Community Forums

angelbones · 08-08-2017, 08:30 PM

While I can't go specific, I can offer a comparison for the OP. We have a 360hp Cummins and we're pulling 5600 lbs as well. I enjoy speed as much as you I suppose. To answer your question, you're not going to have any problems doing 70, 75, probably more. While I've learned to keep it down to about 66 or so, I have NO problem doing 70+. With 20 more horses than me and probably equivalent weight, if not less, you're all good. (Side note, I love Sammy)

Fiesta48 · 08-09-2017, 07:03 AM

I too was speeding everywhere I went.
My newest Tshirt says
"I'm retired go around me"

tropical36 · 08-09-2017, 02:52 PM

Quote:

Originally Posted by Sandy Swede

OP, notwithstanding the ability of the MH to go 70 mph or more, at what speed do you think it unsafe to drive a vehicle of this size & weight?

If I might chime in and according to our government, a motorhome and a semi truck is safe to drive as fast as a corvette. This with the posted speed limits, that makes no distinction, on our nations highways. Not what I've surmised, according to the laws of physics, but what our government has obviously and most carefully calculated.
Discounting everything else and just thinking of those big front tires rolling at max speed or more, is enough to scare the hell out of me.

2-Nickels · 08-09-2017, 03:23 PM

Check the speed rating on your tires. I'd be surprised if they said anything over 75 MPH.

MTK46 · 08-09-2017, 03:52 PM

Quote:

Originally Posted by rtspence

Based on information from Camp Freightliner the ISL9 sweet spot is 1800- 1900 rpm for power & economy. Your speed will be determined by gear ratio an tire diameter.

If I drove my ISM rig at that RPM I would be passing everything in site

MoCoTom · 08-09-2017, 04:41 PM

Normally the bigger hp and torque motors like is in your new coach will have gear ratios that will be more in line with your higher speed concerns. The smaller hp motor has to be geared down in order to pull the weight and consequently revs higher at speed.

tropical36 · 08-09-2017, 05:16 PM

Quote:

Originally Posted by MTK46

If I drove my ISM rig at that RPM I would be passing everything in site

X2.....and at 1400, I'm at max torque, lumbering along at about 57mph and managing to stay in 6th gear over the rolling hills and some fairly steep, so can't get any sweeter for a hot spot than that, in my estimation. Without violating the laws of physics, that is.

asuperheat · 08-09-2017, 05:40 PM

Made several long runs with a few friends traveling together and lock cruse down 72-74. I have a ISB a friend has a ISL, another is also a ISB it is no problem. I assure you our Cummins do not struggle at those speeds. They seem quite happy. Many say its too fast, I feel different. I keep up with tire maint. Factory cruise sets at 74. If windy or poor conditions we slow down but weather permitting we roll on. I am not retired and my time off is important and limited to what I can take at one time.

nehog · 08-09-2017, 06:08 PM

On speed: 65 is as fast as I want to drive. Going faster is too much work!

On economy: (prior vehicle...) I found significant differences in economy between 57 MPH and 63 MPH. We're talking several MPG. I used to travel NH to FL and back several times each year. Long drive to let you learn things like this... One thing I learned was that at 57 MPH, driving was so easy, never have to worry about passing someone, for example. I'd see the same cars and trucks pass me six or seven times over a two day period. Always pushing but not really making any more progress than I was making at a lower speed. I would feel relaxed and not stressed. I can only figure they had to stop and rest due to the stress of going much faster?

My only problem is that both of the rigs we have now really like to be driven fast! The Winnebago ERA will cruise at 70 easily. The HR seems to be always over the speed limit too. I have to watch myself if I'm not using the cruise control in both of them. And once the HR is over 65 it really is more work driving.

Sandy Swede · 08-10-2017, 07:01 AM

Quote:

Originally Posted by nehog

On speed: 65 is as fast as I want to drive. Going faster is too much work!

On economy: (prior vehicle...) I found significant differences in economy between 57 MPH and 63 MPH. We're talking several MPG. I used to travel NH to FL and back several times each year. Long drive to let you learn things like this... One thing I learned was that at 57 MPH, driving was so easy, never have to worry about passing someone, for example. I'd see the same cars and trucks pass me six or seven times over a two day period. Always pushing but not really making any more progress than I was making at a lower speed. I would feel relaxed and not stressed. I can only figure they had to stop and rest due to the stress of going much faster?

My only problem is that both of the rigs we have now really like to be driven fast! The Winnebago ERA will cruise at 70 easily. The HR seems to be always over the speed limit too. I have to watch myself if I'm not using the cruise control in both of them. And once the HR is over 65 it really is more work driving.

I think that you nailed it, nehog. Going faster than 65 requires a much higher level of situational awareness - which equals stress over time. I find that I am much more rested at the end of a 60 - 63mph run than over 65.

Also, if you have ever had to make an emergency stop with wheels locked and tires squealing, you will know how long it takes to stop a big rig. Mine came at 40 mph when some dope pulled out in front of me. I can't imagine what having to stop at 60 or 70 mph would be like.

Crasher · 08-10-2017, 07:14 AM

When picking a speed that I feel comfortable cruising for 10 hours, I ask myself what I would do if I had to make an emergency stop or needed to avoid hitting something that appeared on the road while towing a 10,000# trailer behind my 41,000# motorhome. 62 mph is the sweet safe spot for me. But that's just me. The guy driving 75 is never going to have to make an emergency move, so it doesn't matter to him.

codsimms · 08-10-2017, 07:49 AM

We have a 2017 Discovery LXE 40G with the ISL. 70 mph is about 1950-2000 rpm. I can't tell a difference between 65 and 70 it is so smooth and driveable. The motor is not screaming by any means.

V3600 · 08-10-2017, 07:54 AM

I just drove a Phaeton from Tucson to San Diego and it did 75 just fine. I believe it had the same 380 hp engine.

super_rep · 08-10-2017, 08:05 AM

My Detroit Series 60 just loves to run at 1500rpm which is 64 MPH. It's got lots of power and wants to keep going faster at 75mph, but that's my limit - only when passing. I'm sure it would easily go 85, but I ain't ever going to try it.