Huffdaddy70 and anyone else looking the best mpg's...injection timing is the key but there can be more to it as well. This is kinda like the old H&S box tuning days except we don't have export files to show us what RaceME's timing, pressure, duration maps, etc... look like. We would need to actually see those maps to dial a tune in perfectly with the options that you have now.
Since we don't, it will be a trial and error deal. That's why I think its important for folks to share their settings and how they perform. This will help the next person coming along.
For now let me give you guys a little bit of tuning 101...
3 main things with fueling that effect power and efficiency.
Injection duration: the amount of time the fuel injector is open spraying fuel.
Injection pressure: fuel pressure present in the common rail.
Injection timing: the time of the start of a injection event, measured in crankshaft degrees relative to top dead center on the compression stroke.
Duration notes...
The 6.7 Cummins will want X amount of fuel to maintain a certain amount of work output. X amount of fuel is delivered by the injector being open Y amount of time at Z amount of fuel pressure. So...as pressure goes up, the injector needs to open less amount of time (shorter duration) to deliver the same amount of fuel as it would have needed be at a lower pressure.
Injection pressure notes...
As mentioned above, injection duration will change as pressure changes at the same fueling command. Higher pressure delivers more fuel in time than lower pressure. Higher pressure atomizes the fuel spray better which makes it more the fuel shot more volatile. Too high of pressure can the blow the relief valve or even worse, blow an injector head off! Lower pressure does just the opposite. Low pressure/high duration will make the engine more smokey and requires more timing advance to run properly.
Injection timing notes...
Injection timing needs to increase with duration in order to keep the burning on top of the piston at the critical time around top dead center to work with the mechanics of the engine itself. Too much and you'll literally have the engine fighting against itself trying to run backwards creating way too much cylinder pressure. Too little and you'll have the fuel shot chasing the piston downward trying to catch up. When the timing is perfect and it matches up precisely with the pressure and duration... then you have an engine that runs at peak efficiency. Mileage will be its best at that point and EGTs will be at their lowest ( referring to a highway cruising load and speed). Now keep in mind that there many many things at play I'm not mentioning here. These are just some basic truths.
So how can you tell where you are at with your truck? A little too much timing may cause some pinging or rattling much like poor gas in a gasoline engine. Way too much timing will make your engine feel like its in a bind along with the pinging. Too little timing will cause the engine to feel a little lazy and will causes excessive smoke on acceleration. EGTs will get a little high as well.
Here are my suggestions with your Ultra finding the sweet spots.
1. Never exceed 1900 bar with your max pressure option.
2. 23 degrees of total timing setting is a good all around setting for the lower HP settings.
3. 29 degrees probably will work for most of the higher HP settings. I would never choose the 35 degree setting unless you know the risk and what you're doing.
4. If you want to play with timing to find the best efficiency just for highway cruising, then choose the setting that doesn't cause pinging while at full operating temp and delivers the lowest EGT. Also it may tell you something to watch throttle input. If you notice it takes less throttle % to maintain a speed at a given load as you change timing, then you are getting more efficient.
Again we don't know what the RaceME timing maps look like. So there could be advantage for increasing the timing via the option or there may not be any advantage. It depends if the low and mid range timing changes with the options on your Ultra as you change the settings. Trial and error will tell.
Also again, timing isn't the only factor that effects efficiency. We have only mentioned a few related to fueling. Even the turbo mapping options can effect mileage. You have a lot of power at your fingertips with the box tuning options with your Ultra! Use them wisely!
I personally can't hardly wait to see what we can do when we have the custom tuning software that is soon coming!
Ray
www.doublerdiesel.com
email:
info@doublerdiesel.com
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John 3:16, Romans 10:9-10...Tuning for the Heart and Soul.
Originally Posted by Double R Diesel LLC
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