75hp or 90hp

[Escapeskiing]

Does anybody know if there is a noticeable difference in pull out power between a 75hp and 90hp outboard. I have a 5m rib that is definitely under powered with a Evinrude Etec 50hp?

[two stroke mick]

I would expect that a five meter rib would have sufficient power at fifty hp especially with an etec as they have plenty of grunt. What type of rib have you and what do you do with it?

[jakajuka]

I also have a 5m rib with Yamaha 50 4 stroke which is evident underpowered.
The boat have the possibility to install 100 hp max and I am thinking about 75 or 90 etec.

[Escapeskiing]

I need to be able to pull up a mono skier. The prop on the Evinrude is ridiculously big - about 21 but even so, it strugled even pulling up a wakeboarder. The rib is a Jets Marivent which I haven't heard of before but seems to be great. I have been told that sometimes a 75hp has just as much pull out grunt as a 90 so not sure. Don't know if 4 stroke may have better low end even though heavier?

[two stroke mick]

I suspect you have a problem with the pitch of the prop rather than the size of the engine. My rib 4.9m cannot achieve WOT with a 13 by 21 ali prop. I can use either a 13*17 or a 13*19 prop. I tend to use the 13/17 as it gives acceleration and watch out for over revving of the engine. However You may find you are causing the engine to lug using a 13.25 by 21 prop. This is very bad for the engine and will cause mechanical failure of an expensive kind.

Before you change engine change the prop and then check the engine height. I would probably go for a 13*17 prop from steel developments.

TSM

[Escapeskiing]

Believe or not, i have just found a stainlees steel 13*17 prop in my store room full of boat jumble so will see if fits.
Thanks for the advice.

Chris

[two stroke mick]

Revert with the results
Tsm

[matt h]

a 5 m with a 50 will be pants really, 90 -100 ideally i would say

[beamishken]

A 5m with a 50 isn't going to set the world on fire but should pull a skier you'll only be looking for 25-27mph ish?
The 21"prop is probably your problem dropping to a 17 should help you. Engine should be able to get max rated rpm at wot with relatively light load. IE if rpm range is 5500-6000rpm aim it get 6000rpm or just over at wot fully trimmed.
Don't worry about over revving, the engine will have a rev limiter to prevent damage far better to be under propped slightly if your pulling a skier than overproped and risking engine damage

[spartacus]

Originally Posted by Escapeskiing

Believe or not, i have just found a stainlees steel 13*17 prop in my store room full of boat jumble so will see if fits.

And the award for the best stocked store room (of expensive shiny things) goes to...

[Escapeskiing]

Turns out my prop is same size as one already on - amazingly a 13 x 17.
Do anyone know of a 75 or 90 outboard for sale?

[beamishken]

You should still be able to get better performance by 're propping the engine maybe a 15 or 13 would help

[69cmw]

Originally Posted by Escapeskiing

Turns out my prop is same size as one already on - amazingly a 13 x 17.

Do anyone know of a 75 or 90 outboard for sale?

PM Sent

[davej]

On my 5 m tornado with a merc 60 I use a 13 inch pitch prop as a general run around and if I am going cruising and know I have light loads than I can use my 14 inch one.

The 13 allows it to reach 5500 and spin up easily. I think the prop is the answer.

[Escapeskiing]

Originally Posted by davej

On my 5 m tornado with a merc 60 I use a 13 inch pitch prop as a general run around and if I am going cruising and know I have light loads than I can use my 14 inch one.

The 13 allows it to reach 5500 and spin up easily. I think the prop is the answer.

Thanks Dave. Yes I suspect my prop doesn't help. Iam still on the lookout for a bigger engine if anyone knows of one?

Cheers

[smee]

I have a flatacraft 5m rib with a 2004 75hp evinrude etec running a 17 pitch and it is pretty mental, very responsive and will rev out at 37-40mph, i want to try a 19 or 21 pitch. Although, to be honest, i think thats fast enough for me. it starts planing around 12mph and purrs along at 20-30mph.
I had a yamaha 55 on the back previously which was still very capable. Only changed it because it had no electric tilt and trim.
I would be very surprised if your 50hp etec. was not man enough.(not sure what your hull shape is like) and would think it will be fine with the reduced pitch prop.
All i need to do now is find someone with an old 21 pitch lying around in their store room i could try/buy. ;-)

[smee]

Doh...sorry,just read your earlier posts again, you've got 2 props the same....no 21 pitch...damn!

[Pikey Dave]

The 75hp Etec has a reputation for being a "strong" engine & punching above its weight. The 90hp is the opposite, a tad weedy & not significantly more powerful than the 75. They are the same engine apart from the mapping in the ecu.

[Escapeskiing]

Originally Posted by Pikey Dave

The 75hp Etec has a reputation for being a "strong" engine & punching above its weight. The 90hp is the opposite, a tad weedy & not significantly more powerful than the 75. They are the same engine apart from the mapping in the ecu.

Thanks Dave. I have heard that too.

[jeepster]

A four stroke outboard is not necessarily heavier than an equivalent two stroke...My 3 cylinder Suzuki DF50 four stroke is actually lighter than a two cylinder 50hp Etec! (101kg vs 109kg). And although the Suzuki DF70 weighs 10kg more than an Evinrude 75 Etec, you have to bear in mind that the DF70 is a much smoother four cylinder engine, vs the coarser 3 cylinder 2 stroke Evinrude.