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CampingN_C_'s avatar
CampingN_C_
Explorer
Jul 19, 2015

Black Mountain whooped my butt !!

I've been dreading our trip to Gatlinburg since we planned it and most of my fears came true. I just flat out ran out of horses coming up. When I got to the top I was in second running about 40mph and slowing. If I had another mile to go I'm sure I would have been in first, and much slower.
Honestly, I thought it would've done a little better based on some of my trips in the NC mountains (226,221 and 421). I was expecting screaming RPM's in second but still holding the chosen speed. I guess the difference is there's NO break on the way up, no up and down, just up for about six miles.
I still love my truck but I'll never make that pull again with it. My wife signed off on a newer truck about 100ft past the top !:D
  • Anmacc2's avatar
    Anmacc2
    Explorer
    Jul 19, 2015
    I've pulled all through the Smokies, the Rockies, the Adirondacks... On the toughest pulls doing 25mph in 1st gear. So what? It's all part of the journey. On the downhills my truck will hold it at 45mph in second gear or 25mph in first rarely hitting the brakes. I don't get nervous going up slower in a lower gear. Now going down faster... That will get the blood flowing! ??
  • blt2ski's avatar
    blt2ski
    Moderator
    Jul 19, 2015
    Rocky mtn states that is low. Here in NW 6-7000 is as high as passes go, Most are in the 3-5k range.

    Issue is grade. Assuming 15K lbs, 90 sq ft of frontal area, you need 135 hp to go 60 mph. Then an additional 40 hp per 1% grade. So 240 plus 135 is 375hp. subtract that you have 21% loss of HP in your motor, or add in 21% to the above, you need well over 500 ponies for 60 mph. Obviously I hope, slower speeds need less HP. I am not finding a book I have with the how much hp one needs at different weights, grades etc.

    I'm guessing, your 6.0 was doing what it was supposed to. But that 7K feet elevation also hurt you!

    Marty
  • marcsbigfoot20b's avatar
    marcsbigfoot20b
    Explorer
    Jul 19, 2015
    Looks like at least a 9000 lb trailer. Elevations of the two locations are 2400ft and 1500 ft according to Wikipedia .
    Those elevations are nothing....I was guessing you were at 6000 ft or more.

    Sounds like you are in diesel territory.
  • CampingN_C_'s avatar
    CampingN_C_
    Explorer
    Jul 19, 2015
    Speed limit is 55 and I wouldn't have ran that if I could, too curvy. I would've been fine maintaining 45 or even 40mph.
    I think it's around 7000ft. I know, I know, that's nothing compared to out west, but for us on the east side it's about the worse one we have.
  • blt2ski's avatar
    blt2ski
    Moderator
    Jul 19, 2015
    6% grade will need around 370 ponies to go 60 mph. Than add in a loss of 3% per 1000' elevation. He may need well over 400 ponies to hold 60 mph.

    He is above the J2087 min speed spec. So he has the HP per SAE and auto builders.

    It does not mee HIS and HER personal performance speed spec, but it does meet GM's build to spec.

    marty
  • rv2go's avatar
    rv2go
    Explorer II
    Jul 19, 2015
    blt2ski wrote:
    How high in elevation, and how steep is the road?

    marty



    From the North Carolina section of the Mountain Directory East:

    I-40 (between Black Mountain and Old Fort, NC)

    By law, all trucks except pickups and vans are required to stop at the top of this hill and read the information posted about the eastbound descent ahead. The top of the hill is near milepost 67 just east of Black Mountain. The grade is posted as 5 miles of 6%. It is a strong 6%. There are three runaway truck ramps, all of which are short sand beds with sand piles at the end. There is about a mile of grade left after the last escape ramp. The westbound descent is about 1¼ mile of 6%.

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