are inboards more reliable than outboards?

[Rivernut]

I have gone through my first season with a jet inboard - very little mantainence after 125 running hours. I look at outboards with 200-300 HP that are $10-13,000 and compare them with my 320 HP small block Chevy which cost about $3000. The outboard guys tell me that it won't last as long as their engines. I tell them that aluminum block outboards are ticking time-bombs made worse when they boat in weedy areas. I also point out the simplicity of a jet drive verses a $3000 loweer unit which costs the same as my whole engine. Are there stats on the life hours of these different set-ups? What is the life expectancy of a typical inboard jet verses an outboard prop?

[rivercrazy]

I think its all in how the engines are run and maintained. I've seen jet boat motors and drives go well over 1000 hours before a rebuild. My wife's uncles 460 ford and berkeley drive went over 2000 hours without a rebuild.
I doubt an outboard could go that far without a freshing up.
However, outboards do survive better at sustained very high rpm levels. However, most people don't run their boats that hard.
Jet drives are very simple and require very little maintenance (just greasing the pump bearings) and are very durable. Outboards have gears and props that are more suseptable to damage.
The advantage of the outboards is with the same level of horsepower, they will walk away from the jet in the same hull. However, you have to deal with all that smoke....

[77charger]

Its like comparing an auto engine to a motorcycle engine.The smaller the motor the harder it works.Two cycles do need more rebuilds compared to a 4 cycle(car motor)
The o/bs are faster and make very good hi rpm power.And the o/b can be more sensitive to heat and rich lean conditions.
As far as an inboard wheter it is jet or i/o the motors are the same so there will be no such thing as a jet is more reliable than an i/o motorwise but the jet is less to rebuild and more simple

[Banshee]

I’ll throw my two cents in. When it come to propulsion units. You simply can’t beat a jet for reliability and simplicity. As far as engines go, like RC said, an outboard will survive better at sustained high RPM operation. Less moving parts and a constant supply of fresh lubricating oil help. Although an inboard with some internal modifications can also be very reliable. One thing about 2 stroke engines Vs. 4 stroke is that a two stroke engine will generally make more HP with the same displacement than a 4 stroke will. This is because each cylinder is firing on every other stroke instead of every 4th stroke. I’m not a tree hugger by any means but I think there’s some value to the fact that 4 cycle engines don’t constantly burn oil. wink