We all know the last of the 5.9's was the most powerful, and least fuel efficient of the 5.9's.

 

Cummins didn't put an external EGR on the truck to help it along, but to meet emissions they had to keep cylinder pressure lower by retarding timing... less power, higher EGT's, etc..

 

The common consensus is that a peak cylinder pressure at 9-12° ATDC is best for performance, and efficiency. That means that all the fuel needs to be injected, and ignited prior to that point so the pressure hits when it should.

 

Take a look at this chart and you might see why the EGT's are high and fuel efficiency is lower. This is how many degrees ATDC the injector stays open. Top is rpm's, and left is MM3. OEM tuning runs up to 132mm3.

Don't forget the role the camshaft plays for a 'built in' EGR. Make the valves open and close when they should and they would be more efficient too.

Absolutely, and one of the reasons I no longer run the stock cam.

The stock turbo, pistons, and tuning also played a big role.... But for me anymore.

The 3rd Gen trucks were built around the EPA rules more so that actual efficiency and power.  Kind of like going back in time and seeing the old school muscle cars of the 60's then looking into the 70's of how they smog them out with EGR valve, air pump, modified cam, etc. All EPA junk and killed off the muscle car generation. So now looking at Diesel Trucks we are going around one big circle all over again.

Did you swap your cam without any other mods? Just curious on mileage improvement. When i had my 06 i wanted to swap cams but ended up selling it

I did the cam and saw a small gain in economy, but saw a big gain in drive-ability and low end grunt.

 

I now have a different cam in it, and WOW it's as much better as the first cam was from stock. Still low cruise boost, but spools that turbo like it's for a 2.0L. Great low/mid power and it pulls hard thru 2900 rpms where I start to defuel.

Figuring from a stock truck;  when would one start hearing timing (degrees backward from stock)  rattle by advancing the timing??

 

If I put my Smarty on Timing 4, I get rattle at low rpm.  Drives fine at higher rpm, but I like hearing it.  

 

I truly wonder where my timing is............as I've done the "tone wheel mod" and have my Smarty set on SW5 (default settings) which advances timing slightly.  But as I said prior...................if I put more timing via the Smarty (4) I get rattle.

I rattled more stock then on any Smarty tune I ran, now with the BBi's rattle... what rattle...

 

You are on old Smarty software, TM2 is now more than TM4.

 

It's hard to say, I know I couldn't run the tone ring mod and any smarty timing without issues.. I run less timing that stock in certain places.

 

Rattle is a function of both timing and rail pressure, recall when your rail pressure sender failed?

I rattled more stock then on any Smarty tune I ran, now with the BBi's rattle... what rattle...

 

You are on old Smarty software, TM2 is now more than TM4.

 

It's hard to say, I know I couldn't run the tone ring mod and any smarty timing without issues.. I run less timing that stock in certain places.

 

Rattle is a function of both timing and rail pressure, recall when your rail pressure sender failed?

 

 

Sure do!!  I'm just so glad that there was a Cummins repair shop in Sikeston, MO.  Would've been a bit more challenging otherwise.

 

 

 

 

You also mentioned "peak" cylinder pressure prior.  The "multiple" injection events are there to lower the  peak pressures...................to lessen the creation of pollutants.........................but create more total/sustained cylinder pressure.  Think of an upside-down "V" as the single injection graph.....................and an upside-down "U" as the multiple injection graph. The upside-down "U" should be a lower case letter and widened for the proper analogy.

Yes there are, emissions and noise are the big reasons.

 

I don't care as much about the emissions, but I do like my quiet motor.

The common consensus is that a peak cylinder pressure at 9-12° ATDC is best for performance, and efficiency. That means that all the fuel needs to be injected, and ignited prior to that point so the pressure hits when it should.

 

Take a look at this chart and you might see why the EGT's are high and fuel efficiency is lower. This is how many degrees ATDC the injector stays open. Top is rpm's, and left is MM3. OEM tuning runs up to 132mm3.

Does the Smarty S06 modify when you actually see peak cylinder pressure?  Can it be used to force it to happen so your engine is more efficient? 

 

Do non-stock injectors (i.e. BBi's, 50hp etc.) modify the timing as to when you see peak cylinder pressure?

 

Can the combination of tuning (S06 or UDC) and injectors modify (improve the efficiency of your engine) the timing/combustion cycle that you see much improved efficiency over the stock setup?

 

When is the timing adjustment one can make actually hurt the efficiency of the engine assuming you are not racing, spraying outside the bowls or abusing the engine in any way?

I thought the common rail was supposed to be an improvement over the 24valve. Now your telling me it's a smog motor?

I can't win for losin I tell ya.

Does the Smarty S06 modify when you actually see peak cylinder pressure?  Can it be used to force it to happen so your engine is more efficient? 

 

Do non-stock injectors (i.e. BBi's, 50hp etc.) modify the timing as to when you see peak cylinder pressure?

 

Can the combination of tuning (S06 or UDC) and injectors modify (improve the efficiency of your engine) the timing/combustion cycle that you see much improved efficiency over the stock setup?

 

When is the timing adjustment one can make actually hurt the efficiency of the engine assuming you are not racing, spraying outside the bowls or abusing the engine in any way?

 

Smarty modifies timing, so yes the peak pressure changes.

 

Injectors only do what they are told, but the bigger the injector the shorter the ignition delay. Meaning that if you start to inject at the same time the bigger injector will start and finish combustion sooner.

 

You can take timing too far advanced, or too far retarded to do any good. Too advanced can be very hard on pistons and head gaskets.

 

I think nearly everyone sees a nice efficiency improvement over stock with a Smarty, unless you are always using the added power.

 

My original Smarty Jr tuning (SW1 TM4 original Revo SW) gained 55/100 in middle of the rpm band on no more fuel than stock.

 

I thought the common rail was supposed to be an improvement over the 24valve. Now your telling me it's a smog motor?

I can't win for losin I tell ya.

 

Every motor model has had more emissions based tuning/parts than the previous model.. nothing you can do about that.

 

The 03-04's are the least "smog" laden of the HPCR's, and IMHO all CR's are an improvement over the VP's from power to tuning, even mileage isn't much worse when you consider the weight difference. This is where Micheal will post his stats, but I have no doubt his mileage would take a big hit if he came to town and drove like most people. I also have no doubt I would be in the 20's every tank driving how and where he does, it's not apple-apples for most vehicle owners.

Smarty modifies timing, so yes the peak pressure changes.

 

Injectors only do what they are told, but the bigger the injector the shorter the ignition delay. Meaning that if you start to inject at the same time the bigger injector will start and finish combustion sooner.

 

You can take timing too far advanced, or too far retarded to do any good. Too advanced can be very hard on pistons and head gaskets.

 

I think nearly everyone sees a nice efficiency improvement over stock with a Smarty, unless you are always using the added power.

 

My original Smarty Jr tuning (SW1 TM4 original Revo SW) gained 55/100 in middle of the rpm band on no more fuel than stock.

 

 

Every motor model has had more emissions based tuning/parts than the previous model.. nothing you can do about that.

 

The 03-04's are the least "smog" laden of the HPCR's, and IMHO all CR's are an improvement over the VP's from power to tuning, even mileage isn't much worse when you consider the weight difference. This is where Micheal will post his stats, but I have no doubt his mileage would take a big hit if he came to town and drove like most people. I also have no doubt I would be in the 20's every tank driving how and where he does, it's not apple-apples for most vehicle owners.

 

 

I essentially live "in town", aka. "suburbia" and regularly see 20+mpg tanks of fuel.................and most include trailer towing.  Not a heavy trailer, but it's tall and catches the wind.

If I could ever get a full tank of "normal" driving I would report my mileage... I just do do those anymore.

If I could ever get a full tank of "normal" driving I would report my mileage... I just do do those anymore.

 

 

So what you're saying is that I drive "abnormally"???    

This is where Micheal will post his stats, but I have no doubt his mileage would take a big hit if he came to town and drove like most people.

 

Like my trip I just done on Mother's Day to Ontario, OR I was up to 26 MPG (MoparMom as my witness) cruising around Ontario, OR and doing awesome at holding the number all day in Ontario, OR. Till I turn around and head for home and the winds kicked up and storms where moving in pulled me down to 23.5 MPG when I hit home. Then today really pulled it down crawling the mountain to the "Fire Chief's" house to take care of fire business then head to town and do a computer job. By the end of today and all the BS and crawling mountains roads I'm still barely 21 MPG.

 

I typically get higher numbers in town than on the highway. I gain MPGs in town. I'm also very selective of where I drive I don't look for city streets with lots and lots of stop and go but stay on the rim of town as much as possible.

 

I'm not common rail either but figure out how to gain advantage of the timing curve. (IAT modifier)

So what you're saying is that I drive "abnormally"???    

 

Michael, your like a Prius... good mileage in town and slower speed, but lower mileage up at speed. I wonder if the IAT mod hurts the higher rpm/load. I know the last time you posted 75mph stats it was very low mileage.. relatively.

 

 

So what you're saying is that I drive "abnormally"???    

 

Do you do anything normally?

 

 

I need to get out and do a 65 mph drive, but where and when :-)

 

I did do an empty 75 run last week, and about 70 back from headwinds for over 100 miles. I think I was pulling 18.

 

Michael, your like a Prius... good mileage in town and slower speed, but lower mileage up at speed. I wonder if the IAT mod hurts the higher rpm/load. I know the last time you posted 75mph stats it was very low mileage.. relatively.

 

 

 

Do you do anything normally?

 

 

I need to get out and do a 65 mph drive, but where and when :-)

 

I did do an empty 75 run last week, and about 70 back from headwinds for over 100 miles. I think I was pulling 18.

 

 

My all-time best mileage tank (23.7mpg) came running a steady 65mph for almost a whole tank of fuel. Only one potty break.  The temperature that week was 100-106*F.

 

One trip back from NoDak 5-6 years ago we had a good 15-20mph NW wind pushing us home. No trailer but the truck loaded to the gills and ran 75-80mph the whole way and got just under 21mpg.

 

I'm a "contrarian" by nature.  Don't follow the crowd and do my own thing. I guess I don't understand why it bothers folks to get passed on the highway.  When I drive, I find it stressful to be weaving in and out of traffic passing everyone I can.

Just to add to this mess of VP vs CR....

 

I just made a trip to Missoula, MT from Grand Forks, ND this weekend. I set the cruise at 70 the entire way and stayed on the interstates. I checked my mileage by hand with the trip meter and with a GPS just to make sure. I averaged 22-24 the whole weekend and that included the drive to Missoula and the drive back. About 2000 miles round trip. I left the comp on 4X4 so I did have some extra timing and fuel but I was also running my IAT fooler the whole way as well. I consider these numbers pretty good considering the fact that I am running 35in X 12.50in tires and 3.55 gearing.

I figured going 70 through the mountains between Billings and Missoula would bring it down but it never did. This was with a pretty much empty truck apart from my fiberglass topper. I bet that I would be able to get close to Mike's records if I dropped to 60 mph instead of running 70 the whole time. The only problem is you really cant afford to go any slower when you need to cover 1000 miles in a day.

Just wanted to throw my .02 in there

Judged a retriever hunt test this past weekend NW of Madison, WI.  They were paying mileage, and I needed fuel before the trip anyway, so I filled up with 29.995 gallons and had 628 miles on the tank of fuel for a tank average of just over 21mpg!!! 

 

To and from the hunt test was about 130 miles each way with about 75 miles of driving to the hotel and test sites over the weekend. Had just over 400 miles on this tank of fuel before the gauge dropped below 1/2 tank!! Was a very hot, humid weekend here also.  My truck has always gotten stellar mileage in the hot weather.