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Recently I'd seen a Chevy with with wheel splats (or mini air dam) in front of the rear wheels. I'd seen this long ago on the Audi TT I had and often wondered if there was any benefit to doing something like that to the ram. Well it appears Chevy felt it did contribute somehow to mpg improvement. Took a look at my trucks rear wheel openings to see if it was feasible to add one back there that dose not look obnoxious. Seems like it may be worth trying.

Another mod I'd thought of doing was adding a strip of plastic to close off the gap between the frame and the outer body panel, between the wheels. That would be out of sight, not sure if there would be any benefit or not in that area. Recently I read a writeup on the Ecodiesel that had a higher FE version of it, 2wd and it had side steps... side steps... really? They apparently felt it had an improvement.

Further reading (and getting back to) wheel well aero drag had me realize I have the rear fender liners. Not sure if that reduces drag back there or not when compared to the 1/4 liner that the truck came with. One of the thoughts I had once upon a time was to experiment with an louver on the fender liner in an effort to relieve some of the turbulence that occurs in the wheel wells.

At some point in 2018 I am going to revisit/install the 2nd air dam I had under there once upon a time. I plan to add the rear wheel front splat. That 2nd air dam was not even noticeable unless you knelt down and looked for it. AFter lowering the truck down I would expect it to have more of an affect on airflow under the truck. When I went from 3" spring to 2" spring that air dam started rattling, it was not prior to the spring swap. That told me airflow was actually hitting it. Any benefit from it I never did test for.

New Rams... I noticed a while back that that they had a seal setup somehow between the cab and the bed. I've looked at some of the truck liner seals to see if something could be had that would be cheap to pop in there but have yet to find one that would work ok.

I am thinking it will be hard to detect any change on any mod that is done as it will be a small change by itself. Collectively however it may be easier to detect. How? I'm thinking it will be easy to use the Torque app I use daily and record before and after data, looking at the calculated load on a longer loop that can be easily repeated. Where I"m at up in WA I can jump on the hiway and do an out & back easily to collect data for a 40 minute run... using CC of course and starting and stopping the log at the same points on the hiway.


Anyways, any thoughts or ideas out there worth discussing?

Disclaimer.... motivator, an evil one I will admit is to try and come close if not match the wifes new Mazda CX5's mpg of 24 mpg. Probably not gonna happen but time will tell. Remember, lighter wheels going on, going back to stock height and e-fans going in are in the near future and my truck was consistently getting low-mid 20's for mpg before the fan clutch gave me the finger. Its said that leveling kills approx 1 mpg, the fan is good for 1~1.25 mpg, lighter wheels???? unknown. If I get those 2 mpg from those 2 mods that should put me up into the 22-22.5 mpg range tank to tank (city & hiway combined).

Edit: Adding article link with useful info...
http://media.gmc.com/media/us/en/gm...news/us/en/2013/May/0516-gmc-pickup-aero.html

http://www.pro-touring.com/threads/101460-Designing-Aerodynamics-for-Track-Performance?



Front air dam re-installed


V2_0 of the air dam



http://www.audew.com/AUDEW-Universa...rotector-Lip-Splitter-Body-Spoiler-p-130.html

Look @ pic, velocity of compressed airflow -> rear exit of truck.
http://www.buildyourownracecar.com/race-car-aerodynamics-basics-and-design/3/


http://www.autospeed.com/cms/article.html?&title=Modifying-UnderCar-Airflow-Part-1&A=113181

http://www.autospeed.com/cms/article.html?&title=Modifying-UnderCar-Airflow-Part-2&A=113182


https://www.curbellplastics.com/Sho...93-in-x-48-in-x-96-in)-Haircell-P1-Fire-Rated

Truck aero study
http://people.cst.cmich.edu/yelam1k/asee/proceedings/2011/DATA/7-155-1-DR.pdf


V2_0 Air Dam...

http://www.cumminsforum.com/forum/3.../2412082-diy-air-dam-v2_0-a.html#post28028746


http://ecomodder.com/forum/showthread.php/rear-diffuser-1831-3.html

http://ecomodder.com/forum/showthread.php/underbody-panel-testing-12747.html


Blowing the vortex part 1
http://www.autospeed.com/cms/article.html?&A=113216

Part 2
http://www.autospeed.com/cms/article.html?&A=113217

Part 3
http://www.autospeed.com/cms/article.html?&A=113218

Part 4
http://www.autospeed.com/cms/article.html?&A=113219


aero mods thread... this is where I document what I tried.
http://www.cumminsforum.com/forum/3rd-gen-non-powertrain/2449106-aero-mods.html#post28435634
 

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I’ve also thought about doing the cab to bed seal and also the additional front air dam on the 4wd truck. What are your thoughts on a rear roll pan, do you think that’s acting like a parachute? My 2wd has one and I’d like to seal it off so air doesn’t become trapped there also. Eager to see your results. Come spring time I’ll build an air dam when it gets warmer out. Lots of interesting stuff on ecomodder.
 

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Discussion Starter · #3 ·
Not sure on the rear roll pan since the airflow under there is dirty. The 2nd air dam may actually help back there if its deflecting air far enough downwards. With your truck already being low (IIRC) there may be minimal if any benefit to trying anything back there. The 2nd air dam may be enough for you to see a change. When you do it if your able to track any mpg changes and post up results it will help.

For me, any change needs to not be obnoxious or overly obvious. I am tempted to try to get the rear wheel front splats done while I am down here in Cali. Would not be able to test for any change with the fan clutch hosed though. I have a partial sheet of the thick HPDE plastic with me and can cut out a piece for each side. Exposed area would be small, about the size of an envelope. (That's what I see was done on the Chevy's)
 

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I doubt this would do anything but take a look at the SRT-10 front bumper/air dam and body cladding, rear spoiler. Not sure if any of those pieces would adapt over to a regular 2500/3500 QCSB. The frontal area on these trucks amounts to a 4x8 sheet of plywood. And even with the SRT-10 body work, frontal area didn't change by much. My old "10" RC never ever saw above 15 mpg....averaged about 10-12 mpg combined. I commuted to work with it for a while, 40 miles, round trip = 4 gallons of dead dinosaurs/day :surprise: The Viper motor in the Ram never met a gas station it didn't like :wink2:
 
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Well, my 2wd 3rd gen is lowered 1 inch up front and 3 inches in the rear and I get worse fuel economy than anyone on this forum!

I don't think any aero changes are going to make much difference.
However, lowering the front of these trucks, to get the heavy Cummins lower, will make a terrible handling truck, handle a little better.


There were several threads where folks were installing the deeper late Superduty front air dam on their Dodge trucks trying to improve aero and fuel economy.
It was a simple bolt on but I'm sure it did not make one bit of difference though!

 

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Discussion Starter · #6 ·
That FE Ecodiesel version I read about used a specific front bumper/spoiler off one of the models, engineers found it to be the most FE so I would not doubt if it would be better on fuel. Its the little things that all add up. I posted a video a while back of a ford f150 in a wind tunnel with an engineer discussing the FE mods done to it. One of which was the rear 3rd brake light and its tie in with the tailgate spoiler. That had me thinking of making a small hood of sorts to extend off the 3rd brake light. Nothing big or obnoxious, just an extension off the light that extends maybe 2" or so. The claimed it tied in with the tailgate spoiler.
 

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Discussion Starter · #7 ·
Well, my 2wd 3rd gen is lowered 1 inch up front and 3 inches in the rear and I get worse fuel economy than anyone on this forum!

I don't think any aero changes are going to make much difference.
However, lowering the front of these trucks, to get the heavy Cummins lower, will make a terrible handling truck, handle a little better.


There were several threads where folks were installing the deeper late Superduty front air dam on their Dodge trucks trying to improve aero and fuel economy.
It was a simple bolt on but I'm sure it did not make one bit of difference though!

Any single aero change will be tough to point at for an FE improvement, however multiple changes may all add up to a noticeable change. Like the ford air dam, years back on a 3rd gen a guy did a 4" extension off his OEM air dam and claimed something like 2 mpg change. Something like that or even the super duty air dam is not going to look right on a ram and would be out from my standpoint. The F150 2nd air dam however is low enough and behind the main air dam that it may have an effect on FE.

Do you tune your truck or is it a canned tune from someone else?

What rpms are you getting boost to start coming off 0~0.5 psi?

Gas4wdjr (??) has the same issue as you with crappy mpg for some unknown reason. For your truck with it being a 6sp you should be able to have enough power off boost to get good FE on the bottom end of the rpms. With the exception of 2wd & the twins, your setup similar to mine. With the 33's, 2" level rolling around in rush hour traffic with stop & go's you'd think my mpg would stink, I have half my commute being in the crappy traffic and the commute miles make up a bulk of the miles driven every tank.

I would bet if you tuned it on the bottom end and searched for the lowest calc load under normal driving conditions your mpg would go up... same for IATs.
 

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Here's my take:
1) The electric fan will only offer reduced fuel use because it moves less air. To move X amount of air, you will require X amount of power. Using electrical power to do that is more inefficient than the fan currently on there.

2) Aero mods MAY help but the change will probably be imperceptible unless you have access to a wind tunnel with highly sensitive equipment.

3) Lowering the front from a leveling kit, is always a good idea in my book, but that's personal preference.

4) You really want to increase the efficiency your truck uses fuel, learn up on thermodynamic systems and how efficiency can be increased. The secret is to have as high inlet temperature as possible, and as low outlet temperature as possible. Your intercooler needs to go, that will give you the largest fuel efficiency increase. Next insulate the intake tubes/system from the turbo compressor all the way to the intake plenum, this will keep the intake charge as hot as possible. If you're really inventive, you could preheat the intake charge with exhaust gasses in a heat exchanger you're on the right track! Now for the exhaust side, dodge does pretty good as they are using the heat from the engine combustion cycle to turn the turbine in the turbo. You could try finding a turbo that will utilize the heat more, but diminishing returns because it generally means you'll be compressing more air (which you won't want more air because that uses more fuel). And your FINAL solution to best in class fuel economy, drive like a hypermiler freak. Easy on the acceleration, coast into stop lights trying to time them so your truck doesn't stop moving, as few service brake applications as possible (these brake applications are fuel energy being expelled as heat energy through the brakes).

4) If fuel mileage is the goal, skinnier tires, higher pressure.
 

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Discussion Starter · #10 ·
Replies inline below in red...

Here's my take:
1) The electric fan will only offer reduced fuel use because it moves less air. To move X amount of air, you will require X amount of power. Using electrical power to do that is more inefficient than the fan currently on there.I dont agree with that... s blade fans draw less cfm than the straight/curved blade style. Found this out thru testing of the Taurus & volvo fans (s blade & straight blade as I'll call it). The OEM fan weighs X... call it 15#, that 15# has a constant load on the motor, every RPM all the time. Lock it up and its even worse. E-fans remove that load off the front of the motor and shift some of the load over to the charging circuit. Yes the DC load of the motor will reduce FE, however that load will be constant while the fan is on. My setup has each fan controlled separately, eventually both fans will be PWM'd which will reduce the load further

2) Aero mods MAY help but the change will probably be imperceptible unless you have access to a wind tunnel with highly sensitive equipment.100% agreed, would be tough to detect small changes in FE

3) Lowering the front from a leveling kit, is always a good idea in my book, but that's personal preference.

4) You really want to increase the efficiency your truck uses fuel, learn up on thermodynamic systems and how efficiency can be increased. The secret is to have as high inlet temperature as possible, and as low outlet temperature as possible. Your intercooler needs to go, that will give you the largest fuel efficiency increase. Next insulate the intake tubes/system from the turbo compressor all the way to the intake plenum, this will keep the intake charge as hot as possible. If you're really inventive, you could preheat the intake charge with exhaust gasses in a heat exchanger you're on the right track! Now for the exhaust side, dodge does pretty good as they are using the heat from the engine combustion cycle to turn the turbine in the turbo. You could try finding a turbo that will utilize the heat more, but diminishing returns because it generally means you'll be compressing more air (which you won't want more air because that uses more fuel). And your FINAL solution to best in class fuel economy, drive like a hypermiler freak. Easy on the acceleration, coast into stop lights trying to time them so your truck doesn't stop moving, as few service brake applications as possible (these brake applications are fuel energy being expelled as heat energy through the brakes).
I disagree with some of this... you loose control over the intake temps without the CAC. With it in place at least a fan can be put on it to cap IATs at any given temp. I found this is tune dependent and still my best mpg #'s are up there over 100*f. I feel the key here is to get consistency in IATs & CTs... keep both in a tight range for best results on a consistent basis. Hyper mileing... Still out on whether its better to coast in gear with the injectors off or to go to neutral and ride the momentum.

4) If fuel mileage is the goal, skinnier tires, higher pressure.
285's, either 33's or 34's, pressure needs to be set for a balance of grip vs rolling resistance for safety purposes. My experience with high pressure gave me a riding on marbles sensation, one I will pass on.
 

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Discussion Starter · #11 ·
Look at the end of this video where they have smoke feeding the side of the trailer. I expect the truck might be similar to a point with the turbulence under the center of the truck.

 

· Diesel Filled Veins!
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Replies inline below in red...
The incoming air temps thing: the truck takes IAT into effect when choosing a place on the fueling map to use. The truck calculates incoming air mass and matches the fuel to it. The intercooler isn't giving you anymore consistent IAT than if it wasn't there, it is there to cool the air from the compressor so sometimes it's not able to cool as much (high engine load) and other times is might not be hardly cooling anything. Better efficiency by conserving the heat of compression rather than consistency in IAT - science :D

As for hypermiling, I know very little, I'd go nuts trying to practice it. But, every application of brakes is wasted fuel energy. And I think coasting in gear is probably more efficient than throwing it into neutral because you are conserving the energy used in the compression of air whereas in neutral you are using fuel to keep the engine alive.

And yes, tire pressures are important for safety reasons. For me, a consistent wear across the face is more important than anything. This provides the safest tire and easiest wear on tread. When Dodge jacked up my rear winter tires to 80PSI I told them to lower to 50PSI, TPMS be damned (although no light illuminated, I was right, they were wrong, haha).
 

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Discussion Starter · #13 ·
The incoming air temps thing: the truck takes IAT into effect when choosing a place on the fueling map to use. The truck calculates incoming air mass and matches the fuel to it. The intercooler isn't giving you anymore consistent IAT than if it wasn't there, it is there to cool the air from the compressor so sometimes it's not able to cool as much (high engine load) and other times is might not be hardly cooling anything. Better efficiency by conserving the heat of compression rather than consistency in IAT - science :D

As for hypermiling, I know very little, I'd go nuts trying to practice it. But, every application of brakes is wasted fuel energy. And I think coasting in gear is probably more efficient than throwing it into neutral because you are conserving the energy used in the compression of air whereas in neutral you are using fuel to keep the engine alive.

And yes, tire pressures are important for safety reasons. For me, a consistent wear across the face is more important than anything. This provides the safest tire and easiest wear on tread. When Dodge jacked up my rear winter tires to 80PSI I told them to lower to 50PSI, TPMS be damned (although no light illuminated, I was right, they were wrong, haha).
I dont disagree that the ECU will select the right fueling based on intake temps, however the CAC is going to act as a huge heat sink and it will definitely slow down the temperature swings that would occur without it. Also one thing that needs to be considered is the ECUs sample rate of the IAT sensor. One has to believe it has a fast sample rate giving it the ability to respond quickly to changes. I tried to find a graph that shows my position on it, this kinda shows it to a point, graphs temps vs time



Without the CAC temp swings would go unchecked and heat soak the intake manifold and IAT sensor. Once its heat soaked, it will take time to cool down should the intake temps drop with a drop in boost. While the element is measuring the airflow, the heat radiating off the heat soaked manifold its mounted to will slow its response causing ECU calculations to be off... IMO.

Also without the CAC your boost may have to be limited because of those temps.
 

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Good info there for sure. I would think the IAT sensor may be slow to react, but not sure I would agree with the heat soaking of the sensor itself. I would say once the intake is heated up from the compressor heat, the IAT swings will smoothen out a bit. Also, if the IAT saw higher than actual temps, you'd just be on the leaner end of things - thus saving fuel. I can't honestly see any reason why eliminating the intercooler would cause any adverse effects and only increase your fuel economy. It is there to shed head and get the incoming air charge as dense as possible, thus allowing more fuel to be added.

As for compensating for the incoming air temp, the ECM has to, these trucks run from -50*C to +45*C (-58F to 115F) and have to accommodate for those atmospheric temperature swings, why not a temp swing from the compressor? I will concede the compressor temp swings will happen a lot quicker whereas the atmospheric temps will swing a little slower so perhaps the ECM can't compensate that quickly. BUT, the IAT does swing already with the compressor loading or unloading and the ECM does just fine. Think going up a hill and you're adding fuel, truck does just fine, then when you let off and the IAT is much less (thanks intercooler) the truck still does just fine.

Heck, I'd give the intercooler delete a serious consideration for fuel economy improvement if that was my goal. But then again, I'd consider an old VW if economy was my thing.
 

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FYI--sevearl years ago on another forum I saw pics of someone's truck who had installed (with minor drilling and bolts) a 2nd gen air dam underneath his 3rd gen air dam. The lines matched perfectly and he got the front of his truck another 6" closed off to the ground. It looked a little different, but not strange or bad at all as the lines matched up so well!!

While I have not done this yet, I still want to do this to my truck since a 2nd get air dam is less then $50.

It is part # 15 on this page--

Truck Parts and Truck Accessories
 

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Discussion Starter · #16 ·
Good info there for sure. I would think the IAT sensor may be slow to react, but not sure I would agree with the heat soaking of the sensor itself. I would say once the intake is heated up from the compressor heat, the IAT swings will smoothen out a bit. Also, if the IAT saw higher than actual temps, you'd just be on the leaner end of things - thus saving fuel. I can't honestly see any reason why eliminating the intercooler would cause any adverse effects and only increase your fuel economy. It is there to shed head and get the incoming air charge as dense as possible, thus allowing more fuel to be added.

As for compensating for the incoming air temp, the ECM has to, these trucks run from -50*C to +45*C (-58F to 115F) and have to accommodate for those atmospheric temperature swings, why not a temp swing from the compressor? I will concede the compressor temp swings will happen a lot quicker whereas the atmospheric temps will swing a little slower so perhaps the ECM can't compensate that quickly. BUT, the IAT does swing already with the compressor loading or unloading and the ECM does just fine. Think going up a hill and you're adding fuel, truck does just fine, then when you let off and the IAT is much less (thanks intercooler) the truck still does just fine.

Heck, I'd give the intercooler delete a serious consideration for fuel economy improvement if that was my goal. But then again, I'd consider an old VW if economy was my thing.
FYI--sevearl years ago on another forum I saw pics of someone's truck who had installed (with minor drilling and bolts) a 2nd gen air dam underneath his 3rd gen air dam. The lines matched perfectly and he got the front of his truck another 6" closed off to the ground. It looked a little different, but not strange or bad at all as the lines matched up so well!!

While I have not done this yet, I still want to do this to my truck since a 2nd get air dam is less then $50.

It is part # 15 on this page--

Truck Parts and Truck Accessories
Have some further discussion with you on these 2 posts, just too dirty to tackle it now...

2nd air dam re-installed since I was under the truck anyways...
 
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Discussion Starter · #17 ·
Forgot to get back to this... lost the thoughts... doh!

Just got back from Cali, 298.0 miles from central Oregon to Tacoma, 17.7 mpg, speeds in the 75-85 mph range for most of the run, zero stops other than stop & go traffic for the EXPECTED accident in Chehalis... 2nd air dam was in place, airbox partially open for better performance @ higher rpms. It is possible the fan clutch was performing as expected while being unplugged. On the drive down mpg was definitely lower, no air dam and it is all downhill from Redding to Sacramento.

This week, a baseline tank with an ** on the data for the fan clutch having an issue. Best data I have had was earlier in the year with a slightly different tune and was averaging 20.0~20.3 mpg over 4~5(?) tanks.

Shooting for the e-fan install this weekend... (saturday if its raining, sunday if not)
 

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Discussion Starter · #20 ·
Looks good, but I only see the one air dam...at least I think that is what I see!!!
It is there... not easily seen. Look under the OEM dam on the left side, you can see the brown piece extending close to the tire... that's it. crouching down more it exposes more. Straight on it sits about 2~3" below the OEM air dam
 
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