converting to diesel

nugent · 06 February 2014, 06:04

Volvo Penta 5.7 litreV8 inboard petrol engine with duo prop drive

possible boat purchase with this set up

what can I bolt pretty much straight in there diesel wise?

or do I need to change leg also?

Bushrider · 06 February 2014, 06:40

Quote:

Originally Posted by nugent

Volvo Penta 5.7 litreV8 inboard petrol engine with duo prop drive possible boat purchase with this set up what can I bolt pretty much straight in there diesel wise? or do I need to change leg also?

Diesel & petrol engines have different rpm's @ WOT and therefore different ratios in the gearbox .
With an Diesel engine on the existing leg you will not achieve speed due to missing rpm's and the diesel motor would not work in the economical range .

Chris Caton · 06 February 2014, 06:41

be a tight squeeze but how about a BMC diesel, sure there'll be one knocking about in a old landrover somewhere

biffer · 06 February 2014, 07:29

You might get away with it, depended on horse power, torque, prop size.
Dervs have more torque and can swing bigger props, you could jiggle the props with horsepower, might do it

Searider · 06 February 2014, 08:23

Used Volvo AD41 200hp would go in if engine bay has enough length.

Look at the V8 diesels sold by MDS at Hamble Point - although expensive and usually go on Mercruiser drives.

Or GM 6.2 V8 diesel:
help with a petrol to diesel engine convertion

No easy or cheap options.

biffer · 06 February 2014, 08:37

Volvo and Mercruiser both use the same block units in a lot of there car/ truck marine conversions, a lot of the bits are interchangeable

Rogue Wave · 06 February 2014, 08:38

Vw perhaps ?

nugent · 06 February 2014, 09:08

Oh well just put an offer on it , could not resist

Will ponder over changing it if I find it mega thirsty,

Searider · 06 February 2014, 13:22

What boat is it?

nugent · 06 February 2014, 14:31

Quote:

Originally Posted by Searider

What boat is it?

Proline walk around

Swain Marine · 07 February 2014, 07:34

It's not usually economically viable, but obviously depends on the price you pay for the boat. If you have a boat that has a dead engine that has to be replaced with something one way or another and is cheap it could be viable if the boat not too old, still has plenty of life in it and good resale value with a diesel.
Good used diesels suitable for a sterndrive are very hard to get hold of..
Usually only make sense if you plan to personally keep the boat for a good few years. If the current engine is OK and you're not sure how long you'll keep it then I wouldn't rush into anything. Use the boat as is for a season before making up your mind. The cost of doing a decent diesel conversion will buy an awful lot of fuel!

Ian Austin · 07 February 2014, 08:44

Quote:

Originally Posted by Searider

Used Volvo AD41 200hp would go in if engine bay has enough length.

Look at the V8 diesels sold by MDS at Hamble Point - although expensive and usually go on Mercruiser drives.

Or GM 6.2 V8 diesel:
help with a petrol to diesel engine convertion

No easy or cheap options.

The 6.2 engine is a very old lump and the parts are very expensive.
The 6.5 is the better engine, the one I converted for a customer years ago, he bought a 6.2, a set of pistons, rings, mains, big ends and a gasket set was over £1800 (trade), props were changed to what was recommended and in the end had to drop 4 prop sizes just to get it on the plane and then it ran out of revs, all the power is at the top of the engine rev range.

nugent · 07 February 2014, 09:09

My offer has been upped slightly but yes it's a cheap boat. With a hole in the hull,, but that's kids play to me