Diesel engines in speed boat
#21
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Don't knock the oldies too hard.
#22
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Part 1
Ok, everytime this diesel thing comes up I hear the same dicussuions about what works and does not work.
Physics is physics, it does not change with time. I'm posting 5 pages of a paper from 1990 on here - everything from back then was proven, still holds true today and the reason these projects got canned back then are the same as today and Swamplizard hits on most of them (I would challenge some of his assumptions, but overall he's close)
weight
cost
exhaust size
difference in price of fuel vs economy
One note, today's electronic engines and variable turbos make everything we did years ago that much better today. The advancements in the last 15 years with diesels have been incrediable. That being said, what Mercury has acheieved with gas engines would be unherad of years ago as well. Today's gas engines for small fast boats are a far better choice than using diesels, the gas costs are equal and no one with a "go fast" style boat will ever use enough fuel to offest the cost.
ps when you see the name "gere" it was a generic name used because Cummins had not named the project yet - it would have most likey been SEA HAWK
Physics is physics, it does not change with time. I'm posting 5 pages of a paper from 1990 on here - everything from back then was proven, still holds true today and the reason these projects got canned back then are the same as today and Swamplizard hits on most of them (I would challenge some of his assumptions, but overall he's close)
weight
cost
exhaust size
difference in price of fuel vs economy
One note, today's electronic engines and variable turbos make everything we did years ago that much better today. The advancements in the last 15 years with diesels have been incrediable. That being said, what Mercury has acheieved with gas engines would be unherad of years ago as well. Today's gas engines for small fast boats are a far better choice than using diesels, the gas costs are equal and no one with a "go fast" style boat will ever use enough fuel to offest the cost.
ps when you see the name "gere" it was a generic name used because Cummins had not named the project yet - it would have most likey been SEA HAWK
Last edited by HabanaJoe; 02-03-2008 at 10:28 AM.
#24
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H2owarrior,
The 3208 had many draw backs, it was the first engine we looked at for for hot rodding back in 1982, but it does run forever!!! It was a great engine, very hard to squeeze hp from but man they run and kept running, dependable to no end!
The 3208 had many draw backs, it was the first engine we looked at for for hot rodding back in 1982, but it does run forever!!! It was a great engine, very hard to squeeze hp from but man they run and kept running, dependable to no end!
#25
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Dawg Gone
I believe the boat ran as well as it did because of the surface drives with large dia porps.
The patrol boats were never designed to run over 60 mph, they were designed to cruise at 50 mph for thousands of hours.
You could never get an outdrive to last that long without more maintenance that you would have done to an Arneson.
In order to swing the same dia props you would have needed number 5 or 6 drives. I don't remember exactly but the weight of those were greater than an Arneson plus to be as efficent they would need to be mounted rather high would would hurt low speed plane.
I believe the boat ran as well as it did because of the surface drives with large dia porps.
The patrol boats were never designed to run over 60 mph, they were designed to cruise at 50 mph for thousands of hours.
You could never get an outdrive to last that long without more maintenance that you would have done to an Arneson.
In order to swing the same dia props you would have needed number 5 or 6 drives. I don't remember exactly but the weight of those were greater than an Arneson plus to be as efficent they would need to be mounted rather high would would hurt low speed plane.
BTW,
The prop slip on the SL70 is ~ 3%
Dean
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#28
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Location: Okanagan Falls BC. Canada
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given the fact diesel is available everywhere
on the water with 89 octane gas only at most marinas , diesel makes sense for boating . We have to pump our own 91 octane from drums for my friend's 572 .
My boat had twin mercruiser D-tronic 250 HP engines on loan from mercruiser to test , coupled with Bravo 1 X drives [ 1.65:1 ratio ] before the swapping to new 6.2 MPI engines . My boat is pretty short [ 25'7"] for two heavy engines , but looking at photos of the boat sitting in the water for comparison ,the stern only seem to sit maybe 3" inches lower with the diesels . Have 28 K-planes to help for fast take offs .
Speed was down by ca 10 mph with the diesels .
The diesels had a nice clean look in the bay
The gas , not so much
on the water with 89 octane gas only at most marinas , diesel makes sense for boating . We have to pump our own 91 octane from drums for my friend's 572 .
My boat had twin mercruiser D-tronic 250 HP engines on loan from mercruiser to test , coupled with Bravo 1 X drives [ 1.65:1 ratio ] before the swapping to new 6.2 MPI engines . My boat is pretty short [ 25'7"] for two heavy engines , but looking at photos of the boat sitting in the water for comparison ,the stern only seem to sit maybe 3" inches lower with the diesels . Have 28 K-planes to help for fast take offs .
Speed was down by ca 10 mph with the diesels .
The diesels had a nice clean look in the bay
The gas , not so much
Last edited by spectras only; 02-03-2008 at 02:23 PM.
#29
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Sorry to single you out... I just cringe when someone mentions a 3208, out of reflex I suppose... There are so many other options right now that don't even come close to being the slug that that oil leaking dirty Cat was...
Although, if anyone is looking for a 0 hr reman 3208, I'll make you a hell of a deal, just to get it out from the front window of my parts department... and even brand new, it's only leaking a little bit of oil out of the main seal.
#30
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Suprised no ones mentioned this.....The old Tommy Bahama MTI Race boat rigged with Duramax's....Anyone know the outcome of this project??