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All
the Power is in the head
748r
To increase the power and torque of your
Ducati we need to either increase the airspeed into the engine or both
airspeed and volume of flow. Poorly developed heads result in increasing
total flow only. This results in either a slow engine or an engine that
comes on with an unusable rush of power.
CJS Ducati cylinder heads are tailored to
your engine. Each head is carefully re-worked step by step using a flow
bench to find the hidden restriction which are not always visible to the
naked eye. They are matched to there chosen camshaft, operating speed and
intended use. There would be no point in preparing a head with steep race
type valve angles and a larger port volume for a head which is using a cam
that only lifts to say 10mm. The cam would never see enough lift to use the
extra airflow resulting in poor airspeed a slower bike and disappointment to
the customer. Unfortunately this is a common affair for some companies where
all they can offer is a one head fits all application. However there are
many other companies out there who are worthy of a great job and I have
listed them in my links page.
Examples of How the
Heads are reworked
The Ducati 996 has a
pretty good spread of power and torque already. To successfully port this
head we may need to keep the engines good character. We do this by fitting
a larger intake valve but keeping the cross section of the port around the
same size as the original. The larger valve allows us to move more airflow
from the same size port but the best part is that fact that the air is
delivered at the same great speed as the original head resulting in better
power and torque throughout the whole rpm range. For racing cams that lift
a lot higher the ports can be reworked further to make the most of the extra
lift and duration of the camshaft.
The Ducati 748r has the worst of
the Ducati ports ever seen. The throat sizes of
each port can vary from casting to casting. The ports are a little too
small for there rpm range and totally strangled by its terrible floor and
inadequate valve seat shape. We correct the ports and use the peg fm1 to re-cut the seats to a different profile. This headwork alone will yield
between 7 and 10 plus hp with big gains at the bottom end as well.
Ducati 998/999 race &
high velocity porting
The Ducati 998 and 999 has ports which are
actually to big for there camshafts. They can actually be made smaller with
no loss of flow. We do this by welding into the port and re-shaping the
venturi. This results in a higher velocity and much improved, power and
torque throughout the whole rev range. The mass airflow is mainly improved
through careful seat work and valves sizes not through the port itself.
There are many combinations for this head
listed in competition cylinder head prep
making your cylinder
head reliable
please read carefully A reliable cylinder head should have freshly
cut well defined seat angles being cut concentric to its guide bore enabling
good sealing without the contact area being too thin. A thin contact area
may be great on a race engine that’s stripped every few meetings and it may
gain a few extra cubic feet per minute of airflow on paper but its not good
for RELIABILITY or your wallet. At CJS we gain airflow in other more
thoughtful ways.
Valve guides are seriously important they
must be wear resistant, have good oil retentive properties and have an aero
dynamic profile for improved airflow. CJS designed COLSIBRO BULLET NOSED
RACE GUIDES attain this in every way. These guides are flawless and totally
finish off your porting job by making it look crisp and professional .
However gas flowing is not about looks but who wants there expensive Ducati
heads back looking like they have been attacked by a knife and fork and at
£88 a set who can refuse the benefits of above.
On every port job over the level of a stage 1
CJS may refuse the work unless colsibro guides are fitted.
