HPDI vs EFI

[naturewaterboy]

HPDI or EFI? What are the relative fuel efficiencies? Which one last longer without major maintenance?

[Willallison]

The direct injenction 2-strokes are generally on a par with most 4-strokes in terms of fuel economy, so are significantly more economical than EFI's.
The jury is still out probably as far as longevity is concerned - only time will tell. But the Dfi's are certainly more complex, so there's a lot more that can go wrong...

[naturewaterboy]

they are significantly more economical? Anyone have any specific fuel consumption numbers? Also, I see that Yamaha no longer sells EFI's in big engines at least, only HPDI - wonder why that is. Are the HPDI's meeting the strictest emissions standards?