Re-powering a MacM from 70 HP up

[Gypsy]

I met a liveaboard (Katrina Refugee) who had taken his sailboat (same basic design as a Mac)
and cut out the cockpit , then glassed boards across the gunwales to reclose the aft , opening up the stern section into quite a bit of room .
He then got a 2 cylinder diesel engine out of a tractor trailer reefer and installed it back there as his inboard engine.

On top of his former cockpit He mounted a steering pedestal and bolted down a lawn chair behind it .

As makeshift as this all sounds , He rode out Katrina in the mouth of the Alabama River , and lived to tell about it.
We met him in Montgomery marina where He was trying to get together enough money to get back to the coast , where work was soon to be plentiful .

[Octaman]

Victor/vkmaynard

Octaman, given the 115 is the same weight as the 100 (140 is lighter due to bored out metal removed), why would you not opt for the extra HP? The fuel economy will be the same at same speed with the same displacement.

I don't think the fuel economy is the same. If I recall the air intake is different, the camshaft lobes are wilder and the fuel injector programming is more aggressive - the 115 I believe burns more fuel to get more hp out of the same engine.

As I have said before, I believe cc does the trick with the macs not hp. We'll see.

Octaman

[ROAD Soldier]

As I have said before, I believe cc does the trick with the macs not hp. We'll see.

Octaman

Alright gents give this one a wide berth you can't argue with that "screen door on a submarine logic". At least he doesn't think he can weld on a full gasoline tank as long it is completely full. It's his money and I am sure his 100HP Suzuki will beat my 50HP Honda no matter what logic is used to install it.

[Highlander]

50/50 put/put 50/50 fut/fut , ppppppppuuuuuuuttttttt Fpt!

J

[jschrade]

I waiting for someone to put to or three outboards across that back of their Macgregor!

Jim

[ROAD Soldier]

I waiting for someone to put to or three outboards across that back of their Macgregor!

Jim

I see we share a thought in common. With all these people going to 70,90, and above HP motors I guy can pick up another 50hp Honda cheap.

[vkmaynard]

The new 90 does seem to burn less fuel than the previous 90 (42% less according to the brochure) at high cruise: https://secure.suzuki.com/marine/_m/bro ... savers.pdf

Eric installed the previous 90 and it seems to burn a lot more fuel.

[Hamin' X]

I met a liveaboard (Katrina Refugee) who had taken his sailboat (same basic design as a Mac)
and cut out the cockpit , then glassed boards across the gunwales to reclose the aft , opening up the stern section into quite a bit of room .
He then got a 2 cylinder diesel engine out of a tractor trailer reefer and installed it back there as his inboard engine.

On top of his former cockpit He mounted a steering pedestal and bolted down a lawn chair behind it .

As makeshift as this all sounds , He rode out Katrina in the mouth of the Alabama River , and lived to tell about it.
We met him in Montgomery marina where He was trying to get together enough money to get back to the coast , where work was soon to be plentiful .

I think that I saw his brother up on the bayou.



His other brother of the same name, has a storm shelter in Kansas.



They vaction together at their timeshare Kehma.



~Rich

[ROAD Soldier]

Got to love that Redneck ingenuity.

[Gypsy]

Got to love that Redneck ingenuity.

Trailer Condos ! What will they think of next ?

The economy keeps on like its going and we might be all living in one !

[Octaman]

The new 90 does seem to burn less fuel than the previous 90 (42% less according to the brochure) at high cruise: https://secure.suzuki.com/marine/_m/bro ... savers.pdf

Eric installed the previous 90 and it seems to burn a lot more fuel.

Victor, I think the old Suzuki 90 is the same engine as the new 100 and 115. Generally speaking as it is a bigger engine, 1950cc, it should burn more fuel than the new 90 which is 1500cc. For a given boat I very much doubt it will be 42% less. However, if I compare the fuel consumption of my old DF70 (1300cc) with what I expect to get from my new DF100 (1950cc), I am guessing that for the same cruising speeds I will be burning more or less the same quantity of fuel. The 70 was pushing hard at high revs, the 100 should have the same result with mid revs at ease.
I also think that the new 100 may be more fuel efficient than the old 90 even though the same engine, only because of better programming, timing etc as the trend now is to have a more fuel efficient motor.
I will know only when I am on the water, after the initial 10 hour break-in period, when I can run the motor as I wish.
Then . . . comes the issue of the right prop

Octaman

[vkmaynard]

Does anyone have a 115 or 140 on their M?

[Octaman]

Okay guys,
Here is a sneak preview!



New DF100 sitting patiently on the transom of our 26M waiting for prop to arrive. May take a couple of days.
Then we go out and see what tune she sings - weather permitting, of course.

Octaman

[jschrade]

When you put two of them back there, I will be impressed!

Went fishing with a friend on a flats boat and it had a 115 Yamaha 4 stroke. Man, it was quiet! There was nothing between it and us and the wind made more noise than it did.

Jim

[ROAD Soldier]

I think the old Suzuki 90 is the same engine as the new 100 and 115. Generally speaking as it is a bigger engine, 1950cc, it should burn more fuel than the new 90 which is 1500cc. For a given boat I very much doubt it will be 42% less. Octaman

I don’t doubt it for a second because it is a simple matter of riding the detonation line. I had a Chrysler 440 (7.2L for you metric freaks) that was not fuel injected and after some mods I made it go from 7MPG to 12MPG by riding the detonation line. Beside doing the usual better breathing upgrades like more efficient intake, cam, header exhaust, and air filter, I had also up graded the ignition system with a computerized coil that allowed the spark gap to go from .035” to .055”. This coil could supply the voltage and amperage to do that and also served as a multi-sparker which ignited the fuel many times in a nanosecond as needed to accomplish a complete burn. Then I also installed an in dash timing system that allows me to advance the timing while moving to the extreme limit before detonation. I only did this at cruise where I would advance the timing until I just heard a knock then backed off 2 degrees. What this does is it allows the fuel more time to burn and in the process gives you more HP and increase efficiency, which equates to better MPG and HP. Now since the new outboard are computerized it tells me that the new lean system on the Suzuki 90HP is simple measuring the very limit before detonation and advancing the timing to that point. However since it is computerized it does it throughout the entire RPM range, not just at cruise, and probably several times a second. I had to knock mine back done manually before going uphill or passing or risk blowing up my engine. Also since the new Suzuki 90HP engine is fuel injected it could do something my 440 could not which is vary the optimum fuel ratio for a given RPM. Now if the new Suzuki 90HP does have a multi-sparking ignition system too, which I don’t know if it does. I have no doubt there has been a 42% increase in fuel efficiency with the smaller CC engine over the older larger CC engine. Bottom line anytime you do any mod to an engine that does not increase the volume (CC or CID) like boring it out but instead simple makes it breath/burn better you increase HP and get better MPG. So here again if the 115HP is the same CC as the 100HP then it will get better MPG at the same RPM for the same weight and boat design moved because it is simple burning the fuel more efficiently. Now at WOT it will be less because it simple moves faster running at a higher RPM and creating more drag. The only down side is it will burn hotter at the same RPM which will cause more wear. “Dang man I should charge people for this information.”