G to O



GT3: Usually ferers to Gran Turismo 3 Class of racing cars designated by FIA with its own set of regulations for homologation and racing

g-force: the measurement of forces acting on an object where unity is equivalent to the acceleration caused by gravity on an object. Forces act in 4 vectors
Gas Filled Dampers: Does not mean there is only gas in the dampers, a pressurized gas compartment withoin the hydraulic fluid filled tubes provides better damping progression over a wider range
Geometry: In automotive parlance is the setting of the various angles of the suspension i.e. camber, toe, castor
Ground Effects: The amplification of aerodynamic effects when they interact with the immovable and undisplaceable ground (road)
Gurney Flap: When Dan Gurney riveted a right angle strip of metal to the end of his race car's boot and gained a few more mph at the end of each straightaway his trick caused a minor revolution in the art of aerodynamics and got the name Gurney flap, still used today by engineers


Harmonics: To describe resonances that occur in simple multiples of the original frequency.
Homologation special: FIA mandated that for manufacturers to race in certain categories like Group A or Group N, manufacturers must make and have sold a certain number of the same cars to the public. These pepped up cars were called homologation specials. Examples are the Subaru WRX S204, Mitsubishi Evo range Mercedes 190E 2.3-16, BMW M3 E30
Hybrid Vehicle: A vehicle that has two engines combined, onenormal  petrol (or diesel) and the other electric that also behaves as a generator to recover otherwise wasted energy during braking as electricity to be used later for propulsion.
Hydrogen Fuel Cell: The full name, see Fuel Cell


Ignition: Or ignition timing is the precise point where the combustion process is initiated inside the compressed charge of fuel and air. Usually by a spark plug in petrol engines or upon direct injection of diesel in diesel engines
Intake Manifold: The connecting tubing that mates with the cylinder head on the intake side and the plenum chamber at the other end
Inlet valve: The valve device that controls the flow of air or fuel+air mixture into the cylinder


Joule: Is the unit for energy, 1 Newton force over a distance of 1 metre = 1 Joule (N.m)


Kerb Weight: Supposedly the kerbside weight of the car in running condition with fluids and fuel excluding driver and passengers
Kickdown: Is the phenomenon of the automatic transmission shifting down one or two gears suddenly in response to a heavy prod of the accelerator pedal
Kilowatt: The metric unit of power
Knock Sensor: Specific shock sensors to detect the characteristic shockwave of two flame fronts clashing due to pre-ignition or detonation. This data is used to alter ignition timing to reduce the problem


Lambda: Is a greek alphabet used in engineering to describe the concentration of combustion mixture where 1.0 is the perfect stoichiometric ratio and if Lambda is less than unity it means a rich mixture and more than one is lean
Laminar Flow: Is the situation in aerodynamics to describe a neat undisturbed layered airflow over a surface
Lateral Acceleration: The measurement of g-force due to cornering when the car is traversing an arc and the acceleration is toward the center of that arc where 1g-force is equivalent to its mass as if on its side
Light Emitting Diode (LED): an old technology recently rising to new heights because of its superb efficiency to convert electricity directly to photons of light and because white-spectrum LED light is now commercially feasible
Limited Slip Diferential: Or LSD is a mechanical device to limit torque loss due to one of the driven wheels slipping uselessly. The device usually locks up the open differential to split the torque equally between left and right. Mopdern differentials have the ability to vary that lock up and indeed transfer the entire torque to the gripping tyre. see E-Diff


\M GmbH: Refers to BMW's M-Division run as a separate entity under BMW
MacPherson Struts: A simplified, space saving wishbone suspension system without the upper wishbone leaving the vertical geometric guidance to be borne by the strut itself which also has the spring concentrically wrapped around its axis
Magnesium: One of the lightest metals that can be used commercially in the production of stress bearing car parts. Magnesium wheels and more recently magnesium alloy engine blocks pioneered by BMW. Having low weight is a big advantage but it corrodes easily and burns
Magnetic Clutch: A type of clutch that uses electro-magnetic forces to produce clamping forces especially useful in the air-con compressor
Main Bearings: The bearing surfaces that support the loads of the engines crankshaft and develop excellent hydrodynamic lubrication when combined with engine oil
Manifold: The term used to describe the tubing either on the intake or exhaust side of the cylinder head. Usually metal manifolds are used but lately high temperatire plastics have been used on the cooler intake side. The exhaust manifild has also been called extractors or headers
Mid-Engine Configuration: The layout of the car's engine in relation to its axles. Thought to be the best layout for the lowest polar moments to maximize performance though not necessarily handling
Monobloc Caliper: Thought to be the strongest brake caliper design as it is cast as a whole single piece with no attached parts
Monocoque: A term describing the clever integration of body panels and the stress bearing chassis or frame suited for steel body car construction. Think of it as an exo-skeleton (eg crabs) and the other way to do it is with an internal skeleton (eg us). Also called unitary construction. see opp Space frame


Needle Bearings: A roller type bearing where the inner bearing race consists of fine roller bearings appearing like needles. These are compact in diameter and used where space is restricted like gearboxes
Negative Offset: A front suspension design where the axis of the pivoting (for steering) of the front wheels intersects the ground outside the center line of the tyre
Nitrogen: The most abundant inert gas in our atmosphere used now to inflate street tyres. Used mainly in racing to have better control of inflation pressure as N2 expands less.
NOx: To denote oxides of Nitrogen which usually spew out more from engines with high compustion temperatures, reduced by modern catalytic converters to safe levels


O-rings: Flexible, usually rubber rings that form a seal with another flat mating surface around a tube or bolt
Octane: Is a rating of the knock resistance or characteristic of a fuel mainly seen at petrol pumps to denote the grade of the petrol. the index of 100 is given to the knock resistance of Trimethyl Pentane
OHC: Over Head Camshafts
Oil Cooler: A radiator that is designed to cool oil that passes through it, engine, transmission or final drive
Opposite Lock: What the driver does to the steering wheel to counter the oversteering car or a better term is counter-steer
Oversquare: A term given to engines which have larger bores than its stroke
Oversteer: The handling condition where the rear axle is tracing a wider arc (and higher speed) than the fronts usually because it has lost grip and the fronts are still gripping causing the car to pivot around its center (yaw)

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