I've seen testing on several engines at the same CR comparing PFI vs. GDI, and the VE has always improved when going to GDI. The higher SCR will just add more power on top of that. However, on some of the engines I've seen the higher VE is actually the dominant cause of the higher power.

I would guess that F1 doesn't run GDI because quite frankly at 19,000 rpm trying to have very short fuel injection events at such high pressure is beyond current capabilities. Currently, for what I've seen, they have fuel injectors well up towards the top of their intake trumpets and they basically constantly dump fuel into the trumpets at higher rpm. I'm sure you've seen video of the engines and the absolute mist of fuel standing above the trumpets. I would fully expect GDI to be a benefit in power for them, and the fact that they're not using it reinforces my belief that it's because technology was not advanced enough for them to successfully implement it.

 

Audi used DFI in their R8 series of race engines to win Lemans on fuel economy, not necessarily power. Because of boost restrictions and inlet restrictors, 600 hp or so is about the desired limit. The 4.0L V8 with about 24 psi boost made about 570 hp @ 5500 and was run to 6500. This is very low rpm for a small V8 race engine. They were able to use 12.2:1 SCR which is unusually high for a turbocharged SI engine.

DFI allowed this and the resulting high MPG which allowed the Audi and recently Bentley-badged Audi to spend less time in the pits given the 80L fuel tanks. They got 12 or 13 laps between refuelling stops.

Interestingly, the 7.0L Corvette LeMans engine also produced about the same power, 575 @ 5600, and normally ran 5800/5900 max rpm. The non-blown SCR was also 12.2:1. The torque was very Diesel-like however, with 580 lb-ft @3500, 600 lb-ft @ 4000, and 540 lb-ft @ 5600. They did not use DFI of course.

F1 engines have gone to very high fuel pressure in their above-the-throttle-plate injectors probably to allow the needed amount of fuel to be injected in the very short time available @ 19K. At about 160 pulses per second, it would look like a steady stream to me. At a 4K idle, I doubt that it's continuous.

 

The other thing I was thinking of regarding GDI and F1 engines is one of the weaknesses in GDI right now is the lack of time for the fuel to properly mix with the air. Thus, you end up with some pockets of A/F that are much richer than others. For a passenger car engine the main concern here is the increase in HC emissions. However, unburned fuel is also wasted energy, and this problem would likely be greatly compounded if you were running over 3 times the engine speed. I would assume this is the reason the F1 engines achieve the best power with injectors mounted so far away from the cylinder. It allows them a few more milliseconds of fuel/air mixing time and thus gives them a better burn, resulting in more power.

 

I tend to agree on the placement of injectors on F1. Most of the combustion chamber in an F1 engine is the 4 valve reliefs. That might be difficult for DFI.

The Audi A6 3.2 V6 has a 12.5: SCR with DFI. It gets the same hp/L, and very nearly the same torque/L as the 4.2L non-DFI with it's 11.0:1 SCR. Obviously both pass emission tests, even in NY, MA and CA. I heard recently that the 3.2 V6 (non DFI) in the TT didn't make the emission cut in those states, and maybe a couple others, so isn't being sold there.

Maybe there's something positive about carbs mixing fuel a foot above the intake valve in a 10000 rpm 500 cubic inch ProStock engine.