The GTI Bi-Fuel System operates by blending both diesel fuel and natural gas in the combustion chamber. This is achieved using a fumigated gas-charge design, whereby natural gas is pre-mixed with engine intake-air and delivered to the combustion chamber via the air-intake valve. The air-gas mixture is ignited when the diesel injector sprays a reduced quantity of diesel fuel into the chamber. This diesel "pilot" acts as the ignition source for the primary air-gas combustible mixture. Because the Bi-Fuel System utilizes the OEM air-intake and diesel injection systems, no internal engine modifications are required for installation.