8.1 Pulling Power Question

[MtManLee]

Last January I had the Ultra Power, Plugs and Wires installed in the hope of increasing my power for my Motor Home (Holiday Rambler Vacationer with Tow Dolly and Saturn Vue 2wd) when traveling up hills. Coming to Utah it seemed to have ran better than it had before. Than I took it over one of the local mountains and it sputtered and coughed and almost stalled also said towards the top to check transmission temp. After that I took it in for its 30,000 mile Maintenance and they checked every things and found nothing wrong outside of a dirty air filter.

Well we took it to SD after that and it ran great we went across, Wyoming, South Dakota, Iowa, Missouri, Kansas, Colorado, back to Utah. Well our mileage went from average of 6 1/2 to 7 1/2. Including getting 10 across Wy, 8 across SD, and Kansas. 6 1/2 to 7 1/2 other parts of trip.

Now my problem, I still have poor power going over mountains, dropping to 30 mph, going over the Colorado Range from Denver to Grand Junction. Is this normal? Is there anything else I can do to improve my power going up hill or over mountains?

[RustyJC]

Air density (and, therefore, horsepower on a naturally aspirated engine) varies with altitude as follows:



This is why a turbocharged engine doesn't experience nearly the power loss at altitude - the turbo just spins faster at higher altitudes to maintain intake air mass flow.

Rusty

[Rocket Heart]

I have an 07 Itasca Suncruiser same engine and 6 speed Allison tranny and spent last summer at Yellowstone and the Black Hills area - towing a PT cruiser. Had a 99 Monaco LaPalma with the V10 before that - there is a world of difference between the two. The Ford barely could climb any hill or mountain while my Workhorse seems to do a very good job - I pass all trucks on upgrades and maintain a pretty good speed relative to the length and degree of the grade.

The big boys with the big diesels do a better job but I think I can pull with the smaller ones.

[MtManLee]

Not sure how hard it would be to get the turbocharger installed on the engine but I have heard that changing the air intake to the bigger banks system helps so that may be another change I will have to make.

[RustyJC]

Lee,

I wasn't necessarily suggesting the addition of a turbocharger. Rather, I was just illustrating the horsepower loss that's going to take place with any naturally aspirated engine as their displacement limits the volume of air they can pump per revolution, and the reduced amount of air (in terms of mass) available to burn fuel limits the amount of fuel that can be mixed with it, and the lesser amount of fuel burned at altitude will result in fewer BTUs and, thus, less horsepower.

Rusty

[MtManLee]

I understand that Rusty but I do want to do something, I hate it when I cant even reach the minimum 45 mph speed. I do remember when I had a turbo mustang and all I had to do was barely hit the gas to kick the turbo up and my car would shoot ahead as good as kicking into passing gear.

[Fred and Bonnie]

Lee, I think everything is "Normal", that pull is real tough. If my memory is correct, I believe we dropped down to arouund 35MPH, don't forget the top of the hill is over 10K '. I would make sure the engine RPM is around 3,500 to 4,000 to provide proper cooling.

I have experienced high transmission temps, however they occured going down hill, seems the transmission is working harder to hold back the coach.

In reference to the miss during hard pulls, it's propably related to plug wires, were your wires replaced with GM or Taylor?

BTW the I-70 grade going from GJ to Denver is even tougher.

I really love seeing the MPG increase on flat ground, and where "corn juice" isn't added.

Fred

[vacation on wheels]

You said that under load in high elevations the motorhome was bucking. I would suggest that you have your fuel pump and fuel rail psi checked. Believe me there is plenty of power climbing with the 8.1 with Ultrapower! Obviously the transmission will downshift into a low gear and your motor will be around 4,000 to 4,200 rpm's driving slowly up a mountain (such as Eisenhower Tunnel in Colorado), but that is the nature of the beast of a naturally aspirated engine in high elevations. I know that when the motorhome was fully loaded and towing a car behind we only do about 25mph up that big hill!!!

[Doggy Daddy]

You may of gotten some crappy fuel.
A dirty fuel filter will rob the engine of power.
Change the fuel filter.

[MtManLee]

We had the fuel filter changed in June with the 30 thousand mile maintenance. But that was after the chugging experience. We also had new wires put in with plugs when we got the ultra power in Jan. Seems that I am not the only one to drag up them hills. Since others experience the same problem I guess I will figure its just normal. I do know when money is available I will change the air intake to the banks system and possibly the exhaust as well. I also learned something new while traveling down that mountain, if we put the emergency blinkers on the tranny automatically kicked down and that could have added to our problem going up the mountain, that automatic kick down may have added to the drag. I forgot all about that until a few minutes ago.

[max49]

I don't have Ultra Power but most all of CO high passes are 1st Gear, 30/35 MPH and 4600 to 5000 RPM with my P-32, 8.1, most always pulling a trailer.

The W series are heavier and from what I have seen, even slower.

My friend has a Bounder DP with the milder 300 HP Cummins. Anyone with a gasser that thinks they can pull mountains even close to a turbo charged DP, is only kidding themselves.

I would love for Jon to let me be the Rocky Mountain Ultra Power tester, but I can't afford it.

[ron55]

Ethanol! Since ethanol became unavoidable there are some Mountains I now won't try, (towing a jeep)

[Clay L]

Lee I have made the Denver to Grand Junction and vice-versa many times in my present and previous motor home and I always have to drop to 25 to 35 mph on some of the grades. I think that is completely normal.

Bucking and missing of course is not.

[DriVer]

The 8.1L engine is a good motor to have for any number of road conditions. It's BIG block characteristics are well suited for use in motorhomes.

We're going to miss that engine when it's gone.

My experience with Rocky Mountains in 2005 saw us negotiate the I90 on our way back and forth to Missoula, MT and then later that year we traveled on the I40 all the way out to Needles, CA in August. Coming east from that trip after we went up to Logan, UT we went on the I80 through WY and NE. It is my recollection that with our 38 foot motorhome we did just fine and I couldn't have expected any better performance given the geology.

I will say this though, traveling on the Blue Diamond highway NV160 out to Pahrump caught me unaware when I turned into a grade and I didn't have enough energy built up to proceed at a better speed. We climbed the grade at 27 MPH and that was it. Coming back east it's practically all downhill so there wasn't any problem. Being aware of that grade I had Colleen follow me in the car but after the fact I could have run east with the car attached fairly easily.

Although I can't remember exactly where we were there are a number of state roads in those desert rockies that had a lot or switch backs and instant grades. Those were the most challenging and exhausting to drive.

Our last trip saw us running on VA501 out of Lynchburg to Natural Bridge to I81. This road will test everything you have on your motorhome. The motorhome handled everything I threw at it with ease, it negotiated the turns like a cat and it powered up and down the grades without any problems. The grand kids were looking out the windows and begging "Faster, faster grandpa Mike!" At least someone was having a blast going through the Jefferson National Forest!

All in all the 8.1L engine is an excellent motor.