GEN V Chev smallblock - LT1

[Billzilla]

The port sizing wil have been reduced because with the atomised fuel going direct it is no longer taking up port volume.

I doubt that very much.
Some rough figures.
500 hp engine with eight injectors. Each injector will need to be about 350 cc/min to comfortably work at less than 80% duty cycle at max power.
Looking at the injector pulse width at 6,000 rpm the injector will be typically open about 50% duty cycle so about 175 cc/ min. There's 100 revs per second at 6,000 rpm so the fuel injected in each squirt is about 1.75 cc's.
1.75 cc's is naff-all compared to the massive size of those ports.
I reckon it's more likely just trying to get the airflow up to a decent rate, something like 300 ft/min average at max revs.

[seedyrom]

How do you rebore a block with cast-in iron liners but an alloy deck? Where is the transition from iron to alloy

Been iron liners and alloy blocks since LS1 days.
The darker bits are the liners. With an alloy block, you'd only want to take a limited amount of meat out anyway (and hence why people running boost or are boring out a lot use the truck LQ9 all iron block)

[Stalker440]

Something along the lines of sacrificing peak air flow to gain port speed and efficiency at the revs the engine is designed to run at Bill?

I'm far from an expert in these areas, and have seen the other extreme where a motor can't support the head's ability to supply air flow and consequently been a bit of a dog. Two examples I can think of that mate's built years ago.... One was a reasonably tough 351 Clevo with massive 4V heads that went pretty hard but only at 5000+rpm, and required an over the top 5500rpm converter (for a streeter) and 4:4's to make it work.... The other was a 355ci Holden donk running virtually the same set up as my old 308 (gears/stall/comp/carb/cam) in a lighter car but it ran VN heads off a blown 383. Compared to the VN heads on mine the ports were massive: but my smaller cubed motor destroyed it for mid-range and top end. The thing just never went like it should have, and the bloke who built it put it down to the motor being unable to support the flow rates from the heads and never developing the port speed, and hence the pure response of my old clunker.

[Momus]

I doubt that very much.
Some rough figures.
500 hp engine with eight injectors. Each injector will need to be about 350 cc/min to comfortably work at less than 80% duty cycle at max power.
Looking at the injector pulse width at 6,000 rpm the injector will be typically open about 50% duty cycle so about 175 cc/ min. There's 100 revs per second at 6,000 rpm so the fuel injected in each squirt is about 1.75 cc's.
1.75 cc's is naff-all compared to the massive size of those ports.
I reckon it's more likely just trying to get the airflow up to a decent rate, something like 300 ft/min average at max revs.

LOL at your Gallic answer along the lines of: "we know it works in practice but does it work in theory?"

I won't comment on road engines too much except that GM has been running DI since 2004 and one of their claims is increased power and torque at lower revs because of the improvement in volumetric efficiency that not having the port injection fuel volume allows.
On a much higher revving Porsche LMP 4 valve V8, also with restrictors, the whole power curve was fattened and moved back along the axis. This allowed peak power to increase despite the engine having reached the restrictor choke point, presumably because of the lower friction losses associated with the lower rpm.

Mr Potato Head.
The race versions of the LS blocks that displace 7 litres that use a 4.185" bore don't have the iron liners.
Katech in the US and/or BeckerCCC in Germany produce 355 grade (rather than the production, garden variety 356 grade) blocks with the bores later electro coated with nickel silicon carbide by a company in America.
As you said for high power boosted application the production alloy block falls to bits. Even only moderately powerful NA engines suffer from block issues and bore distortion/blow by which is probably why no one seriously races them in unrestricted NA form.
Given that these engines are a revamp of the original 1955 design with the same 4.4" (111.76 mm) bore pitching and a weaker structure it is a wonder the ally ones do as well as they do.

[Billzilla]

Something along the lines of sacrificing peak air flow to gain port speed and efficiency at the revs the engine is designed to run at Bill?

Yeah a bit.
For normal-ish revs you only tiny little ports so if you can stand losing a bit of top-end power you can make the lower revs much nicer.