Repower

[Lazzlo]

Need to repower my70’s 14’ side console duranautic, It has evinrude 1974 25 hp. Are the new 25 hp motors too heavy and should I look at the 20 hp motors that weigh similar to the old 2 stroke? Thanks

 

[rocknroj]

That would be the safe way to go. Power is measured at the prop on newer outboards so you probably gonna be good. My 14ft starcraft scooted along just fine with a 20hp.

 

[LDUBS]

A 25 HP four stroke might run anywhere from 130# to 150#. How does that compare to the weight of your current Evinrude?

 

[Lazzlo]

New 25’s are going to be 150 lbs plus I think, going to look at 20’s. They should be around 110-115. Interesting to know about the power being at the prop. Thanks for the help

 

[airshot]

That much weight difference between a 20 and a 25 hp ? As a side console, you can shift some weight forward to balance out any difference. In reality a 20 up should do great with two adults on board.

 

[LDUBS]

New 25’s are going to be 150 lbs plus I think, going to look at 20’s. They should be around 110-115. Interesting to know about the power being at the prop. Thanks for the help

I think you are pretty close with the typical weight differences. Tohatsu makes pretty light four strokes. Difference between 20 & 25 is about 30#. I'm guessing a typical 25 four stroke is going to be about 50# heavier than your 25 two-stroke. The 20 will work fine. All things being equal, I would want the 25. The question I can't answer is if adding 50# is too much.

Seems manufacturers, at least some, put 20's at the top of the low range group and 25's at the bottom of the mid-range group. A 15 & 20 will weigh similar. A 25 & 30 will weigh similar.

 

[1pc@atime]

I've been though the same things a few times with my boats. In the end after thinking that the four stroke was the right answer I ended up going back to a two stroke.
I just rather would have the added power of the largest possible motor vs the weight of the four stroke.
If my motor was still a points equipped model though, I'd likely look for a newer two stroke for both the added hp of the power 1984 rated hp increases and the convenience of not having to deal with points that can get dirty, wet, or corroded with age.

I had tried several four strokes over the years and although weight was only part of the issue the lack of performance is what bothered me most.
Not to mention the inability to max out the boats recommended max hp limit.

For my old Grumman 14CSS it meant a 15hp max in a four stroke due to weight despite the boat being rated in 1987 for a 25hp.
On that boat, which had a side console, the seaing position was the sme on eiher a side console set up or the tiller motor as the driver still sat on the rear bench seat. The limit on HP was part of why I sold tha boat when I found my Starcaft which let me run a 35hp two stroke tiller motor.
I've tried many times to like the fours stroke motors but always end up coming back to the two stroke motors. There's just to much to be said for the simplicity and light weigh of a good two stroke.

 

[thill]

Some boats handle the extra weight well, some don't. Put a 50# bag of sand in the very back of the boat and see how it rides. That should correspond decently with an extra 30# hanging off the back.

In smaller engines, the 2 strokes aren't much louder than the 4 strokes, and they are strong performers and weigh less. What I do is scan craigslist and FB marketplace for a good deal in the fall or winter, and pick up an extra motor "just in case." I have always eventually found a good one for a great price. Clean the carbs, change the lower unit oil and make sure it's running well. Clean it up, wipe it down, drain the carbs, and hang it in a dry place, ready to go if ever needed.

Late 80's-90's are typically great motors for this and can be found for a good price. The 25 Evinrude in my Avatar was a powerhouse motor and never missed a beat. Started on the first pull every time. I think I paid $300 for it, if I recall. The fuel system was gunked up, but it was excellent after getting it cleaned out.

 

[Still Afloat]

That much weight difference between a 20 and a 25 hp ? As a side console, you can shift some weight forward to balance out any difference. In reality a 20 up should do great with two adults on board.

Modern 20s are typically the same powerhead as a 9.9. The 25 is a larger powerhead which is often common to the 30 hp models. There is probably some variation between manufacturers.

So the 20hp outboards have a great power to weight ratio.

 

[LDUBS]

Modern 20s are typically the same powerhead as a 9.9. The 25 is a larger powerhead which is often common to the 30 hp models. There is probably some variation between manufacturers.

So the 20hp outboards have a great power to weight ratio.

I'm not following the applicability of that concept. Provided the boat would handle it, isn't performance going to be better with the larger HP?

 

[LaqueRatt]

Wow, that 25HP is an EXCELLENT motor! I got one and love it. You're not upgrading you're downgrading. Freshen that puppy up, run it for the rest of your life, and give it to your grandkids.

 

[airshot]

Need to repower my70’s 14’ side console duranautic, It has evinrude 1974 25 hp. Are the new 25 hp motors too heavy and should I look at the 20 hp motors that weigh similar to the old 2 stroke? Thanks

Reason for depositing ?? If your two stroke is worn out then replace it, but if it still is in good condition, why not just a reconditioning to make it like new. Most 25 hp two strokes were runners...better performance than a four stroke with less weight. However....your money, your call.....

 

[Still Afloat]

I'm not following the applicability of that concept. Provided the boat would handle it, isn't performance going to be better with the larger HP?

Not if the 5 extra horsepower adds 50 pounds or so.

 

[OldSailor85]

I'm not following the applicability of that concept. Provided the boat would handle it, isn't performance going to be better with the larger HP?

He was speaking of power to weight ratio. Smaller powerhead with the 20 hp.

 

[LDUBS]

Not if the 5 extra horsepower adds 50 pounds or so.

I don't understand how that conclusion can be drawn without knowing about the entire setup.

He was speaking of power to weight ratio. Smaller powerhead with the 20 hp.

This I understand. I understand as weight goes up there is a diminishing return and eventually a negative impact. The HP/weight ratio is only going to be meaningful when the entire weight of the boat is included. Add the weight of the motor to a 250# boat, and even with the extra 50#, the HP/weight ratio will be higher with the 25. That is what has me scratching my head. I admit I could be all wet.

 

[OldSailor85]

I don't understand how that conclusion can be drawn without knowing about the entire setup.



This I understand. I understand as weight goes up there is a diminishing return and eventually a negative impact. The HP/weight ratio is only going to be meaningful when the entire weight of the boat is included. Add the weight of the motor to a 250# boat, and even with the extra 50#, the HP/weight ratio will be higher with the 25. That is what has me scratching my head. I admit I could be all wet.

Everything is relative.

 

[thill]

He is talking about the power to weight ratio for the MOTOR, not the whole rig.

On a boat that is maxxed out on weight, the lighter weight may be a big difference, but on other boats more HP is the way to go, despite the weight. Just depends, as you pointed out. I have the perfect experience to share about this...

I put a 25 Merc 4S on a boat that was rated for a 20 HP max. I figured it wouldn't make much difference. WRONG! Almost sunk the boat when I stepped in. Scared me!!! The 9-20 HP Merc sat perfectly and ran very strong. Lesson learned!

 

[Still Afloat]

Just guessing that a 20hp EFI is similar in weight to an older 25 two stroke.