Re-powering a MacM from 70 HP up

[tom clayton]

I have the 09 DF70 on my m its dealer installed. i think the 70 80 and 90 are all the same physical size just bigger pistons, i could be wrong but ther is no problem with the bonnet hitting any where so i dont think the 90 would be an issue either. there are some ms with this motor on them in the video with the 140 x they show the m with a 90 mounted on it.

[Octaman]

I have the 09 DF70 on my m its dealer installed. i think the 70 80 and 90 are all the same physical size just bigger pistons, i could be wrong but ther is no problem with the bonnet hitting any where so i dont think the 90 would be an issue either. there are some ms with this motor on them in the video with the 140 x they show the m with a 90 mounted on it.

From the brochure I have studied, all three A-seriesSuzys DF90/80/70 (1.502cc) have identical external dimensions. And all three have the same gear ration of 2.59:1
I feel that your DF70A should come closer in performance to Highlander's Mercury 75 (1.732cc) - than to my older Suzuki DF70 (1.300cc).
I cannot say about a 4-blade, but if you are looking at 3-blade, I think 14' (diam) X 13' (pitch) should be the right starting point. This is my guess. You may also want to see what prop Highlader swings on his Mercury 75.

Hope this helps.

Octaman

[Octaman]

Macgregor is planning a new model, the 26P with a 125HP engine on the back, . . . . . .

Jim

You're kidding, right

[mikelinmon]

No way is the factory going to test a 125hp motor, too large, too heavy, too much power. Reasons in order of importance (my order anyway);
A) the startup thrust could lean the boat all the way over if wheel is turned fully. Powerboats have chines or hard edges at transom to prevent this. The high hp thrust will just dig the chine edge in and turn the boat. A sailboat can’t have chines, (cruising boat anyway with chines will be much slower than a sailboat without chines). Anyone notice the absence of the “Edge” due partly to chines on a heavy boat. I could have told Hunter that before they built it, but I didn’t/wouldn’t. A boat without chines and a high hp is going to lean over a lot from standing start, tough!
B) Maybe, just maybe the hull was designed for about 25mph as top speed.
C) Maybe, just maybe the transom was designed for up to ?? Does anyone out there know the design hp rating. Maybe it is in the brochure.
D) Steering a heavy motor while sailing, you’d have to disconnect it. The E-Tec 60 can be left hooked up all the time.
E) How about the seat. See those high hp motor 26M’s stored with the seat not closed, notice the prop in the water while they sail because the motor can’t tilt up fully, hits the seat.
F) Add hp and cost, add speed but not so much. It’s only money.
G) Fuel consumption is directly related to displacement and hp. Once the boat is on a plane, at same speed a 70 will burn more than a 60 in about that that ratio, 70/60. pure science, see the mpg rating on automobiles comparing their 4 cyl to 6 cyl. Always the high hp will lose.
H) There is more mostly related to legal problems, so far nothing but the shoe may drop on someone one day.

[jschrade]

Yes, I am. The purple veins should have been sort of telling!



Jim

[DaveB]

Mike, thanks for your report.
I have a 1997 Mac.X that I want to re power to a higher HP . I have now a BF50 Honda with a 4 blade prop and boat has at least 600 lbs added for a week cruise and I top out at 13.5 knots.(3 batteries,66 quart refig.,52 quart Cooler,18 gal. water and others).
Question is do you think a Etec 60 hp will get me to the 15 knots on plane and throttle back to 3/4 rpms to do it.
I think most want to get on plane than throttle back to 3/4 for cruise and I am sure a 90 hp can do this.
I mainly cruise at 5.5-6 knots but if I want to get there fast in calm water I want to do so.
My Mac.X doesn't have enough clearance between boarding ladder and rudder to have a engine width greater than my Honda 50. Maybe the E-tec 60 does but I can not find width on that engine. Max. I can go is 16 inch width on engine.
Honda has 14.7 inch width.
I prefer 4 stroke engines because most of my powering will be in the 2500 rpm's range.
Dave

No way is the factory going to test a 125hp motor, too large, too heavy, too much power. Reasons in order of importance (my order anyway);
A) the startup thrust could lean the boat all the way over if wheel is turned fully. Powerboats have chines or hard edges at transom to prevent this. The high hp thrust will just dig the chine edge in and turn the boat. A sailboat can’t have chines, (cruising boat anyway with chines will be much slower than a sailboat without chines). Anyone notice the absence of the “Edge” due partly to chines on a heavy boat. I could have told Hunter that before they built it, but I didn’t/wouldn’t. A boat without chines and a high hp is going to lean over a lot from standing start, tough!
B) Maybe, just maybe the hull was designed for about 25mph as top speed.
C) Maybe, just maybe the transom was designed for up to ?? Does anyone out there know the design hp rating. Maybe it is in the brochure.
D) Steering a heavy motor while sailing, you’d have to disconnect it. The E-Tec 60 can be left hooked up all the time.
E) How about the seat. See those high hp motor 26M’s stored with the seat not closed, notice the prop in the water while they sail because the motor can’t tilt up fully, hits the seat.
F) Add hp and cost, add speed but not so much. It’s only money.
G) Fuel consumption is directly related to displacement and hp. Once the boat is on a plane, at same speed a 70 will burn more than a 60 in about that that ratio, 70/60. pure science, see the mpg rating on automobiles comparing their 4 cyl to 6 cyl. Always the high hp will lose.
H) There is more mostly related to legal problems, so far nothing but the shoe may drop on someone one day.

[bscott]

Dave,
I have an 08 E-tec 60 on my 01 and there is plenty of room to board over the stern. The 60 has tons of torque even at 8,000' altitude. I also installed the Power Thruster which helps to get out of the hole and seems to reduce the "bow high" while running. The sweet spot on my engine with a 14 x 9 prop is 3,000 rpm. I have not been in the salt yet so I can't give you any info but this is an amazing engine, runs @ 100:1 oil with no smoke, starts on the 1st turn, puts out 25 amps, weighs 240#, quiet and sips gas at 2,000 r's.

I lose 24% HP @ 8,000 and I can run 15kts @5,300 rpm, unbalasted.

Bob

[Octaman]

Dear Mike,

Thank you very much for your input; greatly appreciated.

With all due respect, Mike, I cannot picture a Mac Owner (or any owner, in fact) turning his wheel all the way to port or starboard starting the engine and hitting the throttle to the limit, whatever the engine on his stern. That would mean a total lack of seamanship, common sense, etc. This discussion is not targeted to the very few brainless individuals that can perhaps exist everywhere in the world and that are liable to do all kinds of silly things. I think you have missed the point.

If you make a new driver sit behind the wheel of a Ferrari, he will most probably not be able to drive the car and have an accident. Must we ban Ferrari’s?

I respect your comments and your deep knowledge but please allow me to say that you have an angle of approach on all issues that is completely different to the spirit of this discussion. Maybe justly so, as you come from the ‘factory side’ and need to support your interests in selling new boats as delivered.

I also respect the fact that ‘modifications’ are not a thing for everyone. Many are happy with what they get and think no further. But there is also another breed of Owners out there.

I speak for myself but I feel many, many other Mac owners fall under the category of the ‘restless owner’; the ‘Hobbyists’ – coming from various professional backgrounds, with expertise in different fields, sometimes associated to boating sometimes not, people that think, use their knowledge and experience, research and come up with new ideas, with a desire to make-better, upgrade, experiment, try new things and get satisfaction out of every improvement they make that works, however big or small.
Those that have a restless mind will always try new things and test new grounds. Sometimes they will fail and sometimes they shall succeed. They are willing to take all the associated risks. But every time they succeed there is a benefit that goes around and shared by all (at no cost on this forum).

I belong to this group.
We are not here to make money (we are spending money) but to have FUN!
The feeling of accomplishment is far greater than the feeling of fear should we be crossing any borders in the process.

I think there is a message in the air for the ‘factory’, Mike, . . . . People today seem to want a different boat, an evolvement of the truly great Mac M. If the ‘factory’ listens carefully, the ‘factory’ may benefit from the free message this website is transmitting.

Quote Jim’s post: <<Macgregor is planning a new model, the 26P with a 125HP engine on the back...> Unquote.

I was hoping for a moment that it was true.

My sincere wishes to you from Athens.
Octaman.

[DaveB]

Bob, thanks for the info but I have a 1997 Mac.X with original rudders and boarding ladder. Your 2001 has the Stainless steel rudder brackets ,diffrent rudders and a relocation of your boarding ladder.
What is the width of your 60 hp Eteck? my limit is close to 17 inches but perfer 16 inch width.
This is allow for boarding ladder to raise without hitting engine and boarding width to climb aboard.
Dave

Dave,
I have an 08 E-tec 60 on my 01 and there is plenty of room to board over the stern. The 60 has tons of torque even at 8,000' altitude. I also installed the Power Thruster which helps to get out of the hole and seems to reduce the "bow high" while running. The sweet spot on my engine with a 14 x 9 prop is 3,000 rpm. I have not been in the salt yet so I can't give you any info but this is an amazing engine, runs @ 100:1 oil with no smoke, starts on the 1st turn, puts out 25 amps, weighs 240#, quiet and sips gas at 2,000 r's.

I lose 24% HP @ 8,000 and I can run 14kts @5,400 rpm, unbalasted.

Bob

[bscott]

Dave, I will measure the engine 12/05/10

Bob

[DaveB]

Thanks Bob
Dave

Dave, I will measure the engine 12/05/10

Bob

[bscott]

Dave, the E-tec 60 power head is not a true rectangle and is 14.5" wide. The boarding ladder on my sits mid-way between the port rudder and the engine. Hope this helps. The E-tec 75 is not much wider than the 60 but I don't have the measurements.

Bob

[Octaman]

Greetings once again from Athens and a great ‘thank you’ to all for your contributions to this conversation.

I have tried to evaluate all the responses and information not only on this/my topic but also on many other similar great topics of this Forum, and have come to some conclusions that I would like to share with you and ask for your opinion.

Point 1: To get the Mac moving right, engine volume (cc) seems to be more important that engine power (hp) – especially if you are ‘heavily’ loaded.
For example, if moving from my Suzuki 1.300cc DF70 hp to an e-tec 90 or TLDI 90 that have similar engine volume (approx. 1.300cc) there will be no significant improvement in performance – just minor variations. This would not ideally justify a ‘repower’.
To really make a difference you need to go up in engine volume. I think that the perfect example for this lies with Highlander and beene that both have a 75hp engine with 1.600cc (I believe the numbers to be correct). With just 5hp more than I have it seems they accomplish a far better result than my MacM because they have greater engine volume.

Point 2: Regardless of what your personal preference may be, generally speaking, a 2-stroke engine will give better acceleration, a 4-stroke may take a little longer to lay out its power but is probably more powerful on the upper end of the rpm scale. The tug of war between the 4s Yamaha and the 2s Evinrude that we have all seen on U-tube does not prove, in my opinion, that the Yamaha is an inferior engine. Both engines are good but have features that make them suitable for different applications. The Mac does not require a remarkable hole shot and the changes in speed should be more gradual to limit stresses on the hull. Therefore a 4-stroke should be prefered.

Point 3: I am also not convinced that the 2-strokes are more fuel efficient than the 4-strokes; additionally the difference in the cost of the oil that is burnt must also be taken into consideration when calculating the cost of overall fuel consumption because the 2s oil that is added and consumed has a significantly higher cost than what you pay for an oil change on a 4-stroke.

Point 4: A 2 stroke, due to its firing cycle may give its power more ‘violently’ (thus the better acceleration), but I have also noticed that for a given engine volume all the 2-strokes have lower gear ratio than the equivalent 4-stroke partially ‘choking’ this advantage.

Point 5: A wedge is an absolute necessity for the M when powering up to obtain the required trim angle of the motor.

Point 6: Engine weight is not a determining factor on the Mac


Ladies and Gentlemen, your comments please . . . . ?

Octaman

[Catigale]

because the 2s oil that is added and consumed has a significantly higher cost than what you pay for an oil change on a 4-stroke.

I think you will find in a modern, direct inject 2 stroke the cost for oil consumed is less than a four stroke oil change...especially if you consider changing the oil 4 times in one season because of dunking your engine....

[bscott]

Octaman
My experience is with the E-tec 60 vs the Merc Big Foot 60 so it is not pertinent to your comparisons to the 90 HO class. However, I don't agree with some of your conclusisons concerning the physical comparisons of 2 vs 4 strokes.
1)Weight-the Yamaha 4s @380# is 60 lbs heavier than the E-tec 90. This may not be a negative for the M but a heavier engine does effect the steering effort while sailing. My E-tec 60 weighs 240 lbs and I can definately feel the weight.
I used to race a Capri 25 and we would take the 6hp kicker off the stern for better speed. More weight forward is a good sailing thing.
2)Superior "hole shot" is better when you need it--like slamming into reverse just before you hit your dock mates $80,000 J Boat. I don't have to use it, I just control my urge to drag race my dock mates 4s .
3)I will be buying my first replacement gallon of XD-100 oil after 3 years of sailing--current cost $45.00. I don't know the cost of annual oil changes/time for a 4s but I bet its more than $45.00.
4)Gear ratios of the lower unit don't matter with the proper prop, however, a 2.01 should require a thinner lower unit than a 2.31= less drag.
5)Wedges--nice
6)Weight--Mac as a motor boat, no problem. As a sail boat, see (1).
You cannot compare the new high tech E-tecs and Tohatsu to the old school carb 2 strokes-look what they have forced the 4stroke crowd to do--obviously those manufactures now think "lite" is better too Now the question is how reliable will a new generation lightweight 4s be

Bob