Hello everybody. I am new to the forum, but I will get straight to the point.
I am considering a 2003 Durango with the 4.7, and if I buy it, after installing a few light mods, like a Borla Exhaust, K & N cold air intake and air filter, etc. what kind of HP numbers should I expect? are there any other minor mods i should consider?

Also, I was considering one with the 5.2, but I was reading that it has more low end torque vs high end power, which I figured was not very good for highway passing, and more specifically when you kick down to maintain highway speeds over a mountain pass. Another factor was the 5 speed auto's closer ratios.

So the point of all this is that my friend has an 04 vw touareg v8, and it is pretty quick. It is also very capable of cruising at 140 km/h (87 mph) on the mountainous parts of the coquihalla highway in BC (which I drive multiple times a week). I realize that a Durango would be significantly slower than his touareg, but is the biggest factor the performance of the engine, or the bigger gaps between the gear ratios? And more importantly, is a Durango with the 4.7 capable of higher speed (120 km/h +) highway cruising in mountainous areas? And would I actually be better off with a 5.2 ?(for the record I occasionally tow a light trailer with two PWC on it).
Sorry for the long post btw.

 

4.7L ENGINE
DESCRIPTION SPECIFICATION
GENERAL SPECIFICATIONS
Engine Type 90° SOHC V-8 16-Valve
Displacement 4.7 Liters / 4701cc
(287 Cubic Inches)
Bore 93.0 mm (3.66 in.)
Stroke 86.5 mm (3.40 in.)
Compression Ratio 9.0:1
Horsepower 235 BHP @ 4800 RPM
Torque 295 LB-FT @ 3200 RPM
Lead Cylinder #1 Left Bank
Firing Order 1-8-4-3-6-5-7-2
CYLINDER BLOCK
Cylinder Block Cast Iron
Bore Diameter 93.010 ± .0075 mm
(3.6619 ± 0.0003 in.)
Out of Round (MAX) 0.076 mm (0.003 in.)
Taper (MAX) 0.051 mm (0.002 in.)
PISTONS
Material Aluminum Alloy
Diameter 92.975 mm (3.6605 in.)
Weight 367.5 grams (12.96 oz)
Ring Groove Diameter
No. 1 83.37 - 83.13 mm
(3.282 - 3.273 in.)
No. 2 82.833 - 83.033 mm
(3.261 - 3.310 in.)
No. 3 83.88 - 84.08 mm
(3.302 - 3.310 in.)
PISTON PINS
Type Pressed Fit
Clearance In Piston 0.010 - 0.019 mm
(0.0004 - 0.0008 in.)
Diameter 24.013 - 24.016 mm
(0.9454 - 0.9455 in.)
PISTON RINGS
Ring Gap
Top Compression Ring 0.20 - 0.36 mm
(0.0079 - 0.0142 in.)
Second Compression Ring 0.37 - 0.63 mm
(0.0146 - 0.0249 in.)
Oil Control (Steel Rails) 0.25 - 0.76 mm
(0.0099 - 0.30 in.)
Side Clearance
Top Compression Ring .051 - .094 mm
(0.0020 - 0.0037 in.)
Second Compression Ring 0.040 - 0.080 mm
(0.0016 - 0.0031 in.)
Oil Ring (Steel Ring) .019 - .229 mm
(.0007 - .0091 in.)
Ring Width
Top Compression Ring 1.472 - 1.490 mm
(0.057 - 0.058 in.)
Second Compression Ring 1.47 - 1.490 mm
(0.057 - 0.058 in.)
Oil Ring (Steel Rails) 0.445 - 0.470 mm
(0.017 - 0.018 in.)
CONNECTING RODS
Bearing Clearance 0.015 - 0.055 mm
(0.0006 - 0.0022 in.)
Side Clearance 0.10 - 0.35 mm
(0.004 - 0.0138 in.)
Piston Pin Bore Diameter .025 - .048 mm
(Interference Fit) (0.001 - 0.0019 in.)
Bearing Bore Out of Round 0.004 mm
(MAX) (0.0002 in.)
Total Weight (Less Bearing) 555 grams (19.5771 ounces)
CRANKSHAFT
Main BearingJournal
Diameter 63.488 - 63.512 mm
(2.4996 - 2.5005 in.)
Bearing Clearance 0.018 - 0.052 mm
(0.0008 - 0.0021 in.)
Out of Round (MAX) 0.005 mm (0.0002 in.)
Taper (MAX) 0.008 mm (0.0004 in.)
End Play 0.052 - 0.282 mm
(0.0021 - 0.0112 in.)
End Play (MAX) 0.282 mm (0.0112 in)
Connecting Rod Journal
Diameter 50.992 - 51.008 mm
(2.0076 - 2.0082 in.)
Bearing Clearance 0.015 - 0.055 mm
(0.0006 -0.0022 in.)
Out of Round (MAX) 0.005 mm (0.0002 in.)
Taper (MAX) 0.008 mm (0.0004 in.)
CAMSHAFT
Bore Diameter 26.02 - 26.04 mm
(1.0245 - 1.0252 in.)
Bearing Journal Diameter 25.975 - 25.995 mm
(1.0227 - 1.0235 in.)
Bearing Clearance 0.025 - 0.065 mm
(0.001 - 0.0026 in.)
Bearing Clearance (MAX) 0.065 mm (0.0026 in.)
End Play .075 - .200 mm
(0.003 - 0.0079 in.)
End Play (MAX) .200 mm (0.0079 in.)
VALVE TIMING
Intake
Opens (BTDC) 4.4°
Closes (ATDC) 239.1°
Duration 243.5°
Exhaust
Opens (BTDC) 240.5°
Closes (ATDC) 13.2°
Duration 253.70°
Valve Overlap 17.6°
VALVES
Face Angle 45° - 45.5°
Head Diameter
Intake 48.52 - 48.78 mm
(1.9103 - 1.9205 in.)
Exhaust 36.87 - 37.13 mm
1.4516 - 1.4618 in.)
Length (Overall)
Intake 113.45 - 114.21 mm
(4.4666 - 4.4965)
Exhaust 114.92 - 115.68 mm
(4.5244 - 4.5543 in.)
Stem Diameter
Intake 6.931 - 6.957 mm
(0.2729 - 0.2739 in.)
Exhaust 6.902 - 6.928 mm
(0.2717 - 0.2728 in.)
Stem - to - Guide Clearance
Intake .018 - .069 mm
(0.0008 - 0.0028 in.)
Exhaust .047 - .098 mm
(0.0019 - 0.0039 in.)
Max. Allowable Stem - to -
Guide Clearance (Rocking
Method)
Intake 0.069 mm (0.0028 in.)
Exhaust 0.098 mm (0.0039 in.)
Valve Lift (Zero Lash)
Intake 11.25 mm (0.443 in.)
Exhaust 10.90 mm (0.4292 in.)
VALVE SPRING
Free Length (Approx)
Intake and Exhaust 49.0 mm (1.9291 in.)
Spring Force (Valve Closed)
Intake and Exhaust 313.0 - 354.0 N @ 40.12 mm
(70.3652 - 79.58237 lbs. @ 1.5795 in.)
Spring Force (Valve Open)
Intake and Exhaust 776.0 - 870.0 N @ 28.88 mm
174.4517 - 195.5838 lbs. @ 1.1370 in.)
Number of Coils
Intake and Exhaust 7.3
Wire Diameter
Intake and Exhaust 4.6 × 3.67 mm
(0.1811 × 0.1445 in.)
Installed Height (Spring
Seat to Bottom of Retainer)
Nominal
Intake 40.12 mm (1.5795 in.)
Exhaust 40.12 mm (1.5795 in.)
CYLINDER HEAD
Gasket Thickness
(Compressed) .7 mm (0.0276 in.)
Valve Seat Angle 44.5° - 45.0°
Valve Seat Runout (MAX) 0.051 mm (0.002 in.)
Valve Seat Width
Intake 1.75 - 2.36 mm
(0.0698 - 0.0928 in.)
Exhaust 1.71 - 2.32 mm
(0.0673 - 0.0911 in.)
Guide Bore Diameter (Std.) 6.975 - 7.00 mm
(0.2747 - 0.2756 in.)
Cylinder Head Warpage
(Flatness) 0.0508 mm (0.002 in.)
OIL PUMP
Clearance Over Rotors / End Face (MAX) .095 mm - (0.0038 in.)
Cover Out - of -Flat (MAX) .025 mm (0.001 in.)
Inner and Outer Rotor
Thickness 12.02 mm (0.4731 in.)
Outer Rotor to Pocket Diametral Clearance (MAX) .235 mm (.0093 in.)
Outer Rotor Diameter (MIN) 85.925 mm (0.400 in.)
Tip Clearance Between Rotors
(MAX) .150 mm (0.006 in.)
OIL PRESSURE
At Curb Idle Speed (MIN)* 48 kPa (7 psi)
@ 3000 rpm 240 - 725 kPa (35 - 105 psi)
* CAUTION: If pressure is zero at curb idle, DO NOT run
engine at 3000 rpm.

 

wow thank you... but I must admit that some of that tech stuff flies over my head, however there is a lot of useful stuff I didn't know there. Where do you get all that info?

 

the 5.2 is a more mod-friendly engine, however the 5 speed on the 4.7 is more efficient (so is the engine itself), holding highway speeds either one will do just fine,(they both top out at 120Mph), for towing you want one with 3.92 gears, for highway economy you want the 3.55 gear ratio (in the rear differential), and just keep in mind you cannot compare the durango to the taureg, they are two completely different beasts. The Durango will most likely pull hills in drive (not OD) so the rpms will be up a little higher, but for a 4800 lb beast you have to expect that.

if you have any SPECIFIC questions (we really dont need the story) feel free to ask them and someone will chime in with an answer

 

Sorry about beating around the bush.
I have a few main questions:

from 0-60 would a 4.7 or 5.2 be faster? and what times exactly?

with minor mods, what kind of hp and torque should I expect from each of
these engines?

which engine is better for towing? are the tow ratings the same?

and roughly how many rpms would the 4.7 and 5 speed auto be turning at 80 mph in OD? what would be the difference between 3.55 and 3.92 gears?

 

1. they will be about the same 0-60 (the 4.7 makes 5 more hp, and 5 less ftlbf of torque than the 5.2), iv never timed it, or run against someone w/ a 5.2, in all honesty the 5.9 is quicker than both
2. minor engine mods like a CAI and exhaust will most likely not give you any noticeable gains, its just the way it is, youd see more gain from replacing the clutch fan w/ an electric fan
3. both engines are truck engines and make pretty good low end torque, that said i do believe the 5.2 has a better torque curve on the low end of the rpm range
4. the 4.7 would turn just over 2k in OD @ 80 w/ the 3.55 rear end differntial

 

Thanks for the answers.
I was looking at the 03's because they got 4 wheel disc brakes, but are there any other model year changes that should influence my decision? I know they had rear ABS, but was front ABS an option? How would you tell if it was equipped with this?

Just another thing, my dad had a dakota with the 3.9, which as I know (?) is a 5.2 with two cylinders chopped off, and I always remember it sounding brutal above 4,000 rpms, and unwilling to rev much higher than that. Is the 5.2 the same way?

 

i honestly dont have a 5.2, i have a 4.7, but the 5.2 was not available in 03, so you would have to get the 4.7, or the gas hogging 5.9, your call, the 5.9 is nice for get-up-and-go.

4 wheel abs was an option on these trucks, your best bet is to go to dealer w/ the VIN and have them check it for you, that will give you a full list of features on the truck

and yes the 3.9 is the 5.2 minus 2 cylinders, and the 4k rpm reving shouldnt be an issue, why are you reving a truck engine that high anyway, you dont gain anything by running them up that high, torque is what actually moves the truck anyway so max torque is low, hence the engine doesnt need to rev up that high

 

thanks again.
I don't need a 5.9, so I am not going to get one and its gas thirst (of course I realize that the 4.7 isn't too thrifty). If you are wondering about the reving, it is because the 3.9 is a fairly gutless engine, and we were towing a 2000 lb trailer over the continental divide, and other mountain passes on I-90. They were too long and steep for 3rd, so it had to drop into 2nd. To sort of keep up with traffic (45-50 mph) it had to hover around 4k, and at that engine speed, the sound doesn't exactly inspire confidence. I'm sure any of the V8's would have enough power to do the same hills in 3rd, so it wouldn't be a problem.

 

Just one more question. You can get a 5.9 with part time 4 wheel drive? (like the 4.7 and 5.2). Because I DON'T want AWD. If I did, I would buy a Honda CR-V LOL.