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DriVer 12-05-2007 05:05 PM

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by Fred and Bonnie:
Max, I follow your thoughts, you can't make it over I-70 at 3,000RPM. </div></BLOCKQUOTE>That's true Fred but equipped with the Allison you can make about 4200 and climb pretty steadily IF you can keep that energy level up. I rarely if ever get over 4600 rpm climbing and rarely if ever descending in compression.

Jestme13 12-05-2007 05:55 PM

watch out you don't burn up those plug fire pulling those hills !

BaD42 12-05-2007 07:17 PM

I have to agree with Max49. I don't see how it is possible to climb some of the passes that are at 11,000 to 14000 feet elevation at less than 4600 to 4800 rpm.
This past summer I spent 2 months in the mountains of Colorado. I had my coach weighed at the start of the trip and was at 23,760 pounds with the toad at 3,925 pounds.
I climbed 2 passes at 14,000 feet, 2 at 11,000, 1 at 10,300 and a couple of others at about 9,000. Most of the grades were between 6 - 8% with some of the climbs being for 10-11 miles.

I tried backing off the throttle to lower the rpm's and all I accomplished was losing speed rapidly. I was already down to about 25 miles per hour at 4600 rpm. The factor of weight and altitude preclude going up these passes at the 55 mph and 3000 rpm that some claim. Additionally throw in some 15 mph curves and your speed goes down the tubes rapidly.

Steady Eddie 12-05-2007 08:42 PM

As posted by BaD42:
"..I have to agree with Max49..."
=====================
I have to agree. Your post is 100% right on.
No one can say, by your sig line, that you do not have "the right stuff"...you have it.

What says Brazels?

Seems like your conditions are right where we
find out where the Bear Crapped in the Woods...
shove or push?

Max Hubrich 12-06-2007 04:19 AM

Max

I drove a 2003, H-3 45' Marathon coach, Detroit Diesel equipped, from the eastern part of North Carolina to Branson MO in '05. I was pulling a Lexus 470. My old boss owned this setup. As I approached the climb on I-40 up to Ashville NC, it was raining, And I was in traffic-- when I topped the mountain I was doing a whopping 35 MPH!! I had manually downshifted it several times and It was doing around 2500RPM.

I don't think this is any better than my ole 454 ci Holiday Rambler did some years earlier. Like Driver said, it's the inertia you have built up when you approach such a challening climb. The choice of gas vs. diesel is a personal decision based on many factors. He who gets to the "top of the hill first" is not nearly as important as getting there-- with a functioning, fully operational vehicle on the down hill side of that mountain

FrontRangeRVer 12-06-2007 05:04 AM

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by BaD42:
I have to agree with Max49. I don't see how it is possible to climb some of the passes that are at 11,000 to 14000 feet elevation at less than 4600 to 4800 rpm.
This past summer I spent 2 months in the mountains of Colorado. I had my coach weighed at the start of the trip and was at 23,760 pounds with the toad at 3,925 pounds.
I climbed 2 passes at 14,000 feet, 2 at 11,000, 1 at 10,300 and a couple of others at about 9,000. Most of the grades were between 6 - 8% with some of the climbs being for 10-11 miles.

I tried backing off the throttle to lower the rpm's and all I accomplished was losing speed rapidly. I was already down to about 25 miles per hour at 4600 rpm. The factor of weight and altitude preclude going up these passes at the 55 mph and 3000 rpm that some claim. Additionally throw in some 15 mph curves and your speed goes down the tubes rapidly. </div></BLOCKQUOTE>

I'de love to know where those 14,000 foot passes are here!! https://irv2.infopop.cc/groupee_commo...s/icon_eek.gif

FrontRangeRVer 12-06-2007 05:14 AM

Taking I-70 out of Denver going West will take you from 5,000 feet to 10,666 feet at Vail Pass, and that is a tough climb...I have run it around 4K RPM and stay 40 mph. If my RPM gets higher, I back off my speed as I'm not thrilled about anything over 4.3K RPM.

People who have never driven this route ( only going West on I-70) don't realize that the altitude increase ZAPS your power.... Here, it's not about the percent grade of the road...it's all about ALTITUDE folks.

rgrstndgby 12-06-2007 05:41 AM

Bruce, just want to say...'Good Job" for the way you brought this issue to this board, and stayed informative, and up beat and "on task" thru it all. Im sure your checkbook would have rather spent the $$ at the mall, but it was not to be. Hope the rest of your WH miles are good ones, and a Happy Holiday season to you..rgr...

two2go 12-06-2007 05:44 AM

There are no CO passes you would want to drive your MH on over 14K ft. You might try driving to the top of Pike's Peak or Mt. Evans, they are over 14K. I think one of the most demanding passes is Monarch pass. The east side is steep with tight switchbacks and the west side has a long steep grade that taxes your brakes if you get behind slower vehicles.
I usually hold the coach at 4000-4200 rpms and enjoy the scenery. I had a 1978 class C on a Dodge van chassis with a 400CI engine. It was hard pressed to get 40 mph on most passes going solo at 10000 GVW, and overall got about the same gas mileage as this Dolphin at 22000 GVW pulling a toad.
One thing I would like to see as an option is a small turbo or super-charger that maintains sea-level or slightly higher pressure all the time so you didn't lose power at altitude. Not a hot-rod setup, just a power and efficiency maintainer.

BaD42 12-06-2007 07:01 AM

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by FrontRangeRVer:
I'de love to know where those 14,000 foot passes are here!! https://irv2.infopop.cc/groupee_commo...s/icon_eek.gif </div></BLOCKQUOTE>

You caught me in an unintentional mistatement about the 14,000 feet. When I was entering my post I was looking at a highway map. One of the routes that I had taken was from Ridgeway to Cortez. On the map it showed Lizard head at 14,100. If I had researched the actual road elevation the pass itself is only 10,222.

I concede to your superior local knowledge and want to insure you that I didn't intend to mislead anyone.

The point of my post was to indicate that I couldn't maintain the speed or rpm's that others
achive.

max49 12-06-2007 06:24 PM

I just think the newer diesel engines do better in this altititue. It must be the torque or something. I've never driven a DP, but I've ridden in friends pick up trucks pulling some heavy trailers 12,000 lbs + we were passing cars going up Berthoud pass. This has been with the Ford Powerstroke and the Duramax (Isuzu) completely stock.
I've worked in road construction all my life and people always ask me, 'why did you buy something that big with a gas engine?'
They don't know, that neither the Ford or the Chevy Workhorse does'nt offer a class A with either the Ford or Chevy Diesel. And I have no idea why not either. I think it only a 5 or 6K upgrade on a PU truck.
I've only burnt one SP wire and that was in January, slowly putzing up and down the Pacific Coast Hwy in 80 degree weather

On edit, since I can pull 5000 RPM on some Mtn passes in 1st gear but can't pull 2nd gear, I know a 5 speed would help; but mine is only a 18,000 lb chassis. I would'nt imagine a 5 speed in a 22,000 lb chassis could be much better.

dieselclacker 12-07-2007 04:21 AM

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by max49:
I just think the newer diesel engines do better in this altititue. It must be the torque or something. I've never driven a DP, but I've ridden in friends pick up trucks pulling some heavy trailers 12,000 lbs + we were passing cars going up Berthoud pass. This has been with the Ford Powerstroke and the Duramax (Isuzu) completely stock.
I've worked in road construction all my life and people always ask me, 'why did you buy something that big with a gas engine?'
They don't know, that neither the Ford or the Chevy Workhorse does'nt offer a class A with either the Ford or Chevy Diesel. And I have no idea why not either. I think it only a 5 or 6K upgrade on a PU truck.
I've only burnt one SP wire and that was in January, slowly putzing up and down the Pacific Coast Hwy in 80 degree weather

On edit, since I can pull 5000 RPM on some Mtn passes in 1st gear but can't pull 2nd gear, I know a 5 speed would help; but mine is only a 18,000 lb chassis. I would'nt imagine a 5 speed in a 22,000 lb chassis could be much better. </div></BLOCKQUOTE>

Max, turbocharging on the diesels you speak of makes all the difference in producing power at Colorado altitudes.Pressurize and pack that thin mountain air in thru the turbo makes the diesel think it is at sea level. https://irv2.infopop.cc/groupee_commo...on_biggrin.gif

I would stay away from those 5000 RPM runs on the 8.1 in the intrest of longevity of the engine. I try and limit RPMs to 4000 both under power and during deceleration down hills. Just my humble opinion. https://irv2.infopop.cc/groupee_commo.../icon_wink.gif

Dieselclacker

DriVer 12-07-2007 04:24 AM

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by max49:
I would'nt imagine a 5 speed in a 22,000 lb chassis could be much better. </div></BLOCKQUOTE>Max, Throughout history it has been continously proven that with the proper amount of leverage you can move mountains. The Allison transmission plus the final drive ratio in the axle gives you that leverage. It's not so much an engine thing however the 8.1 certainly does spin that Allison quite nicely. https://irv2.infopop.cc/groupee_commo...on_biggrin.gif

Fred and Bonnie 12-07-2007 07:58 AM

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by FrontRangeRVer:
Taking I-70 out of Denver going West will take you from 5,000 feet to 10,666 feet at Vail Pass, and that is a tough climb...I have run it around 4K RPM and stay 40 mph. If my RPM gets higher, I back off my speed as I'm not thrilled about anything over 4.3K RPM.

People who have never driven this route ( only going West on I-70) don't realize that the altitude increase ZAPS your power.... Here, it's not about the percent grade of the road...it's all about ALTITUDE folks. </div></BLOCKQUOTE>

Going West is a piece of cake compared to going East, that climb is tougher.

Fred


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