Actually it should be just the oposite. Since these engines really are kind of small for this boat, (200ft pounds or torque maybe?) they should be geared down quite a bit to take advantage of the higher rpm's they can acheive.

Racing cats can use gas turbines to spin "chopper" props at insane rpm's maybe 10k+.

Drambui(sp?) On Ice was docked at the yacht club a few years back. This one had a set of jet engines out of some chopper driving big drives with custom props. It sounded like a 747 taking off as they throttled up. Flames shooting out the back and a monster roaster tail. I think that boat could do 180+ knots.

Did you know only the bottom of the prop actually works? On a race boat you only want the bottom half in the water.

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1999 SL500
1969 280SE
2023 Ram 1500
2007 Tiara 3200

Yeah those engines are definatley smaller than what it had before, but he's going to use waaaaay less fuel. The engines he took out were V8 Crusader Marine Engines like these: http://www.crusaderengines.com/classic.html Those monsters probably easily put out 250-300hp....and probably used plenty of gas in the processs A carburated 300hp engine??? Can just head port to port filling it back up.....

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-diesel is not just a fuel, its a way of life-
'15 GLK250 Bluetec 118k - mine - (OC-123,800)
'17 Metris(VITO!) - 37k - wifes (OC-41k)
'09 Sprinter 3500 Winnebago View - 62k (OC - 67k)
'13 ML350 Bluetec - 95k - dad's (OC-98k)
'01 SL500 - 103k(km) - dad's (OC-110,000km)
'16 E400 4matic Sedan - 148k - Brothers (OC-155k)

Those are just small 350's. They have been discontinued actually replaced by the 6.2's which is a better block.

Small blocks don't burn to much fuel, my guess for a pair of fuel injected small blocks in a boat like that maybe 15-20gph each. Depending on how you run it. A diesel should burn 1/2 as much fuel as a rull of thumb. But conversions such as this usually suck fuel.

This is what that boat needs:
http://boatdiesel.com/index.cfm?CFID=4558358&CFTOKEN=85315191&CFApp=19&S=DM&Manu=CUMMINS&CFIDC=NRU2

Stupid messed up links, anyway I was talking about the 155B and the 220B. Afaik the 155B is a drop in for small blocks, the 6 cylinder may require more room.

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1999 SL500
1969 280SE
2023 Ram 1500
2007 Tiara 3200

I think that's a facsinating project and I am jealous. I have heard that marine engines are a league apart from automotive engines, even though the blocks are standard GM 350's, 454's and ford 351's. I've heard comparisons about how an auto engine is designed to handle short periods of even 50% throttle, whereas a marine engine is designed to handle continuous-duty at 80%. But I'm just not sure about how the innards would be different. I can see improved cooling, ss valves, and vibration reduction measures, but not really sure how they'd alter the bearings or lubrication.

I somewhat think it's a bit of bunk and is meant to get people to buy marinized engines instead of automotive...

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89 300te 222,222
92 300e 190,000

Well afaik with gas engines everything is different. Good marine engines are built like race engines with 4 bolt mains and stronger cranks and rods. The heads are completly different. Also the cooling and exhaust systems are completly different.

Companies like Mercury Marine and Crusader spend millions in R&D to build a strong engine.

A good comparision would be to take a 300D and attach a 2k pound trailer. Now run it at 4k rpm up a steep hill on a hot day for 6 hours.

btw GM got ride of the 350, 454, and 502 in 03 I think. Now they have the 8.1 and 6.2. Far better engines actually, they burn less fuel and last longer.

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1999 SL500
1969 280SE
2023 Ram 1500
2007 Tiara 3200

I wouldn't hesitate to put a properly marinized OM616 into a small, displacement-hulled pocket trawler where it spent it's life running at 50% rated max output. But, I agree w/Hatterasguy, despite the workmanship, this project is doomed. Those engines were never designed to be running at max output, pushing a planing hull...and, there are waaaay too many ifs.

Did you notice something weird in the movie of both engines running? The Stbd engine doesn't have any water hoses connected to it.

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Never a dull moment at Berry Hill Farm.

I think the guy has probably spent many nights thinking this through and through. He's clearly got top-notch fabrication capability, marine engine understanding, diesel understanding, as well as geartrain understanding. I'm sure he also is well aware that these are automotive engines. So figure the engines were probably not that expensive and working on a boat is cheaper than therapy. He's probably geared the entire rig down and lightened it up as well. He doesn't need to carry nearly as much fuel, and those engines and geartrain probably weigh less than half what he took out.

If I was 20 miles offshore which would I prefer - a couple of carbureted big blocks from 1974, a hundred gallons of gasoline, distributors, points, and sparkplugs, or, a couple of MB TD's from the early 80's and 50 gallons of diesel?

When I was 14 I built a plywood boat and endured endless nay-sayers. when it finally made it to the water it sat perfectly and planed perfectly. I'll never criticize a DIY boatbuilder or anybody else with an unorthodox way of getting things done.

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89 300te 222,222
92 300e 190,000

I wonder if he understands swimming? That boat is going to be in flames when those outlet pipes crack and break off of those turbos.

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Never a dull moment at Berry Hill Farm.

I'd agree that the outlet pipes look like they'll generate excess stress at the turbine flanges. I would hope that he'll weld on a tab to take the stress. He did double-weld the pipe fitting and that stainless looks like it has an ID of .25". It's possible that he's worked with marine diesels with a similar configuration. I know that the twin turbo-diesel patrol boat I was on had a flexible metal coupling between the turbine and the exhaust.

btw, I would think that a light-duty engine, such as a converted automotive diesel, would do better in a planing hull, not a displacement hull. An auto motor is designed for short periods of 100% power, not unlike getting on-plane, followed by prolonged periods of 40% power, such as staying on a plane. With a properly powered displacement hull the motor would obtain it's most efficient operating speed when the hull reaches its hull speed. The motor would never be taken above this point, as there would be almost no appreciable change in speed (unless into a headwind with high seas). In the diplacement hull the motor would be heavy duty and designed for optimum efficiency around 80% throttle = hull speed. It would not make sense to put in an oversized motor and only run it at only 50%, when it would never be taken above that.

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89 300te 222,222
92 300e 190,000

I think it takes more power to stay on plane...take a look at C.J. Marchaj's book "Sailing Theory and Practice" , the resistance curves for planing dingies have a hump where the hull planes but the overall resistance never drops below what it takes to plane. Thus, more hp is required to plane.

On displacement hulls: You're right about running the engine at 80% ...it would take a pretty daggone long displacement hull to need 50+ hp (80% of the 616's 67hp).

Have you seen Georger Buheler's cruising trawlers?

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Never a dull moment at Berry Hill Farm.

After getting a boat on plane the throttles need to be backed off to avoid acceleration. I could see some relationship to engine RPMs and speed. For example, an engine at 2200 RPMs and full-throttle probably puts out less power than an engine at 3200 RPMS and 50% throttle. At 2200 RPMs it's getting the boat over the hump to reach plane, and at plane the RPMs increase and the throttle is decreased. So even though the throttle is decreased (less stress) the engine is putting out more power.

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89 300te 222,222
92 300e 190,000

Bump.

Found this link again.
http://www.coastalboatsales.com/jfraley/gallery/albums.php

Looks like we overloaded the site again.

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1979 240D- 316K miles - VGT Turbo, Intercooler, Stick Shift, Many Other Mods - Daily Driver

1982 300SD - 232K miles - Wife's Daily Driver

1986 560SL - Wife's red speed machine

Man that guy must've had some serious time off from his regular job to do that. It would take me 6 years of weekends to even come close to finishing a project like that.

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'81 300CD - 180K, cannot be killed by any conventional means
'99 Ford Escort - good MPG

those front motor mounts are junk, the flanges need gussets all the way around
can't see those engines lasting long, they will be run to the wall with a flat sea

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Bill

'82 300SD 195K
'84 300SD 199K