Mercruiser Alpha one max hp

[QBhoy]

Hi
I was going to post this on an American forum for best results, but didn't want a bombardment of smart arse nonsense replies. Hoping for some members in the "same boat" on here !
Just simply to ask if anyone is running more than 300hp through an alpha one mercruiser drive with a proven reliability ?
I have read that this is the maximum recommended and even then to be careful.
I'm right on the limit or there abouts just now and never dare to open her up from a standstill, but wanting to do a bit of watersports this year, I may have to. I don't want to rip the drive to bits, nor do I want to go to a bravo drive.
The boat is only 18ft and about 1300kgs at the heaviest, so not a great deal of load.
Anyone have any experience on such a topic ?

 

[julians]

I had about 260hp going through my alpha 1 genii and it couldnt handle repeated watersport starts. After 3 years (from brand new) it sheared some teeth off one of the gears. I think youre correct to be careful with 300hp

 

[rafiki_]

Actually it is max torque you should be checking out, not hp. It is torque that will fail the transmission, not power.

 

[MapisM]

Actually it is max torque you should be checking out, not hp. It is torque that will fail the transmission, not power.

Spot on. Mercury made a notorious mistake in the past, by selling as stock package a 7.3 liters big block mated to an Alpha drive: it ended in tears.

The Alpha is a great drive for all small blocks, and IIRC the OP has the 5.0, which is well within the Alpha design.
I wouldn't be concerned one bit by putting 300hp through an Alpha with whatever torque the 5.0 can develop.

Of course, the usual caveats apply: by not handling the throttles properly while wave jumping, just about every outdrive can be destroyed, regardless of how much power and torque it's handling.

 

[MapisM]

I had about 260hp going through my alpha 1 genii

5.7 liters, I suppose?
The 5.7 MPI (or Mag 350, whatever) is indeed the borderline engine/torque for the Alpha.
Still OK, but a bit of "handle with care" is required...
As I said, the OP has a 5.0 (IIRC), and while the difference is not huge, the consensus also in the US is that the 5.0 is well within the safe side of that red line.

 

[julians]

5.7 liters, I suppose?
The 5.7 MPI (or Mag 350, whatever) is indeed the borderline engine/torque for the Alpha.
Still OK, but a bit of "handle with care" is required...
As I said, the OP has a 5.0 (IIRC), and while the difference is not huge, the consensus also in the US is that the 5.0 is well within the safe side of that red line.

No,mine was just a 5.0mpi

 

[MapisM]

No,mine was just a 5.0mpi

You are pretty much the first case I ever heard of gear teeth shared off an Alpha drive by a 5.0 engine, too bad...
How many hours did you have on it?

 

[QBhoy]

Thanks all.

It is a bit of a worry. My engine is also a 5.0mpi with a cam. Somewhere between 260hp (standard) and 300hp, I'd guess.
The comments about the torque are correct of course. It's this that does the damage
There are 300hp 5.7 engines running through this drive today. Not too common, but they are out there.
Even with the small block, there is a fair bit of torque.

 

[julians]

You are pretty much the first case I ever heard of gear teeth shared off an Alpha drive by a 5.0 engine, too bad...
How many hours did you have on it?

I think it was at around 230 hours when the drive failed, i had it repaired and kept the boat for another few years, up to 450 hours when i sold it

I was using the hi five prop which i guess could have increased the loadings on the drive.

 

[MapisM]

I was using the hi five prop which i guess could have increased the loadings on the drive.

Yup, that's precisely what I just said to QBhoy in his prop thread.

Still, a stock 5.0+Alpha package failing at 230 hours, urgh...
...I guess you weren't a happy bunny!