Port fuel injection and direct injection are similar but distinct systems, so why do some engine designs include both?

The basic difference between direct injection (DI) and the port-fuel injection (PFI) systems we've become familiar with since the mid-1980s is that PFI sprays fuel into the intake manifold (behind ...

Direct-injection spark-ignition (DISI) engines have been investigated for many years but only recently have shown promise as a next generation gasoline engine technology. Much of this new enthusiasm ...