Fuel Burn for 16v92TA?

[ThirdHatt]

I am having trouble locating a fuel burn rate for Detroit 16v92TA 1450hp. I am surprised that I can't find it online. I saw on another site where CaptDis said that at 2000rpm they burn 140gph, but I was wondering more about displacement speeds like 900-1300rpm.

Does anyone here happen to have the factory fuel curve?

THANKS!

 

[Spellbound]

61 Davis 16V92's @ 1650-1700 rpm fuel burn was 104gph. Should remember the fuel burn at 10kts (but don't) as that is what we used coming back from Bermuda to Stuart 864 nautical miles. Fuel capacity was 1700 and we used almost all of it.

 

[ThirdHatt]

Good info! Do you happen to remember the rpm required for the 10kts on that trip?

THANKS!

 

[SKYCHENEY]

Movin' up, Byron?

 

[Brian Degulis]

With engines that large your going to hit displacment speed at a very low RPM Proubably to low to consider running it like that for long periods of time.

Brian

 

[Canuck Dennis]

Unless these are DDEC models you will wear them out real quick running anything under turbo cut in rpm, those big injectors are just washing the oil off the liners at low rpms. Was told they should run over 1700 if possible, lower is ok for short times only. One of the drawbacks of big HP gained by turbo's.
D

 

[ThirdHatt]

Hmmm. Not sure if they're DDEC's or not until I get there later this week but I did not know that it mattered with respect to low rpm cruising tolerances. I had heard to stay away from the DDEC system if possible. I know that they can be detuned to around 1000hp to last but if you have to run them at 1600-1700rpm the fuel burn will still be 100+gal/hr.

I guess I need some discouragement before falling victim to one of the truly unbelievable big boat deals that are showing up on the market these days!

 

[Spellbound]

Not positive but remember 950-975rpm as the setting for 10kts. These were the 1350hp non DDEC version. FYI -- We rarely, I mean RARELY ever ran the boat over 1700rpm. Most hours were at trolling speed 8-8/12kts, logged 3k+ hrs before rebuild by Palm Beach Power.

Like you, I also had reservations about the 16 92's until (at survey) talking with Joe Stafford of Stafford Diesel who confirmed the lower cruise rpm and keeping heat out of the "Beast" would lend itself to longer engine life. Was satisfied with all aspects except the fuel consumption (104gph) at cruise.

 

[StratPlan61]

Byron, if you are thinking about the boat I think you are, you might check on the cost of a rebuild for one of those motors. You rascal!

 

[Brian Degulis]

Not positive but remember 950-975rpm as the setting for 10kts. These were the 1350hp non DDEC version. FYI -- We rarely, I mean RARELY ever ran the boat over 1700rpm. Most hours were at trolling speed 8-8/12kts, logged 3k+ hrs before rebuild by Palm Beach Power.

Like you, I also had reservations about the 16 92's until (at survey) talking with Joe Stafford of Stafford Diesel who confirmed the lower cruise rpm and keeping heat out of the "Beast" would lend itself to longer engine life. Was satisfied with all aspects except the fuel consumption (104gph) at cruise.

If your boat had been powered with say 8V71 naturals you would have easily logged 10,000 hours before rebuilding. Running those big engines that slow takes it's toll. But yes you will still probably get more hours running slow than pushing them hard. I think if you could run them around 1500 -1600 hundered you would see very good life but that's probably not a speed the boats happy with. You could also consider running displacment speed on one engine. With most boats that doesn't make sense but in a boat that's grossly overpowered for displacment speed it might.

Brian

 

[sandspur1966]

IMHO that one engine logic needs to be qualified. You cant run these big ole girls with one engine either shut down or in neutral for long periods without freewheeling and damaging the gearboxes.

The prop turns them as it drags through the water and without the motor running it has no oil pressure.

I suppose you could live one iddling in forward and engage the other at the speed you wish but I'd seek a more expert opinion than mine regarding possible problems... beyond the awful vibrations that would cause from being horribly out of sync.

I personally would use the boat as it was designed or...if that isn't what you need, look for another design.

 

[ThirdHatt]

The boat supposedly makes 1kt for every 100rpm, with a 23kt top speed. Hull speed is 13.4kts and she'll do 12kts at 1300rpm fully loaded. Eventually the low rpm may wash the cyinders down but running at 1900 on plane would cost much more in fuel burn and sooner rebuilds over time than displacement cruising I would imagine.

Heck, our boats were designed for planing and many of us run at displacement speeds all the time, even though that was not what they were designed for.

 

[Brian Degulis]

13.4 kts hull speed? How long is the boat ?

Brian

 

[stormchaser]

The boat supposedly makes 1kt for every 100rpm, with a 23kt top speed. Hull speed is 13.4kts

You have a boat with an even 100ft waterline? Because that's what it would take to get a hull speed of 13.4 knots. To figure hull speed, it.s 1.34x the square root of the LWL.

 

[ThirdHatt]

That is correct, the boat is 104' LOA and a 100' waterline length. I looked at it yesterday but I am wary because it is a bigger project than even I expected (of course). I am looking at another 104' of the same make tomorrow with 12v92's that supposedly only needs paint. I doubt that is true, but we'll see.

They are all but giving boats away down here at the Ft. Lauderdale boat show. Attendance is way down and real buyers have a serious advantage. Many sellers are in a bind and must get out.

 

[Brian Degulis]

Ok that's a little diffrent for some reason I was thinking this was one of the 65' Cs with those big engines. With that size boat I would think you coiuld run displacment speed without being horribly under loaded. If your thinking your always going to run displacment speed consider larger props to load them up more.

Brian

 

[ThirdHatt]

Brian, That's just what I was thinking. I have no need to plane a boat like that nor do I want to supply the fuel to feed the beasts at those revs. At displacement speeds the fuel burn is still higher than I would like to see, but is manageable. She holds about 9200 gallons so all I'd have to do is bite the bullet and fill up while fuel is (relatively) cheap and it should last me a few seasons at displacement speeds!

The 12v92 boat that I am going to see tomorrow would be more fuel efficient but they are DDEC's and I do not know if that is good or bad. What do you think of the DDEC controls on a 1990's vintage 12v92?

 

[Brian Degulis]

I don't know anything about the electronic DDs. I know Garyd has them on his boat and likes them. In todays engines Cat, Cummins, Deer the electronics are excellent and they eliminate all the concerns about running big engines slow.

Brian

 

[ThirdHatt]

Fair enough. The DDEC boat I saw this morning was more than twice the boat that the 16v92 boat is overall. A complete paint job, update the electronics and service the mechanicals and back in business.

For me, I think one of the biggest issues with these boats is the aluminum hulls. I'm just not sure if I want to deal with blisters, and this coming from a Hatteras owner!

 

[Brian Degulis]

I would be very comfortable with a quality aluminum boat in fact more comfortable than a quality glass boat. I like steel and aluminum (and I sware it has nothing to do with the fact that I build them ha ha) Seriously I like metal because it doesn't fool your not depending on chemistry in construction. If a metal boat has a problem it jumps out and bites you glass boats are a lot more sneaky about it. The blistering your talking about has 2 causes stainless or other metals that are not properly isolated and im proper painting procedures. The most common problem on recreational boats is the heavy use of fairing compounds over a poor intial prime coat. The good thing is both are obvious and unless the boats just been painted you should see it.

Brian