If an engine looses only a tiny amount of power if the scavenging regime is changed by blocking the B.P than all that means is the A & B scavenging system was very wrong to start with.
Running a modern setup with near flat ,huge B ports with a rear wall hook, along with smaller A ports that effectively axially jump over the B port columns, there is no way that
flow regime can create a correct " leaning tower " up the back wall with no B.P directional control included.
By definition a 4 port must have greater axial up angles and no way could you use a front B port wall that is radially perpendicular - like Jan developed at Aprilia.
What we regard as normal axial and radial angles nowdays in a 5 port were slowly and meticulously changed over time to give the highest scavenging efficiency along with a high
trapping ratio - simply deleting the B.P in this setup ( and thereby assuming it does nothing due to no power loss ) would be saying in effect that all that development was a complete waste of time
and a huge effort should have been directed at 4 ports all along - dont think so.
If a B.P makes so little difference to a good 5 port scavenging system, why does it make a huge impact when you cut a radius on the piston timing edge.
I havnt done the test of leaving the edge in front of the B.P uncut , but reports are that it works very well.
All I do know so far from tests is that a radius big enough to make the B.P flow attach to the piston ( and thus less to the rear wall ) kills power badly.
Ive got a thing thats unique and new.To prove it I'll have the last laugh on you.Cause instead of one head I got two.And you know two heads are better than one.
Bookmarks