Engine Upgrade

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Mr T

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I am considering purchasing a twin petrol engined cruiser and wondering if anyone has any advice on swaping the petrol units for deisel. I understand that it is not just a simple swap of engines but a signiicant amount of work that will m=need to be undertaken
 
I believe the general opinion is it's not economically viable and you would be better off buying a boat with diesel engines .
 
Drives or drive gearbox ratios will likely need changing too, twin engined boat to repower with new+drives probably upwards of £80K depending on engines and power required! It won't just be mechanical as if engines are old, transom shields etc probably different and engine beds etc likely to need alteration, so shipwright and engineering work involved. New engines likely to need dealer installation to validate warranty etc...
 
Hi

There is a chap somewhere in Tyneside (from memory) who marinised BMW and Mercedes 6cyl diesels.
He can make the correct adjustment to suit your bell housing and drive, given the usual mercruiser and VP drives. He looks also to be able to match the exhaust, making them a direct fit. Last I saw, these were only a few thousand pounds to buy.

Normally going from petrol to diesel means adjusting gear ratios....that said, from the engines this guy is using, the rpms etc are fairly well matched to your average GM based V6 or V8 engine.
Comparison
Mercedes 3.0d 6cyl runs max hp @4800 rpm, for example (250hp)
Mercruiser 5.7l V8 4 barrel carb runs max hp between 4400-4800 rpm and 260hp.

Fairly similar. Not quite as simple as the above, but not far off. The guy shows up on eBay offering engines and engine/drive packages fairly often.
Atb.
 
Why oh why do people insist on painting engines without masking off the ancillaries? An hour with a roll of masking tape would make all the difference. Makes you wonder about the rest of the attention to detail of the oily bits inside, or is it just a used engine from the breakers with a new paint job?
 
No matter how desperate or skint you are do not go there.
For reasons why search this forum.
If you must empty your pockets and daftly burden yourself with somebody elses money pit folly of a boat with petrols and outdrives, just buy and use as is.
Just hope there is some other mug out there who will buy it off you, especially when you look them in the eye and assure them it is very reliable and costs mere pennies to run. !
 
In spite of all the doom sayers, it's perfectly possible if you go into it with your eyes open.
1st comment about being cheaper to buy a diesel boat in the first place is probably correct tho. It CAN be an option if you already have a petrol engined boat with i/2 dud engines that is otherwise pretty much worthless.
However it will need a reasonable amount of engineering skill to do it.
Lancing marine used to sell reasonably priced diesel engines to suit 290 outdrives.
Just be aware that its not just the engine swap
Fuel lines, Props, exhaust and cooling may all need altering, but its not impossible.
I managed to reengine a 26' cruiser for ~£25k, which became a superb boat.
Also dont expect to get back the spend.... its all about usability rather than making money.
 
With all the gloom about Diesel as a fuel where will the leglislation be going in this regard. Is Diesel actually the way to go ?

Dennis
 
I agree with the forum. Even if your engines are knackered it would be easier to rebuild or replace with reconditioned petrol. Diesels can eat your outdrives and your transom.
Perhaps Brexit will affect the red diesel price and petrol will be the future. Or better still convert to electric and be the future
 
rafiki_ said:
Diesel and petrol will be with us a long time, at least to the end of this century. How long are you planning to live? :)
Click to expand...

Interesting statement.
On the one hand the basic design of the car engine has not changed much in the last 80 years, ie they are still piston driven crankshafts, so why should that be different in the next 80?
On the other hand, the progress made with electric drive of one form or another during the last two decades, isn't it conceivable that IC engines will disappear from new car forecourts in the next 20 to 30 years...or even sooner?
So I can see petrol and diesel still being around at the end of the century, but not sure that we will be using it in vehicles!
 
Getting back to the thread, I'd say those Mercedes diesels look very well worth checking out. Price makes your job viable and hopefully there is a some sort of warranty with the engines and drives. I'd talk to his previous customers if you are serious about re-engining.
 
I did read, long ago, of someone who replaced two big v8 engines in a Searay with small 120hp 2l Mercruiser diesels and was happy with the economy. These should work well with the Bravo one and two drives, I think the moral of the story is that as long as being under powered is ok then there is no for massive surgery to your boat
 
crazy4557 said:
Why oh why do people insist on painting engines without masking off the ancillaries? An hour with a roll of masking tape would make all the difference. Makes you wonder about the rest of the attention to detail of the oily bits inside, or is it just a used engine from the breakers with a new paint job?
Click to expand...

Sloppy in the extreme. And £6.5K for an 18 year old engine?!!!!!!
 
crazy4557 said:
Why oh why do people insist on painting engines without masking off the ancillaries? An hour with a roll of masking tape would make all the difference. Makes you wonder about the rest of the attention to detail of the oily bits inside, or is it just a used engine from the breakers with a new paint job?
Click to expand...

I went to a Boat Jumble and there was a firm there selling reconditioned boat engines, obviously re-sprayed in blue, the respray was dreadful, I felt that had their presentation been better they might have sold some.
 
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