increasing efficiency

[PStauffer]

I am sure this is a question heard often, and maybe thought too simple, but I am a new diesel owner. I have a 2006 Dodge RAM and am considering doing just a few modifications. I am more interested in efficiency than power, although a few extra horsepower would be nice. I have decided to start by replacing the airfilter and exhaust- no chips at this time.

'Just wanted opinions and general info as to what you think I might see as far as increase gas mileage and power and if you think this is a good place to start.



Thanks

 

[JThiessen]

Zero.

You may feel a little faster spoolup of the turbo, but thats about it.

My experience over the years is that even though some claim to get remarkable mileage improvements from various changes, I've yet to have something reliably improve my "efficiency" to the point that I saw any kind of return on investment.

 

[GColeman]

I started with an after market muffler for improved exahaust flow and then an air intake system. Neither improved mileage, but as previously mentioned, I did notice a slightly faster turbo spool-up.



Someone will probably have some amazing story about synthetic oil or other product that improved mileage. The only thing that did it for me was a Smarty programmer. More power and about 2 mpg better on the road.

 

[PRattenbury]

Your sig is not filled out, so I do not know if you have an auto or manual transmission. If you have an auto, you would be very impressed with an upgraded transmission and torque converter. I did it to my '94, and I was amazed.

 

[jelag]

After almost 40 years in this industry and at least 1000 hours using a dyno years ago... it's easy to get HP and torque but very hard to get MPG...

Think of your truck as a set of balance scales in this way... . it has mass, air resistance, and takes a certain amount of time to get to 70 MPH... . this is on one side of the balance scale and MPG is on the other... . if you decrease the time to get to 70 MPH that side gets lighter and MPG increases, the same with lighter truck and less wind resistance... .

Now start changing the engine, fuel system, exhaust, etc etc..... you might get 1 or 2 % but think of this... . the manufactures have whats called C. A. F. E. corporate average fuel economy... a standard their fleet has to meet... this is why you see them give away the low end cars with good fuel economy to gain CAFE points to offset the big trucks we buy... . If they could get 2% better fuel economy for 1000 per truck they'd do it in a heart beat I'm sure...

Just my 2 cents worth...

BTW the posts above are on target... .

 

[JMoberly]

Manufactures also have to meet emissions requirements that end users don't always have to. Emissions can hurt mpg. Thats why they get hit double when EPA increases mpg requirements and emission standards.

 

[AMassaro]

I have no hard proof, but I think if you can advance your timing a few degrees that may help efficiency and get better mileage.

 

[PStauffer]

Thanks for all the input. My G friend had convinced me otherwise. I had dropped off the truck today before reading these replies. After reading your replies, I called up the place I dropped my truck off this AM, yes really, and the muffler had already been sawed off!!! 'What thet heck- guess I am getting my new muffler (and intake as well). So I will repost my MPG on next tank. Anybody hear of the Stryker FE? Heard the chip was made for efficiency in mind.



BTW

truck 2006 quad cab 2500 diesel- was stock. manuel.

 

[jelag]

I can share with you that when I worked with gas engines and we had mechanical and vacuum advance on the ignition systems... . there was some gain in economy with more advance... . however this required higher octane fuel so there was not ping from pre-ignition... . so higher octane means a slower more controlled burn...

Diesel engines require a cetane rating... which is the opposite of octane... octane improves and slows the burning of gasoline so the power is released to the piston in a slow controlled way..... with cetane, as that number increased the amount of time to burn the fuel decreases so that the piston is higher in the block and more power is released to the piston... . IF you fire a diesel before TDC (top dead center) that is before the piston reaches the top of the stroke, the damage to the top of the piston is very damaging... . with the spark ignition engine you want almost the complete burn just as the piston rolls over TDC... .

At least this is as I remember it from my advanced fuel system classes...

 

[Tinman]

As mentioned, the emission standards effect mileage adversely. In these trucks the retarded injection and valve timing is there to meet NOx emissions but harm mileage. Advancing both can help mileage with the cam being the most costly and most impressive improvement. Every little thing can help. EDM or honed injector tips can help. Some added rail pressure may help. A ported head would probably help. Tires and gears are very important as is some aero dynamic improvements like a tonneau cover.

 

[brods]

... . Now start changing the engine, fuel system, exhaust, etc etc..... you might get 1 or 2 % but think of this... . the manufactures have whats called C. A. F. E. corporate average fuel economy... a standard their fleet has to meet... this is why you see them give away the low end cars with good fuel economy to gain CAFE points to offset the big trucks we buy... . If they could get 2% better fuel economy for 1000 per truck they'd do it in a heart beat I'm sure... ...

Light trucks that exceed 8,500 lbs gross vehicle weight rating (GVWR) do not have to comply with CAFE standards. These vehicles include pickup trucks, sport utility vehicles and large vans.



A study prepared for the Department of Energy, in February 2002, by the Oak Ridge National Laboratory found that 521,000 trucks with GVWR from 8,500 to 10,000 lbs were sold in calendar year 1999. The vast majority (82%) of these trucks are pickups and a significant number (24%) were diesel. At the end of 1999, there were 5. 8 million of these trucks on the road accounting for 8% of the annual miles driven by light trucks, and 9% of light truck fuel use.

C A F E Overview



That is why you do not see mpg numbers on our window stickers. If the government decided to include our trucks in CAFE you would easily see that 2% or more improvement in mpg. As it is there is really no incentive for the big 3 to improve the 3/4 ton and up segment mileage. Think about it, they put a cheap plastic tailgate spoiler on the 1500s to gain a small mpg improvement and do nothing for the 2500 and 3500s... .

 

[rbattelle]

By far, the best way to increase your fuel economy is to drive slower. Remember that drag scales as the square of velocity, so mild increases in speed have a tremendous effect on drag. I personally notice much better economy at 65 than 70.

Other than that, making the engine "breathe" easier is usually the next-best approach. Unfortunately, these engines already breath very well right from the factory, which is why people usually don't see much gain from bigger exhaust and less-restrictive intakes.

Best power timing on compression ignition engines usually occurs with peak pressure about 15° ATC. Depending on cetane rating, injection to achieve that is around 25°BTC.

I don't know where these engines are timed from the factory, but it's probably closer to TC. Maybe 20°BTC or so? I don't really know. (Many engines will run injection times closer to top center because that limits peak pressure and rate of pressure rise).

Ryan

 

[Svend]

I have an 04. 5 2500 Ram 4x4 auto 3. 73 gears QC SWB, and the best mileage I've been able to achieve is driving as the above post mentions around 60mph. I got 17. 7 mpg hand calculated. You will read all these posts about about how great mileage is on some of these trucks, but the reality is that if you have an automatic mpg's will suffer. I have a '94 Ram that gets 17. 5 city/ 20 hwy, its a regular cab 4x4 5spd. It weighs less and has less wind resistance and a more efficient engine since there were no EPA restrictions at that time. The 3rd Gen trucks in my present configuration will not be able to achieve the same results as the 2nd Gen trucks. The mpg's on my 04. 5 were only achieved after I installed a Quadzilla XZT towing/economy module. I already had a AEM brute force intake and a MBRP tubo exhaust on it and they still did not help. My sugestion is to by a mild chip and drive conservatively and expect 14-17 mpgs and you'll be realistic.

My . 02cents.

 

[jelag]

Ryan -- To my knowledge, you can't inject a diesel BTDC... . Once injection starts the flame front moves very quickly across the combustion chamber... this knock would be un-controllable in my opinion... . Please understand that all my fuels and engine classes were 40 years ago... . but they haven't changed that much... .

 

[rbattelle]

Ryan -- To my knowledge, you can't inject a diesel BTDC... . Once injection starts the flame front moves very quickly across the combustion chamber... this knock would be un-controllable in my opinion... . Please understand that all my fuels and engine classes were 40 years ago... . but they haven't changed that much... .

Oh, you're just remembering wrong. You might recall there are 3 phases to diesel combustion: ignition delay, rapid combustion, and from the point of maximum pressure to the end of combustion.



You've forgotten the first phase - ignition delay. When fuel is first injected, there's a period of time during which no measureable pressure rise occurs (no combustion). During this phase, the fuel droplets are vaporizing. Ignition will occur where the local fuel-air-ratio is most favorable. I assume modern engines (particularly common rail engines) provide such finely atomized fuel as to help mitigate this delay.



As Taylor puts it:

Shortest delays occur when the delay period includes top center - in this case when injection starts about 25° before top center. Earlier or later injection results in longer delays... Many engines use an injection timing later than that for maximum imep in order to reduce both maximum pressure and rate of pressure rise. Such late timing, of course, involves some sacrifice in output and efficiency.

By "late timing", he's talking between 15° and 20° BTC, based on a plot he's got in the text.



Ryan

 

[PStauffer]

follow up

thanks loads for all of the information. I never did realize a mileage gain. Not at all. At first I thought maybe it even dropped, but if I am lucky I can get into the 18s mpg. Being a stick and lots of highway, i think my mileage suffers ebcause fo the gearing. (why dobn't they may a 7th gear for these things when not towing!!!). Plan to put in a chip this next year. still debateing which one to get.



paul

 

[Red Ram]

Smarty all the way best thing going

 

[LRutigliano]

PStauffer



Tires, Tires, TIRES !!!



Don't overlook this "modification" to increasing efficiency.



Our trucks came stock with either the Michelin ATs or the BFG Rugged Trails. Both of these tires are great for mileage, but when it was time to replace, I wanted something more aggressive looking and performing.



When I replaced my tires, I went with the Bridgestone Dueler AT Revo's and I noticed an immediate decrease in efficiency or "fuel mileage and power".



These tires have deep aggressive lugs and it takes more power to turn them when rolling down the highway.



Do your homework when shopping for tires, its a large investment that could cost you for thousands of miles.



Regards,

Louis

 

[rbattelle]

Tires, Tires, TIRES !!!

Don't overlook this "modification" to increasing efficiency.

That is an excellent point! And it reminds me that proper tire pressure is also a big factor in fuel savings. In general, higher tire pressure should yield better economy (lower drag due to smaller contact patch).



Obviously, this has to be balanced carefully with tire life.



I run my front tires at 60psi and the rears at 50-55 psi.



Ryan

 

[Vaughn MacKenzie]

Best power timing on compression ignition engines usually occurs with peak pressure about 15° ATC. Depending on cetane rating, injection to achieve that is around 25°BTC.



I don't know where these engines are timed from the factory, but it's probably closer to TC. Maybe 20°BTC or so? I don't really know. (Many engines will run injection times closer to top center because that limits peak pressure and rate of pressure rise).



Ryan

I doubt the timing is that aggressive, remember engineers bear toward the retarded side in light of NOx emissions. Also timing on 24V and common rail motors is dynamic, it changes with RPM and load, so there isn't a fixed setting like on 12-valves with the P7100. In fact all Cummins engines except those with the P-pump have dynamic timing (although the 215 pump has a small timing range). Factory is usually 12. 5 degrees BTDC, guys generally reset them to 15-17, more aggressive setups go to 21 degrees or more.



Vaughn