I don't know if the OBs are necessarily better, STOCK power is generally reliable in two stroke or 4 stroke form, OB or I/O. My previous 260/Alpha and 496 Mag/Bravo were both pretty reliable, and the latter was freshwater cooled, so no corrosion issues.
But at refresh time, valves, springs, and head gaskets are more expensive and labor intensive than a set of reed petals and a bottle of SeaFoam for the de-carbon on a 2 stroke OB.
Also, when something goes wrong on an OB, there are really only a few parts sources including the OEM, and repairs are often completed by OEM certified techs. Because the OEM did the R&D, design, manufacturing, and updates the TSBs, OEM is the choice for parts and repairs for many owners.

Conversely, I/O owners often aren't looking to the OEM for replacement parts, instead looking to the aftermarket for upgrades and performance enhancements. Sometimes (NOT ALWAYS) these upgrades occur to the detriment of reliability. Sometimes the replacement/upgraded parts come from manufacturers less consistent in material and process, or are installed by marginal mechanics claiming to be the latest big block performance "experts".


Outboards are "more reliable" because most owners see a horsepower number on a cowl and leave it there, I/O guys go and try to add 100hp to whatever's listed on the sticker.
If you want some anecdotal evidence of how unreliable outboards can be, head over to S&F, those guys are always blowing sh!t up.

Speedracer,

I agree. I think people are a little confused when they just say off hand that outboards are more reliable, anything when you MOD it starts breaking. Plenty of ski boats, pleasure boats and black motor go fasts with stock I/O's that run forever.

I hope Nate comes back on and tells what issues has kept him on the dock with totally stock black closed cooled 496's. His boat maybe is a good example, for that to run the same speed he could now have 2 of the Merc 400's on it. Talk about the added space. I am sure the CG would have to be worked out.

Granted, you no longer are talking a simple 2 stroke but a SC 4 stroke. (the new 400's are supercharged right)?

What AT has been posting I think would be pretty cool, mainly for the added room, and easy of working on.

IMO, the relability boils down to an OB being designed from the ground up as a boat motor vs an IO being a modification of a car motor. The mfg offer 5 and 6 year warranties, not sure what the longest extended warranty on an I/O? A stock black motor is pretty reliable so maybe there is no difference, on older motors I would trust a high hr OB over an IO anyday.

Yes, 95% of OB's are 250hp and below and bone stock so that certainly has a lot to do with reliability. Two strokes have had their share of issues with the fuel delivery system on early Optimax and Yamaha HPDI but they have been worked out now.

I have seen comaprisons on smaller single engine boats but given the power to weight and the setback of an OB on a bracket I would think the OB would be faster with a lot less hp? Twin 300's versus twin 496 on the same hull go fast hull would be a greate test.

I just looked up a test I had from 08, a 28 checkmate w/ 300xs motors ran 81.8, those motors are supposedly about 320-340hp each. What does a 28 run with twin SB or BB?

I think the reliability is a factor, however, the space you can add with not having an i/o is a big plus in a boat around 30'. i think wild man is the first to bring this up and is why many people are a big fan of a CC. so now providing this room in a go fast might start to change the CC craze

Tuff is building a 2015 28 for a customer with the new 400's.
Pics on Facebook.
The very first tuff 28 was powered by twin 250 xs mercs and ran about 90 on an average day. Fast forward, subtract 800 lbs from the boat and add the twin 400's and it will be a missile.
Will be interesting to see how it runs beside the full carbon 28 that has an illmor in it. Lots of cool stuff going on with them.

Here is DBR's side by side test using same dyno same conditions.

Merc 300x at 326hp at 7000 rpm

Merc 300xs at 306 hp at 6400 rpm

The stock comparisons are in the text. The dyno graph is using a stage 1 modified 300xs against a stock 300x.

http://www.davebushracing.com/mercur...0x-update.html

The 33 powerplay with outboards had a huge cockpit. The scarab raider also had a huge cockpit. They did a few 38s with outboards to.

i think that using outboards with extra cockpit space could really take the industry back to where everyone on here hating on center consoles wants it. it may not be as fast as some people want but its going to put people in the water with simplicity and economically. remember larger cockpit means more bikinis. or lack there of

You don't have to stand on your head to work on outboards