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Author Topic:   2001 Conquest 28 Re-power
Blackbeard posted 10-09-2006 11:58 AM ET (US)   Profile for Blackbeard   Send Email to Blackbeard  
Planning a re-power of 2001 Conquest 28. Getting rid of Yamaha Saltwater 250's in favor of Yamaha four-stroke motors. F225s are slightly more fuel efficient but am I surrendering power I'll wish I had; should I go with F250's? Can I expect any trade value on the old Saltwaters (about 200 hours and like new)? Any recommendations of what to watch out for? Thanks in advance.
bluewaterpirate posted 10-09-2006 01:33 PM ET (US)     Profile for bluewaterpirate  Send Email to bluewaterpirate     
What's the max power rating of your Conquest. There is no difference of weight 225 -vs- 250. Go with the max hp your boat will handle. If cost is not an issue. Have you looked at the Zuke 250?

Good Luck!

TRAFFICLAWYER posted 10-09-2006 03:27 PM ET (US)     Profile for TRAFFICLAWYER    
I anticipate you'll shell out at least $15,000 to $17,000 or more for those F250's, that's gonna take a long time to break even on the fuel economy differential.
Blackbeard posted 10-10-2006 08:09 AM ET (US)     Profile for Blackbeard  Send Email to Blackbeard     
600-HP is the max rating. Have not looked at the [outboard motors made by Suzuki]. I've had a couple of Yamaha motors and have always had good results. Is there something about the [outboard motors made by Suzuki] I should look at? Fuel efficency on a cost basis alone would not be enough to justify the repower. With the two strokes, I can't make a (100 mile) canyon run without bladders, extra oil and some prayers I'll make the inlet with more than just fumes in the tanks. Thanks for the comments.
bluewaterpirate posted 10-10-2006 10:45 AM ET (US)     Profile for bluewaterpirate  Send Email to bluewaterpirate     
better torque, fuel efficency inline. Just another option. I have some friends who are running [outboard motors made by Suzuki with] 250-HP, and they can't say enough good things about them.
handn posted 10-12-2006 01:13 PM ET (US)     Profile for handn  Send Email to handn     
At 4,000-RPM I cruise at 23 knots with Yamaha 225 EFI four-strokes on a 305 Conquest and burn 19-GPH. You should do better wiith a lighter 28 Conquest. In most sea conditions, I could not comfortably run much faster. Trolling with one engine at 7.2 knots, I get two nautical miles to the gallon. I get a comfortable range of 320 nautical miles on a 300 gallon tank so the 225's should get you out to the canyon and back comfortably and not deafen you or rattle your fillings while doing it.
The EFI four-stroke motors are not as powerful as your 250 gas guzzlers, but are not slugs, either.
I highly recommend Revolution4 or other similar four-blade props. My Revolution4 propellers are 17 pitch and perform very well on the boat.
Peter posted 10-12-2006 01:28 PM ET (US)     Profile for Peter  Send Email to Peter     
On plane at cruise speeds, I don't think the F225 is significantly more efficient than the Ox66 250s. The F225 will likely need to rev about 500 RPM higher to maintain the same speed as the 250.

The reports of significant fuel savings of a four-stroke over an EFI 2-stroke like the Yamaha Ox66 250 in terms of percentages, like the often quoted 35 percent, is at idle. As you move up in the RPM band to the ideal cruising speeds, the gap narrows considerably. The gap will then widen at the upper end of the band near WOT where the Ox66 250 will guzzle about 27 GPH but of course it will be moving the boat much faster than the F225 would be at WOT. Pull throttle back on the Ox66 250 so that fuel consumption is around 21 GPH where the F225 is at WOT and you might be surprised to find that the 250 is making close to the same speed as the F225 is at WOT.

Take a look at my post of four years ago comparing the fuel economy of the Ox66 225 to the F225 on a Pursuit 2470 Walk Around. It's about 1/2 way down in this thread ==> . Basically the Ox66 design is inefficient by todays standards at low engine speeds but not so bad in the middle of the operating band according to the Pursuit test data. If the bulk of your running time is running out 100 miles, I'm not sure you'll see enough of a fuel economy improvement to extend your range significantly.

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