Glossary: Engine Blocks and Cylinder Heads

A block design that has the cylinder head and the cylinder block bolted together by tie bolts; sliding steel sleeves, which are locked in the block, accept the cylinder head bolt from one side and the tie bolt from the other.

A coating applied to substrate material containing the catalyst. It usually has a porous texture to create a surface area for chemical reactions to take place.

An exhaust bypass valve in the turbine housing that allows exhaust gases to bypass flowing across the turbine and directly enter the exhaust pipe, thus “wasting” some of the exhaust energy.

A slack U-tube device used to measure exhaust back pressure using inches of water (inH₂O) column.

A device that illuminates a warning light that informs the operator to drain or service the fuel–water separator.

A detector that uses an electrical conductivity probe to sense a specific level of water in fuel and cause a dash-mounted light to illuminate. This light or warning alerts the vehicle operator of the need to drain water from the fuel–water separator.

A system that sprays water and methanol into the intake system to absorb heat from the intake air, thereby helping to reduce peak combustion temperatures.

A low-emissions piston design from Volvo that adds waves to the sides of the piston crown to improve mixing and distribution or fuel and air. Six of these curved ridges correspond to the number of holes in the centrally located injector.

An estimate of total vehicle emissions derived from calculating all emissions produced generating and transporting the energy to the vehicle, plus any emissions from the vehicle using the energy.

Used interchangeably with calculations of well-to-wheels emissions. It is an estimate of total vehicle emissions produced from generating and transporting the energy to the vehicle, plus any emissions from the vehicle using the energy.