Max cruise timing

[Tinman]

I too am at the point to where I am trying to tune for the best mileage (pretty much like the rest of my tune). So if I follow this discussion correctly, best mileage is done by increasing main to around 8* (which I have done) and decreasing pilot to around 10*? This will drastically decrease dwell time over stock as the pilot is at over 20* (IIRC). Outside of the cruising range, the pilot is significantly retarded and pilot advanced, increasing dwell time significantly. What are the advantages and disadvantages of changing the dwell time and pilot mm3?

[Ghostman]

I was running down the highway the other day at 75mph. With a pilot tune my total us of duration adding the main and pilot together was around 750. When I turned to the single event tune my us duration dropped to around 600. Just stating what I saw.


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[Tinman]

Running 8* of main timing and 10* of pilot seems to have gained a mile per gallon compared to 8* of main with stock pilot. VERY early testing but this seems to had positive results. I'm gonna continue with this tune for a while and maybe try 10* of main also.

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[Move'n Up]

Good to know, thanks for the update.

[arinkuddy]

I've been running this which my truck seems to like
Capture.PNG
I cruise in the 40-45mm3 range on level road so im pretty much running about 8.5* of timing there. I think 10* is getting a bit high for the 45mm3 cell.
I dont have enough data to say for sure but looks promising.
I can say this table did not yield as high MPG
Capture1.PNG

Also IDK if many of you guys use this feature but use the "load alternative calibration for comparison" and open the unmodified tune you are using. Then you can go back and forth between stock and yours, and it also normalizes the scaling so which can be nice.

[Ghostman]

I've logged some straight highway miles driving from Texas to Colorado. On the single event tune best I got was 18.9 mpg. Got 16.8 on two other tanks. Probably due to 80+ mph speeds. All hand calculated. Stock suspension with 32-33" tires. Seems there is room for improvement.


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[Ghostman]

Originally Posted by arinkuddy

I've been running this which my truck seems to like

Attachment 61736

I cruise in the 40-45mm3 range on level road so im pretty much running about 8.5* of timing there. I think 10* is getting a bit high for the 45mm3 cell.

I dont have enough data to say for sure but looks promising.

I can say this table did not yield as high MPG

Attachment 61737



Also IDK if many of you guys use this feature but use the "load alternative calibration for comparison" and open the unmodified tune you are using. Then you can go back and forth between stock and yours, and it also normalizes the scaling so which can be nice.

What does your pilot look like?


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[Ghostman]

I'm on my way back so I tried a different tune. It's same as my single event tune except it's a pre/main injection tune and the timing tables are stock. Mileage dropped to 14.6mpg. So timing definitely makes a difference and definitely better than stock timing.


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[tylerltr450]

Keep up the good work trail and error are the only ways!!

I would say try to get a millage tune on a 2 setup injection tune.

[Ghostman]

Originally Posted by tylerltr450

Keep up the good work trail and error are the only ways!!

I would say try to get a millage tune on a 2 setup injection tune.

I want to it's just so much harder to know where to start compared to just working on only a main tune.




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[malibu795]

Basics being same... I run 20,000psi rail while cruising. Higher psi equals better atomization, and less injector on time and better throttle response..
As you still need X volume of fuel to generate Y HP.

Pilot timing I haven't messed with much.. Main timing I don't go past 1* per 100uS, regardless of rail psi, while cruising..
I find it rattles more especially in colder temps when there is more then 1* per 100uS timing on stock injectors

Alot of it is trial and error since max effort or close to it are different between engines

[Leiffi]

Originally Posted by malibu795

Basics being same... I run 20,000psi rail while cruising. Higher psi equals better atomization, and less injector on time and better throttle response..
As you still need X volume of fuel to generate Y HP.

Have you ever heard about fuel penetretion ? Too much pressure penetrates too much at low boost and rpm and that means fuel dont mix well with air and might touch cylinder walls and wash oil out of them. I wouldnt change factory pressure vs boost/rpm, they have studied it with better equipment than any of you have.

[malibu795]

Please read what said again

[arinkuddy]

Originally Posted by Ghostman

What does your pilot look like?


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I am running 10deg of pilot time and 2mm3 pilot qty both across the board except idle where i have it stock.

Idk what to think about mileage anymore... there is just so many variables. Dropping timing below stock in cruise area does hurt it for me but raising it much doesn't yield much gains.

I remember running my smarty jr and on timing 4 I got the best, too bad i couldnt peek at what they were running.

[arinkuddy]

Originally Posted by Leiffi

Have you ever heard about fuel penetretion ? Too much pressure penetrates too much at low boost and rpm and that means fuel dont mix well with air and might touch cylinder walls and wash oil out of them. I wouldnt change factory pressure vs boost/rpm, they have studied it with better equipment than any of you have.

I agree, I wouldn't dare run that high of pressure cruising. I actually use slightly lower than stock cruise pressure where it spikes a little around 45mm3. I actually was theorizing that the extra hp used by the cp3 to get that pressure may cause diminishing returns anyway.

I wondered how the old 12 valves got such good mileage with the lower pressure and im assuming wider pulse. Less parasitic losses from injection system? No pilot?

[arinkuddy]

Originally Posted by malibu795

Basics being same... I run 20,000psi rail while cruising. Higher psi equals better atomization, and less injector on time and better throttle response..
As you still need X volume of fuel to generate Y HP.

Pilot timing I haven't messed with much.. Main timing I don't go past 1* per 100uS, regardless of rail psi, while cruising..
I find it rattles more especially in colder temps when there is more then 1* per 100uS timing on stock injectors

Alot of it is trial and error since max effort or close to it are different between engines

running higher pressure always caused a surge in cruise for me and an annoyingly touchy throttle.

[Ghostman]

My pressure runs around 18k in the cruising range. I don't seem to have an issue with that pressure.

@Arinkuddy - so the table with less main timing got worse mpg. I think I would expect that. What kind of mileage are you getting?



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[arinkuddy]

Originally Posted by Ghostman

My pressure runs around 18k in the cruising range. I don't seem to have an issue with that pressure.

@Arinkuddy - so the table with less main timing got worse mpg. I think I would expect that. What kind of mileage are you getting?



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no not really talking about the tables i posted above im talking about dropping the cruise area down to like 5 deg. That seemed to hurt mileage. Where do you cruise? like 1800 rpm 40-45ish mm3?

[Ghostman]

I'm closer to 2000-2100. Our speeds are 70-75. I'm in the 45-50 area. It will jump up a little on hills and such.

Very last tank I checked on way home was a solid 75mph on my single event tune only. Got 17.8mpg.


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[malibu795]

Originally Posted by arinkuddy

running higher pressure always caused a surge in cruise for me and an annoyingly touchy throttle.

On the dmax there are about 8-10 main tables that have to "jive" to get smooth respone on a general tune.

Moving rail pressure in sooner throws throttle, timing, Mm3, boost all off the normal operating area of the charts and they all have to be adjusted to get smooth operations again

Empty I run less then 20% throttle, realy touchy for most, Loaded I'm 25-40% throttle
Stock setup ID be 35-45 Empty loaded be 60-75% for same fueling...

I've got my dmax setup I can go full fuel by 1800rpm with timing adjusted for throttle and RPM, as full timing at 1800 that I run at 3000 would hurt the engine..