Re powering 200hp - 150hp??

[GradyBoy]

I currently have a 1990 200 hp Yamaha outboard on a 20 ft. Overnighter. Max speed has been 43 mph. I have noticed that many people re power this boat with a 150 hp. I hate to lose hp! Has anyone gone from a 200 to a 150? I was told I would get the same power with a 150 hp with a new engine. Is this true?

 

[seasick]

Generally, no. In addition, if the 200 is a 2 stroke and the 150 is 4 stroke, there will be a bigger difference than just the HP loss

 

[GradyBoy]

Generally, no. In addition, if the 200 is a 2 stroke and the 150 is 4 stroke, there will be a bigger difference than just the HP loss

It is a 2 stroke

 

[seasick]

So, question is between 150 2 stroke and 200 2 stroke..
Assuming the 200 is running well, and assuming the 150 is too, you will notice the difference. If the boat doesn't have a hard top. you will really notice a difference. I don't have any idea why someone would say the 150 would perform better unless 1. the 200 has issues that are obvious, or 2. the person has a 150 to sell you

 

[Doc Stressor]

The old 150 and 200 hp V6 2-strokes with the same displacement have almost identical torque curves until you get to the top end of the rpm range. So there is little difference in hole shot or the ability to stay on plane. You will lose a few mph of top speed if you go down to a 150 hp.

I've been on overnighters with both engines (Yamahas) and I can personally attest to this. The 200 had a 19" prop and the 150 swung a 17". Seat of the pants felt like the 150 actually did better at lower cruising speeds as far as staying on plane in a chop. That was probably due to the prop though.

Now if you are comparing an old 200 to a new 150 E-Tec you can ignore my comments.

 

[Fishtales]

If you can swing a 200HP, you should do it. I think most 4S are sub performers to a solid running 2S. 50 ponies less will be noticed. On the other hand, if speed and hole performance are not a huge deal, you may be able to keep more jing in your pocket.

 

[Lt.Mike]

The old 150 and 200 hp V6 2-strokes with the same displacement have almost identical torque curves until you get to the top end of the rpm range. So there is little difference in hole shot or the ability to stay on plane. You will lose a few mph of top speed if you go down to a 150 hp.

I've been on overnighters with both engines (Yamahas) and I can personally attest to this. The 200 had a 19" prop and the 150 swung a 17". Seat of the pants felt like the 150 actually did better at lower cruising speeds as far as staying on plane in a chop. That was probably due to the prop though.

Now if you are comparing an old 200 to a new 150 E-Tec you can ignore my comments.

May be something to what your saying about prop pitch. I have a 225 2 smoke which has a 20 pitch prop. I spun the hub once and while it was getting repaired I used my spare 18p prop. Both are Suzuki stainless props and I did notice the 18p did perform well in choppy water. I just was careful to watch the rpms so that I didn’t over rev the engine and didn’t run wot, though that’s not a problem in rough water as conditions keep speed down.
I personally wouldn’t repower an Overnighter with less than a 200 though. Said it a lot but the hot ticket seems to be the Yamaha 4 stroke, 4 cylinder F200 with a 19p prop. When my 225 gives up that’s the planned replacement.

 

[Doc Stressor]

My old '75 Overnighter came with a 135 hp Johnson. It ran a 15" prop and would cruise at 27 mph with a 35 mph top end. It could handle 3 people, but you really noticed the decrease in performance when I had 4 people on board. After that engine wore out, I repowered with a 140 Evinrude. I mounted it higher and used a 17" prop. I was never satisfied with the performance. They had re-tuned the engine to the top end in order to squeeze out the extra 5 hp. It would top out at 37 mph with just me on board, but it would dog out at cruising speeds with extra people. The pre-SV2 hull doesn't need as much power at the newer models.

I was amazed when I went diving with a guy that had the same hull with a 150 hp Johnson. It stayed firmly on plane at around 27 mph with 3 people and dive gear on board. But did that thing ever burn fuel! We went through 35 gallons on a trip that was not much more than 2 hr.

I agree that 200 hp is the best choice for even the older hull design. But 150 will do the job.