looking to repower 25or30

[FishNHard]

Howdy all, So I have a 16ft Duranautic with a 25hp etec I bought new back in 2011 , nothing but issues since new ,so this year I don't want to spend another $600 on a VST pump which will make 7 . The specs on the etec is 575cc im looking at the Yamaha f25 and not only it looks tiny but its only 432cc, , So when Im in the boat only I get about 25mph with 4 people about 16mph with the Yamaha would the 25 be a bit less on the power since its only 432cc or should I go up to the 3cycl F30 . not really sure how you would compare the 4stroke power on the Yamaha to the 2 stroke of the etec, Thanks John

 

[nccatfisher]

Go with the 30, for several reasons.

 

[wmk0002]

Whats the boat rated for? A 4 man load is pretty big for a 16 ft boat, so if that is common load you definitely need to put on the max hp and prop it accordingly.

 

[turbotodd]

If you were comparing a truck with a 4.8 to one that's a 6.2, guess what? The 6.2 has more horsepower. Outboards are rated by their horsepower, which means if one motor has 25hp and another one has 25hp, they have....the same horsepower. What is horsepower? It is a calculation of torque and RPM. This means that if torque is higher, HP is going to be higher too because the constant doesn't change. Thus, with small outboards, the displacement only means that the larger displacement engine is going to use more fuel at the same horsepower, and they still make---the same horsepower.

Thus, a 25hp ETEC, although a much larger (and heavier) engine is still just 25hp, while the 423cc Yamaha is also 25hp, and because of that they both make 25hp regardless of the engine displacement.

Since I'm in the business, I listen to all of the arguements, and this one comes up often. Look at vehicles, as an example. A Ford pickup with a little bitty 3.5L V6 makes MORE power (and torque) than a MUCH larger engine. Think on that a while. 3.5L V6 makes 450 horsepower in the Raptor. Wasn't that long ago that a 454 and 460-which are both a LOT larger (obviously) didn't make half that much power. Yamaha did lots of homework on their 432cc outboard. They were able to make tweaks internally so that it makes the same power and torque as the rest of the 25hp motors. I have both a 3 cylinder 2 stroke 25hp yamaha, and a 2018 yamaha 25hp, and there is not a huge difference in power. Where the 3 cylinder gets it's "reputation" is when guys start modding them with bigger carbs lighter flywheels shaved heads exhaust and tuner mods, etc. THEN-it wakes up. They'll make 80hp or more if you spend enough money on them. That 432cc 4 stroke, there aren't any mods available for it that I know of, and quite frankly in my case I don't care because it's such a sweet little reliable motor.

In your case, if you are loading it with 4 guys and gear, and you have a 40hp rating, go with the F40. The F30 and F40 are the same motor but the 30 is detuned by 10hp. That means that the F30 weighs 215 lbs (lightest version). The down side is that if you have a short transom, you have no choice because Yamaha doesn't make a F40 in short shaft in the USA. I hate the way they do that. I want one for my war eagle but can't find one so if I want a 40 that bad, I've got to send the boat back to the factory and have them build the transom up to 21" which ain't happening.

 

[FishNHard]

turbotodd, many thanks for an informative reply, 95% of the time its only me and or my buddy only once in a while out wives go with us , what kind of thru me off between the etec and Yamaha was the CC difference but as you said 25hp is 25hp not matter how its produced . So the dealer has 2020 f25 electric/rope start power trim/tilt 5yr warranty $4012.00 he also has a brand new 2013 f30 electric/rope start no power trim and tilt for $4000 plus price of prop with the 5yr warranty , I have the power trim and tilt on my etec and it is nice but the yam 30 seems like a deal whats your guy thoughts on that .

 

[Weldorthemagnificent]

Having power trim would be hugely helpful if you run your boat at different load levels. For instance if sometimes there are 4 of you and sometimes just 2.
However, I run a 16' vee and use an old Johnson 35 (1983 so probably 30 hp at the prop) and that extra 5 HP sure is nice. Would be nice to have your cake and eat it too. Gotta wonder why he has a 7 year old brand new motor? Maybe a little more wiggle room on that price?

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[LDUBS]

I agree with what Weldor says about the PT&T. I'm spoiled by my power trim. I would have a hard time doing without it. But it looks like you have it with the current ETEC, so you know what you would be giving up.

 

[FishNHard]

Yea it is nice to adjust on the fly, your are right it would be hard to go without since im use to it .they want $6500 for a yama F30 with PT&T sucks I have never ending problems with the etec , when its running its a great motor ,

 

[Weldorthemagnificent]

Probably add aftermarket power trim for under a grand. What's the weight difference between the 25 and 30?

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[FishNHard]

With the power trim and tilt on both its an 80lb difference

 

[Weldorthemagnificent]

Yeesh, it's like having an extra kid in the boat. I wonder if the only difference between the 30 and 40 is the ECU. I bet turbotodd knows.

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[turbotodd]

Weight of a 25hp yamaha is currently 125-140 lbs depending on options (PT&T, long shaft, electric start, etc). Mine is 131. Short shaft tiller manual tilt electric start.

Weight of a 30/40 is going to be at the minimum 215 lbs, so figure 90 lbs heavier. More with PT&T and long shaft, etc. I think the heaviest model is 234 lbs but don't quote me on that. Most of the rigs that I put 40's on are actually 40/30 jets now and those guys aren't that concerned with weight. Their main concern is reliability and running shallow, safely.

The difference between the 30 and 40 is the ECU and air intake silencer assembly. There might be other less obvious differences that they don't tell me about but to my knowledge that is the only thing keeping a 30 from making 40hp. BTW, a 40 jet (F40J) ECU is different than a 40 prop, swapping them back & forth WILL cause idle and part throttle issues, so if you pick up a 30 don't go buying a F40J ECU off of ebay and expect it to run properly. They are mapped differently because of the jet's continual loading on the engine where the prop motor's loading is different from 0 to about 1/2 throttle. Also the jet ECU will not "read" the gear position switch, because it's always "in gear". All the gear position switch does it tell the key when to throw power to the starter.