A heat transfer system for use in an internal combustion engine and related methods are disclosed. The heat transfer system may be configured to absorb and transfer heat from a combustion chamber of an internal combustion engine. The heat transfer system may also be configured to reintroduce absorbed and/or transferred heat into the internal combustion engine via a fuel injector or another suitable device. Removal of the heat from the combustion chamber may reduce a quantity of work required or used for compression of a first combustion fluid, increase a charge density in the combustion chamber, and/or increase the compression ratio of the engine. Additionally, the heat transfer system may be designed such that it may be used to retrofit an existing internal combustion engine.

An electric GDI pump is configured to allow fuel being pumped to cool the electric motor and associated motor control/drive circuit, and cool and lubricate a drive region of a high-pressure pump before passing through an inlet check valve of the high-pressure pump. The rotational speed of an electric GDI pump is de-coupled from the rotational speed of the internal combustion engine. In such a fuel supply system, the quantity of fuel pressurized can be regulated by changing the rotational speed of the electric GDI pump. According to aspects of the disclosure an electric GDI pump is driven by a variable speed direct current motor having a motor housing with a fuel inlet and a motor drive shaft connected to a rotor. The electric GDI pump may incorporate a low-pressure pump driven by one end of the drive shaft and an eccentric drive driven by an opposite end of the drive shaft.