alpha to bravo swap

[jknight7656]

Any body on here done a alpha to bravo swap any advice.

[still_fishin]

Start saving

[CVX Fever]

The Alpha and Bravo key hole cut-outs are the same which should make it pretty straight forward. But don't know how the steering/throttle controls differ, if at all.

Curious as to why you want to upgrade to a Bravo? When I was looking for a trailerable cruiser in the 24'-26' range I absolutely wouldn't give any boat a second look/thought that wasn't equipped with a Bravo III.

[Plugcheck]

Not certain on the cutout size, never compared the two, but pretty much everything else is different.  Transom plate, gimbal, yoke, outdrive, etc.  As Tim stated, start saving now.  I'd like to do the same with a BBC engine, bravo 1.  The alphas can take 300hp, and a bit more if your kind to them.  Merc even used an alpha with a big block at 1.36 ratio.  Honestly, if your not making 350+ hp, no need for bravo.  Bravo 3's are nice, but prop changes can be $700 + since its two props.  With no engine change, sticking with sbc, you can estimate dropping $5000 if you shop around to convert an alpha over to bravo 1.  Maybe you can find deals, I came close to buying a 28' fountain for $4100 just to get the drivetrains.  Let us know how your project comes along.

[Hyperacme]

From his post on CGOA ...
http://www.classicglastron.com/phpbb/viewtopic.php?f=22&t=11048


" I now have a little over 400hp . The drive is working now no problems but i know i will ."

[CVX Fever]

OK so now I remember you from the national site. Are you running the BB in your CVX18 currently? Honestly I'd think about an Alpha Gen 2 like I'm putting in my CVX18 instead of the Bravo. The CVX18 is a small, light boat which will take some of the stress off the drive. If you drive it right, i think an Alpha Gen 2 will hold up just fine behind that big block. But the Bravo would obviously be pretty much bullet proof.


EDIT: OK  I got you mixed up with someone else who is putting a BB in a CVX18. What are you running for a motor?

 

[still_fishin]

You could just carry a spare drive with you everywhere you go.......on the boat.........it might be about the same weight as the upgrade would be.

I don't mean to bust your chops here. Before I hurt my motor again I was at 375hp and 470flbs so I have thought about doing the same conversion, I just don't want to spend that kind of money.  Besides, I bought just about all the tools to repair/rebuild my own drives. I now have a few spares the didn't cost me a whole lot of ching. I only put 7 to 8 hours on the drive behind this power, so as far as longevity goes, I don't know.

[jknight7656]

Im running a sbc over 400 hp and im fixen to put fuel injection to top the motor off. ( carb dight now). And yes ahe is fun to drive ao with that i know the alpha is a week drive. Yes bravo is heavier but its stronger.

[CVX Fever]

Let's see some pictures of the boat/motor!

[jknight7656]

I do not have pic of the motor but i will post some this weekend.

[Hyperacme]

Is it this CVX 18 ?
From this thread ...
http://forum.cgoamn.com/index.php?topic=4944.msg64670#msg64670

[Plugcheck]

         I have considered the Bravo conversion on multiple occasions, especially now that I am in the process of restoring a 1985 Intimidator, comes back to the same end result, it is a expensive conversion, heavier, and no real return on the investment.   Not exactly certain what HP level I am at, but its a 388 with 10 to 1 compression, vortec top end, and Qjet marine carb.  I am pretty much aligned with Tim's philosophy, I have the tools and now have 5 drives in storage.   I do not hammer the throttle coming out of the hole, doing so anyway just cavitates the prop.   No jumping, and I rarely go at top speed for very long to keep the drive cool.   So far so good.   Honestly, I've broken more stuff hitting underwater obstacles than blowing up the drive due to excessive HP.   With some minor tweaks on my Timi hull, and some X-dimension mods, I'm fairly confidant I can hit 70mph with a warmed up Merc 260.  Spending my money on making it look and feel nice rather than go all out assault on speed.  Besides, the OB guys are faster.  Quite certain a guy could break 80mph+ with a CVX 20 Sprint and have less money spent than us I/O guys.   Nonetheless, I would enjoy hearing and seeing your projects progress.

[CVX Fever]

OK now I remember that boat. Nice boat BTW!

Not trying to be cynical but I'm a little skeptical about both the 450 HP claim and 73 MPH turning a 23P prop made by the previous owner.  Most guys turning a 23P prop on a CVX18 are running low 60's. Everyone I've known that has approached or surpassed the 70 MPH mark in that boat is turning at least a 25P prop. Now that you own the boat have you GPS'd its top speed? What kind of RPM's were you turning? Have you verified your motor is putting out over 400 HP or are you just going by what the previous owner told you?

Your other options for beefing up the drive without going to a full blown Bravo set-up are this:

A) You can simply bolt on an Alpha One leg keeping the existing transom assembly & trim cylinders. An Alpha One is a stronger more durable drive than what your CVX18 came with originally.  The person that owned my brothers old Intimidator had done this upgrade when he bought it. An Alpha One Gen 2 won't bolt on to your existing transom assembly.

B) You go with an an Alpha One drive and transom assembly. The benefit to this is now you have an outdrive that trims negatively. This will improve holeshot by keeping the bow down.

C) You can go with an Alpha One Gen 2 drive and transom assembly. The Gen 2 was rated to handle roughly another 30 HP over the Alpha One. So it's a slightly stouter design. That drive was introduced roughly around 1991 and it still being used today. so basically you'd running the same drive that you would get in a brand new boat.

Drive showers and gear sets can also be used to beef up the durability of an Alpha. The money you save by running an Alpha can be spent on a nice set lightweight aluminum performance exhaust manifolds and risers. IMHO anything you can do to take some of the weight out of the stern of your boat is always a good thing performance wise.





 

[Plugcheck]

    If those horsepower and speed stats came from the previous owner, I also would tend to be a bit skeptical.  I have the same hull, albeit a CVZ rather than a CVX, with the Alpha and the aforementioned 388 CI SBC.  Now I'm running a four blade 25 pitch prop which I can hit low sixties.   I am hoping that with Tims help(Makinwaves) we can see mid to upper 60's tomorrow on the Missouri river.   The same drivetrain may very well be capable of 73 in the Intimidator but it is a different hull design.   My advice to the new CVX-18 owner is spend some time testing the combination before deciding to drop a bunch of money on a Bravo set up. 

[CVX Fever]

My advice to the new CVX-18 owner is spend some time testing the combination before deciding to drop a bunch of money on a Bravo set up.

Yep that's good advice. I was kinda hoping for replay back by now on what that boat runs. Because if he is getting anywhere near 400 HP out of that 350 and/or running 70+ MPH spinning a 23P prop I wanna know what they did to that SB350!

[jknight7656]

Sorry for the delay guys .Yes that is the boat and No i have not gps the speed yet and it isn't running 73 i know this becouse i have a bass boat that will. As for as neg trim the boat comes out the water and on plane faster than any boat i have had and i am running a 23p prop rpms not sure becouse i know the tac is off a little. I alredy have through hull exhaust aquq sound risers and mufflers but it needs a carb or i need to come off aome money and put a fuel injection kit on it. The boat with the motor is capable of going faster it feels like its being held back probably carb its an edelbrock and i have never like them. I know i cant trim it all that much becouse i can feel the ujoint shaft vibrating so i dont push it that hard.

[thedeuceman]

either way that is an awesome looking boat, did you see this link Mike posted on the thread about Andy's shortened drive ?
http://www.rlcperformance.com/images/projects/tripple_digits/project_trippledigits.html
this guy was running 600 HP into a shortened alpha 1, though he did break it once.

[CVX Fever]

@jknight7656

Hey thanks for the reply. Always interesting for me to see what other guys with CVX18's are running for motors, props, etc and the speeds they are getting. Why re-invent the wheel when you can learn from what others have done/tried. When you get you tach figured out post some numbers.

Not a bad idea to pull the drive off and check everything out. You want to make sure that your drive bellows aren't full of water which can cause all kinds of problems. Always a good idea on these old boats to check engine alignment. The vibration could also be from a bad gimble bearing. 

[jknight7656]

Yea i did see and read that whole artical and i think that is a great idea be8ng that the cvx is a shallow draft boat and i myself think that the outdrive sits to far in the water. I think with a shorter drive unit you would have better performance less lift in the rear and more control over bow lift . Just my thinking and im thinking like my set up on my bass boat.