Alpha 1 gen 2 / bravo 3 swap

[racer17]

Hello Everyone,

I'm new to iboats and need some technical help please...

I bought a 1998 Regal 2760 cruiser 3 years ago with twin carborated 4.3L mercruisers and alpha 1 gen 2 drives. I've had plane issues since day one and am sick and tired of the constant struggle to enjoy my boat. Simply put... there are many reviews and forum comments regarding the many complaints for this issue and from what I can see the upgrade to Bravo 3's is the answer. I have tried EVERYTHING including rebuilding both engines ! Regal started using the Bravo 3's (not sure what year?)and the issue was resolved. I am a self professed "back yard mechanic" and do all my own engine assembly, tuning, trouble shooting, hull repair, etc... What I can't do I learn. Anyway.... I need to get some solid advice on:

A) is the alpha transom collar to bravo collar a simple swap as I'm told? My local tech says all I have to do is drill one additional hole and mount? (engines removed of coarse)

B) does anyone know where to find the proper gear ratio spec I need for the bravo 3 to work with my 190hp 4.3L? My boat weigh aprox 8000lbs from the factory. I seriously looked for 2 hours on Google and can't find squat :mad-new:

C) I understand there are lots of complete bravo 3 set up's in the USA due to, upgrades from the off shore guys, salvage from the hurricane's, etc.. ? Collar, rams, upper/lower,props,drive monitor reservoirs, everything I need (did I forget anything?)

D) where is the best place to start looking closest to East Coast Canada?? Who is reliable and won't rip me off? I was thinking when I find something attractive I might hire a local technician to be my eyes??

Anyway , I hope I'm in the right part of this forum, I'm not really savvy with forums but was told iboats.com is the place to be.

Thank you in advance for any help and,or direction you can offer.

Best Regards... :canada:

 

[agallant80]

Re: Alpha 1 gen 2 / bravo 3 swap

A: You will have to change everything.
B: No idea
C: Yes you will forget something and the project will nickle and dime you to the poor house (example Bravo drives use belt driven water pump where alpha is in the drive you will have to add those to each motor which means reconfiguring the motor, buying pumps and brackets)
D: Ebay is pretty good

There are lots of boats that have twin 4.2 with Alpha drives. What you are considering may not be the right aproach. Have you tried messing with the prop pitch and adding trim tabs if you don't have them?

 

[agallant80]

Re: Alpha 1 gen 2 / bravo 3 swap

What pitch props are you running?

 

[racer17]

Re: Alpha 1 gen 2 / bravo 3 swap

Yes I have trim tabs. I've played with different pitch. factory 19 SS 3 blade Mirage plus, and 4 blade aluminum 18 Quicksilver. Those seem to be the best of the bunch. The 19 works ok when I finally get the pig on plane, rev's 3600rpm. The 4 blade seem to push me out of the hole a bit better but revs 4000rpm. I do however, have a cavitation issue that I can't figure out? When I mash the throttles the props sound like they are loosing traction in the water until it gets on plane?? I checked the obvious for them being all the way in to the transom and that is fine. My boat is just sooooo hard to get on plane with a small crew on board, fuel, water, supplies.... I unfortunately haven"t tried any exotic props because I have no supply local and refuse to start ordering thousands of $$ in props.

The reason I want to go B3 is Regal switched to them for my hull in the early 2000's and the complaints went away I believe. I welcome any and all ideas, and am looking for seasoned advice from the brains on the internet.

Cheers... :canada:

 

[agallant80]

Re: Alpha 1 gen 2 / bravo 3 swap

I have the same issue though mine is caused by having a 5.0 when I should have a 5.7. I feel your pain. I decided to let it go and live with it. The thing I hate is how easy she can fall off of plain and she is a pig with a crew on board.

With that said you are looking at a huge project.

Drive $2,000 (used) to $5,990 (new) X2 $4,000-$12,000
Props $1000 X2 $2000

Just for the drives and props you are looking at $6,000-$14,000

Nevermind the bell housing, water pumps labor etc. It is going to set you back at least 10K on a boat that is worth $30K.

I would try 17P props first or look at trading the boat in on something that is configured the way you like.

 

[achris]

Re: Alpha 1 gen 2 / bravo 3 swap

Changing to Bravos is a big (and expensive) project. What I do see is your revs are too far down. You need to get those engines up to 4800 at full noise. With props only allowing 3600 or 4000 i'm surprised it planes at all. Drop down at least 4" in pitch, and ditch the Mirages... Start with a standard 3 blade (Vengence), get the revs right, then start with the exotic props.

Chris.......

 

[agallant80]

Re: Alpha 1 gen 2 / bravo 3 swap

Merc says your WOT is 4400-4800. You are way under your WOT which is bogging down the motor.
MerCruiser 4.3L | Mercury Marine

I would drop down to 17P props first, that will set you back only $300 for both of the props
You should be hitting WOT with a 19P but I don;t know what your outdrive ratio is, there may be something going on strange there.
Aluminum Prop Mercruiser Alpha Bravo One 15 x 17 | eBay

 

[racer17]

Re: Alpha 1 gen 2 / bravo 3 swap

Changing to Bravos is a big (and expensive) project. What I do see is your revs are too far down. You need to get those engines up to 4800 at full noise. With props only allowing 3600 or 4000 i'm surprised it planes at all. Drop down at least 4" in pitch, and ditch the Mirages... Start with a standard 3 blade (Vengence), get the revs right, then start with the exotic props.

Chris.......

I'm very sorry guys I've been quoting you my RPM while just staying on plane and not falling off. My WOT is different (obviously) with both different pitch props. The 19 SS will pull 4500 ish if my memory serves me...? and the 18 alum will over rev I would guess. My issue is out of the hole. It's hideous with both pitches, while the 18 alum 4 blade is better my fuel @ 4000rpm simply to stay on plane is not acceptable in my books. Other boats in my group are between 3000 and 3200 cruising on plane. This is what I want to achieve.

I would LOVE to solve or merely improve my issue and save this expensive upgrade no question!! Sorry again about the RPM/WOT misunderstanding. This back and forth conversation is good stuff !! Keep it coming, we'll sort out something I'm sure.

Best Regards. MIKE~

 

[agallant80]

Re: Alpha 1 gen 2 / bravo 3 swap

Do you know what gear ratio your outdrive is?

 

[achris]

Re: Alpha 1 gen 2 / bravo 3 swap

Do you know what gear ratio your outdrive is?

They should be 1.62:1...

 

[HT32BSX115]

Re: Alpha 1 gen 2 / bravo 3 swap

The 19 SS will pull 4500 ish if my memory serves me...?
Best Regards. MIKE~

Howdy Mike,


Just about ALL marine engine manufacturers (I/O, OB, IB) suggest a WOT RPM close to the max (4800 in your case) when loaded at a gross weight (fuel, gear, people, etc) and MSL altitude you'll typically operate.

If you're only turning 4500 at WOT, you're still in the range but your holeshot will suffer a bit.

If you use SS 4 blade props, you'll get a little better holeshot.

If you switch to Bravo III's, you'll get MUCH better holeshot and most likely better on-plane fuel consumption!!

If you want to know what ratios to use, I would check with either a REGAL dealer or a Searay dealer. I think there's more than a few models of 270/280 Searays that came with the [twin] 4.3l + Bravo III combination. (I think either 2.20:1 or 2.00:1 are the choices)

Like they said above, it'll cost you a small fortune to 'swap' drives from Alpha to Bravo.

If I was going to do that, I would look for 5.0L or 5.7MAG MPI engines and Bravo III drives on the used market and then sell your 4.3L/Alpha set ups as packages!


If you have the room (inside a heated building!!) , the time and tools for a winter project, (and you don't count your time) it *can* be worth it!

(Back in 2006, I bought a complete 1997 model year (122hrs since new) 7.4L + Bravo III "Firewall-->Forward" setup out of a damaged boat for $5K
I removed my 1987 OMG 460 King Kobra with all the fix'ns and replaced it with the Mercruiser 454+B3 [plus added closed cooling]

I then (over the next 3 or 4 years sold all the OMC 'stuff' for a total of $3500+ ) I got lucky I presume, selling all that junk!!!

You would get a pretty good price for your 4.3L + Alpha drives, since they are used in so many different boats and are a very desirable repower choice for older boats......




However, If you pay someone to do it, it WILL NOT be worth it.


If that's the case, you'll probably be much better off just selling the boat and getting another that better meets your needs......



Cheers,



Rick

 

[thumpar]

Re: Alpha 1 gen 2 / bravo 3 swap

You are still going to have the same amount of power with the B3. It would have better "traction" but no HP increase. It would probably be cheaper and a lot easier to put in 5.7l engines.

 

[DeepBlue2010]

Re: Alpha 1 gen 2 / bravo 3 swap

^^^ This is a good point. When the factory changed to B3, did they keep the 4.3 or changed it to 5.7. If they kept the 4.3 did they use the carbuerated version or FI? I don't see changing the outdrive and continue to supply the same HP to it as a valid solution for your problem but I could be wrong.

 

[HT32BSX115]

Re: Alpha 1 gen 2 / bravo 3 swap

^^^ This is a good point. When the factory changed to B3, did they keep the 4.3 or changed it to 5.7. If they kept the 4.3 did they use the carbuerated version or FI? I don't see changing the outdrive and continue to supply the same HP to it as a valid solution for your problem but I could be wrong.

It would be a performance increase due to the much lower prop slip. So it would translate into a better hole-shot and a tad better on-plane efficiency.

But if I was doing it, I would do either 5.0L or 5.7L EFI engines + Bravo III's.

 

[Fun Times]

Re: Alpha 1 gen 2 / bravo 3 swap

In the second link below would a good guide for what gear ratios you should use with what engine HP you have.

Your engine is the 190 HP so you would want to use a 2.43:1 ratio. Had you had the 220 HP 4.3 MPI, you'd use the 2.2:1.

Mercruiser 4.3L Engine

Click on each engine your interested in knowing about the specifications,
Mercruiser Engine

 

[racer17]

Re: Alpha 1 gen 2 / bravo 3 swap

Thats the stuff I'm looking for.... Thanks a million!

 

[racer17]

Re: Alpha 1 gen 2 / bravo 3 swap

^^^ This is a good point. When the factory changed to B3, did they keep the 4.3 or changed it to 5.7. If they kept the 4.3 did they use the carbuerated version or FI? I don't see changing the outdrive and continue to supply the same HP to it as a valid solution for your problem but I could be wrong.

I have an answer for everything.... lol.

Regal kept the 4.3L but updated to MPI. I added 4bbl domes and Edelbrock 600CFM carbs to mine in hopes to gain a bit of performance and improve my plane issue.... all it did was cost me more $$$ and fuel... DOH!

I spoke to the propulsion engineer from Regal (30 years on the job) about putting 5.7L in when I was rebuilding my carborated 4.3's (two months after I bought it my starboard engine threw two rods into my engine bay via the oil pan... that was pleasant, NOT) . He had never heard of anyone doing this to my hull but admitted they would bolt right in. He did however take a couple days to do some calculations and advised me against it. Reasons : 1) said the boat would porpus due to the extra weight in the stern 2) the water would sit dangerously close to the intake due to the extra weight in the stern sitting lower in the water.

So I took his advice and rebuilt both engines and made sure they were equal in power and performance. He taught me a cool trick to measure if you have a weak engine... from neutral mash one throttle and note how much RPM it will pull... back to neutral, stop, mash the other throttle and note that RPM. If they are equal your running two equally tuned engines... if not you'll know which engine to fix.

Anyway, I realize how much work and $$$ this project is and am fully capable to perform the swap (when Canada thaws...lol) but second guessing the expense. Keep the ideas coming please...

Does anyone know of an aftermarket prop that would offer above average thrust out of the hole and not run high RPM on plane??

 

[Fun Times]

Re: Alpha 1 gen 2 / bravo 3 swap

The bravo T/A should bolt right up with the gen 2 T/A, and if not it would need two holes drilled at the top.

You will need a bravo engine coupler, engine mounted sea water pump, a jumper plug where the shift interrupt switch plugs in, a bravo shift plate, maybe a bravo ICM, I believe the smallest set of Bravo 3 props they make 20p @$1200.00+, bravo 3 prop tools.

Your oil bottle you have now should work fine. You may need a new fitting and longer hose though.

Do you have your engine, T/A and drive serial numbers? also if you buy new or old Bravo T/A's and drives, we'll need the year/serial number to get you part numbers for you.

That all the stuff that comes to mind off the top of my head right now. If I can think of anymore later on, i'll add it here to this post.

 

[racer17]

Re: Alpha 1 gen 2 / bravo 3 swap

The bravo T/A should bolt right up with the gen 2 T/A, and if not it would need two holes drilled at the top.

You will need a bravo engine coupler, engine mounted sea water pump, a jumper plug where the shift interrupt switch plugs in, a bravo shift plate, maybe a bravo ICM, I believe the smallest set of Bravo 3 props they make 20p @$1200.00+, bravo 3 prop tools.

Your oil bottle you have now should work fine. You may need a new fitting and longer hose though.

Do you have your engine, T/A and drive serial numbers? also if you buy new or old Bravo T/A's and drives, we'll need the year/serial number to get you part numbers for you.

That all the stuff that comes to mind off the top of my head right now. If I can think of anymore later on, i'll add it here to this post.

Thanks for the info.... this is the kind of stuff I'm looking for. Can I ask what T/A stands for? lol. I'm a bit of a newbie...

 

[thumpar]

Re: Alpha 1 gen 2 / bravo 3 swap

Transom assembly.