Updated post #1 with mpg data from spreadsheet...

 

filled up for an eco drive next week, the 100% dgas tank after intake tube gave me a 14.6 mpg tank over 280(?) miles. i was not kind to it.

 

reference...

FLUID DYNAMIC STUDY OF INTAKE MANIFOLDS OF INTERNAL COMBUSTION ENGINES IN PRESENCE OF ACOUSTIC RESONATORS (planetsoarer.com)


Soarer - The Intake Resonator (planetsoarer.com)

 

This means we only have a 100% airflow/mass at a certain engine revolution.
Nothing to do with or without a resonator or valve to let more or less air to flow to the cilinders.
When you have a "fixed" inlet/manifold you could only have the best airflow at a certain engine speed, and it all varies with a lot of circumstances.
We are dependable on what the engineers calculated to be the most versatile for the operation of the model car they designed.
When you have a variable inlet/manifold you have multiple airflow schemes that would be best, but still only on fixed points related to circumstances.
It's a trial and error to tune the engine intake at a sweet spot you like, with natural aspired engines.
Therefore a Turbo or Compressor is far more effective and will give the engine the needed airflow in a wider range of engine speeds.

 

It is interesting reading... added another link to that post. When I added that intake tube, engine was definitely louder and it got a good noticeable bump in the mid-range power. I pulled the tape off the air box to allow 100% free-flowing air into it. I'm sure that did not help mpg's lol. One of the discussions talked about the air box and the horns that feed them, with mine removed now for something like 2 months, I forget how it behaved with it in there. May need to revisit that setup now with the TB & IT (intake tube) install.

After this tank, the DTCM goes back in... then the fan clutch has got to come out, the bearing is bad and it wobbles. last thing I want is for it to snap and cause damage. I may have to go ahead and get the HPT tune thing going and get the fan control set better.

edit: that 2nd link I posted references Julian Edgar, the guy who was making the aero videos I linked earlier (I think it was here, if not it is in the cummins forum aero thread)
Another interesting thing is the discussion about inlet resonators for the air box... some designed better for low end torque (larger iirc) and smaller was for higher rpms...

 

I think with this kind of mods and so many variables you are going to choose one way or the other, low end torque or high end hp.
The straight intake like we have make more noise, engineers are always searching for the middle way, even with engine noise.
This was the main complaint of the Jeep GC drivers, which resulted in the Jeep TCM change, lower revs, less noise.

When we look at the changes in Manifolds and Throttle Body's throughout the years, manifold runners made shorter and gained more hp than it did on the torque curve, many said, more top end power, no or little low end torque added in comparison.
I do believe this is the same way on the TB, those changes made a better airflow directly to the cilinders, and added more hp and higher engine speeds ( revs ), but not such a dramatic torque change.
Torque is usually to be find in lower compression and long stroke engines and is much harder to gain on an engine compared to horsepower, even though with an increase in hp you have an increase in torque as well.

When we wan't to add more low end torque i do believe the new manifolds and larger TB's are needed, but there should be more things to change to get the torque band up.
There are almost no tuners who tune for low end torque, same as camshafts, and i do believe these are the changes we have to make to gain serious torque.

I Think we should gather more info in how to add more torque in the low and mid end to suit our needs.

 

Nope... its all about the low end torque. One drive in the Ram brings it all back, estimated 800 ftlbs of torque on tap, heaven. I get my speed fix on the track, cheap & fills the need.

I did a lot of reading on the intake manifolds, mostly on the forums and strictly on the 4.7 engine, only 1 guy mentioned he saw a bump in mpgs. (already know about runner length & air flow velocity to fill the cylinder). What I am looking into now is the helmholtz resonators that are attached to the intake tubes these days. Apparently one of their functions is to reduce the time it takes to fill the intake with air upon cracking the throttle plate. I dont quite understand it yet so will be continuing to read up on it.

My experience with just the TB change makes me believe it should have been 70mm to begin with. Combined with the MIT it does make a good combo and it seems like the bottom end is creeping back in. The 2xx miles that I had on the tank before this one is surely not enough for the ECU to adjust, but it is what it is, will see how it pans out when 200ish miles roll around (at 110ish now). So far this tank (on the fuel gauge) is looking positive. Should be into the 17's for sure, well off the 3/4 tank mark at this point.

Overall I think there is going to be a right setup that would give the best performance from 1k-3k rpms which is where the engine lives under my foot... Oh, and there might be a good bump to be had with the tuning, still have that to look forward to.

 

Ah.... and I forgot to add... pulled the tape off the box for 100ish miles, definitely improved mid range and pulled from the bottom end. The resonator reading I did indicated there were effects on both the intake tube side and air box side. Thinking back to when I had the Mini R53, it had resonators on the air box tube, Never got to playing around with the air box & air intake, too many things in the way at that time. When I do the air box mods on the Dak, will see if there is room to play with resonators on the air box side.

 

Intake tube design... Look at the right side pics, note the bend on the inside radius of the outlet, see how it is a larger radius than the top & bottom designs? What that is doing is reducing the flow separation inside the tube at that point resulting in more flow past the bend. (results shown in the table)... There is a way to design that tube to flow even more cfm...

 

saving this for later...

Horsepower Secrets: Intake Manifolds • Muscle Car DIY