Here's a very interesting wee video which dramatically illustrates the "washing" action of fuel on the inlet valve when the injector is, as here, mounted in the inlet manifold. It probably makes quite a good argument for the increased efficiency of direct injection too as you can see there is obviously liquid fuel burning off the surfaces around the inlet valve seat which a direct injection system would not suffer with. On the whole I think I'd rather suffer that and keep the back of my valves clean even if I'm not getting quite such good MPG and causing slightly more pollution? To say nothing of the claimed increase in particulate emissions of DI petrol engines?
https://www.youtube.com/watch?v=UvmBLqjaZxY
https://www.youtube.com/watch?v=UvmBLqjaZxY
Last edited: