Re powering my Monaro 24 with a 300 hp outboard. What 300 to use

[Tater]

I have a 1991 Monaro 24 was converted by Monaro to an outboard. Currently running a Honda bf250 that’s getting a 27-30 mph cruise speed at 4200-4400 rpm and burning right around 8.5-9 gph and able to top out around 46mph at 6000-6100 rpm. I’d like to upgrade to a 300 hp and can’t decide between a Yamaha Suzuki or Mercury. The Merc sounds amazing on paper but haven’t heard much about it as far as issues or reliability. Hard to go wrong with Yamaha or Suzuki other than they require 89 octane and down here in Washington our marinas only typically have 87 octane. Any one have any suggestions or first hand experience with these motors or these motors on this boat? I won’t be doing the re power until this winter so I have time to make this decision.

Thanks
Chris

 

[Pineapple Express]

I'd suggest to consider proximity to a good dealer for servicing or warranty work (knock on wood).

 

[Tater]

We have all three brands dealers near by with competent shops.

 

[ab1752]

Did you check out the new yamaha 4.3l 350 or the Honda 350 v8?

 

[Pineapple Express]

Did you check out the new yamaha 4.3l 350 or the Honda 350 v8?

I think this is the right path if you're finding a 250 too weak. The 300s are basically the same as 250s with slightly different tuning.

350hp...now you're talking!

 

[macro]

Get the one that makes the most torque at the lowest rpm. Should translate to abulity to stay on plane at lower rpm and better economy. Guessing that's the one with the largest displacement... probably the merc... but no first hand info. Have a supercharged 350 now. Runs super smooth, but needs premium. Not the most fuel efficient

 

[macro]

I would not chose based on transom weight as that's easily changed by going to lithium batteries

 

[Maxpri]

If you were happy with the 250 then you’ll probably be happy with the 300, but I would go 350 all day. Mine has a 300 etec which compares to the Merc 400, in tests, I wouldn’t want any less power.

 

[Pineapple Express]

For the 350s

Yamaha is 650lbs for 25in shaft

Honda is 765lbs for 25in shaft

Mercury has the 350hp V10 which is 695lbs for 25in (same motor as the V10 400)

 

[Rain City]

I would think that fly-by-wire controls and all that stuff would come into the conversation as well. Maybe a second helm at the stern will be nice and simple with one option vs. another

 

[Pineapple Express]

Just wondering...the factory Monaro conversion to outboard. Do you have one of those old school Monaro engine brackets made from pipe? I'd call them to check the weight/power rating for the bracket.

https://www.monaromarine.com/images/gallery/images/bracket%20pod.jpg

 

[Tater]

I have the more modern conversion not the tube one. And I don’t have an opinion on controls fly by wire vs cables. I’ve only ever had cables. What kind of performance are you getting with that 300 etec?

 

[Tater]

I was under the impression that the 24 Monaro was only rated for a 300hp max. And seeing how my Honda 250 was a 3.5l or 3.6l v6, that if I went with a 300 which are 4l or larger should get better performance with the increased torque from a larger displacement engine. Hopefully increasing my cruising speeds some and lowering my rpms by being able to turn a higher pitch prop. Let me know if this assumption is correct or not. Also the 300 hp motors I believe are all lighter than my Honda is, other than the Suzuki duo prop. Not sure if there’s enough of a weight difference to really matter or not. As far as cable vs fly by wire is there a real big difference as far as operating goes? I have no current plans for main motor controls at the stern. Any one have issues with fly by wire systems?

 

[macro]

The merc DTS system is smooth, and easy to add a second station.. Just plugs in vs mechanical, but you pay for it !

 

[kaelc]

Merc 4.6L has the largest displacement. I would really want clarity on Mercs snapping off the transom before buying one, or recommending them, might just be a YouTubers rants but….

Otherwise Suzuki 300 duoprop would be my choice with the 4.4L block.

 

[Maxpri]

I have the more modern conversion not the tube one. And I don’t have an opinion on controls fly by wire vs cables. I’ve only ever had cables. What kind of performance are you getting with that 300 etec?

I cruise at about 35 mph, 4900 rpm fully loaded, with 4 people, burning about 50 lph.

 

[JohnS]

I hope you are upgrading because you want a newer motor, not better performance.. those are pretty good numbers already...

 

[Tater]

Not specifically for better performance but if I could pick up a few mph at cruise that would be nice. The Honda I have is a 2016 with 800 hours and I’m starting to get random parts failing. And I’m just trying to upgrade to a newer hopefully more reliable motor with like I said the possibility of a slightly higher cruise. And id really like to not have to run 89 octane if possible since down here in Washington our marinas have 87 octane.

 

[pacemaker]

Not specifically for better performance but if I could pick up a few mph at cruise that would be nice. The Honda I have is a 2016 with 800 hours and I’m starting to get random parts failing. And I’m just trying to upgrade to a newer hopefully more reliable motor with like I said the possibility of a slightly higher cruise. And id really like to not have to run 89 octane if possible since down here in Washington our marinas have 87 octane.

I’ve got a 2006 Monaro 24 EXL which was ordered with a factory pod from Monaro right out of the box…. One of the very original factory podded versions….It originally came with a 250 HP Zuki. It worked very well and performed equally well. I had to repower it last summer and easily chose to put another 250 Zuki on it again. Full loaded, it jumps right up out of the hole, cruises all day at 4000 RPM @ 30 mph, burning just 30 litres per hour. That’s pretty affordable running for a boat that size. I have no idea what the max speed would be, and have no desire to find out, as things show up really quickly on the water when least expected. JMHO…..Send me a PM if you want……

 

[salmonkiller01]

Mercury 100%. Dts, quiet and are solid engines. Easy servicing also.
APM in alberni is the biggest dealer in Canada.