Swapping GM petrol engine for a diesel

[Cresco750]

Just considering future options here, but if I were to swap my Mercruiser 228 engine for a marinized Toyota diesel engine (or similar), how would I get on with shifting gear on my MC1 drive assuming that the shift interrupt will no longer function?

Any other "gotcha's" when it comes to swapping a petrol engine for a diesel?

 

[Don S]

Re: Swapping GM petrol engine for a diesel

How do you plan on attaching this Toyoto diesel to the outdrive? There is no couplers, or flywheel covers with the rear engine mounts designed for that engine,

 

[Cresco750]

Re: Swapping GM petrol engine for a diesel

I haven't looked into it in any depth, however there is a local company which advertises such a conversion, ie a marinized Toyota engine, which they claim they have matched to a stern drive. I have seen a picture where it appears they have mated a Mercruiser drive coupler to the flywheel.
Can you please explain what you mean by flywheel covers and engine mounts? I can't see that flywheel needs to be covered? And this outfit evidently has mounts coming off from another location? I'm not expecting it to be a 'drop in' installation.

 

[Capt Ken]

Re: Swapping GM petrol engine for a diesel

Even if you did get it in the boat, the drive would not disengage the gears. You would need a Bravo drive.

 

[Cresco750]

Re: Swapping GM petrol engine for a diesel

Ah ha, that's what I needed to know. Thanks.

 

[elkhunter338]

Re: Swapping GM petrol engine for a diesel

My 140 has no interrupter switch and it shifts fine if the rpms are under 800 rpm and you do not tie her to the dock and then try and shift it. If you are moving through the water at idle it shifts fine. Just not tied to the dock, but who needs to put it in gear tied to the dock. I never have. What do the guys say that make the conversion. Do these guys have a web site who make the conversion. A little diesel would be good.

 

[Don S]

Re: Swapping GM petrol engine for a diesel

My 140 has no interrupter switch and it shifts fine if the rpms are under 800 rpm and you do not tie her to the dock and then try and shift it.

Then your engine probably idles so rough that it doesn't need the shift interrupt switch. Or your drive shift dogs are about shot. Going through the water or tied to a dock, there should be enough resistance to activate a shift interrupt switch.

You also may not know how easy they are supposed to shift.

 

[Bondo]

Re: Swapping GM petrol engine for a diesel

I haven't looked into it in any depth, however there is a local company which advertises such a conversion, ie a marinized Toyota engine, which they claim they have matched to a stern drive. I have seen a picture where it appears they have mated a Mercruiser drive coupler to the flywheel.
Can you please explain what you mean by flywheel covers and engine mounts? I can't see that flywheel needs to be covered? And this outfit evidently has mounts coming off from another location? I'm not expecting it to be a 'drop in' installation.

Ayuh,.... I'd love to hear 'bout it,.... got a link,..??

Those are the folks, you should be askin' these questions to....

 

[Cresco750]

Re: Swapping GM petrol engine for a diesel

They were advertising on a local on-line auction site but nothing listed currently. Here is a link to one of their earlier auctions:

diesel turbo 3ltr,marinised dyno tuned | Trade Me

 

[Cresco750]

Re: Swapping GM petrol engine for a diesel

And this one....

Diesel turbo fully marinised dynoed 270hp@3000rpm | Trade Me

 

[Bondo]

Re: Swapping GM petrol engine for a diesel

They were advertising on a local on-line auction site but nothing listed currently. Here is a link to one of their earlier auctions:

diesel turbo 3ltr,marinised dyno tuned | Trade Me

Ayuh,... In picture #11, it appears to be rigged for a Mercruiser....

but again, ask Those folks,...
We're 1/2 the world away, 'n don't see 'em on this side of the planet,... ...... Unfortunately.....

 

[HT32BSX115]

Re: Swapping GM petrol engine for a diesel

And this one....

Diesel turbo fully marinised dynoed 270hp@3000rpm | Trade Me

Nice.

But I wouldn't bolt an Alpha to that engine. I would want a Bravo IIIx and it would have to be a rather low numerical ratio gear model. Mine is a 1.81:1.......... and that might not be low enough.

I think there's a 1.65:1 Bravo III for diesels.

Depending on hull (if planing) type & weight etc, the above combination with 26p props would possibly do about 40 MPH with the above engine at 3000 RPM.......

You wouldn't of course run that engine at WOT all the time (or very often at all)

 

[Cresco750]

Re: Swapping GM petrol engine for a diesel

I was leaning more towards the smaller, 3 liter engine for my application (22 foot plaining launch), more because of weight than anything. But again, no use if I can't mate it to my existing MC1 drive.

 

[Cresco750]

Re: Swapping GM petrol engine for a diesel

Just out of interest, how do you think the 185hp/ 333nm torque of this Diesel engine would compare to, say my existing GM305 petrol engine, assuming that the Diesel engine was also optimumly set up with a stern leg? Is "horsepower" horsepower, irrespective of what sort of engine produces it, and therefor the 185hp of the diesel only doing to deliver 80% of the performance that my 228hp V8 petrol engine does? Or does it come down to torque?

I guess I'll have to wait until my MC1 drive rots off the back of the boat before I can justify the swap

 

[QC]

Re: Swapping GM petrol engine for a diesel

Top speed is horsepower. Buuutttt, horsepower comes from the combination of torque and RPM. Ultimately, if you could gear and wheel it properly, the 185 bhp will have 19% less output. and probably around 160 at the propshaft as they are rated today. It will be slower.

And it is not newton meters, they write lb/ft on the add. Your current engine develops around 285 lb ft. at say 4200 RPM. The rule on Alpha (not sure about MC1) is max 300 bhp, so if you had a 300 petrol engine, at the same RPM that would be 375 lb/ft, so I am thinking the drive could handle it if you could shift it.

 

[HT32BSX115]

Re: Swapping GM petrol engine for a diesel

The rule on Alpha (not sure about MC1) is max 300 bhp, so if you had a 300 petrol engine, at the same RPM that would be 375 lb/ft, so I am thinking the drive could handle it if you could shift it.

The service manual I had for my old 150 hp (6cyl) + MC-1 only showed engines up to the GM 230-6cyl with the MC-1..

(in 1966) They went to the Mercruiser #2 drive starting with the 292 cu-in 6 and above. The optional 409 V-8 (310 crank hp) was offered with the MC-II drive.

Although I knew a few people that had 283/327 SBC Chevy engines in front of a MC-1 drive, I don't think they survived long....

I know Mercruiser does have a current small diesel engine mated to the Alpha. Here's an example of a used one......

I don't know how they handle shift interrupt (ing) With an Alpha....... Most newer diesels are electronic and/or common rail engines and may have a way to pulse the injection system sufficiently to briefly interrupt torque but not for long enough to stall the engine.

 

[QC]

Re: Swapping GM petrol engine for a diesel

SEI swap?

 

[Fishermark]

Re: Swapping GM petrol engine for a diesel

Whether it is wise or cost effective or not I can't answer - but it is my understanding the the diesels mated to an Alpha drive are able to shift due to the inherently rough idle of a diesel. It allows the shift dogs to "unlock" and shift out of gear without the usual shift interrupt required.