Some car jargon.
CVT – Continuously Variable Transmission. A stepless gearbox system which allows infinitely variable gear ratios because it uses variable belts instead of fixed gears for transmission.
USDM – United States Domestic Model
JDM – Japanese Domestic Model
CBU – Completely Built up, cars which are imported in whole fully assembled from another country.
CKD – Completely Knocked Down, cars which are brought into the country in the form of kits. The kits are assembled locally, with alot of the parts not supplied in the main kit sourced from local manufacturers.
NOS/N2O/Nitrous – Usage of Nitrous Oxide to boost performance.
HP – Horsepower, a measurement of work done @ rpm, usually listed at its peak
BHP – Brake-specific horsepower
Torque – A measurement of force acting on an axis, causing a twisting motion. Measured in lb-ft in the USDM markets.
VTEC – Variable Timing & lift, Electronically Controlled. This is a valvetrain feature used in the late 80’s to late 90’s by Honda Motor Co. It allowed switching of cam lobes (and a staged ignition advance in later versions) at a certain rpm to take advantage of two different powerbands.
i-VTEC – Released as a feature in the K-series of Honda’s passenger vehicle engines, it retained the functionality of the earlier version, but added cam-phasing.
Powerband – A term used to describe measured torque and calculated horsepower, displayed on a graph. The means in which these values are gathered is through the use of dynamometer.
Volumetric efficiency – The calculated efficiency of an engine, based upon the metered input of combustible volume and the measurement of power generated. This is almost always a parabolic value, since engines have a peak in power production and falter shortly thereafter.
Dynamometer – A device that measures torque using a reference value, such as resistance. The are two common kinds in the automotive world, the engine dynamometer and the chassis dynamometer. The former measures torque output at an engine’s crankshaft, the latter measures at a vehicle’s drive wheels, which can factor driveline and accessory losses simultaneously. The latter is more favored, because it creates results that are closer to a real-life situation.
Forced induction – The act of forcing more than 0 bar (1 atmosphere) of air into an engine, in an effort to increase power. This can be acheived through several means, such as turbocharging or supercharging. Also, nitrous is arguably forced induction, because with nitrous injection there is more oxygen present in the combustion chamber than is possible under conventional induction.
Anti lag/Misfiring – A system where unburned fuel is introduced into the exhaust manifold to create exhaust fumes that keep the turbine spinning while the throttle is closed.
Downforce – An effect of vehicle aerodynamics, it is a measurement of how much force the wind is applying to the surface of a vehicle. Benefits are conversely related, as an increase in downforce allows more traction at high speed, but causes more resistance. Decreasing has the opposite effect.
Bore and Stroke – A measurement taken during the design of an engine. The bore is the diameter of the hole in the engine block, which contains the piston. Stroke is the distance that piston travels in between its highest point (Top Dead Center, TDC) and its lowest point (Bottom Dead Center, BDC).
Interference engine – A conventional modern engine design. It is a configuration of which when a valve is open at it’s greatest point, it exists in the same area that the piston travels into, and will be in shortly. The benefits of this design are a closer tolerance, shorter engine, more freedom in combustion chamber design and valve angle. The downfall is if and when a timing belt/chain fails, the valve will not not close, and the piston will strike it.
This is a work in progress so it might seem a bit messy. If you want to add anything to this list, please contact me.