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I am a bit confused. The reasoning behind a flat plane crank v8 seems to involve exhaust scavenging, which is easy in a flat plane, but not a cross plane. I have seen a cross plane setup with an "bundle of snakes" type header contraption to achieve the same exhaust scavenging. The flat plane motors have serious vibration problems that the cross plane cranks do not have. Why not take a page from turbo motors and reverse the head flow so the exhaust exits up top? The seriously shortened distance between exhaust banks would allow any header configuration to be achievable. Also, if this were an old school build, it would be awesome to see 2 banks of side draft Webers feeding what people expect to be the exhaust ports. In an FI situation, the intake placement would be of little matter. Just a random thought.
The Ford Indy motor! The beauty of those was with the injectors between the cams, the heads could be swapped side for side to put the exhaust on the outside of the engine if need be. Never saw one set up that way though....
This subject came up recently in a Facebook post about the K48, and someone pointed out that fuel puddling in the intake tract is likely to be much bigger issue with hot-V than with conventional (cold-V?) engine designs. With conventional engines, gravity helps pull the fuel mist into the combustion chamber, whereas with hot-V gravity works against you.
That might be a non-issue with race cars since they run at high power (high air flow) much of the time. But for a street car that idles at stop signs and stop lights, there will be little airflow to help carry the fuel into the combustion chambers.
It's also something that head design can probably help with, for example if you keep the valve angle small and keep the intake ports relatively straight and angled downward as much as possible. But with convention engines it's pretty common to spray fuel on the back of the intake valve and use the intake stroke to blow it in, and with a conventional cylinder head (as in the K48) it seems likely that the fuel will flow backward along the intake walls at low throttle.
ECUs can compensate by modeling the growth and shrinkage of the fuel puddle (and they have to do that anyway with conventional engine design) but it seems like the hot-V design will make that both more challenging and more critical.
You need to keep in mind that while at a stop, airflow is indeed very low, but so is fuel flow. So little is spraying out at idle speeds, that what fuel flow there is, is pretty easily handled or atomized by the existing airflow. When you think about it, this is even true with carburetion. Long-term idling usually was NOT accompanied by any fuel puddling or falling out of suspension.
Gravity actually has some, but very little influence on air/fuel flow. The velocity itself is far greater an influence.
Flatheads were reverse flowed 60 yrs ago. Many flathead Ford V8s were reverse-flowed to get the exhaust ports out of the water jackets. Buddy Shay ran a V8-60 midget that was both reverse-flow and reverse rotation... and mounted in the chassis upside-down. Bruce Crower did a SBC for Indy with both the intake and exhaust ports on the outboard side of the heads.
You need to keep in mind that while at a stop, airflow is indeed very low, but so is fuel flow. So little is spraying out at idle speeds, that what fuel flow there is, is pretty easily handled or atomized by the existing airflow. When you think about it, this is even true with carburetion. Long-term idling usually was NOT accompanied by any fuel puddling or falling out of suspension.
Gravity actually has some, but very little influence on air/fuel flow. The velocity itself is far greater an influence.
When I first heard about the "wall wetting" thing (fuel sticking to the sides of the intake ports) I thought that couldn't possibly matter that much, and I figured that ECUs probably only compensate for it because emissions standards have gotten so strict over the years.
A couple years later I disabled it in my Subaru to see what would happen, and the car wanted to die instead of returning to idle, and when I gave it throttle it would sputter and die unless I pumped the pedal a bit. It turns out that getting the wall wetting compensation right is pretty important for getting a smooth transition to and from idle.
Smooth transitions to and from idle don't matter very much in race cars, and the drivers can just blip the throttle to deal with it. But for a street car, most people have higher standards, and getting that wall-wetting compensation right is pretty important.
I'm sure it can be done with hot-V intakes too, I just expect it to be rather unforgiving if it's not dialed in really well. With a convention design, the film on the wall will trickle down to the intake valves over time. With a hot-V I wonder if you just get a bigger puddle the longer you idle.
Just as a heads up, I never thought my original post belonged in this advanced section forum. As point of fact, I am certain it does not. I originally posted it elsewhere, and it was moved. As for the previous post, those extra tables in most tuning software are there for a reason.
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Hot V N/A motor 
