That's a great video. I hate to say it....but it only reinforces the shortcomings of the carburetor. That's not to say EFI doesn't suffer from faults, also. My lowly Mazda 3 uses direct cylinder injection...maybe that's the answer.
DI has many issues. It’s main attribute is fuel economy, which after 50k miles or something that starts going away because the DI stuff comes the valves when they retard the cam timing and the rest of the BS that CAFE standards cause.
Then again....the video illustrates how fuel can separate from (or perhaps more accurately never join) the air. The question becomes 'how much does it matter?'.
It’s a big deal.
In a fuel economy race, I think it could be pretty detrimental. Same for a HP-per-pound of fuel race. But does that fuel have a net effect on HP? Not sure. The cylinders only care about the mixture they see, and how well they can burn it. The fuel stuck to the sides of the intake becomes a non-participant, to an extent.
Fuel absolutely has a big effect on HP, and beyond that it doesn’t always show up on the dyno. If you have 2 engines making 500 HP at the same RPM and everything being equal, the engine with the lower BSFC will always be quicker and faster.
In other words, if the air/fuel mixture that does make it to the cylinder is 'good' then the engine is gonna be happy. We see that in the impressive power and (generally) clean combustion.
What happens to the fuel that isn’t mixed well with the air??? You can’t have impressive power and clean combustion running raw fuel into the chamber.
It's safe to assume that fuel stuck to the intake walls eventually gets pulled back into the air, molecule by molecule, and into the cylinder. Is it well homogenized or not? The amount of turbulence we see would suggest that the fuel at least has a chance to be shaken and not stirred before it goes into the cylinder.
It’s not safe to assume that fuel running down the walls eventually gets pulled back into the air. Once wet fuel is on a surface, it’s hard to get it back into the air. That’s why the burr finish has been on my mind for years. If you can get the rough finish to cause the fuel to break up into smaller sizes, you have a much better chance of getting the fuel back into the air and making the fuel useable to make power.
Warren Johnson said there is no such thing as a “dry” intake manifold and Darin Morgan said a rough surface finish from 3 inches above the injector to the valve so Morgan is saying essentially the same thing as WJ is.
I agree on the epoxy comment above...no way would I use epoxy unless my back was against the wall.
