Hey all,
I'm new here and this is my first post. I'm interested in repowering my 1993 21' Larson Senza 210 Offshore "speed" boat. It currently has a gen 2 350 mag small block, which produces about 250hp, and a gen 2 Alpha One Drive. I'm wondering which engine/drive would be best for the application? Can I put a 454 7.4l gen VI and a Bravo One Drive? Or should I put a 377? Will it work and can the boat handle it? Is there any other suggestions for engines/drives? The boat officially weighs 2975lbs. I'm looking for a performance boost all around. I really like top end, though. I'm looking to completely eliminate the current power plant, so no upgrades/rebuilds/mods.....

First of all, welcome to OSO. I think you'll find lots of useful information here along with lots of great people.

Getting back to your original question though, I'll say it before anybody else does. Save the money you were going to spend on that boat, sell it and buy more of a true performance boat. You'll be thousands of dollars ahead. There are many, many reasons for this and many others before you - with the very same idea - either heeded the advice and were much happier for it, or didn't heed it and it cost them a fortune.

Basically, you have a hull that's not built for going very fast. Although Larson makes a decent family boat, family boats are not designed or built for high speeds. This leads to several problems. First, the hull will be a handful to drive at higher speeds. Second, the increased forces (pounding) the hull was not designed for will tear the boat apart in short order. And I can say this with true, personal experience. My very first "fast" (58 MPH) boats was a brand new 1984 16' Larson Senza. Not only did I nearly rip the transom off in one year, but literally everything else was hanging on by a thread when I traded the boat in - on a Checkmate.

Second, you will spend a bloody fortune changing out the engine and drive and you'll never, ever get that money back in increased resale value. In fact, the boat will actually be worth less than it was with factory installed power.

I know that's probably not what you wanted to hear, but if you do some searching around here, you'll find my advice to be absolutely true. Sorry.

^^^^ So true.

Gotta agree with Too Stroked

Even if you push forward , stay small block.
I put about 330hp vortec based sbc in my 21 behind a alpha1g2 have had 5blade props on it pulling wakeboarders ballasted , 3 blade running low 60's the extra 100hp made it come allive cheap and easy upgrade the alpha has taken years of abuse suprisingly well

When you get to 60 mph you will need external hydraulic steering. Those Larson's will start to chine walk above 55 or so.

Wannabe

Hi, thanks for the replies.... I was going to post some pictures of the boat, but it appears I can't.... The boat is very light weight, but it definitely does have a hull that's cut for speed (it's a cuddy, for those not familiar, not open bow "family" oriented style). I haven't gotten a GPS reading at WOT, while I am using stock gauges and a pitot tube speedo. The speedo has said 63mph at one time, usually sitting at about 60 at WOT. Basically, I'm asking what you would put in the boat if you had no choice but to re-power. The boat is a great little boat and I just figured I could put a 383 or 377 or something like that with a B1 drive. The 454 is too big/overkill, I think.... I don't think a little more power will kill this boat, but don't want to blow up into a million pieces on the water.... I actually was going to put that line in my original post.... I figure anything putting out over 400hp/torque could be a problem for the transom, let alone weight difference. On another note, I have been looking at some Fountains, primarily 27'-32' Fever's. My uncle has a 27' Fever with a 496 HO and Dana Header's, does 72mph. He's looking for a 35' Lightning with twin 525's, at least. I want my own Fountain, though. What would you say my boat is worth? Updated interior, cockpit cover, sound system, graphics, and many other updates. Thanks - Brandon