Direct injection vs port injection

[TCJBOLDIE]

Direct injection petrol motors seem to becoming more popular so is it more efficient in producing more power and lower fuel consumption than port injected motors ?

One downside is the DI motor over time will have a build up of carbon/gunk on the inlet tract and back of the valves that cannot be removed/reduced/prevented by the regular use of injector cleaners.

https://www.edmunds.com/autoobserver-archive/2011/06/direct-injection-fouls-some-early-adopters.html

The power loss is shown in the dyno charts.



A penny for your thoughts on this

 

[obi_waynne]

Direct injection allows much higher compression ratios, especially on turbo engines and you get a more efficient burn as well.

The carbon build up is a pain but is usually down to poorly designed EGR systems and dirty burn from low quality fuel. IMO exhaust gasses should never be pushed unfiltered into the intake.

A good BG clean will remove these deposits, I've done a couple now and the performance has been restored. Good quality fuel and avoiding short journeys makes a big difference.

 

[TCJBOLDIE]

Exhaust gasses entering the inlet tract cannot be eliminated due to the camshaft timing where the inlet valve is starting to open before TDC on the exhaust stroke.

The power loss due to the carboning up of the inlet tract is a bit like old age, it creeps up on you and gets progressively worse over time and many will be unaware as to what is happening and the proclaimed fuel efficient benefits of DI petrol motors will be reduced in high mileage vehicles.