Reply
 
Thread Tools Search this Thread Display Modes
 
Old 11-03-2016, 10:34 PM   #1
Veteran Member
 
City: Rock Island, IL
Country: USA
Join Date: May 2013
Posts: 74
SB Engine Uses 26 gal More Fuel

On my Meridian 490 PH, Cummins B5.9MTA, starboard is 330hp, port is factory reconditioned 315 hp, any ideas why SB Engine used 26 more gals over a 200 mile run? Only used the penny for 4 hrs. Any idea on fuel consumption rate for an On an 13.5 Jenny? Thanks!! Dick
__________________
Advertisement

sammy999 is offline   Reply With Quote
Old 11-04-2016, 12:40 AM   #2
Senior Member
 
The Other Gary's Avatar
 
City: Toronto
Country: Canada
Vessel Name: Adios Dinero
Vessel Model: Bayliner 3988 2 x 330 Cummins
Join Date: Sep 2016
Posts: 334
The 315 and 330 are the same engine if the CPL numbers are the same. They were marketed under two different HP designations.
Check the info plate on the port forward corner of the engine.
It should say CPL 1970 with Bosch pump or CPL 1928 with Nippondenso pump. Both are marketed as 315/330 hp depending on whether they use flywheel HP or shaft HP
If so, the stbd. engine may have more wear, and need more fuel to operate.
Failing that I would look to the condition of your props, engine alignment etc. and tach. accuracy
__________________

The Other Gary is offline   Reply With Quote
Old 11-04-2016, 02:08 AM   #3
Guru
 
North Baltic sea's Avatar
 
Country: Finland
Vessel Model: Nordic Tug 37
Join Date: Sep 2015
Posts: 916
Hi, four things for which consumption difference may be due to.


1. Injection nozzle, The expoer did not complete-Check opening pressure and spray form
2. Injection pump, offers too much food-Adjust the pump
3. Check the air supply, the filter and the channels.
4. Turbo problem, possibly carbon deposits, or check whether the shaft is free.


Point 1 and 2 require professional and specialty tools. Point 3 and 4, it is possible to check in early to keep the mess on your hands.


The other Gary told of the good points as well, the gearbox, the propeller and the shaft line really can bring the consumption differences as well.


I hope this could help ...
North Baltic sea is offline   Reply With Quote
Old 11-04-2016, 02:14 AM   #4
Guru
 
BandB's Avatar
 
City: Fort Lauderdale
Country: USA
Join Date: Jan 2014
Posts: 17,435
Quote:
Originally Posted by sammy999 View Post
On my Meridian 490 PH, Cummins B5.9MTA, starboard is 330hp, port is factory reconditioned 315 hp, any ideas why SB Engine used 26 more gals over a 200 mile run? Only used the penny for 4 hrs. Any idea on fuel consumption rate for an On an 13.5 Jenny? Thanks!! Dick
What are you basing that on? How did you calculate the usage and difference?
BandB is online now   Reply With Quote
Old 11-04-2016, 07:48 AM   #5
Guru
 
City: Northport
Country: USA
Join Date: Aug 2015
Posts: 1,425
Quote:
"On my Meridian 490 PH, Cummins B5.9MTA, starboard is 330hp, port is factory reconditioned 315 hp, any ideas why SB Engine used 26 more gals over a 200 mile run?"
If you are running your engine by matching the rpm then the difference may be attributed to the difference in your props demanding different hp port and stb to reach the same rpm - pretty typical on many boats. If you have calibrated fuel flow gages or have boost or EGT gages then you can likely prove this in real time.




Quote:
"Only used the penny for 4 hrs. Any idea on fuel consumption rate for an On an 13.5 Jenny?"
a diesel genset will typically use about 0.1gph per KW produced. Often I see folks with your style boat cruising with the genset while using between 5,000 and 7,000 watts or less so that would be between 0.5 and 0.7 gph use at those loads.
FWIW - most of the 490 Meridians came with 12.5 KW gensets.
smitty477 is offline   Reply With Quote
Old 11-04-2016, 07:50 AM   #6
Guru
 
City: Carefree, Arizona
Country: usa
Vessel Name: sunchaser V
Vessel Model: DeFever 48
Join Date: Apr 2008
Posts: 8,068
Quote:
Originally Posted by BandB View Post
What are you basing that on? How did you calculate the usage and difference?
sunchaser is online now   Reply With Quote
Old 11-04-2016, 11:04 AM   #7
Guru
 
City: gulf coast
Country: pinellas
Join Date: Jun 2014
Posts: 2,798
To the above must be added the question of whether both engines were operating at the same load. How did you determine they were loaded equally?
bayview is offline   Reply With Quote
Old 11-04-2016, 11:59 AM   #8
Guru
 
MYTraveler's Avatar
 
City: West Coast
Country: USA
Join Date: Apr 2014
Posts: 1,079
If you traveled that 200 miles at 8 knots, then the 26 extra gallons were consumed over 25 hours, or about 1 gph. My engines never have that large a discrepancy (at least not when both are engaged). In fact my engines' total consumption are within 1/2 %, with the engine that drives the stabilizer pump consuming the extra fuel. That extra 1 gph that your engines are burning is too large to be explained by normal variation between engines, etc.

Logically, it must be either that the loads are significantly different (as could be the case if a prop was damaged, etc.) or that your measurements are wrong. If you are confident in the measurements, I would focus on load, and disregard the possibility that it is normal engine variation.
MYTraveler is offline   Reply With Quote
Old 11-04-2016, 01:15 PM   #9
Guru
 
City: Northport
Country: USA
Join Date: Aug 2015
Posts: 1,425
Quote:
"If you traveled that 200 miles at 8 knots, then the 26 extra gallons were consumed over 25 hours, or about 1 gph."

Although that is possible I would guess that he is asking about a trip that was made at twice that speed or more where prop variations make larger contributions to unequal loading.
But heck - I don't know so lets see what is posted back on this in good time.
smitty477 is offline   Reply With Quote
Old 11-04-2016, 01:33 PM   #10
Guru
 
djmarchand's Avatar
 
City: Litchfield, Ct/Punta Gorda, Fl
Country: USA
Vessel Model: Atlas Pompano 23
Join Date: Aug 2012
Posts: 4,832
Some reasons:

1. Inaccuracies in calculating fuel burn.

I assume that you are basing your numbers on running each engine from separate tanks and measuring how much it takes to fill each. This method is influenced by how full you got each tank each time you filled and can easily be off 5% up on one and down on the other.

2. Port to starboard gear ratio differences.

This is often the case when the gear box is used to counter rotate port vs starboard.

3. Prop pitch differences.

4. A combination of 2 and 3.

You could adjust the pitch on one or the other prop to get the fuel burn closer.

5. Your genset if running at half load will burn about 1 gph, so not significant in 4 hours.

6. Engine differences

Every engine data sheet says that their numbers could be as much as 3% different which goes both ways. So maybe 3% up on one and 3% down on the other.

The injection pump, injectors, turbo, etc. discussed above are mostly BS.

You don't say what the percentage difference is. Anything less than 10% I wouldn't worry about.

David
djmarchand is online now   Reply With Quote
Old 11-04-2016, 01:58 PM   #11
Guru
 
koliver's Avatar
 
City: Saltspring Island
Country: BC, canada
Vessel Name: Retreat
Vessel Model: C&L 44
Join Date: Nov 2007
Posts: 3,152
How are your engines synchronized?
Do your transmissions have the same reduction gearing?
Are your props pitched exactly the same?
Do you run your engines at the same temperature?

All of the above will influence fuel burn. None are easy to compensate for, if those differences exist.
__________________
Keith
koliver is offline   Reply With Quote
Old 11-04-2016, 02:06 PM   #12
Guru
 
BandB's Avatar
 
City: Fort Lauderdale
Country: USA
Join Date: Jan 2014
Posts: 17,435
I'm guessing we'll next get some clarification from the OP tonight.
BandB is online now   Reply With Quote
Old 11-04-2016, 02:07 PM   #13
Guru
 
City: Northport
Country: USA
Join Date: Aug 2015
Posts: 1,425
Once again we need sammy999 to post back but I am a bit familiar with his boat so I will put up a few more 'guesstimates".


1. "I assume that you are basing your numbers on running each engine from separate tanks and measuring how much it takes to fill each."


Each tank is amidship and at 222 total gallons each. They tend to fill and refill with no issues as long as you take some care.

"2. Port to starboard gear ratio differences"
Gears are 800 series with both "A" an "B" at 1.96:1


"5. Your genset if running at half load will burn about 1 gph, so not significant in 4 hours."
Estimates from about 0.7 or so are often near the mark on these boats.


"You don't say what the percentage difference is. Anything less than 10% I wouldn't worry about."


With his 490 Pilothouse running at 16 knots over 200 nautical miles Sammy's total fuel burn should be around 222 for a port and stb variation of 98 vs 124.
At hull speeds I will guess that his genset hours would be higher but just making guess's rarely yields good data.
smitty477 is offline   Reply With Quote
Old 11-04-2016, 02:18 PM   #14
Guru
 
BandB's Avatar
 
City: Fort Lauderdale
Country: USA
Join Date: Jan 2014
Posts: 17,435
Quote:
Originally Posted by smitty477 View Post
Once again we need sammy999 to post back but I am a bit familiar with his boat so I will put up a few more 'guesstimates".


1. "I assume that you are basing your numbers on running each engine from separate tanks and measuring how much it takes to fill each."


Each tank is amidship and at 222 total gallons each. They tend to fill and refill with no issues as long as you take some care.

"2. Port to starboard gear ratio differences"
Gears are 800 series with both "A" an "B" at 1.96:1


"5. Your genset if running at half load will burn about 1 gph, so not significant in 4 hours."
Estimates from about 0.7 or so are often near the mark on these boats.


"You don't say what the percentage difference is. Anything less than 10% I wouldn't worry about."


With his 490 Pilothouse running at 16 knots over 200 nautical miles Sammy's total fuel burn should be around 222 for a port and stb variation of 98 vs 124.
At hull speeds I will guess that his genset hours would be higher but just making guess's rarely yields good data.
Where does the return fuel go? Perhaps all to one tank? How did he measure the fuel usage? I'm sure he'll respond later.
BandB is online now   Reply With Quote
Old 11-04-2016, 04:49 PM   #15
Guru
 
Lepke's Avatar
 
City: Between Oregon and Alaska
Country: US
Vessel Name: Charlie Harper
Vessel Model: Wheeler Shipyard 83'
Join Date: Jun 2016
Posts: 1,603
Usually in twin installations with engines of similar condition, fuel consumption differences are caused by loading differences. Engines not in sync. Also if one engine has bilge pump, alternator the other doesn't have.
Get a portable heat gun and check temps of exhaust ports to see if engines are producing similar exhaust gas temperatures. If turbo driven, check boost pressures.
One prop could have slightly more pitch.
Etc...
Lepke is offline   Reply With Quote
Old 11-04-2016, 07:19 PM   #16
Guru
 
Capt.Bill11's Avatar
 
City: Sarasota/Ft. Lauderdale
Country: USA
Join Date: Apr 2014
Posts: 5,436
Way to little information to even start guessing.
Capt.Bill11 is offline   Reply With Quote
Old 11-04-2016, 08:48 PM   #17
Guru
 
Steve's Avatar
 
City: Thibodaux, Louisiana
Country: USA
Vessel Name: Gumbo
Vessel Model: 2003 Monk 36
Join Date: Oct 2007
Posts: 3,873
Post #4 is the key.
__________________
Steve W.
http://mvgumbo.blogspot.com/
Steve is offline   Reply With Quote
Old 11-04-2016, 11:37 PM   #18
Senior Member
 
Brisyboy's Avatar
 
City: Brisbane
Country: Australia
Vessel Name: Malagari
Vessel Model: Island Gypsy 36 Europa
Join Date: Mar 2015
Posts: 272
Quote:
Originally Posted by Steve View Post
Post #4 is the key.
I`d also be interested in post #14 - fuel return, but of course the method of calc is probably the key
__________________
George
Brisbane
IG 36 Europa
Brisyboy is online now   Reply With Quote
Old 11-05-2016, 08:47 AM   #19
Guru
 
City: Northport
Country: USA
Join Date: Aug 2015
Posts: 1,425
Regarding post #4. When fuel valves are set to return both to one tank the results is moving more than 10 gallons per hour from one tank to the other dependent upon speed at the time. With the same boat we have actually added 100 gal on one side only and used the returns to transfer fuel over the next 4-5 hours to come close to 'equal up'.
Here is a pic of the fuel valves that should be on Sammy's boat....




smitty477 is offline   Reply With Quote
Old 11-05-2016, 09:07 AM   #20
Guru
 
City: Carefree, Arizona
Country: usa
Vessel Name: sunchaser V
Vessel Model: DeFever 48
Join Date: Apr 2008
Posts: 8,068
Smitty, as the de facto respondent how did 99 determine the per engine fuel use?
__________________

sunchaser is online now   Reply With Quote
Reply

Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off





All times are GMT -5. The time now is 03:41 PM.


Powered by vBulletin® Version 3.8.8 Beta 4
Copyright ©2000 - 2019, vBulletin Solutions, Inc.
Search Engine Optimization by vBSEO 3.6.0
Copyright 2006 - 2012
×