Fuel System

Fuel Pump (K Series cars)

The standard S1 fuel pump runs at approximately 3bar pressure (set by the pressure regulator on the end of the fuel rail on a K-Series).

Pumps of this type have the characteristic that as the flow rate increases (which is required for higher powered engines) the pressure the pump can maintain drops. The exact pressure and flow rate varies from pump to pump, but sufficient fuel for around 220bhp @ 3.3bar pressure is possible from the standard pump.

If more pressure and flow is required (as is the case in Honda engined cars) then currently the only option is a secondary pump. This requires additional plumbing and electrical work, although a higher spec replacement pump for the standard pump is under investigation by 3rd party suppliers.

Fuel Pressure Regulators

It is incorrect to say that more pressure will result in more power. The ECU is programmed to deliver as much fuel as required for any given engine condition. Increasing the pressure will result in rich running unless the ECU is altered accordingly (which is not possible with the standard ECU).

Highly modified engines with high power outputs require more fuel pressure in order to deliver the amount of fuel required in the time available. These engines all have aftermarket ECU's to cope with the changes. The standard regulator can be adjusted to give increased pressure (from 3bar to 3.3bar for K series engines) and has proven sufficient in nearly all cases. This modification should only be performed by experienced people.