Yamaha HPDI vs Evinrude Ficht

[jim dozier]

Having recently read and learned interesting stuff about the Ficht process I wonder what is the difference between the OMC Ficht and the Yamaha HPDI? Anybody know?

 

[RJS]

Re: Yamaha HPDI vs Evinrude Ficht

Of all the DFI systems, the Ficht is the least complicated and potentially may be the best system. For high HP applications, 2 strokes inherently have advantages. I think Bombardier recognizes this. The problem with OMC was the same problem with the US automobile industry in the 70's and 80's. Crappy, poor quality products. Bomabardier's first step was to improve quality. From what I've read, they've done a good job in getting the parts in spec and providing a good product.

 

[Forktail]

Re: Yamaha HPDI vs Evinrude Ficht

Both use basically the same principle. Fuel is injected under high pressure directly into the cylinder above the piston, after the exhaust transfer port is closed or blocked off by the piston. This results in better fuel/air atomization and minimizes fuel scavaging (unburned fuel exiting the exhaust port). <br /><br />The main difference between the two is the pressure and rate at which the fuel is injected. And both use similar, yet somewhat different (if that makes sense) methods of controlling ignition charge and ignition timing.<br /><br />The Ficht injects fuel about 150 times per second at up to 400 psi into the cylinder. Yamaha's HPDI injects fuel up to 1000 psi.<br /><br />Ficht "least complicated and best"? That's a matter of opinion. Obviously Yamaha's HPDI hasn't been plagued with the problems that the Ficht has. Updates to the Ficht problems are recent and not necessarily proven over time. The jury is still out on both. At this time, neither the Ficht's nor the HPDI's seem to be going 3000-5000 trouble-free hours on the water like traditional carbed or EFI 2-strokes, or the carbed and EFI 4-strokes commonly do.<br /><br />One inherent problem with high pressure injection in 2-strokes is cylinder temperature. 2-strokes have high cylinder temperatures to begin with because they fire every revolution and can not get rid of all the heated (fired/burned) fuel in the cylinder. The high fuel pressures and more complete atomization of the fuel now introduced by the direct injection cause even higher cylinder temperatures. I think you'll find more piston failures on the direct injection 2-strokes. JMO