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Knock
See detonation.
Knock
Sensor
Sensor that threads into the side of the block
and detects knock. If knock is present, the sensor will tell
the ECU to pull some
timing temporarily
until the knock disappears. This practice makes for a loss
of power, but potentially saves the engine. The knock can
be from poor gas, a poor running motor, too much timing, etc.
The knock sensor is a safeguard to make sure that the damage
doesn't continue.
Kouki
Japanese term for "late" or "after change."
Usually is used when referring to a certain generation of
vehicle after they made changes to it. For example, the 97/8
240sx is kouki because they kept the same body in 95/6 but
changed certain features like the headlights and taillights
for 97/8. The opposite term would be zenki.
Leakdown
A method of testing the health of a motor. Usually done in
conjunction with a compression
test. The leakdown test requires a special tool and an
air compressor to pressurize the cylinder
and measure how much pressure is lost. The less pressure lost,
the healthier the motor. The test is conducted as follows.
1)
Turn the cylinder to TDC
so that the valves
are closed.
2) Thread the spark plug extension into the spark plug hole.
3) Turn the regulator on the air compressor (or leakdown tool)
down to a low pressure like 30 psi.
4) Connect the air compressor hose to the leakdown tool. This
step will pressurize the cylinder.
5) Slowly turn the regulator up to 100 psi.
6) Look at the second gauge on the leakdown tool (the one
closest to the engine) and note its pressure reading. This
number is the pressure inside the cylinder. With this info,
you can figure out the pressure lost inside the engine. If
it is at 90psi, you lost 10 psi, or 10%. 5 psi is 5%, and
so on.
All
engines have some leak, even new cars leak 1-3%. In general,
5-10% is average leakdown for an engine with many miles on
it, while 10+ starts to get a little sketchy. Just because
an engine has major leakdown, doesn't mean it is complete
trash. Because the cylinder is pressurized, you can see where
the leak is at. If you hear air coming out of the exhaust,
the valves are most likely the culprit. If the air steadily
comes out of the PCV,
then it is most likely the rings.
A valve can be fixed with the engine in the car by removing
the head, while rings
require the engine to be removed and rebuilt.
Lift
A spec for a camshaft
that denotes how far the valve
is being pushed open. The further it is being pushed, the
more air can get in and out of the head, which means more
horsepower. Also, the more lift, the greater the need for
stronger valve springs.
Lobe
The triangle shaped hump on the camshaft
that pushes on the valve.
LSD
Limited slip differential. This part of the drivetrain
senses when one tire is spinning and gives power to the other
wheel as to evenly distribute the power and ensure traction.
The LSD helps in the rain/snow/mud because you do not have
as much wheelspin and its harder to get stuck or spin out.
MAF
Mass airflow sensor. This piece sits in the intake
pipe and measures how much air is going into the motor. It
tells the ECU, which
then determines how much fuel to inject based on this information,
along with other info. A leak in the intake pipe between the
MAF and the engine will cause the car to run poorly as air
the ECU thinks is going into the motor is actually not and
thus the calculation of fuel to inject is wrong.
MAP
Manifold absolute pressure. This method of measuring airflow
into the engine is based on pressure, not actual measured
airflow. This system requires no sensor in the intake tract
and simply attaches onto the intake
manifold or a hose from the manifold runs to the MAP sensor.
A MAP based car can run with no intake pipe whatsoever because
it can still determine the pressure.
Meats
n skinnies
Slang for a car running wide tires in the back, and skinny
tires in the front. However, front wheel drive cars do just
the opposite. The wide tires provide traction while the skinny
tires ensure the least amount of friction as the car goes
down the track, thus helping reduce times.
MKI
(submitted by FD3S
on the Fighters forums)
Mark one, or 1st generation.
MKII
(submitted by FD3S
on the Fighters forums)
Mark two, or 2nd generation.
MKIII
(submitted by FD3S
on the Fighters forums)
Mark three or 3rd generation.
MKIV
(submitted by FD3S
on the Fighters forums)
Mark four, or fourth generation.
NA
Normally aspirated, it breathes normally. An engine with no
turbo or supercharger.
Narrowband
An o2 sensor that cannot be used to
tune a vehicle. It simply tells the ECU
if the car is running in stoich
or not.
Nitrous
Injected into the motor to boost horsepower. When nitrous
oxide is present in an engine's combustion chamber, it greatly
increases the amount of oxygen that can be burned to produce
horsepower. Normally, oxygen makes up about 20 percent of
the earth's atmosphere which means that about 20 percent of
the average intake charge is also made up of oxygen, and it
is this amount that combines with vehicle fuel to produce
power. But when nitrous oxide is introduced to the engine,
the percentage of oxygen rises dramatically and allows for
substantially more fuel to be used to produce a significantly
more powerful explosion. Nitrous oxide alters the content
of the air entering the combustion chamber; specifically,
the oxygen content.
An
interesting side effect of using nitrous oxide is the cooling
effect it has on intake temperatures. When released from a
pressurized container, nitrous oxide drops to around minus
125 degrees, which can cool the overall intake charge by up
to 75 degrees, resulting in even more horsepower.
The
amount of nitrous that is injected (horsepower) can be altered
by the size of the shot.
If you call it NOS, nobody will take you seriously. NOS is
a nitrous kit company, not the actual nitrous itself. You
can call it nitrous, n20, juice, spray, squeeze, etc.
O2
Housing
Part of the exhaust that bolts onto the turbo and holds the
oxygen sensor.
O2
Sensor
The oxygen sensor in the exhaust. It determines the ratio
of air to fuel (AFR)
in the exhaust and can determine if the engine is running
efficiently or not based on that ratio. The o2 can be either
narrowband or wideband.
Oil
Pressure Gauge
Measures the engine's oil pressure. Can be electrical or mechanical.
Mechanical oil pressure gauges have a line that runs from
the engine to the gauge itself. This type of gauge is generally
frowned upon because the line has hot oil running inside the
cabin of the car and could burn you if there was a leak. Electronic
gauges have a sender that threads into the block, then wires
run to the gauge itself. Electronic gauges are easier to install
with less mess.
One
tire fire
A burnout where only one tire spins. This tyoe of bournout
means the car has an open
diff.
Open
diff
A differential that is not LSD
equipped, meaning one tire can spin forever and no power will
be given to the other wheel.
Oxygen
Sensor
The oxygen sensor in the exhaust. It determines the ratio
of air to fuel (AFR)
in the exhaust and can determine if the engine is running
efficiently or not based on that ratio. The o2 can be either
narrowband or wideband.
