Gas Motorhome Power Struggle ???

[Moxxi]

Do all Class A “Gas” MHs have to struggle, when it comes to climbing hills & mountains?

Are there any gas MH engine/transmission combinations that are better than others?

I realize that, not driving a diesel MH, going DOWNHILL, you will not have the benefit of having a “jake brake”. But, at this point, I’m more concerned about the struggle to get up the mountain.

Also, pulling one up a mountain, what about overheating?

[Bahamaniac]

Climbed some BIG mountains in Colorado and never had an issue with overheating. I put a K&N air filter on and helped with power pulling big hills. 36 footer with a v10 Ford.

[Quincy]

If it were me I would choose a Workhorse chassis with the 8.1L and Allison combo. but you have to buy it pre. owned if you want one.

You dont want the motor to overheat so if the needle starts to get close to the red then it is time to stop for thirty minutes or so. We had to remove our Toad to get over Cajon Pass with our 454 Chevy and I still had to stop so it would not overheat.

Downhill is not really a problem with a gasser if you use the tranny to brake the coach, especially if it is an Allison.

Hope this helps.

[Bosunmate]

We have a 2017 Winnebago Vista 29ve with a Ford V10 and six speed tranny. We have traveled from Ohio to Tx and the southeast. This rig is doing a fine job, even in the West Virginia mountains. Hope to test her out west soon.

Patrick

[TonyMac]

For pulling, you need torque. For acceleration, you need horsepower. Torque comes from a long stroke, horsepower comes from a bigger bore. Most semi's you see on the road have an inline six with 17 or so liters, and they redline in the 2-3,000 range. My CAT C7 is an inline six cylinder diesel, 7.2 liters/440 cubic inches with 350 horse and 860 torque, redline for me is 2,500, max torque is 1,800.


The Ford v10 is a 6.8 liter, the GM 8.1 is a V8. I'd have to say, by those numbers alone, the 8.1/v8 would be a much longer stroke than the 6.8/v10, and likely a larger bore as well. I'd assume, by these numbers, the 8.1, with over a liter in each cylinder, would be a better torque engine, and a lesser horse engine with only 8 vs 10 cylinders.


Jake brake is a misnomer. Most RVs have an exhaust brake, and it serves about the same function as your throttle plate in the 'slow the rig down' arena. A diesel has no throttle plate, the diesel rams as much air as possible into the cylinder and meters fuel. When one comes off the accelerator in a diesel, there is no vacuum (sucking the intake stroke against the closed throttle plate) to restrict the motion of the piston. So we use an exhaust brake, blowing the exhaust stroke against a closed exhaust brake plate.


Lots of BS, but I'g go with the 8.1 over the v10. I drove a v10 and it seemed to roar a lot and shift too much. It convinced my I had to have a DP.

[FIRE UP]

Originally Posted by Moxxi

Do all Class A “Gas” MHs have to struggle, when it comes to climbing hills & mountains?

Are there any gas MH engine/transmission combinations that are better than others?

I realize that, not driving a diesel MH, going DOWNHILL, you will not have the benefit of having a “jake brake”. But, at this point, I’m more concerned about the struggle to get up the mountain.

Also, pulling one up a mountain, what about overheating?

Moxxi,
Gas engines do just fine. Of course they're going to be hindered a bit by weight etc. of a large motorhome, that's a given. But, the proper use of gears (as in getting maximum engine performance in any given gear) is a key factor in just how well one does in climbing any given grade. A bazzillion of us have had gas coaches before we migrated over to the diesel world and, we all made it to where we wanted to go. Yeah, maybe a few coach lengths behind our diesel powered coach buddies but, we made it.

Diesel coaches are not immune from over heating. Seen plenty of them do it. Again, the key is proper driving and proper control of the trans and engine rpm (which means also, the proper used of the engine cooling fan, if directly attached). If a gas coaches cooling system is maintained correctly and, the driver knows how to properly control his engine, weight and trans, there'll be no issues. And, if it does happen, you pull over, let things cool a bit, then take off. The same exact thing is done with DIESELS.
Scott

Originally Posted by TonyMac

For pulling, you need torque. For acceleration, you need horsepower. Torque comes from a long stroke, horsepower comes from a bigger bore. Most semi's you see on the road have an inline six with 17 or so liters, and they redline in the 2-3,000 range. My CAT C7 is an inline six cylinder diesel, 7.2 liters/440 cubic inches with 350 horse and 860 torque, redline for me is 2,500, max torque is 1,800.


The Ford v10 is a 6.8 liter, the GM 8.1 is a V8. I'd have to say, by those numbers alone, the 8.1/v8 would be a much longer stroke than the 6.8/v10, and likely a larger bore as well. I'd assume, by these numbers, the 8.1, with over a liter in each cylinder, would be a better torque engine, and a lesser horse engine with only 8 vs 10 cylinders.


Jake brake is a misnomer. Most RVs have an exhaust brake, and it serves about the same function as your throttle plate in the 'slow the rig down' arena. A diesel has no throttle plate, the diesel rams as much air as possible into the cylinder and meters fuel. When one comes off the accelerator in a diesel, there is no vacuum (sucking the intake stroke against the closed throttle plate) to restrict the motion of the piston. So we use an exhaust brake, blowing the exhaust stroke against a closed exhaust brake plate.


Lots of BS, but I'g go with the 8.1 over the v10. I drove a v10 and it seemed to roar a lot and shift too much. It convinced my I had to have a DP.

Tony,
Got a question for ya. You mentioned max torque for your 350 CAT C-7 as being at 1,800. I've always been lead to believe the max torque is at 1440 rpm. Below is a Pdf on CAT specs for the C-7 and, it states 1440. Not a big deal, just wondering if you've read something I've not and, I'm always learning.
Scott

[twinboat]

Its not struggling, its doing its job, working to move a large load.

A bigger engine may seem to struggle less and get you up the hill faster, but where would you put it in your MH. The one you have just fits. Nobody want less room in the RV.

Big displacement engines can't burn clean enough for EPA standards so GM walked away and Ford built the V 10. Actually Dodge built a V10 also but you don't hear much about them.

The V10s have small pistons, just more of them. You can run a small piston engine faster then a large piston one.

Remember the piston is changing direction twice every stroke. Thats why diesels need to turn slower, big heavy pistons and motorcycle engines can turn up above 8000 RPMs. ( Except for the big piston Harley )

It will get you over the hill, when it needs to, and be economical and burn clean the other 95% of the time.

[l1v3fr33ord1]

Originally Posted by Moxxi

Are there any gas MH engine/transmission combinations that are better than others?

Ford has coupled 4-speed, 5-speed (2005) and 6-speed (2016) transmissions to the V-10. Each improved on its predecessor.

If you end up in the Ford chassis line I suggest getting a 6-speed if you could (clearly, newer coaches only), or a 5-speed. The 5- and 6-speeds have a "Tow-Haul" feature that helps slow the coach on downhills by downshifting when you push the brake pedal firmly. It also modifies the transmission shifting pattern to help with towing.

[TonyMac]

Originally Posted by FIRE UP

Tony,
Got a question for ya. You mentioned max torque for your 350 CAT C-7 as being at 1,800. I've always been lead to believe the max torque is at 1440 rpm. Below is a Pdf on CAT specs for the C-7 and, it states 1440. Not a big deal, just wondering if you've read something I've not and, I'm always learning.
Scott

Nope, you're right. Thanks for the info.

[barmcd]

"Struggle" is one of those words open to interpretation. Our coach slows down going up hill in the west as do gas coaches. We can usually keep it going at least 45 mph on the steep hills, especially if we see it coming and downshift to keep in the power band. We go to Taos NM a lot and have no problem going up the Rio Grande valley to the Pueblo. I think most gas coaches can do the same speed, we do it at 1800 RPM and they do it at 4000.

[Waiter21]

I have the early version of the Ford V10 (275hp) and the 4R100 4 speed tranny. When towing our Saturn Vue, we weigh around 23,000 lbs.

No problem, no struggle climbing the steepest mountains at the highest altitudes. I just do it slower than my higher hp friends.

A climb eastbound I-70 up to the Eisenhower tunnel (11,000ft altitude), the last couple miles up the hill I do in first gear, turning 4k rpm, and doing about 25 mph..

Never seen any signs of getting hot or overheating...

[Trickdog]

Originally Posted by barmcd

"Struggle" is one of those words open to interpretation. Our coach slows down going up hill in the west as do gas coaches. We can usually keep it going at least 45 mph on the steep hills, especially if we see it coming and downshift to keep in the power band. We go to Taos NM a lot and have no problem going up the Rio Grande valley to the Pueblo. I think most gas coaches can do the same speed, we do it at 1800 RPM and they do it at 4000.

Agreed "Struggle" is open to interpretation. I put a 5 Star Tune in the motorhome and a K&N air filter and it really changed it for the better. Very responsive and seems to "Struggle" less. The tune also adjusts transmission shift points as well. If you put the MH in Tow/Haul mode when going downhill it also helps.

[m.elliott63]

Originally Posted by Bosunmate

We have a 2017 Winnebago Vista 29ve with a Ford V10 and six speed tranny. We have traveled from Ohio to Tx and the southeast. This rig is doing a fine job, even in the West Virginia mountains. Hope to test her out west soon.

Patrick

Those aren't mountains, they are hills! Go west young man and you will see mountains. Took our 98 Chevy 454 7.4L on a P37 chassis out there twice pulling a 2014 JKU with no heat issues. Slow climbing but not an issue for us just those behind us. We went south through NM to avoid the 2 high passes at Denver and Aspen.

[cruzbill]

I've never seen a Runaway Truck lane on an uphill. Patience is the solution for going up, but gearing is the trick on the downhill, that's where you can get into trouble.