When to upgrade the Bravo 1? 570hp/640ftlbs
 

My bravo 1 is the original from 1990. Never had issues running it with a 7.4l. Short story is I’ve bought new motor pushing 570hp and 640ft pounds of torque. I boat at 6800 ft, the motor was Dyno’d at sea level. There will be a power loss. What’s going to be the way to go on the Bravo 1, 1.5 ratio? Rebuild and beef it up or put in XR internals?

boat is a 23’ cuddy cabin ( for the kids). It’s around 4klbs in weight.

quick calculation is a loss of 100hp 115ft/lbs so 470hp 525ft/lbs

I would keep running the drive as is. The older Bravos held up much better than the newer ones and the older gears were better. If it fails, I would go to Bravo X upper. Avoid going to an XR unless absolutely needed. The XR gears usually only last around 200 hrs

Agreed. relatively lightweight boat, as long as you're not beating on it mercilessly, it should live a decent life behind that HP level.

Griff,

What's the cutoff between "older" Bravos and "newer" Bravos?

Thanks. Brad.
(937)545-8991

thx griff!

Regular Bravos used to come standard on power up to 600SCs. In the early 2000’s the failure rate seemed to increase behind the 496HO’s so Merc came out with the XZ and XR and the X

What is they difference between bravo 1 and bravo 1X ???

Found this.
I remember seeing it on this site awhile ago.
Came across it on another site.
Originally on Bam's site. Couldn't find it there.
https://cimg6.ibsrv.net/gimg/www.off...ad372288ad.png

Thanks for the information!

Griff,

So, I'm a bit confused....

It sounds like you're saying the durability of the B1 diminished in the early 2000's, and Merc's solution was to develop several stages of stronger outdrives. But the chart shows a different story. I *THINK*. The drive on our PQ is a B1, MFRd in 2001. I'm just trying to figure out what we've got.

Thanks. Brad.
(937)545-8991

IMO, Merc did not address the root of the problem which was the quality of the gears and shafts. Instead they improved the overall design to make the drives stronger. I know a bunch of people, including me, with 800-1200 hours on older/pre 2000 Bravo drives behind 502/454 mags with 385hp-415hp. Yet when the 425hp 496 HO came out, regular Bravo's were failing regularly with 100-200 hrs. Merc then started putting X drives behind 496HO's. My regular Bravo behind a 525SC let go at 210 hrs. People are now lucky to get 210 hours out of an XR behind a 525EFI. The reason is the quality of the gears.

What they did fix was the problem with blowing the bottom floor of the driven gear out
by making the gear floors thicker, I’ve never seen this happen on a OM s/n set, but as Griff
mentioned, the quality seemed to go down in other areas