Engine swap from Mercruiser 5.7L V8 to Chevy 6.5L V8 Diesel Turbo.-gctid826358

[Guest]

Hi Everyone,

I have removed my Mercruiser 5.7L v8 petrol engine with Alpha 1 drive to fit a Chevy 6.5L v8 Turbo Diesel.

I have a few things to modify and alter.

My first issue is the outdrive, it always causes arguments. so here goes. This is my theory:

The Diesel has less RPM at WOT than the petrol so top speed will be reduced. I think the leg will cope if I don't change the prop size. Same load.

If I change the prop size to a larger one to gain my speed back, the outdrive WILL fail.

Also the momentary cut out switch to get out of gear, will not work with this diesel but my understanding is coz the lower idle speed of the diesel, getting out of gear is ok.

The engine is going to run a closed loop cooling with a belt driven pump for the salt water flow through the heat exchanger.

Exhaust and salt water exiting through a flap at the rear.

I can't make my mind up whether to take water in through the hull or outdrive. Comments please.

Flywheel and bell housing from petrol bolts straight on and fits fine. Done it already.

ALL THESE THINGS SEEMED TO BE WORKING OUT OK TILL I FOUND A BRAVO 2 WITH GIMBLE HOUSING.

So now all changes.

I am not familiar with the bravo 2 drive so I need some help with these questions please:

1. Is the input shaft to the bravo 2 outdrive the same diameter as an Alpha 1 and splines?

2. I believe there is no impeller on a bravo 2, will a belt driven pump suffice?

3. Are the engine mounting positions on the gimble housing in the engine bay in the same position as an Alpha 1?

4. I believe the bolt holes line up but 2 extra holes need to be drilled for gimble housing. Is this correct?

5. Can you think of anything other than prop sizes that could cause an issue?

Answers on a postcard or a piece of toilet paper please

Thanks for your comments in advance, please be gentle.

[builderdude]

What are the hp and torque ratings of the 6.2?? Even though it will idle at a lower rpm than the gasser the torque curve of the diesel may not be nice to the alpha. IMO the Bravo drive hands down, make sure the gear ratio is correct for your new set up. Personally I think pulling water through the leg would work fine, helps cool the drive but a seperate through hull with strainer can be added.

[Nauti_Mike]

I don't think the Alpha will hold up to the torque of the diesel.

Bravo uses a different coupler, don't know what the difference is.

Yes a belt raw water pump will work as long as it flows what is required for the diesel. All Bravos use a belt driven pump.

I believe you are correct on the transom assembly, two additional bolt holes. Not sure about the rear mount location between them.

[Pcpete]

Bravo!
..........

[Ruffryder]

"GTO_paul" post=826358 wrote:
Hi Everyone,

I have removed my Mercruiser 5.7L v8 petrol engine with Alpha 1 drive to fit a Chevy 6.5L v8 Turbo Diesel.

I have a few things to modify and alter.

My first issue is the outdrive, it always causes arguments. so here goes. This is my theory:

The Diesel has less RPM at WOT than the petrol so top speed will be reduced. I think the leg will cope if I don't change the prop size. Same load.

If I change the prop size to a larger one to gain my speed back, the outdrive WILL fail.

Also the momentary cut out switch to get out of gear, will not work with this diesel but my understanding is coz the lower idle speed of the diesel, getting out of gear is ok.

The engine is going to run a closed loop cooling with a belt driven pump for the salt water flow through the heat exchanger.

Exhaust and salt water exiting through a flap at the rear.

I can't make my mind up whether to take water in through the hull or outdrive. Comments please.

Flywheel and bell housing from petrol bolts straight on and fits fine. Done it already.

ALL THESE THINGS SEEMED TO BE WORKING OUT OK TILL I FOUND A BRAVO 2 WITH GIMBLE HOUSING.

So now all changes.

I am not familiar with the bravo 2 drive so I need some help with these questions please:

1. Is the input shaft to the bravo 2 outdrive the same diameter as an Alpha 1 and splines?

[color]blue wrote:
Yes[/color]

2. I believe there is no impeller on a bravo 2, will a belt driven pump suffice?

[color]blue wrote:
yes[/color]

3. Are the engine mounting positions on the gimble housing in the engine bay in the same position as an Alpha 1?

[color]purple wrote:
yes[/color]

4. I believe the bolt holes line up but 2 extra holes need to be drilled for gimble housing. Is this correct?

5. Can you think of anything other than prop sizes that could cause an issue?

Answers on a postcard or a piece of toilet paper please

Thanks for your comments in advance, please be gentle.

Truck engine or is this a peninsula engine?

Chevy 6.5 turbo should put out about 215 HP, but modified to 320HP even more.

[fritzman]

Adding my 2 cent. My preferred drive is the Bravo III 220 ratio, as for fitting the Bravo ii yes it will all fit you may need a spacer on the bell housing to clear the steering on my set up the exhaust going to the turbo was tight. Did you change the motor mounts?
Water intake through the hull is better 1.5 inch intake, from the drive it is restricted to 3/4 at the drive. What is the marine conversion - exhaust, heat exchangers and so on?