Grossing 16-17k in the Northeast, should I expect more from truck?

[AH64ID]

Cruise timing wont be effected by the cam too much, but spool timing is. Between my cam/turbo/pistons I am able to run a considerable amount more timing in the 35-55% load range than on trucks without those mods. 

 

An SSR will give you some additional UDC options, but there aren't any box tunes. 

 

I still think you should save for UDC pro and run SW3 until then... you're not looking at a huge mileage gain over SW3 anyhow. 

[JPhauler87]

The price tag to go to Pro is hard for me to swallow, even with some saving.

 

I actually ordered the dongle this afternoon. I really do understand the silliness of spending good money after bad... but I also kinda wanna see what I’m getting myself into before I spend $1300+... ?

[JPhauler87]

Dongle came. Unopened in the box for now.

 

Downloaded Pro. Hooollly crap there is a lot going on there.

[AH64ID]

34 minutes ago, JPhauler87 said:

 

 

Downloaded Pro. Hooollly crap there is a lot going on there.

 

Yes, like everything!!! 

 

It looks daunting at first, but it gets better... with a dew dozen tune revisions 

[JPhauler87]

AH, what kind of mpg gains were you able to make with pre and post injection changes? I know I will eventually need to access the rail map to lower pressure but as far as basic vs Pro for what I’m looking to do, those things seem to be the biggest items that could effect mileage that I won’t have access to with basic. I know the guys at Smartyresource have told me they haven’t found either to have much effect.

[AH64ID]

I cant say with the post as I haven't ran with the post on in over 100K miles.

 

With the pre I saw maybe a 10% gain by adjusting it. The biggest thing I saw was better EGT's, less noise, and less haze. I was able to reduce the cruise pilot and advance the main cruise timing to get a little bit of a gain but it's not huge.

[JPhauler87]

58 minutes ago, AH64ID said:

With the pre I saw maybe a 10% gain by adjusting it.

 

A 10% gain in mileage? That’s significant IMO.

 

Is that on top of what you gained with UDC and S06?

[AH64ID]

I never ran the truck stock so I cannot comment on that.

 

10% while towing is 1 mpg, at most and lots of variables in there. That's where I saw the biggest gains. In cruise it was maybe .5 mpg at 16-17 mpg.

[JPhauler87]

On 3/14/2018 at 8:40 PM, AH64ID said:

most of my gains were made when I was able to reduce the pilot timing and rail pressure.

 

Can you explain how reducing the rail pressure helps? As I continue to read, this seems less clear to me when using a timing calculator.

 

I understand more rail pressure means more fuel injected for the same duration which requires less timing in order to not rattle (right?) and vice versa. So as long as you balance the two and ignore CP3 loss from making 20k psi instead of 15k, and you have a pilot that helps ignite whatever fuel you’re injecting almost immediately... what difference does it make? (Rhetorical, I’m sure it does make a difference.)

 

Is it that less fuel gets injected because the rail pressure is lower? Meaning, less fuel with more timing at the same load/rpm would be more efficient.

 

I am still a little fuzzy on the order the ECM uses the tables and have a feeling that coupled with the weird labels in UDC basic are throwing me off track a bit.

[AH64ID]

My understanding is that the ECM determine how much fuel it needs, then it references the rail pressure table, and lastly the duration table to determine the injector open time. Then it applies the desired timing and adjustments... etc. 

 

Under general terms rail pressure won't effect the quantity fuel injected, but rather how long it takes to inject it. So lower rail pressure means a longer injection duration, and higher pressure means a shorter duration. 

 

My theory on lower rail pressure producing better mileage is that it takes less power to compress the fuel, and the longer injection event allows for a more efficient burn at low fuel volumes. At high fuel volumes we're going for as short of event as possible. 

 

Where we get into needing more pressure to get the fuel injected is high rpms and/or high duration where crank angle degrees happen really fast. For instance using a stock 04.5-07 duration table, 140mm3, and 26K psi it takes 1890us to get the fuel injected. At 1800 rpms that is 20.4° of crank rotation and timing isn't an issue to get it all in. At 3500 rpms it takes 39.7° of crank rotation which can mean some pretty advanced timing... and that's on a stock duration table, just imagine if the duration is stretched 50%. This is why, with custom tuning, I am a fan of slightly oversized injectors that can run stock or less than stock duration. I only run about a 1600us pulse WOT so I don't need too much timing, less than 20° until I'm above 3400 rpms. 

 

 

Clear as mud?

[JPhauler87]

20 hours ago, AH64ID said:

Clear as mud?

 

That’s my manager’s favorite saying!

 

But yes, I think I understand now. 

 

So at a given load/rpm, the ECM, based on throttle position and other things, makes a determination of how much fuel it needs in mm3. It then references pressure and duration tables to determine how much pressure and how many us to stay open for, then when to start injecting.

 

I see why increasing pressure with load and rpm makes sense and why the stock map is so ridiculous in the lighter load/medium rpm areas.

 

Is 15k too low for the cruise hump? I read a 2012 thread about you going to 14k at cruise and it was too low because boost and EGTs went up... but then also continued on to discuss how pressure related to timing and the need to make a calculator. Did you find 14k (or even lower) was ok with properly balanced timing and pressure at cruise?

 

What would the symptoms of a rail pressure that’s too low, even with timing within reason based on calculator?

 

If I’m prying too much into your trade secrets, I understand and my feelings won’t be hurt

 

Really appreciate the help!

[AH64ID]

The 6.7's will run as low as 8-10K in cruise but I haven't had good luck that low. I think I've running 14-15K with good results lately, but that's with UDC Pro and modified pilot timing vs 2012 which was UDC.

 

Too low will probably end up with increased EGT's and possibly decreased mileage but I haven't played with it since UDC Pro came out.

[Killer223]

6.7 load at my Cruze speed of 70 is usually in the 10-12k rail pressure. And I’m getting good mpg there as well. But if you are not talking about the 6.7 then my mistake. 

[AH64ID]

17 minutes ago, Killer223 said:

6.7 load at my Cruze speed of 70 is usually in the 10-12k rail pressure. And I’m getting good mpg there as well. But if you are not talking about the 6.7 then my mistake. 

 

Yes I was talking 6.7 cruise rail pressure. I was trying to think back to the 2010 I've got a few miles in, but that cruise was around 55-60 mph.

[JPhauler87]

So, I chickened out and am sticking with Basic. Got a couple lines cheap, used S06s.

 

I am running a timing map similar to the SW3 sample tune with a couple exceptions. Enlarged cruise hump, not quite as negative timing at very low rpms, little more timing in the ~50% load cruise rpm area to help with towing mpg.

 

No towing for a few more weeks so I am working on the cruise hump. I am trying to find the max timing limit. I was under the impression the combustion rattle I’ve read would indicate too much timing in the 6-31% load range would sound like a second gen truck. I’m around 9.5* and am not hearing that, or really hearing anything much different. I’ve noticed since installing the new turbo at lighter loads that I hear what kind of sounds like a lighter, soft hollow kind of flutter, very faint. Not sure I could even capture it on camera it’s so faint. I have not noted a huge change since UDC. Am I listening for something that subtle, or will I KNOW when I’ve gone too far?

 

https://smartyresource.com/forums/topic/737-cruise-timing-for-2005/

[AH64ID]

When looking at the SW3 sample make sure you don't go quite as static on the timing in upper loads. 

 

I've tried similar with more timing in the middle but on UDC it got me slower boost response and more haze while towing, I think mostly due to the high pilot timing. My lowest timing at 2000 rpms is 3.5° but I only have 12° of pilot at that point (Stock pilot timing is 45° at the same fuel flow!). I also can't run that much timing on most trucks with 04.5-07 pistons or they haze really bad.

 

Stock pilot timing is at 57° for 2000 rpms and WOT. 

 

Looking at the stock timing table you can see why mileage drops off fast above 2000 rpms. 

[JPhauler87]

I have been continuing to add .5* of timing waiting to see some indication not to... and I'm now at 14* in my cruise region.

 

No knock or combustion rattle, probably a bit more injector tapping (remans)

Truck is still responsive and builds boost quickly at the cruising loads

Exhaust is clear, no haze

 

Rail pressure reads on my OBD app what I'd expect to see at those loads based on looking at the stock pressure map.

 

Up to 2000rpms going through the gears it seems I can here a little more 2nd gen-esque noise, but pretty faint.

 

Should I keep going until I see some sign I've gone too far? This is a lot more than I'd have expected to get away with!

[AH64ID]

The 2nd gen noise, and likely the injector tapping noise, is timing rattle. 

 

What is your mileage doing? I'd expect its getting worse the more timing you add at this point. 

[JPhauler87]

Last full tank was 16.4mpg cruising my hilly commute at 65mph. First 1/4 of that tank was SW3, the rest was UDC starting at 9* and adding .5* every 100 miles or so.

 

Best ever mileage (17mpg) was achieved on this same route, but middle of summer.

 

Is there any harm in running it as-is to see how it does?

 

I have noticed SW1-9 sample tunes all have the same cruise timing profile, and really, the biggest differences are at the high loads and rpms. I read a thread over on Smarty Resource with Brian saying he gained like 3mpg grossing 20k lb running SW7 vs stock tune. Looking at all the timing profiles, I am curious how he achieved such a large gain given where I'd expect the truck to run when towing, even with an optimized rail map.

 

 

[AH64ID]

The samples are just that, samples. They really aren't how the actual tunes look. Prime example is that SW1-5 all use the same, stock, duration table, but there are differences in the limiters but the samples all show different duration tables. 

 

There probably isn't any harm as long as you drop the timing by 45mm3.