I
only had three days to work with these heads so I immediately set up
an initial flow test measuring port flow with valve fitted and bare
port flow (no valve fitted) to establish some type of discharge
co-efficient .With a little bit of matching/applying a
harsh stoned inlet port finish and adding a new multi angle valve job I was able
to release a small amount of inlet flow. I was quite disappointed
hoping for much more of a gain but when the shape is good its good and
Ducati did a good job this time. However after running a velocity
test it was revealed that the ports airspeed was quite lazy meaning
the heads would respond very well to a higher lifting cam such as the
15mm lifting RS items. Moving onto the exhaust ports a flow test
revealed much improvement could be made. The lower valve seat shape
and throat size was strangling the flow giving the exhaust no ware
near the amount of inlet to exhaust flow ratio I would like to see for
a racing engine. I changed the exhaust seat lower angle to a steeper
cut which automatically opened the throat diameter. I then
sculptured the exhaust port to a more adequate shape paying careful
attention to the radius which did not exist in stock form. After re-
testing I had found to have made a very modest gain to the exhaust
port. This gave me new confidence of giving this superbike some extra
hp.
Initial flow
testing pulling 28 inches of test pressure through the
inlet ports.
The finished
inlet ports with stoned finish and a fresh seat deal.
After changing
the seat angle far left to a steeper cut which opens out the port
throat I set about blending the cliff face to create a nice
radius ( right hand port) that the factory failed to make as
standard.
The finished
exhaust ports re-shaped and seats with non standard seat angles
applied.
Moto Rapido’s
engine builder collected the heads and blueprinted the engine over
the weekend. A week later I received a phone call from steve saying the result was awesome and the rider could feel a big difference with the power hanging
on for longer with no loss of mid range or tractable power.
I wont be
publishing dyno data for this bike as its confidential but
I will say it leaves 1098r with full exhaust system for dead. These
heads will be back later in the year for some further development
time. If you want the same conversion just ask.
