Max RPM on Alpha 1 Outdrive

[man-of-war]

I have a 454 Big Block V8 and I just had the engine rebuilt 15 hours ago. The boat came with an Alpha 1 outdrive and I want to know how much RPM I can put on the outdrive before it breaks? Thank you.

 

[Don S]

Re: Max RPM on Alpha 1 Outdrive

Any engine comes with a WOT (Wide Open Throttle) rpm that protects the engine. Usually between 4200 and 4600. The drive isn't even considered in the formula.<br />HOWEVER, the Alpha drives were only use for a few years by Mercruiser because they were not strong enough to hold the torque of the big blocks. So, fast hole shots and big "hammer downs" from low speed and the drive should be ok. Even the 4 cylinder engines using the Alpha drives can handle 4800 rpm, it's the sudden increase of throttle and torque that does the drive in.

 

[Bondo]

Re: Max RPM on Alpha 1 Outdrive

You can Probably figure that things will start coming apart around 5500rpms or so...(that's Input rpms)....<br />But,<br />That Big Block will Smoke that Alpha Before it even cracks 3500rpms............<br /><br />It's the Torque,+ Sudden rpm Changes(Wake Jumping, etc.)....................<br /><br />It's "Rated" at 300hp........