Constant Flow Nozzles
CONSTANT FLOW NOZZLES
Constant flow systems are very flexible and cost effective for many types of
racing, engine configurations, and fuels. They are capable of supplying a very
wide range of fuel requirements. The system can be easily configured and
tuning is accomplished by increasing or decreasing the systems operating
A constant flow system uses a mechanical fuel pump to increase/decrease
the supply flow to the injection unit directly related to engine rpm. This variable
flow creates pressure against the fixed orifices of the main bypass jet and the
nozzles. Using a barrel valve assembly the idle and the part throttle fuel rate is
controlled. Kinsler can supply additional bypasses and enrichment circuits to
give added flexibility.
Basic components of a constant flow fuel injection system :
A) Air control - individual runner (I.R.) manifold or throttle body.
B) Kinsler Fuel Injection manufacturrer's throttle linkage. Special jackshaft
kits (like the one shown above) are available for most manifolds.
C) We stock heavy duty Morse throttle cables and shut-off cables. We also
offer S.S. quick and bolt down release mounting clamps.
D) Barrel valve assembly - barrel valve houses the spool. The spool controls
fuel for idle and part throttle. There is a selection of spools for different
engines and fuels.
E) Nozzles - fixed orifice in the runner or plenum of intake manifold. Sized for
specific engine and fuel being used.
F) Nozzle lines - connects barrel valve or distribution block to nozzles.
G) Main bypass jet can - houses poppet and spring for basic idle fuel
pressure and holds main bypass jet.
H) Main bypass jet - this orifice works in conjunction with pump and
nozzles to set the overall fuel delivery of the system. It can be
quickly changed to adjust the base fuel rate.
I) Fuel pump (mechanical) - positive displacement pump.
J) Fuel pump drive - typically setup to run fuel pump at 1/2 engine rpm. Can
be mounted to camshaft or belt drive.
K) Fuel shut-off valve - stops fuel flow to barrel valve to allow the engine to
L) Fuel filter - filters the fuel to protect nozzles, bypass valves, and barrel valve.
Optional components :
M) Secondary bypass valve - allows tuning flexibility of part throttle.
N) High-speed bypass valve - allows tuning flexibility of higher rpm fuel delivery.
O) Electric lean-out or enrichment valve - special function valve to allow
tuning of a specific area or range of the fuel deliver.
P) Kinsler Jet Selector Valve - holds eight main bypass jets. Allows main
jet to be adjusted while engine is running.
Q) Kinsler Vapor Separator Tank (VST) system - typically used when the
main fuel tank is mounted too far away from the mechanical pump and
a transfer pump is required. Kinsler specially designed system keeps a
constant feed pressure to the mechanical pump to prevent cavitation.
NOZZLE DISCHARGE STYLES :
'A' type : fuel is discharged at 45 to body through notch cut in deflector,
commonly called 'whistle' or 'notched'. 'AS' type : fuel discharged in line
with body through a diffuser screen, commonly called 'screen tip' or 'shot-gun'.
K-TYPE JETS :
Even a perfect fuel injection unit is of little use to the owner unless he has
a good set of jets to use with it. When using commercially made jets, it is
not unusual when going .005" smaller in jet size (in an attempt to richen
the unit) to actually find no fuel rate change, or perhaps go grossly rich,
or even to go a bit leaner! This makes it impossible to "tune in" the engine
for best power and consistence.
EACH K-type jet is precisely machined and stamped with the "KINSLER"
name to identify it. It has a reamed orifice controlled within .0002", a precise
radius leading to the orifice, and a regulated finish.
Every K-type jet is tailored on the flow bench to within 1/2% of the flow rate
of the master reference jet of its same size. Therefore, even though the
increments between the K-type jets are very small (.002" available), the
change in flow rate between each jet is the same. Every jet of the same
size flows the same, if one jet is lost, an exact duplicate can be shipped
A) Because of the larger radius entrance to the metering orifice in the K-type
jets, you must start with a K-type jet that is about .008" smaller than the
conventional jet that you are replacing, if you want to retain your present
B) Always install the jet so that the number is facing up as you drop the jet in,
then the fuel will flow into the radiused side of the jet. After the jet can has
been assembled, the number will be facing toward the poppet.
C) Make sure the jet can end has an o-ring receiving groove and that an o-ring
is in place for the jet to sit on. Note: the jet sealing o-ring should be replace
periodically to make sure that the compound has not "dried" out.
We can make variations of these nozzles and special nozzles just call us.
Also see pg 10 of main handbook.
+ or - approx. 4% from flows shown at left Crower and Enderle nozzle size (they code their inserts differently)
'A' Type: Fuel discharged at 45 degrees to body through notch cut in deflector:
commonly called 'whistle' or 'notched'.
'AS' Type: Fuel discharged in line with body through a diffuser screen:
commonly called 'screen tip' or 'shot-gun'
Nozzle Venting Vents let air premix with the fuel inside the nozzle for better
Externally Vented : For
Non-Vented & Z-type : For supercharged or
Constant flow nozzle
For nozzles, bypass jets, carb jets
A sharp edge at the orifice entrance causes the flow stream to converge, the
smallest flow cross section being termed the vena contracta and is the point
of lowest pressure. The vena results in less flow through a given hole size than
a piece with a rounded entrance.
The particle of fuel coming straight down
The particle a bit off
The particle a bit
We use only fully radiused type orifice approaches in all our nozzles and jets.
Every nozzle and jet we make is done with great care, but they still don't all
turn out properly. Each piece is flowed at three different pressures, then
compared to the master flow sheet If it isn't within tolerance, it is scrapped.
Testing at three pressures is important because some pieces will flow perfect
at low flows, but then go turbulent (due to imperfections on the surface) at
high flows.... we call this a "shift" in the flow. All of this quality control costs
more money, but it assures you of receiving the best possible peices in the
Flow through an orifice
Pressure rises as the square of the flow through an orifice, so to double the
flow through a jet nozzle takes four times the pressure:
If we know the flow of a jet or nozzle at some pressure , we can figure out
the flow at a new pressure: