Scientific Intake Selection and Review

6.7Bison

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You should have bought a No Limit filter and system. I've run the same one for over 100k.


More "power" from an intake alone isn't going to happen.


By all means, post your experiences and findings. If you discover it works for you then so be it. If you discover it was a waste of money then so be it. You will either discover what many already know, or show a different result.


Just remember you are only changing a small portion of the airflow path.

I was heavily considering the no limit but a few minor things pushed me to the S&B. If the S&B doesn't do what I want I will get the No Limit as I have heard lots of positive reviews on it with data to back it up.

I understand more peak power won't really happen which for me is only a bragging number. I would appreciate more power lower in the curve for towing but again not a requirement. I am keeping in mind that I am changing less than three ft of underhood piping and a filter. I'm not expecting it to make a world of difference, but I do expect incremental benefits over the stock system.

I appreciate your openness and willingness to have a conversation. I am here to share my experience whether it's good, bad, common knowledge, or new information.
 

6.7Bison

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Installation:
I watched the installation video the morning before I started the replacement. It all looked pretty straight forward. I had a couple buddies over for some beers while they watched me. I did my MAF data run for the before. I grabbed numbers shortly after start up, 2000 rpm, 3200 rpm and back to idle. I then started the tear down. Taking out the old air box was a tighter fit than I thought but I didn’t unhook the positive battery cable out of the way of the mounting tab. The intake tube was very easy to remove. The old mounting bracket was easy to remove as well. In order to take the intake “funnel” behind the headlight the video had me taking off the grill to get the headlight out to access it. I didn’t bother with this and just removed it from the inside. It took a bit of prying but wasn’t terrible. Looking at the inlet size of the stock air box I can see why it would be a limiting factor to air flow. The intake tube with its corrugated flexible portion and large resonator also didn’t look great for airflow. Removing the “funnel” not only made lots of room for the giant filter but also opened up the front of the truck for airflow. Can’t say at this point I’m too concerned about needing to make modifications for more fresh airflow. If other open filter intakes don’t instruct you to remove this piece in the instructions, I would recommend it for more fresh airflow. Fitting up the new mount bracket and adjusting it around the coolant and condenser lines was easy. Assembling the intake was easy. Installing the whole thing was easy. The notch in the tube was to avoid some of the condenser and coolant lines. Looks cleaner under the hood than the stock unit. Upon fire up for my post installation MAF data run, I noticed a little more growl and a little more turbo whistle.

Looking at the data and comparing between my two runs I’m not sure I got an exact apples to apples comparison. I also have data for boost so I will include that in an attempt to explain what went wrong. The data is as follows:

Before:
Start up: 158.29 kg/hr 1.02 psi, 2000 rpm: 618.41 kg/hr 8.06 psi, 3200 rpm: 1120.5 kg/hr 10.75 psi, idle: 144.79 kg/hr -0.05 psi.
After:
Start up: 146.03 kg/hr 0.7 psi, 2000 rpm: 675.68 kg/hr 7.26 psi, 3200 rpm: 1048.39 kg/hr 8.15 psi, idle: 80.89 kg/hr -.15psi.

So the numbers look to be all over the place for mass flow of air. Some cases show more air flow, some show less. I believe that my data snapshots were not perfectly timed to be exactly the same as shown by the boost pressure. I also am dependent on what the engine is needing at the load it’s under. My rpms were the same and my ambient conditions were as close as I could get them, but my turbo was messing with me depending on where it was on spool when I took my data. Assuming volumetric flow is the same as displacement didn’t change and rpm was the same, I could use a kg/(hr*psi) scalar to compare between before and after. The problem is I don’t know the temperature after the turbo which is the missing piece to the ideal gas law. The best I can determine is that at 2000 rpm it appears that after the intake upgrade I was flowing more air at a lower boost pressure indicating more air flow. Everywhere else I was running less air flow and less pressure. I’m not sure what that would indicate. Less power loss maybe?

In summary my test was flawed and my MAF data doesn’t really tell me anything. At this point I can’t confirm or deny real world similarities to S&B’s claims on airflow. But installation was simple, the engine bay looks a little cleaner, and I get a little more intake sound.
 

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Sterling6.7

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It’s nice to see someone with a little enthusiasm again and taking a real interest in coming up with the best way.

When BigR started fabbing the NL intake, he did a dyno comparison with the big hitters of the time including S&B. It would be worth finding that to help prove, or disprove, some of your work. It’s a good read and probably came out in 2014? There were some issues with the scaling on MAF with the original version, so that had to be tuned out and wouldn’t work on a stock truck.
 

HeavyAssault

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Now you see all that other plastic intake routing funnel junk that's another part of the problem.


Drive it a bit more, keep logging data.
 

Connor M

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NAPA 6637 filter with a washable filter sock has been proven to flow enough to make big power in 7.3s for years. And it’s like 50 bucks for the filter and the cover. I’d imagine there would be enough room in a 6.7 to put that filter in also.



I think jakes done that on both his 6.7’s @linconlocker
 

6.7Bison

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Initial driving impressions and temperature data.
Finally I was able to drive the truck after installing the intake. I did my same start up routine as the previous data runs above and did my morning commute with the truck. Let's start with my impressions.

The truck definitely sounds more aggressive. It’s not too loud to have a conversation or to feel the need to turn it off in a drive through but I am surprised just how much the old intake was muting the truck. I can still hear my highway tires sing on the pavement so again it can’t be that much louder, but definitely more aggressive sounding.
The throttle feels smoother. It used to have some hesitation when moving the truck from a stop with a weird pause when shifting from first to second. That seems to have smoothed over and the throttle seems more pleasant to operate for me. It might be slightly more predictable but I won’t confirm that without more miles on it. I would say the truck is more responsive but again want a few more drives under my belt before I commit to it.
Towards the end of my commute I got on it and it feels a fair bit faster. Could be a placebo effect, but I’m not too worried about 0-60 times in an empty truck anyhow.

Now for the numbers.
After 5 minutes of initial start up and idle. Truck was parked inside a three sided shed:
Ambient temperature was 41F. Intake air temperature was 48.2F.
Really not a whole lot of increase in temperature. But the truck was cold. So far no real cause for concern.
After getting warmed up during the commute at 60-65mph (engine temperature needle was directly in the middle):
Ambient temperature was 41F. Intake air temperature was 43F. CAC temperature (directly after the intercooler) was 77F on the flats. EGT from the factory stock location 470F on the flats.
Basically all in line with one of the previous runs almost exactly. Close enough it could even be a rounding or resolution difference between my monitor and the sensors.
Just as I started to get into the steeper hills where I gather data my test took an interesting twist. I got the message on my dash that the truck had started a regen. After exhaust temps leveled out at the new higher level I saw the following:
Ambient temperature was 41F. Intake air temperature was 45F. CAC temperature (directly after the intercooler) was 80F. EGT from the factory stock location 720F.
The truck continued the regen into the end of my commute where I hit a couple stop lights and town speed limits. Sitting at a light for a good while as the truck finished up the regen I saw intake temperatures as high as 100F and CAC temperatures around 90F.
From this test I can say with confidence my new intake does draw air from the engine bay. I can also say that going through a regen makes things very warm under the hood. Depending on the exact situation the increase in intake temperature over ambient can be drastic. For most scenarios I find myself in it shouldn’t be a problem. I drive 90% of the time at highway speeds where I normally catch a regen. If the intake does its job of more air with less restriction at or near ambient temperatures it should actually bring down soot load as I should have a more efficient and complete burn. This should make regens less often and quicker. By how much? Probably not a lot but still the problem should get better not worse. If you are someone who operates a truck in a lot of city driving scenarios this temperature data may affect your decision on selecting an intake.

I’m not too concerned with the increase in temperatures I saw in this initial drive. I will continue to monitor temperatures and mpgs as I’m ready for a fresh fil lup after this commute. Should temperatures trend upwards or mpgs not improve I might look into trying to shield the engine bay from the intake. Right now, a 2 degree difference in normal driving (that could just be an error) isn’t worth pursuing. The jury is still out but so far I’m liking the intake overall for my purposes.
 

HeavyAssault

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So you go thru all the effort to "shield" the intake.....yet the CAC still warms up the air before it gets to the intake manifold.



Why do that???????
 

6.7Bison

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Why am I looking at temperatures and other thermodynamics?
It seems like I have had a lot of questions around temperatures and why I bother looking at them. The turbo super heats the air and the intercooler cools it back down so it doesn’t matter what temperature the air goes into the intake. Right? Why don’t we find out. I am going to go a little bit into the weeds and dive into some thermodynamics on the intake side of these 6.7L Powerstrokes. I will do my best not to get into what goes on inside the cylinder and exhaust side of it to stay somewhat on topic. I may be repeating some things you all may know or it may be new information. You can decide if you want to read, skim, skip, or flat out ignore this post. Please call me out if I didn’t do a good job explaining something. If I screwed up the science, school me on it. I’m here to learn too and would hate to spread misinformation. All my equations use metric units (Pascals for pressure, Kelvin for temperature, grams for mass, cubic meters for volume, and mols for number of molecules) I have done the math and converted to english units. I will try to attach a spreadsheet with my calculations to check my work or play with if you trust my equations. Just change the values highlighted in green. Let me know if you find something that doesn't work, doesn’t make sense, or is plain wrong.

I’m going to skip around a bit and start with the end of the intake system, the cylinder. Diesel combustion is different from gasoline combustion in a few ways but I want to highlight a major point. Diesel combustion has no real downside to a lean condition as far as fuel burn. In fact it’s almost preferable to have more air (oxygen) than necessary to allow for plenty of air to completely burn with the fuel and give more air to absorb combustion temperatures keeping egts from climbing too high. Adding more air has power and efficiency benefits (more complete burn), particulate emission benefits (more complete burn means less unburnt soot), higher power potential (more air could burn with more fuel making more power), and possibly reliability (lower exhaust temperatures).There are many other balances at play that may cause an OEM to keep air from entering the cylinder. Things such as higher NOx emissions, costs, harder to reach regen temps, etc.

Back to the cylinder. The displacement is going to be the first limitation of air. There is only 6.7L available to be able to cram air into every two revolutions (4 stroke engines hold the air for two revolutions as it works through the different strokes). Imagine for a moment that we have the heads wide open to the air. The most air we can push into the engine in two revolutions without some intake and exhaust scavenging wizardry is 6.7L. At what 70F ambient temperature and 14.7 psi ambient pressure that is only 0.0177 pounds of air with only 23% or so being oxygen. One of the great things about air is that it follows the ideal gas law, Pressure x Volume = number of air molecules x a gas constant x Temperature. This means if we are limited to a volume, we can still increase the mass of air (number of molecules) inside that volume by increasing the pressure of the air or decreasing the temperature of the air.

Let’s start by increasing pressure. There are a couple of ways of doing it but I won’t bother with the positives and negatives of different superchargers and turbochargers. I’m going to stick with the diesel industry standard, turbos. Turbos boost the pressure of the air from ambient (approximately 14.7 psi) to something higher. Different turbos do this to varying degrees of success but I won’t go too much into depth on that. What we need to know is that when the air is compressed it heats up. There is no free lunch in thermodynamics. The equation I have for a temperature increase from turbo is Temperature increase = ((((Pressure out/Pressure in)^0.283) - 1) x Absolute temperature in) / Turbo efficiency. What we can gather from this is the higher the boost the more heat that is made, the higher the temperature in the higher the temperature out, and since I have yet to discover a completely efficient turbo, the turbo inefficiency adds more heat. Like some of the first twelve valve cummins let’s just slap a turbo on and pipe it straight into the heads. At 20 psi boost, 70F ambient temp, and a turbo efficiency of 80% (pulled out of thin air), the temperature out of the turbo is 252.17F. But with the increase in temperature and pressure our mass of air for two revolutions is 0.0311 pounds. Not too shabby. But what else can we do?

Let’s drop the temperature of the air out of the turbo. Intercoolers or charge air coolers (CAC) do just that. They take the warm air and run it past a fluid, either air or liquid coolant, to exchange heat from the warmer air out of the turbo to the cooler fluid of the intercooler. There are other methods to cooling air such as water injection. I’m going to stick with the factory equipment. The air to water style intercooler in the 6.7L Powerstroke helps to limit the amount of pipe routing and pressure loss, using coolant boosts the efficiency of the intercooler, but since the coolant then passes through a radiator the coolant will always be warmer than ambient air. The equation I have for an intercooler is Temperature drop = (Temperature in - Temperature of the fluid) x intercooler efficiency. What we can gather from this is the larger the difference in temperature the larger the drop and since I have yet to discover a completely efficient intercooler, the intercooler inefficiency adds more heat. The inefficiency shows up more the larger the difference in temperature meaning the higher the temperature in the higher the temperature out. There is a possible case where the turbo is adding very little boost and the air to water intercooler actually warms the air slightly. Let’s add the intercooler in between the turbo and the heads. Since the turbo is cramming air into the intercooler it is maintaining the pressure and we don’t see a drop in pressure due to the drop in temperature. At the 252.17F air coming out of the turbo, 75F coolant temperature (an educated guess), and an intercooler efficiency of 80% (pulled out of thin air) the temperature out of the intercooler is 110.44F. With the temperature drop our mass of air for two revolutions is 0.0388 pounds. We have over twice the amount of air we started with. Now for the last piece of the puzzle.

Obviously we want to source air to the turbo and prevent dirt and debris from entering the system. So we add an air filter to keep stray birds out of the turbo. Filters cause a loss of ambient pressure as some work has to be done to draw the air through it. Effectively you are decreasing the ambient air pressure. We’ve also been paying attention and noticed that air density is dependent on temperature. We’ve also noticed that for both the turbo and the intercooler, the higher the temperature in the higher the temperature out. So we try to route to the coldest air available, ambient air outside of the engine bay. We find that we have two competing solutions. One air intake uses a small restrictive filter but is able to fit in a spot where it only collects ambient air. The other intake uses a large much less restrictive filter but can pull some warmer engine bay air. The first intake has an intake temperature of 70F and a pressure drop of 1 psi (pulled out of thin air). The second has an intake temperature of 72F and a pressure drop of .5 psi (pulled out of thin air). Doing the math over for both of these cases the first intake ends up having a mass of air for two revolutions of 0.0298 pounds. The second intake has a mass of air for two revolutions of 0.0303 pounds. I think this clearly shows that 1 psi of pressure change has much more impact than 1 degree F in temperature change. And similar to the data I have and what others have seen with highway driving, it is better to have a free flowing intake even if it means pulling slightly higher intake temperatures.

Let’s take the less restrictive filter and put it in two new scenarios. The first is we go above and beyond to make sure we have nothing but ambient air. The second is we don’t even worry about it. Both are sitting stopped with no air flow under the hood building boost ready to launch for a drag race or with full GCWR trying to make it through the intersection. Because the engine is working hard the underhood temperatures are high. So this first scenario we would see an intake temperature of 70F leading to a mass of air for two revolutions of 0.0305 pounds. This is only 0.66% more air than the scenario before. Hardly looks like it would be worth the effort to block off engine bay heat. For the second scenario we would see temperatures of 110F (a 40 degree rise above 70F doesn’t seem too far fetched from the near 60 degree rise I saw above 40F) leading to a mass of air for two revolutions of 0.0283 pounds. This is less than the more restrictive filter in a situation that may be more important to someone than just cruising down the highway.

There are other methods to add even more air density. Compound turbos to boost the already boosted air. Nitrous (NOS) both increases the concentration of oxygen and has a cooling effect when injected.Water/methanol injection also has a cooling effect. Using ice to decrease the fluid temperature in the intercooler. Along with other tricks.

As you saw I don’t have exact numbers for the system. The intake system is also dynamic and more complex in reality than what I have laid out here. Similar to the filter there are pressure losses through the piping and intercooler. The faster you move air through the piping the higher these pressure losses are. The turbo’s efficiency depends on how much air it’s moving and what pressure it’s compressing to. Engine load can influence the amount of air requested. RPM changed the amount of volume per minute available. Other temperature influences under the hood can raise or lower temperatures moving through the system. These trucks add cooled recirculated exhaust gases back into the airstream at different rates which affects oxygen concentrations and air temperatures. The outside weather can change what ambient pressure, amount of oxygen, and ambient temperature is available. Along with many other factors. This makes it difficult to simulate our exact engines and know exactly how big of an impact certain changes will have.

This is why I am looking at temperatures with the intake. Not because I think dropping intake temperatures 2 degrees will completely change the truck for the better. But because I know that in principle, keeping temperatures as low as I can will keep the truck headed towards an ideal case. If I don’t bother looking at temperatures they can quickly compound and get out of hand, leading me away from that ideal case and possibly worse off than the stock system. I am also attempting to remain grounded in reality, making myself justify time, effort, and cost for any benefits gained. My current data gathered shows there is not enough benefit to gain from the effort of adding shielding to my intake for my purposes. But I still have many other cases to cover and lots more data to collect. I hope this clears some things up.
 

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6.7Bison

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It’s nice to see someone with a little enthusiasm again and taking a real interest in coming up with the best way.

When BigR started fabbing the NL intake, he did a dyno comparison with the big hitters of the time including S&B. It would be worth finding that to help prove, or disprove, some of your work. It’s a good read and probably came out in 2014? There were some issues with the scaling on MAF with the original version, so that had to be tuned out and wouldn’t work on a stock truck.

Thanks for the encouragement! I tried to find the topic with this in it as I thought it might make for an interesting read. Found a couple topics relating to the 6.7 intakes but none with a dyno test. Any way you could help me find it?
 

6.7Bison

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Quick update.
Made a large trip to Texas to bring back a trailer and Farmall H before a lot of the pandemonium. Drove into a headwind both directions. I'm also guessing that all the stations were still running winter diesel based on not seeing anything too different. On the way down I got two full tanks burned at 16.5 and 15.8 mpg hand calculated. I had a tank that was half unloaded and half towing that was 14.8 mpg hand calculated. This tank may have been "summer" fuel but it's hard to tell just from the numbers. The rest of the fill ups back were 10.4, 11.9 and 11.2 mpg hand calculated. Not too different than what I was seeing before the intake on winter fuel. Slightly less but I want to chalk that up to the headwind and higher speeds (75mph most of the time). I hope to get some better comparisons with a tank or two on my normal commute.
Running interstate into the wind I was seeing intake temps 2-5 degrees higher than ambient. Not enough for me to get worked up about but the perfectionist in me knows they could be better. Might be a cheap mod I can do if I end up with nothing but free time, short on cash, and an itch to improve the truck. I see other larger improvements I can make first.
I think there is some throttle response improvement after this trip. On ramp drags and passing pulls seemed improved if only marginally.
I haven't peeked at the filter but I can't imagine it accumulating much of anything yet.
 

6.7Bison

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Gonna button this up as I have been nudged towards adding some other mods that will move me out of the vacuum that was just the intake.

Looking back at some of my data my MAF peaks for the same drive appeared to have increased from approximately 1200 kg/hr to 1300 kg/hr. My towing a trailer around has yielded me an average of about 13 mpg. I did not get a full tank of just commuting with the new intake but I appeared to get about the same mileage maybe slightly less according to the lie-o-meter. But shortly after adding the intake my turbo started surging at about 52-54 mph under light load steady throttle conditions. I was also doing slightly more stop and go driving than I used to.

So I have now installed a new steel bearing 2014 style turbo with a WW2, BD exhaust manifolds, some thermal exhaust coating, and some other reliability mods in the valley. All of this should play nice with the intake but won't tell me any more about just my intake. I should be posting some reviews on some of the newly added components in other threads as per requested. Thanks for reading guys!
 

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