Drag Illustrated Issue 114, October 2016 | Page 66

PRODUCTS & PRESS
KINSLER K-140 PRESSURE RELIEF VALVE OFFERS
EXTREMELY PRECISE FUEL PRESSURE CONTROL
Kinsler’s new K-140 pressure relief valve has
less pressure rise (less slope) because of its large
efficiently-flowing pintle and seat. As the flow is
decreased, the pressure decreases. Ideally, this
would form one slightly slanted straight line (see
graph below), but friction in the valve makes the
closing pressures slightly less than the opening
ones. This result is called a hysteresis loop.
Pressure relief valves (PRV) have a diaphragm
assembly with a pintle or ball, with spring(s)
above it to force it down onto the seat. Fuel pressure from the pump must rise to the set point
to exert enough force on the diaphragm to lift
the sealing device off the seat, allowing fuel to
pass through the valve. To bypass more fuel, the
spring(s) have to be compressed slightly more
to open the valve a bit further, causing a rise in
pressure.
The new K-140 valve has the tightest loop of
any valve Kinsler has tested: the closing pressures
are just .2 (2/10) psi lower than the opening pressures. The swivel pintle valve is self-centering as it
closes. The piston that carries the diaphragms and
swivel pintle on its nose prevents any spring end
angle from cocking the pintle carrier, but even if
it could cock, the swivel pintle would cancel it out.
Kinsler uses two thin diaphragms, installed
with the weave at a 45 degree angle to each other,
so if a thread were broken in one, it is backed up
by the other diaphragm. The two diaphragms are
crushed a total of .0044”, which forces some of
the elastomer from them into the four retainer
grooves in the tower and the
body, clamping them very
securely. The diaphragm
material is quite special:
The fabric is premium quality, vacuum coated with a
primer, then two different
elastomer coatings to be
compatible with gasoline,
alcohol, ethanol, and blends
thereof.
All the components, including the springs, are
carefully measured for
each valve build, recorded,
and kept for future service.
The flow performance and
hysteresis loop are also recorded.
If the 3AN side-of-thetower breather port is connected below the throttles
in the intake manifold, the
PRV will lower the fuel pressure when it sees vacuum. If it sees boost, the
PRV will raise the fuel pressure. This broadens
the useable range of the injectors.
It is critical that any PRV has a maximum of

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10 micron (.39 thousandths of an inch particles)
to it, as any dirt that gets between the valve and
the seat will prevent the valve from closing fully. Much better would be the 10/3 filter, which

Kinsler developed for NASCAR cup cars.
It has a top layer of 10 micron paper to
take out 90% of the dirt, to protect a 3
micron (.12 thousandths) absolute fiberglass bottom layer. It is also best to supply
the injectors with 3 micron filtration, so
placing this filter before the fuel rails will
protect the injectors and the PRV better.
For more details check out the Kinsler.
com home page.
Weighing in at just .45 lbs, the K-140
valve components are premium hard coated and sealed, then the moving parts are
micro lapped to a high polish. For use with
Gasoline, Methanol (alcohol), Ethanol,
and E85.
Kinsler designed this valve in 1996 for
General Motors, as they were getting ready
to field Oldsmobile Aurora engines at the
Indy 500. Kinsler has made 8,000 of the valves
since then and have not had one failure in the
field except for dirt problems from teams using
inadequate filters.

Issue 114