AllDodge

iTrader: (1)

This may not be an issue but I've read a couple post (not here) that the Bravo drives have a maximum rpm. This came from a discussion that Merc wants to keep the prop rotation between 2300 to 2500 rpm. I'm looking into going from a Bravo 3 with a 2.0 ratio, to a 1.81. Anyone hear of anything regarding this?

JaayTeee

You would just need to change the upper gear set... the 1.81 B3 is the same as the 1.36 B1 gear set ( 27/29 tooth count)

AllDodge

iTrader: (1)

Thanks and I'm sorry, must not have asked the question correctly. Can props be spun faster then 2500 or better yet 2700 RPM without damaging the drive or prop? Is there a max RPM for the drives?

buck35

Most people on here spinning their engines between 4800&6000,so I don't think that is correct.
Hope this helps. Ken
Just noticed you said bravo 3, no idea sorry

AllDodge

iTrader: (1)

Thanks, what I read was for any bravo drive (1, 2 or3). It's probably not an issue but want to make sure before I buy a new drive. Currently turning 5200 with a 2.0 which gives me a prop rpm of 2600. If I go to a 1.81 that will bring it up to 2872 rpm

Rbesola

I was kind of under the impression that rpms are a bravos friend to a certain point. Like 6000rpm input rating on say a cat with 1.36 drives will be over 4400 prop rpm. I don't think id concern myself over a few hundred rpm even being a b3. Granted there's going to be more strain but i don't think it'll be the difference of lasting 10years vs exploding the first run. If they couldn't handle the rpm they pry wouldn't offer it in that ratio. Just my opinion

SB

iTrader: (1)

Half a kazzillion boat owners with 1.5 Bravo Drives are spiining there engines 5000-5200 rpm even with black motors. Example: 502MPI's are propped to run 5000-5100 rpm with 1.5 drives.

A higher # gear turns the prop slower. A lower # gear turns it faster.

Schit, 10 kazzillion 1.5 Alpha propelled boats have there engines spinning to 5k also.

Thinking quickly outloud, maybe those propspeed #'s you brought forth are help for boat manufacturer's to gear there boats ? Or maybe further, a certain type of boat (Express Cruiser vs performance boat vs.........)

I dunno...throwing it against the wall.

AllDodge

iTrader: (1)

Appreciate it much guys. Couldn't find anything but one thread and could not find any backup. Either way just trying to verify before I drop the coin. If 6000rpm cats are running 1.36 (prop at 4411rpm) then that tells me there should not be an rpm issue. Wonder what the max rpm is for any bravo drive, 10K ? Wouldn't be a bad thing to know.

Cobra100+

iTrader: (3)

I spin my XRs with 1.36 gears and 35p 5 blades on a 36 cat 6200rpm all the time. Let it turn.

AllDodge

iTrader: (1)

Thanks, sure appreciate put this one to bed