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5.0 mpi-5.7 mpi

Old 03-18-2014, 08:04 PM
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look up the mercruiser reman on the 383 it is a complete drop in with the computer completely reman by Mercruiser with a warranty and more hp and torque than the 6.2 / 377 CID.
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Old 03-18-2014, 09:45 PM
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5.0 usually takes same ratio as 5.7. unless it is a 1.62 some builders put in bigger boats with smaller motors. with either ratio you are probably going up 2 inches of pitch. and be ok with that drive. a dancer is no speed boat. you would need previously mentioned 575 sc to go up 4 inches. all the power in the world will not noticeably change that hulls performance characteristics. it will make it not feel underpowered though.

Last edited by dereknkathy; 03-18-2014 at 09:47 PM.
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Old 03-18-2014, 09:54 PM
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I've already stated I know it will never perform. The point of not feeling underpowered is what he is looking for .Doesn't a 6.2 run a 1.5 to 1 ratio also ?Boat has 5.0 bravo setup .He doesn't want weight of bb
Originally Posted by dereknkathy
5.0 usually takes same ratio as 5.7. unless it is a 1.62 some builders put in bigger boats with smaller motors. with either ratio you are probably going up 2 inches of pitch. and be ok with that drive. a dancer is no speed boat. you would need previously mentioned 575 sc to go up 4 inches. all the power in the world will not noticeably change that hulls performance characteristics. it will make it not feel underpowered though.
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Old 03-18-2014, 11:03 PM
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2004 only lists the Bravo apps for the 6.2 no alpha apps for the 6.2. Alpha stopped on the 350 MAG 300 hp engine. I have the OEM Mercruiser 2004 dealer handbook in front of me now and double checking plus dealer ordering on new boats in 2004. I am Mercruiser dealer and had new boats at that timeframe. Also confirmed it 3 times now with 2004 brand knowledge product handbook Mercruiser guide.

The 5.0 MPI 260 hp alpha outdrive the primary gear ratio was 1.62 and the 1.47 was optional so you have check which gear ratio you have.

The 5.7 carb 250 hp alpha outdrive used a 1.62 as the primary gear ratio.
the 5.7 MPI MAG 300 hp used a 1.47 alpha outdrive as the primary gear ratio. There was no Mercruiser engines in between what I just mentioned for 2004.

the 5.7 MPI Horizon 300 hp only used a bravo app also no alpha app on this model either. Bravo was 1.50 for the primary gear ratio.

The MX 6.2 320 hp 377 CID again only Bravo app used a 1.65 gear ratio as the primary.

the MX 6.2 320 hp Horizon only Bravo app used the same 1.65 gear ratio.

Now the bravo drives between the 5.0 MPI 260 hp and the 5.7 MPI MAG primary gear ratio was 1.50 and 5.0 MPI 260 hp primary gear ratio was 1.65 again Bravo 1 drive apps and primary ratios. Of course their is the optional and high altitude gear ratios but that's something you are going to have to check out for yourself.

Prop pitch will have to be changed regardless no matter how or what you put in their unless the same app. I understand that. My point was gear ratio's moves the rpm in which moves your torque curve. You want to keep your highest torque number around 3200 to 3600 rpms.

If anyone wants to disput this PLEASE call Mercruiser as this info is from all their dealer product books and new boat orders hand out materials. I know how everyone up here thinks they have better info. If you need Mercruiser's phone number I will gladly give it to you. Your swap over is not just a easy bolt in / easy plug and play / easy lets go boating.

We do 30 to 60 repowers per year with new or reman motors. Mostly stock Mercruiser and Volvo Penta. Anyone have more experience lets hear it.

Last edited by BUP; 03-18-2014 at 11:31 PM.
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Old 03-18-2014, 11:17 PM
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Originally Posted by motor
I've already stated I know it will never perform. The point of not feeling underpowered is what he is looking for .Doesn't a 6.2 run a 1.5 to 1 ratio also ?Boat has 5.0 bravo setup .He doesn't want weight of bb
i was joking about the big block, and a 330 hp454 wouldn't be a bad choice but 575 sc? no way! no, what i am saying is it will be fine with that drive regardless of ratio. 1.47 to 1.62 is 10%. 2 inches of pitch is roughly 10%. if a 1.5 drive you are not running much more than a 15 or 16 prop. with 1.62 drive 17 mebbe 19 tops. most likely 17. do motor upgrade. go 2 inches bigger on the prop. down the road consider changing drive ratio but won't be much diff in cruise-fuel consumption either way. boat may be a lil better on fuel cuz it isn't working so hard just to do 25. i took 350 out of 79 24 dancer and put 406 small block in. very little change. but i wish i still had the 406 now.
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Old 03-19-2014, 12:54 AM
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Originally Posted by BUP
next anytime CID = cubic inch displacement gets bigger the need for more air to enter & exit the engine. More air always = more fuel. Of course it will start and run with any computer installed on it but you want it to run properly and looking for an upgrade in performance. Correct ?

Next the 5.0 and the 5.7 do not share the same cylinder heads nor the same intake valve. 5.7 has an intake valve that is slightly larger - larger intake valve means more air & fuel.

Also the bore of the 5.7 is 4.00 inches compared to 5.0 bore is 3.74 inches. Motor 101 tells me the stock 5.7 compared (apples to apples) to the 5.0 is the 5.7 needs more fuel as it is a heavier breather than the 5.0. Again more air always means more fuel to achieve proper air / fuel ratio's.
The problem is the Merc motors are set fat to begin with. I've done back to back testing between a stock 350 Mag EFI/MP and then modified it (stroke, cam, heads, bigger valves, displacement, compression) keeping the bone stock tune and injectors and the bigger modified motor was not lean. Was it perfect? No. Would the layman even notice the difference standing next to the motor idling? No. Would I recommend using a stock tune on modified motor as a long term solution? No. Point is you can modify a motor and get it up and running with the stock tune.

MEFI maybe technically going backwards but it has infinitely more access in the tuning department. If you need the smartcraft, DTS etc, then by all means stick with the 555.

The MEFIs were utilized on TBI and MP motors as far back as 1995.

A crate motor drop in is obviously the easiest route, but not always the cheapest.
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Old 03-19-2014, 10:16 AM
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MEFI 1 for Mercruiser started in 1993. It is long gone. If anyone is looking for the cheapest route just drop in a carb app. You can buy a 5.7 bobtail for around 3500 bucks brand new with a warranty. Again just saying, no tune - no fuel injectors - no remapping.
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Old 03-19-2014, 01:41 PM
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I have the Bravo1X diesel drives with 1:65 ratio in my boat behind MX 6.2 Mercs. Engine turned 5150 with B1 26P props that I found were less than 25P on the gauge, engine now turns 5000 @ WOT with props tuned to true 26P. . I'd recommend to the OP 6.2 takeout or reman 383.
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