power specs for 1980 12V71TI

[captmikes]

Any one have info on HP, Torque, and fuel consumption for these engines.

[MicroKap]

ENGINES – 12V71TIs (N90 Injectors produce 690 BHP @2,300 RPM, 660 SHP; Twin Disk Transmissions (514 with 2:1 Ratio). Straight from Detroit Diesel.

Ross MacDonald, owner of a 60’ Hatteras Sportfish with 650 HP 12V71TIs reported the following:

1900 RPMs – 54 gallons per hour – 16 knots
1450 RPMs – 24 gallons per hour – 11 knots
1000 RPMs – 18 gallons per hour – 9.5 – 10 knots

1979 Hatteras 60C Performance Table from Motor Boat & Sailing

True RPM Knots MPH GPH
800 7.2 8.3 5.4
1,000 8.5 9.8 9.0
1,200 9.5 10.9 14.2
1,400 9.9 11.4 21.4
1,600 10.2 11.7 31.4
1,800 15.0 17.3 43.2
2,000 19.4 22.3 65.4
2,400 21.1 24.3 76.2

[rsmith]

Ross's # are what I saw on the 60 I fished on in the early 80's except we ran to the offshore canyons for day trips so we needed a little more speed for the 70 nm run. We ran 2150rpm which gave 60gph or so and 16.5-17.5 kts.Because these boats hold so much fuel and h2o speed and fuel burn vary with loading.(It was always faster coming home)
Now I'm going to make ppl mad. This hull design had the most pronounced pressure wave effect Ive ever seen. On the way offshore loaded we would be pushing 17kts as soon as we passed Five Fathom bank (off cape may) and entered deeper water (over 30') the speed would drop to 15kts and change.You could feel the loss of lift and the boat settle as it entered deeper water .Now this was in 1980 and we had just got the new loran c which replaced loran a. We were using the new Northstar that not only automaticly tracked both td's but gave a suedo ground speed, so it wasnt all that accurate.But I still position plotted on the chart and it was pretty close.
Did I mention the boat is stable as a rock?LMAO

[captmikes]

Thanks.
I should have given more detail. i have two of these in my 1973 53C. they were installed in 1980 by original owner who wanted more speed. they still run good but smoke some on startup and after idling for a while. am considering a pair of Cummins QSM-11's as replacements and wanted to compare power and torque curves. Talked to Tom Slane the other day and he indicated that his customer is happy with his. any suggestions?

[rsmith]

Was the name of the boat "Hey Bett" out of Cape May NJ?

[REBrueckner]

The 690HP DD engines are still only about 0.8HP/cube, so those engines are not really souped up and should give good service life. You can search here for other comments on the Cummins QSM-11's which have gotten good reports. The Cummins should be more fuel efficient.

It would be interesting to see the weight different between a pair of the two engines with their gears.