tug57
New Member
I have a Volvo Penta 290-SP sterndrive and a Transit 2.5 di engine coupled to it, would a Volvo penta GMC Chevy 6.5v8 diesel inboard engine be compatible with my sterndrive
I have Penta 290-SP sterndrive
- Thread starter tug57
- Start date
ChromeDome
Well-Known Member
The drive, if in absolutely good order, will have to cope with the torque and hp, so you'd need to know that for the GM as well the exact type of drive (Volvo drives come in several variants within the model ranges)
Depending on the boat hull design and increased GW the speed potential might change and as the engines most likely operate in different rpm ranges, the drive gear ratio and the propeller pitch/design could need to be changed in which case an overhaul or change to DP comes into play.
As a side note, the common recommendation is to buy the right thing instead of making it as the cost and trouble involved in the project can't be justified.
To mind springs that if not already done you'd have to marinise the engine (cooling is crucial), engine room layout/mounts, flywheel adaptor, coupling, instruments, electrics, remote control and cables and then some.
All should be factored into your budget and time plan
Depending on the boat hull design and increased GW the speed potential might change and as the engines most likely operate in different rpm ranges, the drive gear ratio and the propeller pitch/design could need to be changed in which case an overhaul or change to DP comes into play.
As a side note, the common recommendation is to buy the right thing instead of making it as the cost and trouble involved in the project can't be justified.
To mind springs that if not already done you'd have to marinise the engine (cooling is crucial), engine room layout/mounts, flywheel adaptor, coupling, instruments, electrics, remote control and cables and then some.
All should be factored into your budget and time plan
tug57
New Member
The previous owner said the drive could take up to 190hp, the engine is fully marinised as far as I know about 150hp. As for my hull with the right engine could reach speeds of between 25 - 30 knots.
Thanks for your reply
Thanks for your reply
Chris_d
Well-Known Member
Those GMC engines have a really bad reputation I would avoid anyway.
tug57
New Member
Thanks for your advice, think I may just carry on as I am until a change of boat comes to mind
Alicatt
Well-Known Member
In my trucks it was the preferred option, either the GMC 6.2 or 6.5 V8 diesel, they proved to be very reliable and quite high revving engines, masses of torque from them too. I had them in 3 ton 4x4 offroad vehicles and 5 ton 6x6 off roaders the main problem for us was the torque, the gearboxes were not up to what these engines put out, 6.2 was around 120hp and it was replacing a 4.2 V8 petrol engine of around 149hp
But the truck engine is not a marine engine and quite different in the way it is set up and cooled, the 6.2 and 6.5 were designed to replace small petrol engines in light trucks in the US and is a light duty engine, they are economical, in the 5 ton truck the fuel consumption went from 7mpg to 26mpg and the engine paid for it's self in a very few months.
For it's size it is quite a light engine in weight that is being aluminium with wet liners, but they do require a huge amount of cooling and that was the biggest constraint we had with them even above being able to chew up and spit out gearboxes
But the truck engine is not a marine engine and quite different in the way it is set up and cooled, the 6.2 and 6.5 were designed to replace small petrol engines in light trucks in the US and is a light duty engine, they are economical, in the 5 ton truck the fuel consumption went from 7mpg to 26mpg and the engine paid for it's self in a very few months.
For it's size it is quite a light engine in weight that is being aluminium with wet liners, but they do require a huge amount of cooling and that was the biggest constraint we had with them even above being able to chew up and spit out gearboxes
madabouttheboat
Well-Known Member
I think @Mr Googler has some experience of marinised GMC 6.2/6.5 diesels.
Mr Googler
Well-Known Member
I do….noisy, thirty piles of crap.
if it’s painted blue run away! ???
mine where a decent conversion. Bowman exchangers, stainless manifolds but they just never felt comfortable at cruising revs.
There was a Swedish company that did quite a good marinisation but not sure they are still going .and I can see why people use them to change petrol v8 to diesel. I think it will tear up a sp drive…depends how it’s geared too etc…
I had 290 dp with non turbo 6.2 and I think it was close to the torque limit.
QBhoy
Well-Known Member
Hi. It’s likely your boat once had a petrol engine in it. Usually of the GM type or perhaps a 4 cylinder car based cam belt engine from Volvo. Each of which usually had an rpm range of around 4400-4800 rpm. What usually happens when people put a transplant diesel like your in a boat...is that it end up terribly unsuitable to the gearing in the outdrive, which was meant to suit the higher revving petrol engine originally.
The GMdiesel you refer to, along with very few other diesels (like the 6 cylinder merc and bmw car engines) are one of few diesels that actually have a suitable and similar rpm range to the original petrol engine you likely had. Making them very suitable diesel alternatives. Only issue to over come then, might be to suitable prop the outdrive.
The GMdiesel you refer to, along with very few other diesels (like the 6 cylinder merc and bmw car engines) are one of few diesels that actually have a suitable and similar rpm range to the original petrol engine you likely had. Making them very suitable diesel alternatives. Only issue to over come then, might be to suitable prop the outdrive.
