What are the advantages of an I/o or o/b?

[steven s]

I have a 1971baby donzi 16 o/b and I was wondering how come these days every classic is a i/o.But what are the true advantages of one.

[tiger lily]

the clamp ons are way cool, i dont know of advantages/disadvantages, but i like OB's myself, my next boat is going to be in the 25 foot range with a big ass merc on it, i personaly think nothing sounds cooler than a o.b at 7500rpms

[gcarter]

I know there has been an 18 and a 22 OB built.
If you were converting one, I think it might be important to consider CG and balance, especially if one were to use an OB bracket.

[Cuda]

Outboard advantages:
Less maintainence
Easier to replace
Run in shallower water
Easy to winterize
Much less prone to corrosion
Generally starts every single time


I/O advantages:
Sounds cooler.


:)

[steven s]

Outboard advantages:
Less maintainence
Easier to replace
Run in shallower water
Easy to winterize
Much less prone to corrosion
Generally starts every single time
I/O advantages:
Sounds cooler.
:)
I saw a 27 magnum in a port in the bahamas and it had 2 300 mercs on it with the exhaust drilled out or a open exhaust kit couldn't tell.But when it started up it sounded like a million bats out of hell the guy said it ran 80 in a 2-3 ft chop.After that I am buging my dad about drilling out my exhaust.It would only be for the sound

[pmreed]

Don't do it Steven. :shocking: It'll drive you nuts after the first thrill.
Phil

[WingWing]

I always liked the 16 ob. The I/O has a cool sound, but given the choice, I would take to OB baby donzi any day over the I/O.

[steven s]

I always liked the 16 ob. The I/O has a cool sound, but given the choice, I would take to OB baby donzi any day over the I/O.
Yea I would to.On a day were I have to navegate water in the keys gulf to go to marvin key,the most beautiful beach I ever seen.I would rather tear a cheap lower unit up than an expensive outdrive$$$$$$$.Also there are a group of guys with action crafts that run 100 plus and they think they are the coolest thing to hit since Elvis .I hope there is a 2-4 ft chop so I can introduce them to DEEP V's:moped: :wavey:

[Carl C]

More advantages of an outboard:
2 strokes have a higher power to weight ratio.
It gets the motor out of the boat leaving more room.
It shifts the weight further back.
You can mount it on a hydraulic jack plate for more versitility.
Better fuel economy.
2 strokes have fewer moving parts so can turn more RPMs.

I say go for the relieved exhaust and re-jet the carbs. Get rid of the air box and install velocity stacks and install louvered openings in the cowl. Or you could just put that big merc. back on it!!:nuke:

[Carl C]

Disadvantages of an outboard:
Higher repair cost. (debatable)
Expensive.
Larger boats need multiple motors.
Must burn oil. (2 strokes):cards:

[maddad]

Also, as soon as you need 600 h.p.(2x300 o.b.), there's less weight with a single motor/outdrive combo.

[Cuda]

[QUOTE=Carl C]
Better fuel economy.
QUOTE]
I disagree with that. I used to make the same trip in my 18 CC with a 175 Johnyrude, as I did with my 20 Formula with a 350, and I'd burn considerably more fuel in the fish boat, not to mention oil.

[gcarter]

The classic two stroke has a fuel rate of .8 to 1.25 Lb/HP/HR,
while our favorite auto based four strokes are about .5 Lb/HP/HR.
The two strokes have made significant improvements in the last ten to fifteen years.

[Cuda]

The classic two stroke has a fuel rate of .8 to 1.25 Lb/HP/HR,
while our favorite auto based four strokes are about .5 Lb/HP/HR.
The two strokes have made significant improvements in the last ten to fifteen years.
Yes they have. My dad had a 1959 75 horse Evinrude, and I swear that thing was damn near as big as an sbc. :)

Anther reason for I/O's is that you simply cannot buy an outboard over 300 horses.

Just for the record, I'd prefer an OB Sixteen myself. That's what I was looking for when I bought the Checkmate.

[steven s]

Yea it needs a 200 merc for speed .I have on with a broken crank shaft that is mine in a couple years!!!:shocking: :shocking:

[Team Jefe]

Well I guess I, of all people, need to chime in here.

Joe and George are right, OB's are NOT more fuel efficent than I/O's (especially 22 year old V8 OBs)but the gap has been greatly reduced in the last few years. All indications of the new Evinrude E-Tec show they are right there, and I'm sure the others will follow simply because the 4-stokes are not catching on like everyone thought they would. The power to weight ratio is all off making the fuel savings from a 4-stroke negated by the weight.

Speaking of weight, that is really the 2-stoke OB's biggest advantage. Agreed you can't BUY a STOCK OB over 300 ponies, but you can sure MAKE one that way:biggrin.: and weighing in at about 1/2 an I/O you don't need as much horsepower.

Carl got everything else about right for the OB's I know the jack plate on my 22 can really make a difference in perfromance....and I still haven't even got her dialed in yet.

Also, I have a great Trunk for storage to keep the coolers out of the way and other personal stuff:wink:

for a 16 I think OB is the way to go...but then I've seen FishBoy's restoration of a 16 he did for his mom and its flawless, so obviously I'm a little biased.

[joseph m. hahnl]

Way Back when the principles of propulsion came about. 2 strokes didn't have that much horse power and the were very bulky.
Now today althoe slimed down hey are still large they have dramatically increased the horse power due to the 4/cycle engine. the problem is even thoe they are high horse power their Rpm curve doesn't make them efficient for all boats.




The Direct Injection E- tec ."Bombadier" walks all over the 4/cycl in there horse power range. Yet still I don't think they go much over 225HP.
If They made an 8 Cylinder 2 stroke direct injection stern drive it could probably push 300 to 400 Hp easily. I think right out of the box it would smoke any thing that has come before it.

The biggest advantage to an I/O is weight displacement.

I think the major advantage of an out board is the space saving inside the boat.


Preformance wise . I think they are equally efficient.



As far as damage to the lower unit of an out board being less expensive to repair. They are the same lower unit.


Joe

[steven s]

Way Back when the principles of propulsion came about. 2 strokes didn't have that much horse power and the were very bulky.
Now today althoe slimed down hey are still large they have dramatically increased the horse power due to the 4/cycle engine. the problem is even thoe they are high horse power their Rpm curve doesn't make them efficient for all boats.
The Direct Injection E- tec ."Bombadier" walks all over the 4/cycl in there horse power range. Yet still I don't think they go much over 225HP.
If They made an 8 Cylinder 2 stroke direct injection stern drive it could probably push 300 to 400 Hp easily. I think right out of the box it would smoke any thing that has come before it.
The biggest advantage to an I/O is weight displacement.
I think the major advantage of an out board is the space saving inside the boat.
Preformance wise . I think they are equally efficient.
As far as damage to the lower unit of an out board being less expensive to repair. They are the same lower unit.
Joe
Yes it is the same lower unit.But isn't the mercruiser more expensive than a 115 yamaha lower unit.:confused:

[joseph m. hahnl]

Yes it is the same lower unit.But isn't the mercruiser more expensive than a 115 yamaha lower unit.:confused:


I would think the Jap parts would be more expensive!:smash:

joe