I have seen improved mpg and power from the mods I have done. It really sounds like your truck has just been neglected and needs a tune up. How many miles does it have on it?

Here is what I would do if I was you- all this stuff is relatively cheap:

Oil change a/ good synthetic oil
Seafoam treatment
Ebay intake ---- http://cgi.ebay.com/ebaymotors/DODGE...Q5fAccessories

New high flow muffler
Change spark plugs (autolite 3923's)
REMOVE clutch fan (add e-fan if necessary)

Start there and see where you get. If you do these things you should see improved power and gas mileage. Unless there is something else wrong with the truck, which I doubt. Sounds like she just needs a little tuning up and you should be able to get to around 200 hp at the crank (thats only like 160 at the wheels but hey thats how it works)

 

You can do the seafoam treatment, remove the clutch fan, and change the spark plugs tomorrow for around $25-30. Do that and report back. Also, if you have an android phone, download teh Car Performance app. IT will give you a pretty accurate idea of 0-60 and 1/4 mile times. If not, use a stopwatch and do the best you can.

 

seafoam also works really good if you can find the machine that vaporises it and it sucks it into your vacume system and cleans that all out but i would second on having the fuel system cleaned and a good tune up done on it fuel filter the works on it

 

Clutch fan gone. New spark plugs. Seafoam treatment done. New air and oil filters (the old ones were pretty bad). And a synthetic oil change. After driving around for a bit, I feel a little more power, but the biggest thing is that it is just running more smoothly. I feel a bit of a difference in the city, but I don't think much has changed on the highway as far as passing power goes. Timed a 0-60, took 12.5 seconds (almost a second less than before).
If this is all I'm getting, I am going to have to get radical. Ideally, I'd like more of a 10 second to 60 time if it's even possible.

 

holey crap a 12.5 second 0-60? my parents 4cycl camry is faster. my stock 4.7 was like 8. something wrongs.

well i just noticed you have a durango. but still that is hideously slow for a 4.7. you need to rip out all the seats in the rear and start modding!

 

Sorry if there was any confusion... My durango with the 4.7 will do it in like 9.1, but the 12.5 is for the dakota with the 3.9 that I had the pleasure of having dumped into my care by my father. Considering it weighs like 4800 lbs and only puts out 175 horses, its not terrible.

As I have said before I am still considering an engine swap, with a 5.2, 4.7, or 5.9 if I can find one... (I have heard there is not a huge mpg difference between the 5.2 and 5.9?)
Only because I just can't handle a really slow vehicle. Reminds me too much of my first car. Total piece of crap. VW van, with the diesel (like 65 hp when new, more like 20 when I had it). One cylinder just plain wasn't working, the clutch slipped occasionally, and the 4 speed trans would occasionally just pop out of overdrive into neutral. 0-60? Forget it. Under its own power I got it up to 58 with a tail wind. Actually coming down from snowqualmie pass in WA, I was flooring it down it, probably got to maybe 65, and then it popped out of gear, and I realized that it actually went faster just coasting in neutral. I got it up to 80 or so, but things got really sketchy really fast, so I brought the speed back down.
Moral of the story is I want something that can at least maintain highway speeds up a long grade, and with more than me in it, the dakota can't seem to do that.

 

ahhh ok i was about to say. i had my 4.7 dynoed with mods and it made 181. i doubt your 3.9 makes 175.
either way, yes you need a larger engine in it.

 

Based on how it drives, I would be surprised if it made 130.

 

Thunder your power was at the wheels, after 15-20% loss...that's more like 220 hp at the crank (where they measure factory hp).

TC- I don't think a 10 second 0-60 is out of the question, and if you dropped a full second from your 0-60 times that's not bad at all. The motor needs to BREATHE easier..that means intake/ exhaust mods.

City driving is all torque, which the 3.9 was designed for. Highway passing power is where HP comes into play, and that motor wasn't designed to make big HP. It revs low, and is designed for torque. It's a truck motor.

Consider this- my 3.7L quad cab weighs the same as yours, and my 0-60 times are about 10-10.2 seconds if it's cool outside. That is after removing clutch fan, spark plugs, intake, and new muffler. Bone stock my 0-60 times were around 12 seconds. So I knocked off about 2 seconds. Not too shabby, I'm basically satisfied. I might get a high flow cat and Fastman throttle body when I get some more $$ in the bank. High flow cat + throttle body might get me another 20 hp and knock another second off my 0-60 time. That would put me at 9-9.2 seconds. Not bad for a V6 hauling around 5000 lbs of truck.

My truck was rated @ 210 hp from the factory at the crank. I assume my mods have given me another 20-25 hp, so at best I have 235. So, to get a 10 second 0-60, you are going to need another 50-55 hp over stock. Removing clutch fan might have given you about 5, so let's say you have 50 hp to go.

Good intake will give you 10 hp. Intake + new muffler + high flow cat probably = 30ish HP. So you need to find another 20 hp. Throttle body might give you 10-15? Just a guess. Do all that and I would be surprised if you werent in the 10-10.5 second range.

The biggest problem with my truck's 0-60 time is the launch. MY truck doesn't make much power at all until about 3000 rpm...it revs to 5700 before it changes gears. I'm sure I could change the shift point to 6000, but whatever. My engine is more like a car motor, it has to rev to make power. Yours doesn't. Any more than 5000 rpm and it's probably just wheezing and not making any more power. So maybe having that extra torque down low (1500-3000 rpm) might make up for the lack of high-end power. My truck doesn't even chirp the tires when I launch it, even if I power brake it. That's because it doesn't make much torque at low rpm.

Just doing the seafoam, plugs, and clutch fan and getting 1 second improvement is pretty damn good.

Spend $50 on an eBay intake like the one I posted before, spend another $300 on a new muffler and high flow cat, and you might get remarkably close to where your trying to get.

The advantage that you have is that your motor will make decent power through most of it's RPM range, probably good torque between 1500-3000 rpm and HP between 3000-4500 rpm. My truck doesnt make any torque or HP until it hits 3000 RPM, which really hurts my 0-60 time. My 1/4 mile times are slow, because the launch sucks, but my MPH is relatively high for a V-6 because once I get above 3000 in 1st gear the motor stays in it's power band through the gear change from 1st to 2nd, and it actually pulls pretty damn good at higher rpm's. Also consider this- the '99 R/T model w/ 250 hp 5.9L V8 does a 1/4 mile (stock) in 15.4 seconds at about 88 mph. My truck's MPH is about 81-82, so I'm only 6-7 MPH off a truck that weighs 1000 lbs less and has an engine thats almost twice as big. BUT....the 1/4 mile times are like 2.5 seconds faster than my truck, because that thing will launch like it's *** is on fire while my truck fumbles around until it hits 3000 rpm. So the MPH is similar because my truck will rev high and makes decent high-end HP, but that R/T will SMOKE me off the line. The first 100-200 feet are the most important for 0-60 and 1/4 mile times.

Spend a few hundred $$ on the intake and exhaust mods before you drop $1000's on a V8 if you will be satisfied with a 10 second 0-60. I bet you will be surprised what you end up with when you are done.

 

So I have gone ahead and ordered the intake. I'm now looking at mufflers. Any suggestions? Also I forgot to mention earlier, my truck has just over 103k miles on it, and the body is in really good shape. It has been babied. It is also very red, and I must admit it is a bit intense for my liking...

I have stopped driving my durango for now, because in O/D, if I try to accelerate (3/4 or more throttle) the revs just get higher, with no speed gain, feels a lot like when the clutch slips on a manual. The dakota's trans was rebuilt at like 40k miles, and has been perfect since.

And one last question. Do supercharger or turbocharger kits exist for the 3.9? And if they do, how much power would you gain? (100% out of curiosity, seems like a massive pain to add a turbo or supercharger to any vehicle)