Because they're convinced there is no reliable I/O power. IMO, that false opinion usually stems from guys asking WAY too much out of what they've engineered. Perfect example- 700s are bullet proof. Stage 4 700s less so. Gm rated that GenVI block for 700hp. When Mercury built the 850SCI, it was a totally different animal and for a reason. These guys slapping 3.8L Whipples on 502s and making 8-900HP is very impressive (we've done it), but it HAS to be application specific. That engine will last forever in a 27 fountain. In a 36 Skater? Nah.
We made 950hp on a 509 with a 3.8 for a 28 Checkmate. That engine runs great and met the owners budget and plans for it. When we built a set of 900s for a 36 Skater, we used World blocks, 572cid, much bigger heads, Callies Magnum Cranks, Callies Ultra rods, so on and so forth. The same HP was achieved with way less stress and heat.....and also for a lot more $. Want reliable HP? Build an engine capable of 200hp more than you need and de-tune it.
Cheap, fast, reliable. Pick two!

They're closer than you think if done correctly with a budget that allows for it.

Exactly, my HP500EFI motors have been more reliable than friends older OB's. They hate me.

How reliable would a new 500HP outboard be modified by a shop for 600, 700 or more HP?

Edit:

Saris, I was typing when you posted. You are right on the point.

And for the record, I dont hate outboards. We're a merc racing gold dealer, premier level service center. They're awesome engines....although not as angry as a 2.5OS....I just hate the constant comparison of BBC cats to outboard cats. Both have a reason to exist, but if they we're truly equal in performance Supercat would have no reason to exist once the 450R boats upgrade to 500s.

Great minds my friend! lol.
Ok..im out! Go head and kill eachother lol.
When I was a kid it was fountains vs cats. My how the world has changed.

No argument. But that does not reflect where the vast majority of the high-performance market lies. Those who call outboard power a "fad"—and that isn't you—are ignoring reality. Or need a dictionary.

i am not an outboard hater.. actually, my 500 efi have been 100% reliable, beside changing the fuel pumps...after 23 years !
ok i am not racing them, i have a water condo so if speed was my number one priority i would choose another model.

so reliability is not a point that would make me go to outboard.. the interior space it creates, even more noticeable in a smaller 22-29 feet boat, maybe would, or could !

I also get it is easier to work on OB standing right beside, while you are not head up side down !
but if it break in the water, access to fix whats wrong might be more out of reach than an IO boat IMO
but i never had to fix an OB boat in the water so...
just my uneducated thoughts... !!

I too, don't hate out boards. I could get to like a Velocity VR 1 with twin 350 outboards. That being said...I don't care for the fish boats that they put them on.. Hell, most of them don't even have rod holders.

Padraig

These days, you can buy reliable inboard power from Mercury from 1100 hp per engine and upwards, and reliable outboard power from 500 hp per engine and downwards.

It is not clear to me that reliable inboard power is less expensive based on the prices I see for engines and drives, even before taking into account installation.

Getting some guy to build you an engine based on a big block with push rods or based on an Evinrude V6 with carburetors can certainly result in low-cost power, but it is not in the same league when it comes to reliability, either for inboards or outboards.

Always the comedian. )