Engine Efficiency

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My numbers as observed and recorded.



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tpbrady said:
I generally tried to run between 1500 and 1600 RPM
Tom
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Wow... You run her slow (or slower than me at least). ;) I keep mine at 1900 to 2000 about all the time, cruise at 8 MPH (I don't do knots) and get 2GPH over the life of the full tanks. Sure, there are 160to 1700 times, but they are most rare. Interesting to see what other 6.354 owners do. :socool: Thanks for sharing.
 
If you consider your fuel put into the tank and engine running time one would think they know how many GPH they burn.

NOT SO. There is lots of running time recorded on the hour meter that is NOT at cruising load (rpm) and skews the picture considerably. They are liking the fact that it makes them look very fuel efficient but it may not be very close to reality. Many are but most are not.

I don't know how accurate fuel flow meters are but it would seem that would be one of the only ways of really knowing.

Tom B it looks like you're one of the few that are not overpropped. Good.
 
manyboats said:
NOT SO. There is lots of running time recorded on the hour meter that is NOT at cruising load (rpm) and skews the picture considerably.

Tom B it looks like you're one of the few that are not overpropped. Good.
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That's interesting. I never considered the time idling as a percentage of GPH figures... Although, what percent is it in actually? I don't idle THAT much. Even so, it's the big picture I look for. The amount of fuel I used to get x number of hours run time. To me, the actual running burn matters very little. If 2GPH is what I get, that's what I plan for on my local grounds. So unless I plan to run at cruising speed through the entire tank to cross an ocean, that is when I see that an inaccurate burn rate could... well... burn me :D

FYI... Propped at 17... I think. Running gear work this Fall and I will report back.
 
Tom,

I think the time spent below cruise load is probably considerably greater than most all of us think. No I'm sure you don't idle "that" much but we enter long approaches to harbors, slow for "no wake", slow to let other boats pass ect ect. May take some time to set your anchor too.

I never think in mpg .. I always think of gph. With 100 gallons of fuel and a 1gph (approx) burn I have no need.


Rick says "What is the equation at the bottom of the page".
I finally figured out what you were referring to. Yeah I'd like to know too. I think he knows ... But I don't.
 
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Is there a rule of thumb or a constant for the diesel consumed per hour per horsepower?

Using Tad Robert's post as a guide, it appeared to me that he calculated using my fuel burn data that 2.66 GPH was required to develop 52HP. If that is correct, is the non-turbodiesel constant 19.55 HP/GPH diesel consumed?

In other words, for every 1 GPH fuel consumed, we're generating 19.55 HP?
 
I do not know. Would MPH or GPH be more dependent on ERPM? I would think HP is a constant. Max HP is a known quantity. To vary your engine output would effect Fuel burn. You must decide which is more important Fuel efficiency or Power. They are connected.
 
manyboats said:
I think the time spent below cruise load is probably considerably greater than most all of us think. No I'm sure you don't idle "that" much but we enter long approaches to harbors, slow for "no wake", slow to let other boats pass ect ect. May take some time to set your anchor too.

I never think in mpg .. I always think of gph. With 100 gallons of fuel and a 1gph (approx) burn I have no need.
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You're probably right.... I am definitely going to start making a mental note of it. Might be cool thing to have a light-bulb-moment about :thumb:

I have a friend with a 50' Sea Ray and he ONLY thinks in MPG. I get frustrated talking to him when he says it because his math about it is weird because I don't think he realizes that SOG doesn't have his math working out correctly. I just let it go.

As a big picture... I see it like this. From the low-end toy-boater's place in the world:

I have x amount of fuel
Our destination is x miles away
Skinny Dippin' goes 7-8 MPH average speed anywhere we go
We burn 2 GPH about all the time

Soooooo... The math for figuring out how long it takes to get somewhere, how much fuel it will take, and how much it will cost is embarrassingly easy. Does that make be a bad sailor? Perhaps, but I still enjoy it :blush:
 
Tony w my tanks full at 100 gallons and my consumption at 1 gph all I need to ask is can I make it where I'm going in 100 hrs?

When I had new tanks made I asked for smaller tanks 35 or 40 gal I can't remember. They just ignored me and made 50 gal tanks.
 
It doesn't matter whether you use NMPG, SMPG, hours of operation based on burn...etc...etc...whatever works for you and where you get with a reasonable reserve is all that's needed. Saying one method is all you need or one is better than the next is just foolish...a good skipper can usually do any method...many in their heads...

The real point is knowing how much you'll need for a leg including idling waiting for bridges, marinas, restricted areas, tides, chop etc...etc... none of that is really possible without a combination of any of the above methods and a good guess at the rest...or an average derived at from many miles/hours of cruising all sorts of destinations.
 
For a 480 nm day's run (20 kt) I would burn 125 tons of fuel. Glad I didn't have to pay for it.

At the other end of the spectrum, Greenline 33 owners can do a 30 nm day on no fuel burn.
 
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DO,
In your avatar it looks like you're shaking your fist because of the fence behind.
 
FlyWright said:
What it boils down to is that I'm interested in three things:
1. Maximizing the use and enjoyment of my boat
2. Maintaining safety on my boat
3. Maximizing the efficiency of my boat
----------------------------------------------
Flywight
Hey Al, interesting facts on your fuel burn experience. I had an engine performance card on my n/a 6.354's like yours, but haven't been able to find it in recent years. (Another good reason not to have partners on a boat!!)

Besides fuel consumption, I am curious if you have noticed a change in lube oil consumption at different RPM's? You mentioned the top engine speed of 2800 rpm, which is the same as the 6.354, have you ever run at or near the high end for extended periods and noted any difference?

I used to run mine a lot harder and would burn considerable lube oil between 2600 - 2800 rpm. About 1/2 quart per engine over 4 hours of continuous cruising. Since I've slowed down and cruise around 2400 now, I'm burning that same 1/2 quart of oil every 15 - 20 hours of cruising. If I push them above 2400 rpm they will start sipping lube oil again. It would seem that 2200 - 2400 must be the "sweet spot" for my Perkins 6.354.
Larry B
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Yes Larry, I've experienced the same oil consumption pattern. I posted quite a while back on another thread that I was adding a quart every 10-15 hrs when I used to run at 2350RPM. Now at 2000 RPM, I might add 1/2-1 qt every 20-25 hrs. I track this stuff, but the records are on the boat.
 
Burning oil can be part of the duties of the oli control ring. They are designed to wipe only most of the oil off the cylinder. Engines vary greatly in this regard. Jaguars are notorious for "burning oil" but their cylinders are well lubed. Talking to other Perkins owners may reveal that your oil consumption is related to the oil control ring.
 
Oil consumption amount/change... used to be and may well still be the parameter for engine overhaul. Cat used to publish the numbers for several of it's engines from my experience.
 
Perkins engines seem to lose oil at every gasket, every joint, every bend and every opportunity.

A while back, I removed a fuel shut-off solenoid for replacement. Simple job, right? When a mounting bolt was removed, oil started seeping out the threaded hole! Surprised the hell out of me. I've never been a real gearhead, but I would think threaded holes into case of an engine would be placed into a reinforced areas with enough material to accommodate the bolt without allowing penetration into the inside of the case. Whodathunk?

At my present oil consumption rate, I'm not the least bit concerned about the health of my engines. They both start instantly (without preheat) and only smoke for a short period when cold upon start up.
 
I'm at 25 hours since last oil change a d oil levels are constant. Although my RPM's are 1700-1900 range.
1200 total engine hours
 
FlyWright said:
Perkins engines seem to lose oil at every gasket, every joint, every bend and every opportunity.
Click to expand...

Isn't that called Perkins patina? :flowers:

You could always tell when an old Harley I used to own was low on oil, it quit leaking. :blush:
 
CPseudonym said:
Isn't that called Perkins patina? :flowers:

You could always tell when an old Harley I used to own was low on oil, it quit leaking. :blush:
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If a Harley (Perkins) isn't leaking oil... You're out of oil. :angel:
 
In approximately 300 hours and 2 oil changes I haven't used any oil the way I am using my Perkins. I have a few seeps but nothing leaving drops on the pads in the bilge. Based on hours and fuel I can pretty count on 1.2 gph. At my typical cruise that's what the Floscan shows and the totalizer is within 2% on filling up.

Tom
 
Haven't noticed any drop of engine-oil level during routine checks or annual oil changes on my JD4045. (Now undergoing routine valve adjustment, oil change, and so on after 260-hour/26-month use.)
 
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FlyWright said:
Perkins engines seem to lose oil at every gasket, every joint, every bend and every opportunity.

A while back, I removed a fuel shut-off solenoid for replacement. Simple job, right? When a mounting bolt was removed, oil started seeping out the threaded hole!
=============================================

Ha Ha Ha!! That's a good one. Same thing when replacing the exhaust manifolds; you also need to remove the studs from the block, clean, inspect and dab a little sealer on the threads before screwing them back into the block. Some of the studs penetrate the oil galleys and may weep oil when hot if you don't.

You're right Al, those N/A Perkins engines will run forever if they're maintained properly. Unfortunately, running old technology engines means a little smoke when they're started cold, which some folks find objectionable.

LB
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