One of the most important aspects of cylinder head optimization is the
design of the valves. Several issues must be addressed when we look at valve
design, including the environment the valve will be "living" in, and
of course, the shape of the valves. The materials the valves are
manufactured from must exceed the requirements for the application, as any
failure can contribute to the loss of a complete engine in most instances.
Another associated consideration is valvetrain wear under high stress conditions
presented by today's highly competitive dual purpose (race / street) engine
The shape of the valves, on both intake and exhaust sides is critical to
promoting and supporting flow rates necessary for breathing in these high RPM
engines. The shape of the valves also affects it's weight.
Endyn's been involved in designing winning cylinder heads for over 27
years and we've used our flow technology and experience to design the shapes of
our valves to promote the best overall flow rates and quality in the Honda heads
that we've targeted so far. We've configured the stock sized valves to flow
better than the OE valves with stock, or near-stock ports. These same valves can
be "customized" to work with ported heads by merely adding a slight
back-angle, as prescribed by the head porter. Our oversize valves are configured
to work with ported heads, or those that have properly reconfigured valve seats
and bowls. We've even developed valves with flat chamber sides to help promote
the combustion kinetics we desire in certain specialized situations.
Endyn's been preparing heads for endurance racing since 1976. Over all
these years, we've become keenly aware of the fact that, in order to win the
race, you must finish with a healthy engine. To this end, we've become sticklers
for making valves from materials that exceed the requirements for the
application. We selected a stainless steel (SAE EV8 21-4N) for our Honda valves,
and to insure that the stems won't wear themselves, or your valve guides, the
valves are black nitride coated. These valves have been in use for two years in
international competition, including factory sponsored team cars.
Stock sized B series valves. Note that the intake valve stems aren't
undercut, as our testing has shown that reducing the stem diameter on the VTEC
heads doesn't promote additional flow. These intake valves are, however,
comparable in weight to the factory ITR valves.
As can be seen in the picture above, we reduced the stem diameters in both
the intake and exhaust valves we designed for the D series Honda applications.
Extensive flow testing showed significant gains in these small-port cylinder
heads with this configuration.
We currently have valves in stock for the following Honda applications,
with valves for other import brands arriving 01-01-02. We can also custom make
valves in sizes that aren't listed.
||Intake Valve Diameter
||Exhaust Valve Diameter
||33.0, 33.5 and 34.0 mm
||28.0 and 28.5 mm