Can anybody tell me what the exact differences are between a Bravo Xr and a Bravo XZ drive. I know that XR's have straight cut net forged gears and can handle more HP, but I know nothing about XZ's

I need to to know which one would be better to put behind 750hp blower motors.

The only difference between a XR and a XZ is the top gear set. They both have the same lower unit shafts and guts.

The top end is straight cut on a XR and helical on a XZ. I have had both and never had any problems out of the top gear sets Just the lower units.

The XRs do make more noise than the XZs, I ran 700hp thru XZs for two years without a problem

Wish I could say the same.

Here's a breakdown of the differences between them:
http://www.go-fast.com/mercruiser_bravo_sterndrives.htm

I have XR's

Even though I had to put a pinion gear
and a vertical shaft bearing in the starboard
drive, and had to replace the complete upper
on the port, due to a gear failure, that broke the housing.

I don't know if it was due to bad material in
the gears, or the former owners operating habits,
or if it's that they just have a shorter
useful lifespan( the gearsets)???

I bite my tongue and say that XR's are
probably your best bet.

Thanks J.T. !!! Good info. It looks like the XR is the better of the two. I am also looking at Imco, Teague etc.

Stay away from Imco, email Pather for his experience of bending over for them. They wouldn't stand behind brand new drives that had an assembly problem. They suck!!!

At probably a few $$$ extra, you can get a set of custom built drives from TNT. XR uppers, with custom TNT HD cap, Imco gears, shafts and Imco sportmaster lower.

700 hp/770 lbs torque.

IMCO doesn't make the gears, they use the merc gears, they only make the shafting and other misc. stuff. The only thing some of they do is cyro treat them on occaision, which anyone can have done.