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ParkCityKota
Dodge Dakota
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5/04/2004
13:07:15
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 Subject: 4.7l performance @ high altitude
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I moved to Utah from New England about 3 years ago and noticed a HUGE loss in power from my Dakota. When I first got here I asked the dealer if there was anything they could could do to help me get my power back and they said no. When I was at sea level I could just let the tires spin whenever I wanted. Now that I'm 7,000 feet above sea level I can't get them to spin at all at stop lights. I installed a cold air intake and a cat back MBRP exhaust system about 2 years ago. Of course it didn't help with my low end tourque but it did give me a lot of top end gains to get up some of the mountain passes around here.
So, naturally I want to get my low end tourque back. I know cams and headers would do the trick but until money starts growing on trees I'll have to put that off. Would a larger TB help me out much? High flow cat too or is that a lost cause and waste of money? I also would like to get rid of the clutch fan to lose some rotational weight. I'm concerned because I do live in a high alpine desert environment and that I climb up some pretty steep canyons that not having that fan will make my engine overheat...is this a valid concern? Will the electric fan do just fine?
I'd also like to get a tuner too (not a chip but a tuner so I can have a few different tuning options...not just one). I know that Hypertech and Superchips are working on one for the 4.7...think this plus the intake and exhaust alone will help me get my power back?
Thanks guys....
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Paul
Dodge Dakota
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5/04/2004
14:30:37
|  RE: 4.7l performance @ high altitude
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For the price of a tuner, intake, and exhaust you could just get the HO or KRC 206 cams and REALLY get some torque.
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ParkCityKota
Dodge Dakota
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5/04/2004
16:10:29
| RE: 4.7l performance @ high altitude
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ok...so I would skip the tuner and go with the cams but is it easy to install myself? I've never worked on my engine but I'm comfortable learning so long as I don't mess up something. Or, how expensive is it to pay someone to install them for me?
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Paul
Dodge Dakota
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5/04/2004
20:33:24
| RE: 4.7l performance @ high altitude
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If you have access to the tools and you can get a buddy to help you, the install is really pretty straight forward and takes about 4-6 hours. I forgot to install the lash caps the first time so I had to do it twice. The first time it took me 6 hours and the second time it took 4 hours. The only special tool you need is the wedge tool and it comes with the kit if you get it from www.krcperformance.com . You can get a lot of info on this site by searching for HO cams, 4.7l cams, etc. I think graphitedak posted pics once, I'm sure he could give you the link again. Instructions are also available at www.buymopar.com. Most of the 4.7 guys will tell you this is the most "bang for buck" mod on the 4.7.
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.boB
Dodge Dakota
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5/04/2004
22:33:41
| RE: 4.7l performance @ high altitude
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On average, you lose 2-3% per thousand feet in altitude. That's because there are fewer gas molecules (particularly oxygen) per cubic measure. Boyles Law of Gasses.
So, in order to get your power back, you need to force more air into the cylinders. More efficient cams will work to an extent. But Boyles law still rules. But be carefull, too radical a cam will cost you. Remember "RV" cams?
The best bang for the buck is forced induction; worked well for my Harley.
For my Dodge (5.9L), I used a hypertech tuner with a great improvement. Good power and mileage on mid-grade fuel. Tows easily.
As for cooling, an efficient electric fan like a Black Magic will work very well and free up a little power. But not as much as you might think. A clutch fan is pretty efficient and reliable. Life's full of trade offs, isn't it?
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ParkCityKota
Dodge Dakota
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5/05/2004
01:22:41
| RE: 4.7l performance @ high altitude
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Great information...I knew I should have paid attention in Chemistry class when I was in college. Obviously I'd love to have a supercharger but again, when money grows on trees I'll get one. If I want more air then how 'bout an aftermarket, larger bore Throttle Body? Not as effective as a supercharger but it is getting more air in there. Also, how about the HO intake manifold...will that get the engine more air than the stock on the 2000?
As my original post stated I want to get my low end back. I also have very erratic shifting out here as well mostly when coming up the canyon from Salt Lake City to where I live which is about a 3k foot gain. The engine, when in Overdrive will shift from 4th to 3rd and the engine just dives once at 2,000 rpms and then will upshift again for a few seconds...and back down. It's so hard to explain but I guess it comes down to me looking for a good cam that produces good low range and mid-range and maybe it will take care of this problem. Someday I'll post a question specifically for this problem once I can word it correctly.
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Rob C
Dodge Dakota
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5/06/2004
00:10:02
|  RE: 4.7l performance @ high altitude
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You're not going to get that power back without some major mods to your engine. There's just no substitute for that sea-level atmospheric pressure other than forced induction. Supercharging would be the choice for off the line grunt. The throttle body upgrade is going to give you top end power with the extra flow. The factory cat isn't that restrictive and a hi-flo cat is for top end power.
If you haven't done much engine work before but, are mechanically inclined, I'd read the instructions carefully several times and make sure you understand every step before trying to do the cams. Changing the cams on this engine isn't difficult. It's getting all the stuff that's in your way removed and reinstalled so you can do the cam change, that's the biggest pain in the butt.
Even with the cam change, you may still have to limit your tire smoking to the Salt Lake valley.
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.boB
Dodge Dakota
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5/10/2004
11:50:50
| RE: 4.7l performance @ high altitude
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Rob is right. It's simple physics. As for the transmission, it's hunting for the right gear. Just turn the O/D off, and let the engine do the work. That constant up and down shifting (hunting) will quickly wear out the transmission. The little bit of extra fuel you use will still be a lot less money than a new transmission. Even at $3 a gallon.
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Deeridge
Dodge Dakota
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5/11/2004
16:28:55
| RE: 4.7l performance @ high altitude
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I've driven that road to Park City. I'm not as high as you are, but I pull at capacity alot with my 03 RC Awd. Headers will give you a very noticeable improvement in low end torque. I'm guessing close to 20ft lbs. Other postings here indicate that the catback moves the torque back up the curve and defeat the headers for low end torque. The headers and the cams cost about the same, both would be best.
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