LSD, ULSD, Cetane, and timing
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Lead Driver
Joined: Nov 2003
Posts: 6,900
Likes: 3
From: Campbell River, B.C.
LSD, ULSD, Cetane, and timing
Just thinking out loud here.
With the newer fuels that we have to run now, I am wondering if the different properties mean that we should change the timing curve of our diesels.
I recently started messing with the timing on my truck, both static and the retard lever on the side of the pump. I have retarted the static timing only slightly, but I made several adjustments to the lever adjustment (screw on the bottom end).
The fuel economy has improved very slightly, but exhaust smoke is down so much that I ended up turning up the fuel slightly. Chances are the timing was too advanced to begin with, but what are your thoughts on the new fuel? Could this be part of the reason that MPGs seem to be down across the board here?
With the newer fuels that we have to run now, I am wondering if the different properties mean that we should change the timing curve of our diesels.
I recently started messing with the timing on my truck, both static and the retard lever on the side of the pump. I have retarted the static timing only slightly, but I made several adjustments to the lever adjustment (screw on the bottom end).
The fuel economy has improved very slightly, but exhaust smoke is down so much that I ended up turning up the fuel slightly. Chances are the timing was too advanced to begin with, but what are your thoughts on the new fuel? Could this be part of the reason that MPGs seem to be down across the board here?
Posting Guru
Joined: Mar 2005
Posts: 1,701
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From: KY
There are definitely differences in the fuels which could require different timing curves. To really know we would need to know the combustion temp of the new fuel compared to the oil fuel.
I have been to no telling how many classes about this over the years and the full combustion temp has always been between 1000 to 1100 deg. Depends on what engineer was giving the class.
What the answer is I don't know.
I am VERY fortunate that I can fill up one of my tanks and run for 2 to 3 weeks. I drive like 10 mile round trip everyday and I only 1 mile of it a 55mph zone. Most is 25 to 35. Well I changed my oil 2679 miles ago and that was last August. I use the Trip to keep up with it.
I have been to no telling how many classes about this over the years and the full combustion temp has always been between 1000 to 1100 deg. Depends on what engineer was giving the class.
What the answer is I don't know.
I am VERY fortunate that I can fill up one of my tanks and run for 2 to 3 weeks. I drive like 10 mile round trip everyday and I only 1 mile of it a 55mph zone. Most is 25 to 35. Well I changed my oil 2679 miles ago and that was last August. I use the Trip to keep up with it.
Elder User
Joined: May 2004
Posts: 790
Likes: 0
From: Danville, Pa
so the screw on the side arm is for advancing the timming sooner, and the screw on the back is for limiting max fuel(for high altitude adjustment)?
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Elder User
Joined: Mar 2008
Posts: 912
Likes: 0
From: Marianna, Florida USA
The cetane rating is supposed to be equivalent for the different fuels. The ULSF has less BTUs per Gallon than the high sulphur stuff. Therefore lower MPG.
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Senior User
Joined: Nov 2004
Posts: 118
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Has anyone tried this amsoil cetane booster? AMSOIL - Synthetic 10W-30/SAE 30 Heavy Duty Diesel Oil (ACB)
Post Fiend
Joined: Nov 2003
Posts: 21,285
Likes: 15
From: Nutter Fort, WV
Cetane is how easily the fuel ignites.
High numbers ignite easy, low numbers are harder.
I have found my non stock engine likes advanced timing, more with lower cetane value's.
Since low cetane fuel is harder to burn, the longer it has to burn the better.
Also the low cetane is part of where the MPG went, all the fuel is not burning.
BTU content is the power contained in the fuel.
More BTU, higher power and MPG for where the rest of the MPG went.
High numbers ignite easy, low numbers are harder.
I have found my non stock engine likes advanced timing, more with lower cetane value's.
Since low cetane fuel is harder to burn, the longer it has to burn the better.
Also the low cetane is part of where the MPG went, all the fuel is not burning.
BTU content is the power contained in the fuel.
More BTU, higher power and MPG for where the rest of the MPG went.
Elder User
Joined: May 2004
Posts: 790
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From: Danville, Pa
So, what curve would I look for with ulsd? I've changed my timing more than 2 dozen times. I can get an exeptional advance curve, but is lost in around a third of the throttle. If I advance it, knocking never really stops till after 1600 or so, but good smooth power till top.
Median is slow start good through the middle and falls on it's face on top.
retarded is simmilar to too advanced, cept way too much smoke and NO power after 2600ish.
Median is slow start good through the middle and falls on it's face on top.
retarded is simmilar to too advanced, cept way too much smoke and NO power after 2600ish.
Senior User
Joined: Jul 2007
Posts: 118
Likes: 1
From: Winthrop, Minnesota
You guys may want to contact Agnem on Oilburners.net about his Moose Pump rebuilds. You should talk to him personally about the pump.
Jim
Jim