12
Chapter 3 Tuning
Table 2 Tuning Suggestions for SNIPER Kit Number 07166NOS
Configuration
N
2
O Jetting
Fuel Jetting
75 RWHP*
35*
18*
100 RWHP*
40*
21*
125 RWHP*
50*
27*
150 RWHP**
57*
31*
*Jetting Included in kit
**Will require an upgraded fuel system
NOTE:
It is recommended to install one to two steps colder, non-Iridium or other fine wire spark plugs when using Nitrous Oxide.
Chapter 4 Determining Optimum System Performance
The jetting combinations included in your 07166NOS kit are intended to generate power gains of 75-150 HP. These combinations are
designed to be used with 950 psi of nitrous bottle pressure and 60 psi of flowing fuel pressure. Spark plug inspection and/or the use of
a wide-band O
2
sensor can determine optimum system performance. Inspection of the spark plugs should be done on a consistent
basis.
1.
Perform a dynamometer pull or a full throttle pass down the racetrack. Note the power reading or vehicle mph (not e.t.). Examine
the spark plugs for an indication of lean or rich nitrous/fuel conditions (refer to for tips on reading the spark plugs). For this
application, the air/fuel mixtures at WOT tend to be very rich in stock form. You may wish to examine a plug after a NO-nitrous
pass or dyno pull for comparison purposes.
CAUTION!
Terminate test immediately if pinging, knocking, detonation is noticed during the test. If engine does not pull hard
(expected HP or torque gains are not observed), terminate test and investigate before continuing.
1A. If spark plugs appear to be excessively rich, decrease the fuel jet size 1 step (ex. 28 to 26 or 26 to 24).
1B. If spark plugs appear to be excessively lean, increase the fuel jet size 1 step.
1C. If
spark plugs have a “like new” appearance on the porcelain and electrode, do not make a fuel jetting change.
2.
Repeat these steps until the desired mixture is obtained.
How to Read Spark Plugs from a Nitrous Oxide Injected Engine
A. Correct Timing, Mixture, and Spark Plug Heat Range
The ground strap retains a “like new” appearance. The edges are crisp, with no signs of discoloration. The porcelain retains a clear
white appearance
with no “peppering” or spotting.
B. Excessively Rich Mixture
The porcelain may be fuel stained, appearing brown or black. In extreme cases, the ground strap, electrode, and porcelain may be
damp with gasoline, or smell of fuel.
C. Detonation
The edges of the ground strap may become rounded. The porcelain has the appearance of being sprinkled with pepper, or may have
aluminum speckles. During heavy detonation, the ground strap tip may burn off. This phenomenon can result from excessive ignition
timing, too high a heat range spark plug, inadequate fuel octane, or excessively lean mixture.
D. Excessively Lean Mixture
The edges of the ground strap may become rounded. Under moderate overheating, the tip of the ground strap can discolor, usually
turning purple, or the entire ground strap can become discolored.
Figure 10 Spark Plug Condition