in the air mix that is burnt late due to the retardation of the ignition and therefore the quantity (and therefore energy and pressure) of hot gases blowing through the EBD system. The FIA's objective of setting a maximum limit of 10% is intended to constrain the effectiveness of the hot blown EBD but not outlaw it completely (yet) since they recognise that there are issues for the teams in making the design changes in areas of the car that will be affected by the removal of the system.
There's a couple of other issues but this post is already a bit long so I'll leave it there for 21st century engineering buffs (considering Scarb's take on things my buffness is still 20th century it seems) to take this up.