87 Alpha and 95 Bravo used together as twins. Is it possible?

[HighCountry69]

I’m building a 24’ fiberglass over plywood boat. I have multiple questions. First, can I use a higher H.P. Mercruiser engine than the ones that came with some Alpha and Bravo stern drives that I have laying around? (181 cu in 140 hp). I’d like to use either, as single, or both, as twins on my build, if that’s even possible. If I can increase the HP on a single up to 200 HP, which sterndrive would be better, the Alpha or Bravo? Thank You.

 

[HT32BSX115]

Howdy,

Welcome aboard!

In general, The Alpha is good up to about 300HP or so. The Bravo is good for more.

 

[achris]

If you are referring to the 181cu in, then 140hp is about the maximum you'll get from them with any sort of reliability. When Merc were setting them up for MPI, they pushed them to about 150hp, but they tended to 'self-disassemble' rather quickly.

If you are thinking of running an Alpha and a Bravo side by side on the same boat, nah, can't be done.

If you want more power, buy a bigger engine. 200hp will still be a bit short for 24 foot. Start thinking 5 litre V8 as a minimum. Personally, a 350 with a Bravo would be perfect for a boat that size.

Chris.....

 

[HighCountry69]

Thanks for the quick response guys! I’ll go the 350 with Bravo route. Most excellent!

 

[HighCountry69]

My ‘95 Bravo came on a 3.0 140hp. If I’m going to change to the 350, what gear ratio would I need? Are there other things that I’d need to change to make them work together?

 

[HT32BSX115]

I think I may have misunderstood your original post.....I thought you were asking what an Alpha or Bravo could withstand in HP.

Most drives (Alpha or Bravo) are very close to 1.50:1 if operated behind a 5.7L V-8

You'd be fine though with twin (5.0/5.7L) V-8's or twin 4.3L V-6's and either Alphas or Bravo I's

In a big boat like yours with a single engine, I would want a Bravo III and at least a 5.7L .

I would choose the Bravo if available because they're a little "stronger" and are cone-clutch vs dog-clutch.
More money to buy and/or rebuild though.

I'll also add that the engine/drive (7.4L + Bravo III) in my 21ft Four Winns came out of a 1998 24' Bayliner Cuddy.

 

[Bondo]

My ‘95 Bravo came on a 3.0 140hp. If I’m going to change to the 350, what gear ratio would I need ?

Ayuh,..... Welcome Aboard,..... A 3.0l, Bravo drive,..?? I must admit, I've never seen or heard of such a thing,.....

As Rick says, ya need taller gears when ya raise the horsepower,.....

Most everything I work on is various Alpha drives,.....
Current project barge is gettin' a Bravo though,.....

This 24' glass over wood boat yer buildin,..?? is it a Go-Fast type hull, a Cruiser type hull, or a ???? type hull,..??

Twin 3.0ls, I'd think for a houseboat, or displacement hull cruiser,.....
Anything else, it'd be a waste of space, for very little horsepower,......

If yer hull is a Go-fast type, a BBC/ Bravo or 2 would be the way to go,.....

Hot Roddin' a 3.0l is gonna make you Unhappy,.....
Boat motors are built for Reliability 1st, horsepower 2nd,.....

 

[HighCountry69]

The Bravo came on a ‘95 model year Glastron bowrider, connected to a Mercruiser 3.0, 140 hp engine. As far as the current 24’ build, it’s a pilothouse style boat used as a possible daily driver from my land in the Alaskan bush to town and back through the saltwater inlets near Ketchikan, AK. Those bays are pretty protected, but can get somewhat nasty at times and I just need enough power to handle the rough water and get me back home safe carrying a load of weight. No hot roddin’ here. More of a work boat. Looks like I need to find a definite model/ serial number on that Bravo before I ask anymore questions. Than you guys for all the great info. I know a lot more now than I did before.

 

[HighCountry69]

Bondo,

I stand corrected. After further inspection, Both of my stern drives are Alphas. I apologize for my ignorance! For the life of me, I thought I had one of each. I guess the question now is can the Alpha handle a 5.7?

 

[AShipShow]

Yep! Many a merc 5.7 came with an alpha drive. As stated before, the rule of thumb is up to 300hp... so as long as you're not modding it drastically you're good to go.

 

[achris]

If those Alphas are off 3 litre engines, they'll have a higher reduction than you could get a prop for if you use it with a V8. The 3 litre drives use a 1.94:1 and the 350 would require a 1.47:1.... You'll need to either change the top housing gear-set or 'acquire' a new one with the right ratio. And unless you have ALL the right special tools yourself, don't even think about it! A new SEI upper housing is cheaper than just buying the tools to do the job. (unless you live in Australia. :facepalm

Chris.........