90 HP Outboard (2-stroke or 4)

[Lease]

What is the deal with advertised horsepower? I noted when researching that some OEMs advertise the HP rating (of course in the modern world it should be Kw) at the prop, and others at the propshaft (don't know if any still advertise the power rating at the flywheel).

That makes a difference and leads to the question (can it actually be answered) 'what is the lightest genuine 50hp motor with the lowest fuel consumption?'

Clearly there are some engines that have better credentials (such as the bigfoot with its higher torque) for different applications, but what is the lightest and fastest?

Any takers?

[Robert]

Lease,
I will vote for the Suzuki DF50 as the best power and economy for a 50hp outboard available today. The DF50 has tuned intake manifold and four valves per cylinder operated by DOHCs for excellent free breathing. The DF50 has direct ignition with an ignition coil over each spark plug for timely and powerful sparks. The DF50 loves to rev up and remains smooth all the way. My Suzuki dealer and the regioanl rep told me the DF50 would be happy to run 7000 RPM all day every day without problems. Hp is proportional to RPMs and I propped my Mac26X to run up to 6800 RPM without ballast so that it could be 6400 RPM with ballast for maximum power and smoothness taking advantage of the DF50's ability to rev up smoothly. The DF50 is IMHO also the quietest 50hp outboard.
..
http://www.suzukimarine.com/sr06/df5040/
http://www.suzukimarine.com/brochures/i ... 040bro.pdf
http://www.suzukimarine.com/sr06/df5040/advantages.php
..
I will however concede that the bigfoot or high thrust 50hp outboards with their larger 14" prop have an advantage over 12.5" prop 50hp outboards for pushing a really heavy load like a Mac26. But the Suzuki and Honda are medium for thrust applications, they have a decent reduction gear that allows a good match for the Mac26X with a 9 or 10 pitch prop, this gives the Suzuki and Honda an advantage over outboards with 1.85 gear ratio such as the Tohatsu/Nissan and non-bigfoot version of Mercury and Yamaha. Only the Tohatsu/Nissan offer a 4 blade 7 pitch prop that is a decent match for pushing the Mac26X.
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The Etec 50 has a 2.67 gear ratio and I think that means it turns the 14" props, and its the same weight as the Suzuki DF50, so IMHO the Etec50 sis the closest competitor for the DF50 as the most powerful and fuel economical 50hp, but the Etec is probably not as quiet.
http://www.evinrude.com/en-US/Engines/2 ... ations/50/

[Mark Karagianis]

Robert, I have been using a 12.5 x 10 x 3 Michigan-style prop on my DF-50 and, without a tach (which I soon plan to remedy), think that I can still rev higher and go faster than my as-now indicated 14-knot GPS top speed (fully-loaded). I just bought a Piranha 12.5 x 9 x 3, and am going to test it out next week. What prop are you using? Granted that the X is slightly different from the M, I believe the M is harder to plane but the deeper "V" is better for the swells at speed.

Oh, my DF-50 was $6400 plus tax, with a rigging charge $400. Total out the door price: motor, extras, tax and labor $7328.

Mark

[Robert]

Mark,
..
My all around favorite prop is the Solas Stainless 3 x 12.25 x 9 pitch but it needed a slight extra cupping so it would not suck air in from the surface. My second favorite smoothest at low speeds and awesome reverse is the Solas Aluminum 4 x 11.8" x 9 pitch which works right out of the box, but has a ringing sound (like a finger going around the top of a stemware wineglass) at 2000 +/-50 RPM.
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I never tried a Michigan Wheel prop, I think I would have liked the 3 x 12.25 x 9 that they have.
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I sized my Props to make it up to the top of the WOT RPM range with ballast full, fuguring that boats tend to gain weight over time and figuring that I would always keep ballast full out on open ocean swells. With ballast empty both these props go up to 6800 RPM where the engine loses torque. The over-rev limiter on the DF50 is at 7250 RPM, the computer only records >6000 as the top RPM (as of my 1999 model) and the dealer and Suzuki Rep. said the DF50 is happy to run high revs all day, so I fugure I was safe to let it run 6800.
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Thank You for testing the Piranha Propellers 9 pitch prop on your Mac26!
Robert

[delevi]

Just got my original (chewed up prop) rebuilt. I had 1/2" diameter taken off, so it's now 13.5 x 13. I'm hoping to get a few hundred extra RPM. When I tried ta 14 x 11, my RPMs went up by 800, probablya could have been more but I think the rev limiter kicked in. My top speed also dropped from 21 mph to 17. I think the 13.5 x 13 should be perfect for the E-tec 50. I'll report back after I have a chance to use it.

Leon

[Jeff S]

Could controls and indicators for the Tohatsu 50 (Carb) be used with the Tohatsu 90 TLDI? If so that could save me money if I decided to upgrade.

[Chip Hindes]

Jeff, a few months ago when I was faced with major repairs to my carbed Tohatsu 50, I had the same question. As nearly as I could determine, from a control standpoint they are identical.

[Bobby T.-26X #4767]

does it look like this??? a "single throw" controller?



that's what they put on mine...

Bob T.
"DaBob"
'02X w/ '04 90 TLDI

[craiglaforce]

Hey Chip, what happened to your Tohatsu?

Just wondering if there was any advice to those of use that have the same engine?

I had to clean my carbs last summer, but so far I have not had any problems, other than the overheat alarm, which I removed several years ago, (probably foolish, but I just got tired of it giving what I figured was false alarms). I just keep an eye on the telltale. Seems like a weak stream, but not sure if that means much. Runs terrific though since the carbs are cleaned and I replaced all of the fuel hoses, filter and primer bulbs this year. .

[Chip Hindes]

Craig:

Accident

I could ask where you've been.

Any advice I can give toward avoiding such would not be limited to the brand of motor. In fact, the guy that hit me has a Nissan 50 2S on his Mac; do you suppose that was the problem?

How about this: all you guys with a single axle trailer and only two marginal brakes, get another axle and two more brakes.

$4400 and a new lower unit later later (incuding trailer repairs, new winch and jack) and everything appears just about as good as new.

$4500 in fiberglass repairs, too; funny how the costs nearly equalled out.

First time in five years my Tohatsu has been seen by a pro. Maintenance has been limited to annual lower unit oil and plug change, one time fuel filter change, period. Never changed the water pump impeller, but I got a new one with the new lower unit, so it's probably good for another five years. Though since first mate and purser says when the original note's paid off (two more years) we can think about a bigger motor, so it may not have to last that long.

[craiglaforce]

Thanks Chip. I've been travelling quite a bit and must have lost track.

Hope the repairs went well. I guess we can't blame the Tohastsu for needing a lower unit replaced if it got hit by a truck.