Motor Upgrade question.

[Chip Hindes]

Comparisons between the ETEC and 4 stroke shows the ETEC double in torgue and speed.

You're leaving something out of the comparison.

Horsepower is directly proportional to torque and speed. The only way a given engine can be double in both torque and speed of (for example) a 50HP four stroke is if that engine is putting out 200HP.

[Bobby T.-26X #4767]

LOUIS B HOLUB

Hang on to that trim light weight Louis. That has to be the bonus for sailing, and you can still pull 50 horses like the heavy weights. I have a Suzuki 50 and know you have 100 lbs less weight on the transom, not to mention the compact size of your engine.

i had a Suzi 50 for 24 months.
the slowest two years of my life...



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

[crackles]

Firstly, thanks everyone for your assistance so far. I really do appreciate all the help given so freely on this forum. For a learner like me, it is invaluable.

Well, the 50 Mercury Big Foot is on and now I can't wait to try it. Trouble is, when the dealer fitted the motor, he advised me that there was no propeller in the box, so he fitted a - 17 pitch - prop, off another boat in his yard. "try it, and let me know". He said. Well, I'm doing that tomorrow. I already think it will be much too - and will swap it for a more suitable prop. My question is what size/pitch would you recommend.

Just for the record, the tacho connections were also missing from the box. I have the tacho, but currently for decoration only. I hope the engine performs better than the factory packing.

[They Theirs]

LOUIS B HOLUB

Hang on to that trim light weight Louis. That has to be the bonus for sailing, and you can still pull 50 horses like the heavy weights. I have a Suzuki 50 and know you have 100 lbs less weight on the transom, not to mention the compact size of your engine.
DaBuba for DaBiggest

[Moe]

Mercury makes some special versions of their Black Max aluminum props for the BigFoot motors. They paint them silver to distinguish them from the other Black Max props. Instead of the Flo-Torque II interchangable hub system, they have a pressed in soft rubber hub that slips easier if the prop hits an obstruction.

I'd recommend the 14" x 10" for general use, or 14" x 9" if you're going to be loading up heavy with a family and pulling a tube. The one that I bought came with the thrust washers, tab washer and prop nut in the box.

--
Moe

[Robert]

crackles, I would go easy on your motor while it had the 17 pitch prop on it especially without the tachometer to watch your results. Here is how I think it will behave, please tell me if I get it right.
..
The motor will idle fine and you will be suprised how fast you travel at idle, maybe 4+ mph. The handling around the dock: you will have trouble to go slow enough, so your landing might be a little rough. When all warmed up the idle speed might be lower and that will help.
..
Your acceleration will be weak as soon as you go above hull speed and either the prop will loose traction and allow the motor RPMs to go up very quickly or the prop will not loose traction and your RPMs will be limited well below (like 1000 RPMs too low) the minimum RPM required range. Damngerous either way for the motor, the fast revving caused by loosing traction could overspeed your motor and the lugging when unable to get up into your required RPM range is excessive torque loading on the motor and drive line. You might experience the prop loosing grip on turns at speed or loose grip with sudden acceleration and keep grip with slow acceleration.
..
When you get the correct prop pitch you will notice a quieter smoother sound from your outboard. The outboard will sound much better with the right pitch at a higher RPM than with too much pitch and too low an RPM. The correct pitch prop will also have bigger blade area and excellent grip on the water.

[DLT]

I don't know if this is too late or not, but I wouldn't even attempt the 17", especially not on a new engine without a tach...

I presume a little too low, rather than too high, RPM is going to be better for break in, so I'd start with an 11" pitch.

Remember, your boat is likely as light as it will ever be. So, you'll only go down in pitch from here...

11" should keep you well under max RPM, without being as dangerously low as that 17...

You are going to want a spare prop anyway, so if you don't want to ask the guy to swap it out without having tried it, just buy one... In this case, I'd buy a 10" pitch, as that is what you'll likely end up with... I'm only suggesting the 11" to make sure you stay under max RPM with a new, and therefore light, boat... So, you might want to be careful with that 10", during break in, just in case...

Now, I'm talking uncupped props here. So, if you're using a cupped prop things are even worse, as cupping effectively adds an inch or two to pitch. Our boats don't generally benefit from cupping, and the negatively impact reverse, so I'd recommend choosing a prop without any cupping.

If you have a choice, get a prop designed for a houseboat, or at least a pontoon... I find that the newer go fast designs just don't work as well as the older props I've tried... I have one that looks like it was on the Merrimac, and it works the best... Besides, with 50hp, you're not going to be a speed boat...

For these boats, diameter is real simple. Get the absolute biggest diameter prop your motor can safely use... You will be far too slow for this to be detrimental...

[delevi]

My E-Tec 50 doesn't reach the mid RPM range, usually tops out at 5400, but I frequently it speeds of 20.5 mph. In heavier current & chop, 16-18 mph no problem. WOP of course. Cursing speeds of 15 mph at 4800-5000 RPM.

DLT,

What's the deal with that EMM? Any idea what the cost is to buy those extra horses? I would be interested but I have almost 2 yrs on the warranty.

[Bobby T.-26X #4767]

My E-Tec 50 doesn't reach the mid RPM range, usually tops out at 5400, but I frequently it speeds of 20.5 mph. In heavier current & chop, 16-18 mph no problem. WOP of course. Cursing speeds of 15 mph at 4800-5000 RPM.

DLT,

What's the deal with that EMM? Any idea what the cost is to buy those extra horses? I would be interested but I have almost 2 yrs on the warranty.

Two things...
1) IMHO, one should use a prop pitch that gets the outboard to max RPM at WOT on a medium loaded boat. Otherwise, if you becopme a heavily loaded boat (with a 50hp on a Mac), you'll lug the motor and cause possible damage.
2) What's that acronym "EMM" stand for???

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

[DLT]

The "brain" of every E-TEC engine is its Engine Management Module (EMM), which can perform more than 8 million calculations every second. In fact, an E-TEC has been described as a very simple engine controlled by an extremely powerful computer.

The EMM measures every possible variable and controls every aspect of injection, and therefore horsepower.

I dunno why the big difference in price, this "brain" being the only factor. Neither did my dealer... Just all part of their pricing scheme I guess...

delevi, You must have a pretty light boat... I don't get anywhere near those speeds... Of course, I have 10 fewer HP and the same weight engine...

I would certainly drop down an inch or two in prop pitch if I were you. You should get even more performance once you get the engine RPM's right...

I'm tempted to just say screw it and buy the 60HP EMM now. I could always swap it back out before taking the engine in for service. The only problem would be that the EMM also tracks performance. So, downloading its data can help diagnose problems. You wouldn't get anything useful if I swapped the EMMs back...

[Catigale]

OK...Maybe this is an ubergripe, but any dealer who puts a prop on your boat, almost certainly overpitched, when you dont have a tach, and says try it out....

shouldnt be dealing in boats imho

(Steps off soapbox)

[They Theirs]

Catigale
Step back up on that box! Youre doing fine.
They need to be held accountable for such marginal performance.

[Divecoz]

I must agree with others here as well. . . You don't have a tach on a new expensive dealer installed Outboard and for sure you have the wrong prop . . . what was that dealer thinking ?? another sale ?? Hope the rev limiter works well at least. . Be careful till that tach is working and get the right prop asap . .

[Hamin' X]

dunno why the big difference in price, this "brain" being the only factor. Neither did my dealer... Just all part of their pricing scheme I guess...

If all other things about the motor are equal, I would say:

More HP=More stress and wear=More warrantee claims. Higher price would be used to offset the higher rate of claims. Maybe? Just a thought.

Rich---Hamin' X---N7ZH

[DLT]

Rich, now that you mention it, I think that was along the lines of the dealer's guess...