5.0l Efi 1998 bravo. What transom and drive ratio do I need

Bennettrj

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I have a 1998 Mercruiser 5.0 bravo engine that I am fitting in my 18ft regal speedboat that originally had a 3.0 v6 engine and drive I have the engine and have been offered a brand new never fitted transom assembly and gimble with rams it's a mercruiser alpha one gen 2 transom serial no.ow778135. Can I run my bravo Efi engine ontonthis transom plate *** and what ratio leg do I require ??? Can I run an alpha leg too a bravo engine as I believe my engine has a raw water pump built in can I use the alpha leg with impeller too feed bravo pump ?? Lots of questions I know but I am new too Mercruiser inboard engines but unlearn fast just need some guidance many thanks
 

Bondo

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Re: 5.0l Efi 1998 bravo. What transom and drive ratio do I need

I have a 1998 Mercruiser 5.0 bravo engine that I am fitting in my 18ft regal speedboat that originally had a 3.0 v6 engine and drive I have the engine and have been offered a brand new never fitted transom assembly and gimble with rams it's a mercruiser alpha one gen 2 transom serial no.ow778135. Can I run my bravo Efi engine ontonthis transom plate *** and what ratio leg do I require ??? Can I run an alpha leg too a bravo engine as I believe my engine has a raw water pump built in can I use the alpha leg with impeller too feed bravo pump ?? Lots of questions I know but I am new too Mercruiser inboard engines but unlearn fast just need some guidance many thanks

Ayuh,.... Welcome Aboard,.... Time spent in the Adults Only section at the top of the forum is a Geat place for learnin',...

Yer gonna need a different 'puter to drive the Efi/ ignition,....
You can use Either raw water pump, but not both together,...
The rear motor mounts match the Alpha transom, so that, 'n the drive don't care,...
'n you'll want a 1.50:1 ratio outdrive,...
 

thumpar

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Re: 5.0l Efi 1998 bravo. What transom and drive ratio do I need

If you stick with an Alpha drive you will need to figure out something for the shift interrupt. Bravos don't have them.
 
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Re: 5.0l Efi 1998 bravo. What transom and drive ratio do I need

Most places online say with the 5.0 EFI to use the 1.47 gears. But Regal put in 1.62 gears from the factory on their 21' with that engine so either ratio should work fine. I would recommend the 1.47 though
 

Fun Times

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Re: 5.0l Efi 1998 bravo. What transom and drive ratio do I need

Hi there, welcome to iboats! Is there any chance you can get ahold of and post the engine serial number of both your old and new engine so we can have a look and post a link of the differentness of what needs to be changed between the engines?
 

Bennettrj

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Re: 5.0l Efi 1998 bravo. What transom and drive ratio do I need

Hi there, welcome to iboats! Is there any chance you can get ahold of and post the engine serial number of both your old and new engine so we can have a look and post a link of the differentness of what needs to be changed between the engines?

My new engine is a 5.0 Efi 1998. It is a complete turnkey engine package it has been running in boat but without transom assembly engine number

4m32027n1 bravo
And transom is an alpha one gen 2 ow778135.

I have no drive leg at the moment as I am unsure of ratio and which drive to get. May need advice on thru hull water pick up for bravo engine ??? Is this the way forward ???
 

Fun Times

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Re: 5.0l Efi 1998 bravo. What transom and drive ratio do I need

My new engine is a 5.0 Efi 1998. It is a complete turnkey engine package it has been running in boat but without transom assembly engine number
Without the engine serial number it's more of a guess vs confident information being provided. But if your sure it's an 1998 then you should have the MEFI-1 or 2 ECM and it should work for either drive system you run.:) Here is your parts catalog. http://www.mercruiserparts.com/selectSerailRange.asp?doc_nbr=5.0L+EFI+++++GM+305+V-8++1998

If you look through the parts list, you will see the notes on the right hand side of the part numbers, some will say alpha and some will say bravo. That should help tell you what you may need.

From your first post I can't tell if you originally had a 4 cylinder or 6 cylinder engine as you listed both. 3.0l is a 4 cylinder while the 4.3l is a V6. If you still have the original engine, You may have some parts already to help make the switch.

Do you have or what happened to the drive from the original engine combo? If you still have it look for the gear ratio and serial number.

4m32027n1 bravo
This is not exactly a mercruiser serial number. If it was it would look more like 0M320271 which would put the manufacture year right around 2002ish and putting this serial number all together would have made this an MERCRUISER 5.0L ALPHA carbureted engine. From what you have mentioned so far, I don't believe you have that engine combo.

And transom is an alpha one gen 2 0W778135.
This is a good number as it comes up as an MERCRUISER ALPHA TRANSOM W/ENGINE ALPHA TRANSOM. Here's the parts catalog for it, http://www.mercruiserparts.com/selectDocs.asp?doc_nbr=809759+98

I have no drive leg at the moment as I am unsure of ratio and which drive to get.
1.50:1 or 1.47:1 ratio outdrive should work best with the 5.0 efi engine/boat size you have. Newer model drives are the 1.47:1.

Not sure if you have access to them where you are but you may want to check into a company called sterndrive engineering as they have more affordable new stern drives. iboats sells them as well.:)

May need advice on thru hull water pick up for bravo engine ??? Is this the way forward ???
Yeah it's not really recommended to run both alpha and bravo impellers together. It's one or the other. If you don't want to run the bravo impeller housing by way of adding a thru hull water pick up, you could just remove the engine mounted water pump and install one water hose from the transom to the oil cooler. See item numbers 10 and 11. You'll remove items 26 and 27. If you have a serpentine belt, You may need a new smaller belt as well. http://www.mercruiserparts.com/Show...r=2704&bnbr=130&bdesc=STANDARD+COOLING+SYSTEM

If you plan to run or add a closed cooling system (antifreeze) you will need the engine mounted bravo sea water pump system with a thru hull water pick up for best results.

Some items you will need to make the switch are:
1) Alpha engine coupler and hardware.
2) Alpha shift plate assembly with interrupter switch.
3) The drive oil reservoir components may be of different styles as there was a transition year in 98.
4) Water hoses mentioned above.
5) Exhaust Y pipe?
 
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