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Diesel Engine Question

Old 09-10-2004, 03:20 PM
  #21  
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Default RE: Diesel Engine Question

Sure the modern engines are better, but it may be tough for someone to rationalize paying $100K on a new repower versus $10K on a rebuild of an old detroit. I don't think it'll bump the resell price up by $90K a few years down the road.

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Old 09-10-2004, 04:40 PM
  #22  
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Default RE: Diesel Engine Question

what lunges forward or aft ? the boat or just the engines rocking on their mount... if the engines, that's not true... unless the mounts / beds are shot. if the boat, I dont' really see what you mean... when I engage one of my trannies (8V71s), the boat starts moving gradually. Lots of torque with these big props but nothign that woudl cause a problem.
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Old 09-10-2004, 05:46 PM
  #23  
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Default RE: Diesel Engine Question

pascal - 9/10/2004 4:40 PM what lunges forward or aft ? the boat or just the engines rocking on their mount... if the engines, that's not true... unless the mounts / beds are shot. if the boat, I dont' really see what you mean... when I engage one of my trannies (8V71s), the boat starts moving gradually. Lots of torque with these big props but nothign that woudl cause a problem.


I was talking to some guy's at Hawks Cay and they commented about how the boat would lunge forward or aft when they would put the Detroits in gear. Put it this way, they liked the Cat and Yanmar setups MUCH better.
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Old 09-11-2004, 11:33 AM
  #24  
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Default RE: Diesel Engine Question

I currently have a 4-53 Detroit and previously owned a 6-71. Both engines naturals, in other words no turbos or aftercoolers. Both have been totally reliable. Put full insulation in the motorbox for the 4-53 and that took care of the noise problem. Yep, you still have to take care of an occasional oil leak.

The 6-71 was in a 34' Crusader which was built in the Fla. Keys. It would run 23 mph with little n60 injectors, a 1.5:1 Allison gear, 24x24 4 blade prop and the governor set at 2100 max. A Detroit factory engineer said I could run it pretty much continuous at 2100 rpm with those injectors. I cruised all day long at 18 mph at 1800 for reliability and low fuel burn. Set up and run like that you will have extremely long engine life and low fuel cost. The fellow I sold it to put N80s in it and turned the gov. up to 2300. Gave him well over 25 mph.

Currently own a 27' "Lindsey" with 10'+ beam and full fly bridge and full keel, built in Miami in late 1970s early 1980s then built after that under the "Burpee" name. The little 4-53 Detroit with n-50 injectors and 128 HP at the prop shaft shove it along at 18 mph max (GPS two way run average), at 2800 and cruises at 15.5 mph at 2550.

I purchase parts from my friendly Detroit Dealer in Stock Island Fl. NEVER had the first "we can't get that part anymore response." I buy the "Reliabuilt" Detroit brand parts. I don't need many of them, the price is always right and so is the warranty. In fact when I purchased the "Lindsey" a couple three years ago I pulled the motor out and replaced the blower, totally overhauled the raw water pump with ALL new parts, replaced the freshwater circulating pump, thermostat and the fuel pump. Cleaned the motor of all rust and crud then painted it with factory "Detroit alpine green", also available from my friendly Detorit dealer. Came to around $800 or $900 for the parts. Not even enough for me to keep close track of the cost. The parts purchase also included friendly, professional advice on installation tips......... what more can you ask for? The motors are easy for anyone with a little mechanical ability/ experience to work on. Buy a shop manual take your time and have at it. You don't need to hook up a "laptop" to figure out what's going on. Tuneups are easy also, adjust the rack & governor, time the injectors, adjust the valves and forget it. If you can't do it then there are lots of experienced mechanics around who can. You'll probaly never hear "we've never worked on one of them before".

By the way, I have a friend who owns a 3196 Cat with the infamous intercooler problem and all the latest gee whizz electronics and computers. Yep, he had to have a warranty rebuild. The price I heard to just replace the intercooler was around $5000! Good thing he had warranty coverage.

Everything in life is pretty much a trade off. If you value reliability, easy to work on, cheap parts and long life then you will problably like a Detroit. The price of a time tested and proven Detroit compared to the new technology makes the Detroit attractive.

The new motors are better on fuel but the average guy will never come anywhere close to putting the hours on the new motor to make up for the price difference in engines. Lighter and more speed, but you'll sure pay for that extra few mph.

 
Old 09-11-2004, 11:59 AM
  #25  
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Default RE: Diesel Engine Question

The "lunging" being referred to has nothing to do with engine make. It has to do with props/transmission set up. I am not sure if I can explain this correctly but here goes. The lunge is created when the engine is put in gear and the prop initially turns, there is alot of torgue available and that lunge equates to a higher in-gear idle speed. When the boat lurches forward, check out the prop wash. Take the next boat that does not lunge when it goes in gear and you will find a different gear/prop set-up. That lurch is not a defect in any way. I still don't think I explained that correctly.
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Old 09-11-2004, 01:29 PM
  #26  
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Default RE: Diesel Engine Question

We understood you Jags... sort of. Your main point is correct, though, the alleged lunge has nothing to do with the egines, unless the idle is set way too high.
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Old 09-12-2004, 06:30 PM
  #27  
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Default RE: Diesel Engine Question

A single screw boat will lunge when you put it in gear and so will any twin of any make. A lot of the lunge effect had to do with the gear and wheel setup and probably more importantly, the weight of the boat. A lighter boat wil jump or lunge a lot easier than a heavy boat. When I put mine in gear, those 30" diameter and 38" pitch wheels are going to push something somewhere. It leaps out of the slip. The solution is just bump it in and out of gear.

With a single or twin, if you just put one engine in gear, the first movement is a sideways movement. That is what allows an experienced operator to move a boat around in a tight space with a single. Without any other influences, tide or wind, you can just about spin one around in its own length. Just bump it in gear long enough to kick it sideways but not long enough to get forward motion. Using a single to get out of a slip just requires holding it in gear long enought to begin to get that forward motion.
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Old 09-13-2004, 02:26 AM
  #28  
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Default RE: Diesel Engine Question

I don't suppose any of you guys have heard, Detroit still builds marine diesels. They just don't build the 71 or 92 series anymore. I didn't look long enough to see if they mentioned the MTU line of motors, That is a mercedes/Detroit hybrid. Very good motors, or so I have heard.

The bottom line is how much cash you want to part with, How fast do you want to go, and how long do you plan on keeping the boat?

Good Luck in your search.

http://www.detroitdiesel.com/markets...pecs/index.asp

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