Re: Fuel consumption diff: Yam 250 ox66 v 200 HPDI?
I just removed a set of 225 OX66s from my 25 Contender. Those engines are the same block and almost identical to the 250s. I repowered with 200HPDIs. Here are some examples: 4000 rpms used to be 26-29 gph, now it's 17-19 GPH. 3300rpms used to be 18-20 gph, now it's 12-14 gph. Those are fuel burn #s for twin engines, off the same Yam Fuel Managment gauge using the same exact props. Speed actually went up a mph(or two) at the same rpms. The lower unit on the HPDI 200 is much smaller and displaces less so it's more efficient. Much quieter engines, much smoother engines and a little lighter engines. I think the OX66s are 538lbs and the HPDIs are 475. I lost about 3 mph off WOT, I think. I really havn't tested WOT except once with a ton of scuba gear and three guys aboard I got 52 mph. I have seen 56 with the 225s and no load. I figure I can probably stretch 54 out of it with the 200s with no load, but who cares. My situation was a settup for a super improvment since the 225s were major overkill. If you buddies boat only needs 200hp to run correct then he should see major improvments also. The 250 will definatly shine if the load is enough to require a 250. Overloading a 200 will not see near the improvment I saw. I even could use the same props. If your buddies engine is only making 5200rpms or less right now you will need to go to a 19 prop with the 200 and then you might not be so happy as the 250 with a 21. It all depends on everything!