I did exactly that to my 1988 30ss with 320 efi's and alpha ss drives. I replaced the motor package with 500 Hp's and Bravo one drives. Before I had a real problem getting on plane so when I changed the drives it made for a perfect combination. The X dimention on the Alpha ss drive is the same as the Bravo set up at least mine was.

I then was able to sell the drives an the motors to recover my cost and yes I only had to drill two additional holes and the big blocks sit right on the same motor mount set up.

Steve, the problem you make mention of, getting on plane, I seem to have trouble too. The props don't seem to bite all that well, and you have to work the throttles forward slowly to get rolling. Once on plane it's OK. Is that due to the SS's or engines.
I like the idea of changing the whole pakage out, but I don't think I could recoup the expence when I'm ready to sell,(did you?).
I'll probably move up to a 42 in a couple of years.
BTW just how rare an option were these combos? Most have never heard of the engines.
Joe

As an FYI, my brother has a 32 Sea Ray Pachanga with Twin 454/330's and Alpha drives with factory 3 blade cleaver type props. Not the SS Drive. This boat flys out of the hole. He needs to add showers as when on plane as the entire drive from where the upper/lower units bolt togather, the entire upper section is totally out of the water !
Only the lower section is in the water. Kinda kills the myth of big blocks destroying the Alpha drives, atleast with 330 hp in stock configuration. This boat will run 70mph. Nice solid boat.

This boat has over 600 hrs, and the drives look like new inside. Rarely does he firewall it out of the hole, but has on occassion, the boat has no problem getting on plane whether using or not using the Bennett twin cylinder trim tabs... Only draw back is both drives are right hand rotation and prop torque is aweful and causes the boat to list. Have to use the tab to straighten her out.

If you are having trbl getting on plane, may be a prop issue. Try a 4 blade bravo prop. I beleive the prop shafts are the same size as a Bravo 1. I have 4 blade Hydromotives, and they suck getting on plane ! They will blow out easily comming on plane unless I ease the throttles forward slowly until 3000rpm, then throttle up. Is real bad in heavy sea's comming on plane, especially with full fuel and alot of people on board. Changed props, now she flies out of the hole, no matter what condition. Once on plane the hydromotive bite real well, but out of the hole suck big time, at least on my boat.

Brand new Hydromotives, I have them for sale currently: SS 4 Blade 24p, R & L props.

Also I beleive the drives have the same lengths B1 vs Alpha. As far as x dimension, thats determined by the builder when the boat is set up. Cant comment on the specs for same size sonics of different years and sizes also. Dont have a clue. You can correct X dimension by using drive spacers or changing to shorter lower unit housing, bit I beleive this will only apply to B1 for shorter lower unit housings.

Lastly, the one nice thing about Chevy motors, is the motor mounts will bolt up to either small or big blocks & usually in the same location. And some pulleys can be reused. Clearence is usually the only issue when from small to big blocks, especially in cars.......

Prop torque is some thing I am all too familier with, without the tabs boats lists HARD to starboard. It took a few hours of playing with it by myself to get used to setting the tabs.
The ss are a "semi surface piercing drive" so I've been told , so I added showers before I even put it in the water, I don't have any chalking and they don't seem too warm after running for a while.
I've got 3 blade S.S. Mirage props on it now, will 4 blades cost mph?
Team- I thought you said the 4 bld Hydros' suck coming on plane, I don't need that! Once I'm back in the water I'm going to have to experiment this season, to get a better prop for my application. Now that the engines are both in good shape, I'll be better able to work on the prop issue. I fugure with more power the'll just blow out worse.

The Hydromotives do suck on my boat. Unless I add a diffuser ring to stop the blow out, but this would cost me top end on this prop. Once on plane & top end they are great as is. But with 42' of boat to get on plane, I need good bite out of the hole. Fountain did use Hydromotives on their boats as standard props. Dont know how they worked though, guess they worked ok, depending on boat. Several other makes put Hydromotives on their boats but dont know any specs. Hydromotives work well on several apps, just not mine, and as is.......

When I got the boat, the Hydromotives were on there. Spare set of Mach 24p 4 blade props were on it as spares. Tried them out, BIG difference. Flies out of the hole now. Just heard some bad stuff like the ears/blades commin of the machs. I imagine these were just spares for the " Just in case times ". I want overall best performance, out the hole, cruise speed & top end. Dont race the boat so dont care who is faster than me.

Im going to a Bravo 4 blades. The 4 blade should not really hurt you any. It should help...more bite. I have always been told/heard that you will see higher top end with a 4 vs a 3 blade, depending on app. I would think you would apply for your app.

Bear in mind, that the drives have the hardest load & stress conditions put on them when commin on plane. So some slip gives them a little leeway and reduces some of the stress loads. I never firewall the throttles out of the hole anyway as it puts alot of stress on the drives.

With the Mach 4 blades, my cruise mph went up a good amount at the same RPM vs the Hydromotives. The mach blades have a slight cup to them, are more rounded than the hydromotives. The Bravo props are pretty much the industry standard for props, depending on power. They give you an all around best scenario.

If you add more power, you can prop up & or change drive ratios to keep the engines off the limiters and acheive the best top end & overall performance. Dont think you have the gear ratio option the Alpha or SS drives as they are really not for high HP apps. Bravos only as far as I am aware......

I would contact Merc to see what props would work best for your app. If you can find someone/someplace whom may be willing to let you try their / or some props to experiment that would be nice,
but that may be tough due to damage/liability issues. I by no means am an expert with this, just relating what I have found to work, and also what I have been told.

If you add power, you will have to prop up. But trial & error/buying props can be expensive. I would consult an expert. I would consider going to a Merc 4 blade. Once you find one that works with your app. You can have it labbed to tweak even more out our your combo.....

Hope this helps. Just my .02........

Team thanks for the info, I'm really not going to race the boat either.
I'm looking for all around preformance too, we figured that the old owner may have used the 3 blade to protect the drives, when getting on plane.

No problem........ Good luck & let everyone know how everything works out.

Joe,

I had my 30ss for 10 years before we bought our 42 Sonic. I had the same problem with. the list to starboard, and by dragging the starboard plane it scrubs off speed. Whithout counter rotating .

Bravo 1 props would help you get on plane but I beleive the smallest bravo prop is a 22 and you are most likely running 21's

The ss drives do have stronger gears than the alpha drive so you can run more horsepower thorough them, but the efi system you have dosn't allow for any modifications to the motors. This is why we changed to the 500hp set up.

To answer your question in regards to recouping your cost, You wont. But it will certainly help your resale value. We sold our 1988 Sonic 30ss last year for over 50 k, but the boat was garage kept since new and in perfect condition.

Sonic Steve,
Thanks for the info.
It is frustrating to know that I'm scrubbing off speed, to prevent list. I'm thinking about the B-1 set up for next winter, before adding more power. I really did not like the handling when I first got the boat. As I said in another post it took a while to get used to correcting the list,as this is my first boat. Nothing like jumping in both feet first.
I learned quite a bit about this EFI set up this winter. I'm working with a great FI guy. He flowed the stock injectors, figured out what they were and updated them to a more modern type.
Not any bigger just better spray pattern. We talked about modifications, and with todays eqipment we can upgrade the ECU's and keep the benifits of the EFI, so upgrading the power is possible with some $$$. I figured it would cost much less than going to a big block setup. Another friend is a dealer for Vortec , so the plan is a mild boost increase, and EFI upgrade. NEXT year I've still got a lot to learn about handling at speed!
BTW did you ever have any problems with the ECU's or anything else in the engine systems?
I had a fuel pressure regulator go last season, and detonated two pistons so bad they were rocking in the bores and sounded like a rod knock UGGH! Now have fuel pressuere guages!
Joe

Please dont be offended ...It may look awesome in the boat .. But when I first saw the pics of the interior all I could think of was a taxi cab race..