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Best outboard 90hp

noe173

New member
"hi there
i need help in choo


"hi there
i need help in choosing the correct outboard to upgrade my nissan 40hp outboard to 90hp, as too small for my 15feet RASCALI (OP15) boat.

Any help? 2 stroke (Di) or 4stroke?
4 stroke a bit heavy... so guess better 2 stroke?
or then not very economical? ..when at low revs (fishing) and high revs (fun)????

what about servicing issue? 2 stroke more expensive then 4 stroke?


The oil need for 2 stoke engine more expensive
or normal tcw3?

best brands i can get for 90hp?..even thought the max rate for my boat is 75hp..but for the same weight i get a 90hp..better somme extra power in hands?

thanks for your help"
 
"The direct injected 2 strokes

"The direct injected 2 strokes are anywhere from a little lighter to alot lighter than their 4 stroke counterparts, and depending on the mfg can be considerably cheaper to buy.

The DFI's will kick the snot of any 4 stroke in any comparison you want to do.

They are just as quiet, get better fuel economy, the maintenance is 100 times less etc etc.

If you like your Nissan (built by Tohatsu), then Tohatsu's DFI 90 is a great motor and probably the most economical of all the DI 2 strokes, otherwise your choices would be a Merc, Yami or Evinrude (and personally that would be my order of preference).

Both the Tohatsu's and Merc's use a low pressure fuel system, the Yami's/Ev's use a high pressure (which just seems like it would be more likely to have issues in the longer term).

But if you like spending money on maintenance, want less torque etc you can always go with a 4 stroke..."
 
"thanks graham for your reply.

"thanks graham for your reply..

another thing, is it true that the tohatsu have to be programmed by laptop but local dealer when installed or just "plug & play"?

I was reading the review of Tohatsu..sounds a good outboard out of the bunch..but didnt understand the 3 setting in motor revs by key?? can anyone explain please? Is this outboard good for SALT WATER???

What is the oil used by outboard?normal TCW3 or someother expensive oil?

Anyone using Tohatsu TLDI 90 out there had any problem with it?

thanks"
 
"YES - Tohatsu has a company p

"YES - Tohatsu has a company policy of not selling any motor over 40 horse (I think it's 40) directly to the customer for "self installation". The dealer has to rig it and fire it up the first time for you - but I am not aware of all what is involved in the entire process. It will cost you an extra 250 bucks or so for this service.

The 3 settings are advertised as "trolling speed options". Through the key switch, while the motor is at "idle" you can select either 700, 800 or 900 rpms to allow you a little wiggle room to get your preferred trolling speed.

Any outboard is good in salt water as long as you are vigalent about flushing them after each use. Even models desinged as "salt water" versions will corrode if not flushed. A salt water edition/model will specifically have a few more stainless steel components than a "normal" motor, but with care both will work fine in salt.

Any injected motor whether EFI 2 stroke or the new DFI 2 strokes should at minimum use semi-sythetic oil. The injectors in these do not like regular "dinosaur oil". It is still TCW3, but will be listed for "injected motors".

However, in the case of the DFI's they use very very little oil. Their mix ratio (computer controlled of course) is upwards of 300-600:1 at lower speeds so 6 to 8 times more "oil efficient" than your old 2 strokes. So yes, oil is more expensive, but you use way less - flip the coin


The DFI Tohatsu's are still a relatively rare outboard if you hang out at boat launches, but have never heard anything bad about them. Tohatsu is in bed with Mercury in both production and R&D so their product is right up there with one of the big North American players.

Besides, every Nissan out there is a Tohatsu and so is every 4 stroke Merc below 40 horses - just painted up with someone else's decals - says something about Tohatsu quality....

Personally, if I was looking for a NEW outboard under 100 horse, would definately be a Tohatsu DFI and over 100, has to be a Merc Opti...

If you are looking for a more informed opionion, ask "Tohatsu Guru" in the Tohatsu forum. He gave me quite a bit of insight to these motors as well. I seriously considered one for a build I was working on and after doing my own homework he filled in anything the dealers leave out - but all in all, no complaints or major/intrinsic problems with these motors. Like anything, take care of it and it lasts....

(sorry got a little long there)
"
 
"For what it is worth. In the

"For what it is worth. In the 70's I researched OB's from merc and I also contacted their service staff in New Brunswick NJ. Interesting find was that, at that time, due to weight factor the performance of a 90HP, 4cyl, 2-stroke was near conparable to the 115HP, 6 cyl, 2-stroke. The 115 ran smoother and a bit quieter, but not needed for the price difference. I dont have the phone numbers anymore but I not only contacted them at NJ but also the high performance division in Michigan. Service Techs and Engineers are very willing to help you know these type of facts."
 
"Yes, the performance differen

"Yes, the performance difference in motors that close in horsepower is almost undetectable unless you lie to yourself.

Guys will often try to squeeze a few more horsepower out of their motors. They have a 90 and want to make it a 115 etc.

The difference in on boat performance between a 90 and 115 might be 2 mph on a perfectly calm day with a light load, yet they are willing to replace multiple carbs at hundreds of bucks a piece to try and achieve that.

You should fit your boat with the lightest motor available at a horsepower that will not leave you disappointed in the performance.

Rule of thumb - horsepower should be 80% of the max rating for your boat. Many "package deals" will include the smallest motor you can get away with, leading to terrible disappointment at the underperformance.

Spend your money up front for something you will be happy with - trying to "hop it up" later will cost triple what it would to simply have bought the right motor in the first place.

And definately keep the weight in mind. A 300 pound 90 horse is going to run your boat better than a 450 pound 115.

Boat mfg's of fish/ski models lowered the horsepower rating on alot of there models over the past couple of years. I queried Lund as to why their 17 footer (05 model) had a rating of 150 horses and the 06 only 115. The answer they gave was because a 115 4 stroke weighed more than an older 150 2 stroke. The boat could handle the horsepower but not the extra weight hangin' off the back, so it was either redesign the hull or lower the rating (obviously lowering the rating only required a change in the printing of the little plate)
"
 
"thanks for you reply..

my


"thanks for you reply..

my problem is not regarding outboard EXTRA weight. This is because both 75HP and the 90HP have the same weight.So although the MAX outboard tested & so recommeded on the RASCALA FM16 (16feet) is 75HP (and minimum is 60hp)..i was thinking that when loaded or need soome extra power, the boat will trim better at lower revs and so loxer consumption..

what you think mates?

another thing.. i know very little about is the propeller..Does it makes a difference (in power or performance) which one you have? the normal one or Stainless steel one.. With evinrude, stainless steel propellers are standard!!so SS props are better? why? or which the best to fit of so to my boat (RASCALA FM16)

thanks"
 
"Keep in mind my point was the

"Keep in mind my point was the comparison of a 90HP 4cyl; vs a 115HP 6 cyl.; so there was a weight difference. Unfortunately the HP difference made up for the weight. Conclusion, performance would basically be the same.

Basic prop information is this. SS is good cause there is no deflection of blades. Keep in mind if you hit something, your chances are greater for damage to the lower unit even though you have a slip hub. Aluminum props have improved and are safer particularly if you are boating with rocky or hard bottom or likelyhood of debris in the water. Simply said, an alum prop is easier to repair than SS or the lower unit housing. If you are concerned about power to get up and plane, and then are looking for speed., consider a prop tuned with slightly lower pitch for torque and then cupped to give you the speed back once on plane. Another thing is to limit, as best possible, the amount of weight you have on the transom. Eample: 100# on the transom will require more HP to plane than if you have 100# mid-ship.
lol.gif
HAPPY BOATING!"
 
"thanks for the reply

so i


"thanks for the reply

so i guess if both have have weight 75hp and 90hp, the 90hp might be a bit overpowered for my 16 feet boat?... so the extra power is not lost with the extra motor weight..and both engines have same weight and cc.

Still dont know how if engine have same weight & cc produce different power (hp).. maybe the 75hp will have more torque??

thanks"
 
"Noel, the "on boat" p

"Noel, the "on boat" performance difference between the 75 and the 90 (in models that share the same powerhead) is minimal at best.

The 90 produces 20% more horsepower at it absolute top end. That is not really that significant in translating to "more speed" or "more umph" from the motor. A jump of 50% or 100% would be noticable.

You can take any given motor out there and with a decent tune up and a correction to the prop on it you will easily gain 10-15% more horsepower.

Here's some numbers comparing Merc's 75/90 horse normally aspirated 71 cu in powerhead, 3 cylinder models. The 90 is still in production (at least until next year). This is specific to Merc but the pricipal (and the math) applies to any model/mfg.


The 75 horse (75 shaft horsepower) is producing:

77 ft pounds of torque at the brake (crankshaft)
at 5250 rpms (max wot for the 75).

geared with 2.3:1 lower unit gears, that produces
75 shaft horsepower with a propeller rpm of 2283 which equates to 172 foot pounds of torque at the prop.

The 90 horse, given the all the same above, except that max wot is 5500 rpms

produces 89 foot pounds of torque at brake, 90 shaft horsepower, turning the prop at 2391 rpms which translates into 198 foot pounds of torque at the prop (or a difference of 26 foot pounds, or 15% more torque) at wide open throttle.

On your boat will you NOT LIKELY notice the difference between 172 and 198 foot pounds of torque at the prop. You can measure it on your gps in the form of maybe 2 more mph.

So is that worth exceeding the boats recommended horsepower? not in my opinion if for no other reason, should an accident occur and you are found to be "over horsed" you could be on the hook for alot..."
 
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