Yeah yours is pretty big. for reference the one I have on there is 15" long by 1.5" diameter. I had 2 on there for a bit and pulled the 2nd one off while working on the #6 issue but have not re-installed it. I also put back in an un-molested stock airbox to remove the valve I installed. I can hear it fluttering and need to figure out a way to stop it from doing that. I'm thinking of using a chamber in front of it to smooth out the pulses going to it might do the trick. maybe a 1/2" or 3/4" pvc pipe with ports on each end might help. Will need to test it and figure out what works best.

 

Steve,
First, great write up man. Way to pioneer getting this information and helping the community.

I am intrigued by a few of your mods and will be starting to explore these on my 2002 Dakota 4.7 manual 5-speed.

I recently swapped in a new 4.7 and added the HO cams and 2008+ (think I snagged mine off a 2012 jeep) intake (slightly shorter runners than the previous HO intake on the 2002-2007 HOs).

My current MODs are:
JBA headers (have been installed for... 6+ years now maybe closer to 8)
True dual exhaust with the 3rd CAT/CARB deleted (still passes smog, completed in 2011/12)
Air Raid CAI (installed since I bought the truck in 2008)
HO CAMs and 2008+ intake (June 2024)
SAS Dana 44 HP (eaton locker and manual hubs) and Dana 60 rear (yukon air locker) (2010)
5.13 gears (2010)
35" tires (used to be on 37s)

I average about 11-12 MPGs which makes sense due to the added weight, gears, and larger tires but I was hopping to get some back with the new engine and cams. Based on your write-up I should be looking at adding the intake wind turning vane (need to figure out how to make one), adding a longer pickup/forced air port onto my intake box and running it to the grill some place, maybe some newer injectors (I tried this with some other 12-pin injectors but the truck ran worse and very rich), a tuner (tried reaching out to Nick at AirRam but haven't heard back), and maybe these potato launchers (great name by the way).

What are your general thoughts? Really wanting to gain whatever I can in MPGs. I feel most my power in the 2800+ RPM range but that is not to say that I have lots of low end torque with the gears. Currently, at highway speeds of say 70mph I am at about 3000 rpms (wish I had a 6th gear).

-Marshall

 

Some serious customization going on there. Pretty deep gearing for the tire size though???

Nice Truck.

 

Haha, thanks man! It has definitely been a fun project. Started with leaf's upfront, then swapped to the coils (should have listened and just started with them). The gearing was a back and forth. Started with 4.10s on the 37s, but 5th gear was non-existent. Chatted with an off-road guru and landed on the 5.13s (recommended for most manuals with room to run 37s). Honestly, it runs fantastic with those gears, even on the 35s. An extra top end gear on the trans would be ideal but for what it has, I honestly cannot complain.

 

I complain anyway. But, I am just old and jaded. I have 4.56 gears with 33" tires, and that is too much gear for my tastes. No trailer towing on the freeway, the engine is SCREAMING at 55 mph.

 

Fair enough! I suppose a small complaint is fair. I misspoke in my early post; 3k rpms at 78mph. Still tho, it would be nice to drop those rpms another 300-400.

as for my lower gears, I usually start in second unless pulling a trailer. It is nice having that extra power for certain applications.

 

Hey Marshall, nice truck for sure!!! Sorry I missed your posts, no notification & had not been back in a while.

On your question... let me share a recent experience on my setup...

The airbox mod with the exhaust dump, it will flutter under certain conditions, I have tried a couple of different methods to get it to stop and have been un-successful so I disabled it (normally open). Top end improved as expected but the bottom end drops a bit (mpg's zone). Recently I went back to it and removed the intake snorkel on the air box for added flow and as expected, more top end power. This was OK as it was but then I decided to add back in the 2nd potato launcher (PL) mod, a 12" piece iirc, and as expected the top end dropped but the bottom end had a very noticeable gain on the bottom end torque. So currently I am rolling with that setup and love it however.... I want the top end back as well. So a new challenge is getting the PL #2 vacuum line pinched off/closed under high load conditions with the goal of getting the best of both worlds.

With the current setup a new wrinkle has come into play, I can hear airflow fluttering in the airbox. I already have a divider in there to control the airflow across the filter but will need to find a solution to the new fluttering.

On the turning vane in the intake tube... I used 5" garden edging and trimmed it down to fit. I then added a divider that interlocked into the middle section so it could never come out. I think the pics are posted in this thread, if not lmk & I'll post them here.

 

another comment... if you have not heard of it, there is a jeep TCM swap mod that makes the 4spd into a 5spd trans. One problem I found with it is the 4th gear is very rare to actually get into & use. I have this controller and pulled it in favor of the performance of the oem controller. IN my case the power output (at the last time I ran it) and gearing (75 series tire with 3.55 gearing) made it miserable to drive. Now however that might be a different story as the output power on the bottom end is stronger then it had been.

Looking at replacing that exhaust dump valve with a velocity stack I have this afternoon..., Need to see if it will fit in the area (diameter wise). Once that is done, then will need to fix the air flow within the box as there is something going on in there, which is probably hurting power

 

Update... pulled the exhaust dump off of the air box as well as the air box divider I had installed. The divider was fluttering in the box with the incoming airflow, need to fix that.

Spent yesterday re-dialing in the tune with HPT as it was running rich in certain areas of the tune. As expected, the tune is now "smoothed out" so to speak where its power is flatter then before the air box changes and tune changes. I also put a ball valve inline with the 2nd PL mod to fine tune how the performance is PRIOR to the tuning. With rising fuel prices here in the PNW, mpg's are a higher concern. Last tank, with speeds in the 65~70 range came in at 16.3 mpg (hand calculated), which is not bad considering how I drove it. Going to keep my foot out of it for the next few trips to work (thru Friday) and see how the fuel gauge does. Will probably short fill it to see what it is doing with the current tune & setup.

On the ball valve inline on the 2nd PL mod, with the valve open 100%, there is a shift in torque down low but again at the expense of upper end power. The reason for the valve was to balance out the performance. I'd still like to get a vacuum switch in there to cut off the line to the 2nd PL mod under low vacuum conditions. I have the parts, just need to find the time & get out there to get it done.

One other thing, not sure if I mentioned this but in October my motor developed a mis-fire on cylinder #6. Swapped coil, injector, plug & no change. Tuned it and it appeared to get better but not 100% gone. Sea foamed it and it also got better but not 100% gone. The misfire occurred 1st thing in the morning on a stone cold motor and performance would never miss a step after temps started to climb. I could clear the code a mile down the road and it would not come back until the next morning. I suspected it was either the ECM was failing or the winter fuel we switch over to in October-March. Well guess what... here it is April and the mis-fire is gone & temps are still in the low 40's. I'd have to conclude that cylinder is weak compared to the rest (never did do a compression check on it) and the winter fuel highlights it with the mis-fire.

 

The short fill tank with 2 work trips, 150.3 miles = 17.93* mpg.... Again, been seeing 16s.