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Going from petrol to diesel

Post Options Post Options   Likes (0) Likes(0)   Quote Ed114 Quote  Post ReplyReply Direct Link To This Post Topic: Going from petrol to diesel
    Posted: 30 Jun 2020 at 5:52pm
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Hey guys, anyone here has been through the process of swapping out the petrol motor over to diesel power?

Boat is a 8m westcoaster currently has a
mercruiser 5.7l v8 260hp with a bravo3 leg duo prop.

It’s a new boat to me, I’m picking it up this Friday. Have been toying with the idea of going diesel depending on cost.

New diesel motor is not an option due to price, and looking for a good used motor is another challenge again.

Ideally my plan is try find an engine that can be bolt straight onto my leg.

Apart from engine cost what other cost can I expect?

I know it’s abit of a how long is a piece of string situation. But would like to hear some rough figures to help me decide weather I would even bother.

Cheers
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Post Options Post Options   Likes (0) Likes(0)   Quote whippersnappyr Quote  Post ReplyReply Direct Link To This Post Posted: 01 Jul 2020 at 8:11pm
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The first thing to check is which bravo 3 leg you have. Diesel engines produce a lot more torque and I think the bravo 3 diesel legs are different spec to the petrol ones. For the engine only the modern common rail engines are as light as the v8 petrol engines coming out of your boat.

So the trick will be finding a power plant at a reasonable price. The Mercury TDI 3l is 260hp, replace now by a 270 fiat Chrysler engine. The engine was around 60k new so the trick will be finding a reasonable priced 2nd hand engine.

It may be the case that it isn’t worth it. The cost would buy a lot of petrol.
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Post Options Post Options   Likes (0) Likes(0)   Quote SaltyC Quote  Post ReplyReply Direct Link To This Post Posted: 03 Jul 2020 at 11:54am
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I did this back in the mid 90s.

I had a Markline 850, 28ft, with a Volvo 260hp V8 petrol motor (Chrysler) and 280 leg.

After much research I bought a second hand Volvo AQAD41 (200HP 6 cylinder diesel) and 290 DP leg as a bundle with only 350 hours on it and did the transplant.

As I remember there weren't a lot of extra costs as it was a straight remove/replace operation. Tanks were just emptied completely and then refilled with diesel with no issues.

Interestingly the boat handled a lot better with the higher torque of the diesel, and in my case we lost no speed with the drop in horsepower as the torque on the diesel  kicked in lower and held throughout the rev range. The handling in a following sea was dramatically improved, it simply didn't bog down anymore. So, as above, be certain that your leg can handle the extra torque if you are keeping it.

Also if you are intending to sell the existing motor, then it may be more saleable as a complete package including the leg.

Having said all that the Markline was a heavy boat for its size, basically a 900 with half a metre chopped out of the middle, so it really needed the extra torque 





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Post Options Post Options   Likes (0) Likes(0)   Quote Gappy Quote  Post ReplyReply Direct Link To This Post Posted: 03 Jul 2020 at 6:15pm
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Have done this going from a volvo v6 4.3 petrol to a D3 using the same leg issue you have is ratio diesels spin a bigger prop slower so the pertrol has a different leg ratio.

Diesel tanks need return lines engine mounts are generally different and exhaust is different its not just a straight swap.

Cheers
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Post Options Post Options   Likes (0) Likes(0)   Quote MacSkipper Quote  Post ReplyReply Direct Link To This Post Posted: 05 Jul 2020 at 6:53am
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No expert on diesel - 2 of my neighbours have Mercruisers so are common here, if you follow/look at US websites heaps of info on them - as pointed out you can buy a lot of fuel for cost of conversion sure its a gas hog but how much are you going to use?Seem to be cheap and easy to repair compared to diesel?  Get a full service and check out now and if ok stick with it?  If major repairs needed then maybe upgrade?
Good fishing trip nothing breaks, great trip catch fish.
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Post Options Post Options   Likes (0) Likes(0)   Quote SaltyC Quote  Post ReplyReply Direct Link To This Post Posted: 05 Jul 2020 at 9:51am
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The decision/economics may not revolve solely around the cost savings on fuel.

In my case the boat did become a lot cheaper to run but the handling performance improvement was also important, as was not sitting on 450 litres of petrol all the time.

I bought the boat in 1991 for $65k, because of the petrol motor and running costs, but sold it, post transplant, in 1995 for $92k,so the ease and value of resale can also be a factor
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Post Options Post Options   Likes (0) Likes(0)   Quote Snapper12 Quote  Post ReplyReply Direct Link To This Post Posted: Yesterday at 7:21am
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Buying and selling it as usual and making huge profit and telling people u cant keep 2 boats.
U sell more boats then a average boat yard in Auckland.


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Post Options Post Options   Likes (0) Likes(0)   Quote SaltyC Quote  Post ReplyReply Direct Link To This Post Posted: Yesterday at 9:24am
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Originally posted by Snapper12 Snapper12 wrote:

Buying and selling it as usual and making huge profit and telling people u cant keep 2 boats.
U sell more boats then a average boat yard in Auckland.




Huh?? What?? Care to elucidate?

I've owned 2 boats in 30 years, only ever sold one and owned the current one since 1995.

No idea what you are on, or on about!
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Post Options Post Options   Likes (0) Likes(0)   Quote whippersnappyr Quote  Post ReplyReply Direct Link To This Post Posted: Yesterday at 10:59am
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What did it cost to put the AQAD41 in?  I guess being an older lump it would have been quite a bit heavier than the gas v8 it replaced.
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Post Options Post Options   Likes (0) Likes(0)   Quote SaltyC Quote  Post ReplyReply Direct Link To This Post Posted: Yesterday at 11:16am
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Yeah, from memory I think the combined motor and leg weight difference was around 90Kg more, the changeover cost after I sold the petrol motor and leg was around $18k-$20k I think.

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Post Options Post Options   Likes (0) Likes(0)   Quote Joker Quote  Post ReplyReply Direct Link To This Post Posted: Yesterday at 11:31am
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Originally posted by Snapper12 Snapper12 wrote:

Buying and selling it as usual and making huge profit and telling people u cant keep 2 boats.
U sell more boats then a average boat yard in Auckland.




That's not accurate nor helpful - another weekend warrior sitting in piss stained undies.

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Post Options Post Options   Likes (0) Likes(0)   Quote Rozboon Quote  Post ReplyReply Direct Link To This Post Posted: Yesterday at 11:44am
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Originally posted by SaltyC SaltyC wrote:

Originally posted by Snapper12 Snapper12 wrote:

Buying and selling it as usual and making huge profit and telling people u cant keep 2 boats.
U sell more boats then a average boat yard in Auckland.




Huh?? What?? Care to elucidate?

I've owned 2 boats in 30 years, only ever sold one and owned the current one since 1995.

No idea what you are on, or on about!


The guy is referring to the original poster, Ed, who seems to have had more boats in the last two years than I have had hot dinners.

A reasonable response to this thread would be "who cares, you won't own it in 3 months anyway :P"

I can think of at least 6 boats OP has owned in the last couple of years, and I'm probably missing a few.
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Post Options Post Options   Likes (0) Likes(0)   Quote Snapper12 Quote  Post ReplyReply Direct Link To This Post Posted: Yesterday at 12:53pm
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That's for Ed saltyc
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Post Options Post Options   Likes (0) Likes(0)   Quote Ed114 Quote  Post ReplyReply Direct Link To This Post Posted: Yesterday at 4:53pm
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Thanks everyone for the helpful reply, have taken it all onboard. After pricing up a new diesel motor and leg I’m looking at close to 60k which just isn’t do able. The petrol motor is in great condition and has been well serviced so I will just stick to that.

Snapper12
Yes I have owned afew boats this year, so what? Talk to anyone I have sold my boats to and I can guarantee they are all happy with their purchase. I buy boats that need work, I use them and fix anything that needs doing then sell them on so I can upgrade each time. What’s the problem? You think I make huge profits off them so can understand maybe your jealous about that but the last boat I brought the engine blew up on me and I had to wear the cost of that.

I hope we can squash this little fued you have towards me. The same opportunity are out there if you wanna buy boats aswel I’m not gonna come and rain on your parade. All the best mate
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