Nitrous Jet Charts:
Correct Nitrous and Fuel jets for different power outputs and fuel
PDF file for printing:
Or scroll down
to see HTML Jetting Chart.
settings should be OK for MY SYSTEMS ONLY!
(Due to types of solenoid, the
actual Jet positions) - They MAY be OK for other systems as well, but please
All engines and setups
will vary a little from these settings for optimum performance. These
settings should give you a slightly “over rich” and a "safe" starting point under
This slightly over rich setup is preferred for standard
production cars anyway, although racers with stronger, modified engines and ignition
systems & timings
may wish to tweak them a little later on. This chart below applies to systems that are
jetted at the solenoid outlets only!
US Style systems that are jetted at the
"nozzle" may well be different. And such things as the diameter of
the Nitrous Supply Line, has an effect on total flow too. All My systems should
be using 3.75mm bore "braided brake pipe type hose" from bottle to solenoid or
4mm nylon for sub 70bhp systems. If you use 4mm Nylon type pipe, with 1.7mm bore, then its only
OK up to about 70BHP, after which the length of the pipe becomes a problem
due to the pressure loss over long lengths.
Remember this is only a starting guide! If you want really BIG power boosts
you may need to go slightly “richer” still (more fuel) than this or very
occasionally leaner. With most healthy engines a small (20% to 30%)
increase should be OK with standard ignition timing. If in doubt or it
sounds “harsh” then retard it by a few degrees! Should sound smooth, and
simply accelerate harder.
Actual power gains have been calculated from known constants (theoretical
calculation) and tested in
practice, when dynamometers (Dyno's) were used to actually measure the
results over many years.
The measured power gains have been extremely close
to what is actually calculated on a variety of different naturally aspirated
vehicles once correctly set up. All engines use Nitrous Oxide at different
efficiencies though, so results will vary lots. Turbo cars and bikes
are a good example here since the actual power gain given is often far
higher than expected, and turbo lag is all but completely eliminated with
full boost at much lower RPM's. In all cases it is best to begin
testing with smaller Nitrous & Fuel jets first (say 25bhp on a car or big
bike) and then listen carefully and check spark plugs as you go up to your
desired final BHP increase. There are limits though! Don't go too far!
Weber "carb" jet used here screwed into the (modified) fittings, that
in turn screw into the Solenoid valves outlets so the jets are as close as
possible to the actual solenoid valves seating. This gives far more accurate
flow control than fitting the jets into the actual injectors or "foggers"
especially when used with a pulse width modulation type Nitrous
These cheap plastic fittings
will work, for testing and development work, but its FAR better to use
brass, stainless steel, or metal plated fittings with nuts and olives in the
plastic push lock type fittings as shown its not unknown for a pipe to fall
out when they get a bit "hard" with age! It's ok provided you check condition
often, but not as good as the metal / nuts & olives "permanent" solution! Be