dyno

between 500-600 your pretty safe....my.02

cigarette1

I run twin 540+hp in a 9500# boat .... with plenty of airtime in rough water.

I believe the drives are 1992 originals and I've run them for three seasons without any issues ... except for a gimbal(pre ext steering)

I have no drive showers and run it like a .....

It's all in the Hands ... and the 1.36 gears

Nordicflame

I would think that twins will survive much better than a large single just by simply sharing the torque load. In other words two 700 hp motors with Bravos in a 32-35 footer would probably last much longer than a single 700 hp Bravo set up in a 28-30 single.

Hope I'm not setting myself up to fail; 28 foot, 750 hp, new style Bravo?????????????????????????????

timucin

thnx all
this is not my boat; Actually there is not such a boat for the moment.This is the most common combination (wieght-length-single inboard) here in Turkey.

we usually dont have problems with new drives till its rebuilt...then problems never end till you buy the new one. sure mechanics are not trained and experienced enough.

-but new drives are not strong as they were...?!? I dont know the reason.I thought maybe they are importing rebuilt drives;painting them perfect and selling as new (a possibility).but I talked with lots of people they say it is impossible...

-do you think older drives are stronger?
-most breakable part of drive is upper unit? are you agree?

the most common engine is 415hp 502 cu.in... isnt it strange to break the drives with this hp?!?

you may think that the reason is drivers: but no.they had boats before;they dont go 2 much stressed ; I mean these are pleasure boats...
I am a bit confused??

rhino

Older design stronger than XR/XZ !! You must be joking! Even the old drives should have no trouble with 425hp. The new HD Bravo units are only sold to support 575hp MAX. On your own from there. Unless you do some serious modifications you can not "convert" a pre 1998 drive to XR/XZ. Even with the new gearset (much better than original) you are still dealing with the aluminum bearing tower. You can put the heavy duty straight propshaft/lower gearset with HD carrier in though. As the experienced drivers have pointed out though, a good hand on the throttle makes all the difference in the world, along with weight/torque load. Nice to hear about people with the skill to make the drive survive.

blown formula

....9000# Formula SS 1993, full roller 454 & 7# boost 'charger & Stainless Marine headers.... ran for 3 seasons on original drive no failures, but used a Simrek drive shower also!! That is a big help in addition to "throttle work".

26scarab

Rhino,
just some info for you...doesn't really mean much though.

My late model Bravo (1997) lasted 40 or so hours behind my 675hp 540.
My spare Bravo (1st gen ) has lasted about 80 hours so far.
I'm not saying the olds ones are better but its kind of weird that is still holding together.

bmesser

I had a '96 26' SCARAB and changed the 502 (415HP) with 135hrs this year to 535HP, dyno'd and blueprinted, it busted the std bravo I in 60hrs and had to change to a XR and ran great. Supposedly, the std bravo is only good for 500hp and that depends on the age of the drive.

Brad Perry

Timucin;

"we usually dont have problems with new drives till its rebuilt...then problems never end till you buy the new one. sure mechanics are not trained and experienced enough. "

Funny, we have that problem here in Texas too.

rjcardinal

A 7000# single engine V bottom is going to be very hard on a Bravo One even with stock power while getting on to plane. Most failures occur when getting on plane or when re-entering the water after some airtime.

Ron