Mercruiser 4.5ltr inboard

zippyzip

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Jul 22, 2015
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Hi Guys, I want to fit a Mercruiser 4.5MPI in a classic wooden speedboat, but it has to be on a prop shaft and a P bracket. Does anyone know if this is possible? if so what gearbox will fit and bell housing etc. Also any ideas on seawater pump configurations?
 

Bondo

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Ayuh,.... Welcome Aboard,.... There ain't no 4.5l Merc motors,..... 4.3l, yes,....

Donno what a P bracket is,....

You can rig a Merc motor to an Inboard drive, but you've gotta pick which driveline ya want,.....

'n sea water pumps can be had in many configurations,.....
Depends on what yer needin',....
 

Scott Danforth

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Bondo, its the new V6 for 2015.

zippy, your best bet is contact Mercruiser directly
 

zippyzip

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What do you mean by driveline? are you talking about the output angle of the gearbox?
 

Fun Times

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Ayuh,.... Welcome Aboard,.... There ain't no 4.5l Merc motors,..... 4.3l, yes,...
There is now my friend :),https://www.mercurymarine.com/en/us/...ercruiser/45l/

This engine is so new that you may want to try Contacting MerCruiser Customer Assistance for other options that may be coming available such as sea water pumps that would fit the inboards. But looking around on Merc website some more it seems that this engine package will fit the bravo drives so that means you should be able to buy the engine with the sea water pump already installed on the engine from new.:cool:

https://www.mercurymarine.com/en/us/...specifications
https://www.mercurymarine.com/en/us/contact

Just noticed that there are two HP versions of this new engine, 200 HP and 250 HP. 200 only fits the Alpha drive and 250 HP fits Alpha and the bravos drives.

Here's the list of engine models so far,
1998+ MERCRUISER , 4.5L
For a parts catalog of this engine, you could search one of the model numbers online like this for example, http://www.crowleymarine.com/mercury-outboard/16591.cfm?mdl=QLI71Y
40450020A ALPHA MPI
40450021A ALPHA MPI
40450022A ALPHA MPI
40450023A ALPHA MPI
40450024A ALPHA MPI
40450025A ALPHA MPI
40450026A ALPHA MPI
40450027A ALPHA MPI
40450028A ALPHA MPI
40450029A ALPHA MPI
40450030A ALPHA MPI
40450031A ALPHA MPI
40450032A ALPHA MPI
40450033A ALPHA MPI
40450034A ALPHA MPI
40450035A ALPHA MPI
40450036A ALPHA MPI
40450037A ALPHA MPI
40450038A ALPHA MPI
40450039A ALPHA MPI
40450040A ALPHA MPI
40450041A ALPHA MPI
40450042A ALPHA MPI
40450043A ALPHA MPI
40450044A BRAVO MPI
40450045A BRAVO MPI
40450046A BRAVO MPI
40450047A BRAVO MPI
40450048A BRAVO MPI
40450049A BRAVO MPI
40450050A BR DTS MPI
40450051A BR DTS MPI
40450052A BR DTS MPI
40450053A BR DTS MPI
40450054A BR DTS MPI
40450055A BR DTS MPI
40450056A BRAVO MPI
40450057A BRAVO MPI
40450058A BRAVO MPI
40450059A BRAVO MPI
40450060A BRAVO MPI
40450061A BRAVO MPI
40450062A BR DTS MPI
40450063A BR DTS MPI
40450064A BR DTS MPI
40450065A BR DTS MPI
40450066A BR DTS MPI
40450067A BR DTS MPI
40450069A ALPHA MPI
40450070A ALPHA MPI
40450071A BRAVO MPI
40450072A BR DTS MPI
40450073A ALPHA MPI
40450074A ALPHA MPI
40450075A BRAVO MPI
40450076A BR DTS MPI
40450077A BRAVO MPI
40450078A BR DTS MPI
40450079A BRAVO MPI
40450080A BR DTS MPI
40450081A BR DTS MPI
40450082A BR DTS MPI
 
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zippyzip

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Jul 22, 2015
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Funnily enough i am a Mercruiser dealer! But over here in the UK we just run them on outdrives, so i have very little knowledge of running them on a gearbox!
 

zippyzip

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Jul 22, 2015
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The UK importer says it cant be done but i cant see why we cant do it? Gearbox, bell housing and seawater pump, was hoping someone might have done it already!
 

Fun Times

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The UK importer says it cant be done but i cant see why we cant do it? Gearbox, bell housing and seawater pump, was hoping someone might have done it already!
With an open mind, I'm sure you can do it.

Let us know how it turns out, good luck.:)
 

Bondo

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Ayuh,..... My learnin' moment of the day,.....

Wonder what flywheel cover bolt pattern was used with this new Mercruiser motor,..??

Wonder whether they were smart enough to stick with the standard Chevy pattern,..??

If they Did,..... Buildin' an Inboard, oughta be a piece of cake, with off the shelf parts,......
 
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Bt Doctur

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i know the 4.3, 5.0, 5.7, 8.1 all share the same bolt pattern so with the proper inboard housing any inboard trans can fit
 

Bondo

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i know the 4.3, 5.0, 5.7, 8.1 all share the same bolt pattern so with the proper inboard housing any inboard trans can fit

Ayuh,..... All the Chevy motor We play with use the same bolt pattern,.....

The BBCs have an extra hole top center, but still the same bolt pattern,...
 

Scott Danforth

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If I remember, I will send an email to the designer that worked on the 4.5 to get the flywhee housing bolt pattern. He used to work for me in a prior life.
 

Scott Danforth

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Per Jose, its designed as a direct drop in replacement for the GM motors. So bolting to any trans adapter will be easy
 

Bondo

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Per Jose, its designed as a direct drop in replacement for the GM motors. So bolting to any trans adapter will be easy

Ayuh,.... That's Good news, 'n a smart move on Merc's part,....
 
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