i would avoid it if at all possible. they are ok if run easy, under 1400 rpm but are still thirsty and dirty

 

That's what i've heard. I think the advertised "20 Gal/Hr of fuel at 20 knot cruise" seems questionable.

The hull is a beast so if I could get the seller to price it as the kit boat it basically is it might be worth using it for a season and doing a repower over the winter to a CAT 3406E or something.

 

Burn rate depends on HP, as with any diesel. 600hp detroit burns just as much as a 600hp name your brand. being that alot of boats STILL run them, after 30 + years give you an idea on longevity.

Just remember, that repower pays for alot of fuel

 

Imho. They are very sensitive to improper loading. Make sure the motor is making proper rpm's, dont try to run the snot out of them either.

I run a boat with twin 6v92(550hp). So far so good but they do not have alot of hours since the overhaul and the owner is still trying to get the correct pitch in the props.

Like any motor the less fuel you run through them the longer they will last.

I know alot of people use them commercially and run them forever.

Good luck with your decision.

 

The Elizabeth Thomas- 43 Lowell?

 

Ive always had respect for the old 2-strokes, like everyone has said, and it applies to EVERY engine, make sure you pitch it correctly so it isn't overloaded. I don't know if i agree with running it easy all the time, the old engines want to be run and run hard, it keeps them clean. I've seen 2 strokes run easy their entire life and they didnt last as long as a pair run HARD most of the time. They need the air pressure and movement to keep everything clean and happy!

 

Wound up marine: I cant argue with you on that esp that i dont have all the time in the world with 2stroke diesels. I kinda have been a believer in hours and how much fuel goes through a engine are two differant life determining factors. But this may apply more to the 4strokes like a cat with the amount of fuel.

Im not an expert in this field nor will i ever try to come off as one.

 

The 6-71's and 8-71's are great engines. The 6-92's at 550 aren't too bad but the 660's are good for about 500hrs. They tried to crank too much HP out of these blocks. You have to run them up to temp and monitor the exhuast temp or they don't last long. You can't give them a steady diet of easy cruising, not with a 2 stroke.

 

I think you should run it harder than 1400. I've seen them run for many thousands of hours at 1600 to 1700. 892 will last a lot longer w/ smaller injectors too. Cooling system needs to be tip top also. Unless you run about every day, it is hard to justify a repower from 2 stroke to 4 stroke on a fuel price basis in most cases. Kind of like the part timer in a small boat w/ a gas engine. Takes a lot of use, especially to crack the nut of a 600 plus horsepower engine and installation.

 

Takes a lot of use, especially to crack the nut of a 600 plus horsepower engine and installation.

Agreed. I wasn't thinking fuel so much as reliability. 100 mile haul to get home is what's in my mind. Especially when you potentially have a group of paying dive charter customers stuck on board who have work the next day.

 

They have been pretty damn reliable in a lot of boats, less so in others. They work very well within certain parameters. I did not used to like them, but I bought a boat w/ 671 TI's and they have been good to me, but I take care of them and don't run the piss out of them either.

 

they even run when broken

 

We ran one with a couple burnt valves and a couple scored liners for the remainder of the season last year, maybe a little over a month. She still made rated rpms when asked, smoked like a chimney though! This is a 12-71ti. If they have fuel and enough battery to turn them over, they are one engine i would feel very comfortable having beneath the deck as far as reliability goes.

 

Dirty, thirsty, smokey, loud and reliable. Sounds like my kinda woman!

 

Most of the hard core stories are about 71 series or even 53 series, 92 is a different story.

 

92 is a different story.

How so if you don't mind me asking? Anything specifically?

 

92 series doesn't share the same reputation as the 71 series. We have a few 692's that have been good but they are 1800 or less RPM engines in barges that don't get abused.

I personally am not worried about the reliability of them since we try to take care of them. I just don't like all the smoke, noise, and leaks which seems pretty typical. Not to mention the fuel economy. Plus, Detroits to me always seem hard to work on in tight areas.

It always comes down to money. If you can deal with what you got, go for it. My $.02

 

92's have wet liners, so that is something to watch out for.

 

92 series has wet sleeved liners as previously stated, 71 series is dry fit. The cooling system is absolutely critical in any of the GM series. In a DE application I would expect long life from these 2 stroke engines. Prop it to run easy and with proper maintenance it will last many, many more years. Most horror stories with GM diesels stem from trying to squeeze every knot out of them in the deep V sportfisherman world.

 

If it don't leak oil it not runing right

 

Kind of like an old Harley:roll:

 

Our big boat has 892's... Rebuilt twice since 1978. Runs day and night from may to September. 1500 rpms they will run forever.. 1800 to 2000 rpms and they show heat...

As stated.. If it ain't leaking... It ain't running right..

As far as emergency vehicles... I know a lot if fire engines with 692's....emergency generators in buildings, emergency pumps for the Lincoln and Holland tunnel are detroits... I've seen some cats recently also.

Tanks have detroits... Our small boat has 671's... At one point these two motors were bolted together in a tank.

 

In my old mans house they had a ward with 892. It was the fastest truck in the house at the time.

 

I have the high hp 692s in my current boat. Run great. If i run them slow trolling or bay cruising, i run them up for a bit on the way in. Many motoryacht folks run them this way and get thousands of hours. If you wail on them or let them get hot, they live short lives. I have not had issue with them at 625 hp, and have almost 1000'hrs on them. Minimal smoke at start and turn to 2350. At 735 hp, 892s are ok, but you could de tune them to 650 and have them last you longer.

That said, when i can finally get into a DE boat, i want a cat/cummins/volvo that will last me my big boating life and be cleaner and quieter. My $.02.

 

Thanks for the input everyone! The deal didn't work out on the boat I was looking at but I found a better one that fits my needs closer. This site has some really great members and info and I really appreciate it.

 

What did you find if you care to share with us?

 

Found a novi. I posted it in another thread, the link is below... Sea trial and survey is this week! Hopefully it works out.

http://downeastboatforum.com/downeast-projects-boat-building/quad-berth-4750.html#post47716

 

Didn't realize that was you. Good luck it looks like a real nice boat! Much more set up then the Lowell.