how much hp can a stock bravo 1 take before it brakes or is unreliable

475? (Guess)

People break them with 400 HP stock 454's if you run them "wrong"....people run them awhile with 700 HP in lighter boats if you run them "right". Just depends on the driver, but they all break eventually.

Any where from 500-600hp and probably have a 100-300hr life expectancy before a major break.

With good throttling and no abuse.

It really depends on the driver. How many hole shots, or out of water experiences in relationship to hp? And, it's usually the uppers that go first.

It seems to me that to extend life you need to cool the drive and change oil often. I've noticed that people tend to increase power but don't put any drive showers on. Look at all the fast boats with their stickers peeling off the drive, that's caused by heat. I have raced cars for years and currently have 3 race cars. I've never lost a diff but I change fluid frequently. Others with the same diff loose them every year or so. Thus, keep it cool and if you like to hammer across lakes, change fluid on a more regular basis. Just my opinion.

What if the drives are mated to stock 7.4L/330's and have drive showers for cooling? What's the "average" life expectancy assuming good care and minimal abuse?

Damn near forever.......well probably 500-1000 hours.

Thank you, Griff! You da man!

There are alot of factors that need to be considered when destorying a standard Bravo1.
The driver seems to be a major factor. Torque curve of the engine and load on the drive also come into play.
The old Bravo1 with the old style gears is generally good, if driven with respect up to lets say 500hp. I have a couple of customers with much more power. One is around 800hp on a 5700lb boat the other is 1000hp on a bit lighter boat.
The first boat ran 7yrs without a tear down of the drive. 3yrs with 310hp and 4 yrs with 750-800. I rebuilt that drive after 7yrs and 350hrs if I remember correctly, and it is on it's 5th year since then. I think average hrs/yr.. is around 50-60hrs/yr. Now this is a 600" NA motor.
The other drive spent two summers behind a Procharged motor, 1000hp. And did not break.
Both of these drives are old style Bravo1's with thin floored gears and small stock shafts.

So to put a limit or number on what they can handle isnt all that accurate. The Bravo drive was designed to produce metal particles.. They literally eat themselves! Hence the more often you change the drive oil, and cooler it runs, the better.
Now with 330hp.. they dont eat themselves as quickly as 700hp does.
And one missed wave jump can destroy an old style Bravo in a heartbeat.
Properly setup, and driven they can live. Sometimes a long life sometimes shorter. There are several weak points in the bravo that can be upgraded, but they are still limited to use and abuse. Generally when you fix one problem the next weakest link will appear.
If you start from scratch and put all the best pieces in a Bravo, you have the best chance at survival. In some cases it is a matter of routine maintance to change worn out gears at the interval that some people change their drive lube.

In the end it is "How fast do you want to go?" and How much can you afford?"

Hope this perspective helps.
D*ck