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Author Topic: feedback on 5.9L Cummins with Allison trans.?  (Read 1176 times)

oldryder

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feedback on 5.9L Cummins with Allison trans.?
« on: November 18, 2017, 12:01:13 PM »
Rookie looking to buy.  Occasionly see Cummins diesel.  I know it's a good motor in a pick--up.  Enough motor for a 35' winnebago.?  Other comments?

Thx for advice.
Mark in MN

Hfx_Cdn

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Re: feedback on 5.9L Cummins with Allison trans.?
« Reply #1 on: November 18, 2017, 12:12:01 PM »
It worked fine on our 34 ft Coachmen, however it is light on the power scale.  So, if you drive with a heavy foot or like jack rabbit starts, you will always be cursing its performance.  But, we used ours for 14 years, 2 west coast trips so over the Rockies and the Sierras, and the torque allowed us to go up and down without difficulty, albeit at a slightly reduced speed.  It gave us reasonable milage and no major overhauls.

Ed
Ed & Donna
Winter-Pinellas Park FL, Summer- Maritime Canada
2000 Coachmen Catalina 34' DP (owned 2004 to 2015)
2006 Jeep Liberty Toad

RedandSilver

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Re: feedback on 5.9L Cummins with Allison trans.?
« Reply #2 on: November 18, 2017, 03:32:36 PM »
Depends somewhat on IF you ever plan on towing anything.

IF you plan on towing a car or trailer then I would look for a bigger motor.
When I was looking for my MH I knew that I would be trailering and going through mountains to get to the place I wanted to go to.
So for me I wouldn't accept or look at anything that didn't have at least 330hp.  But that's just me because I knew in advance
that I would be trailering through mountains - that makes a difference IMO.

IF you never plan (although plans can change) on towing anything and you live in a flatland area and don't plan on
going too far from home then a smaller engine might serve you very well.
2002 Rexhall Rose Air  Cummins 8.3  350hp
West MI Summer   Central FL Winter

WILDEBILL308

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Re: feedback on 5.9L Cummins with Allison trans.?
« Reply #3 on: November 18, 2017, 03:57:54 PM »
Rookie looking to buy.  Occasionly see Cummins diesel.  I know it's a good motor in a pick--up.  Enough motor for a 35' winnebago.?  Other comments?

Thx for advice.
Mark in MN
First what year? I have  one of those little 5.9 Cummins engines in a 38 ft. coach that has ben over every major pass and grade in the US. NO PROBLEM, You need to learn to drive any large coach it isn't like driving your car. Nothing sadder than watching some one with a 330hp and up coach that can't get over hills easily because they don't know  how to drive.
If you have any questions just ask.
Bill
2003 Bounder 38N
300 HP 5.9 Cummins
Allison 3000MH Trans.
Towing 2014 Honda CRV
Home base Fort Worth, Texas
A man who carries a cat by the tail learns something he can learn in no other way.
-Mark Twain-

muskoka guy

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  • 2000 Coachmen Santara 370 isb cummins diesel
Re: feedback on 5.9L Cummins with Allison trans.?
« Reply #4 on: November 18, 2017, 05:34:39 PM »
The year makes a difference. Mine has 300 hp in a 38 ft dp. I dont find any trouble getting up to speed on the highway, and it takes hills better than my previous v10 gasser. More horses might be better but they do say they are the mileage king. I find mine gets pretty good mileage for a 38 ft coach. Mine has the 3000 series Allison, which I believe is better than the 2000 series. My friend had a 92 Bounder with the 5.9 and it only had 250 hp I think.
« Last Edit: November 18, 2017, 05:37:50 PM by muskoka guy »

WILDEBILL308

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Re: feedback on 5.9L Cummins with Allison trans.?
« Reply #5 on: November 18, 2017, 06:51:18 PM »
I just want to add that the accepted benchmark is one HP per 100 pounds GCW (Gross Combined Weight which is weight of loaded coach and anything you are pulling). When some one starts bragging about having 500 hp ask what the Gross Combined Weight is. Some of the heavier coaches are close to 50,000lbs. They perform in much the same way as the lighter coaches with smaller engines. :))
Bill
2003 Bounder 38N
300 HP 5.9 Cummins
Allison 3000MH Trans.
Towing 2014 Honda CRV
Home base Fort Worth, Texas
A man who carries a cat by the tail learns something he can learn in no other way.
-Mark Twain-

Gary RV_Wizard

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Re: feedback on 5.9L Cummins with Allison trans.?
« Reply #6 on: November 18, 2017, 08:20:10 PM »
Bill has the right of it. Horsepower is horsepower and if you have enough for the weight of the rig, you will be fine. 1 hp per 100 lbs yields only moderate performance (your car or a pick-up probably has 4x-6x as much power), but it will get you going from a standing stop and climb any mountain, though probably not as leader of the pack in either case.

The 5.9L has come in a variety of horsepower ratings over the years, as low as 190 in the motorhomes of the mid-90's and as much as 340 hp today (in its newer 6.7L form), so you need to query what specific version of the engine is in  a coach and what the combined weight of the rig will be.
Gary
--------------
Gary Brinck
Summers: Black Mountain, NC
Home: Ocala National Forest, FL

Larry N.

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  • Westminster, CO
Re: feedback on 5.9L Cummins with Allison trans.?
« Reply #7 on: November 18, 2017, 08:46:35 PM »
I just want to add that the accepted benchmark is one HP per 100 pounds GCW (Gross Combined Weight which is weight of loaded coach and anything you are pulling). When some one starts bragging about having 500 hp ask what the Gross Combined Weight is. Some of the heavier coaches are close to 50,000lbs. They perform in much the same way as the lighter coaches with smaller engines. :))
Bill
Definitely. The Beaver I had had a max gross weight of 50,000 lbs and it had 525 HP. My current Ventana has a max gross weight of 36,400 and it has 360 HP, actually accelerating (and holding speed on grades) a little better than the Beaver did, both with the same Jeep toad.
Larry and Mary Ann N.
2016 Newmar Ventana 3709 -ISB6.7 XT 360HP
2015 Wrangler Sahara Unlimited toad
Formerly: Trailmanor 2720SL, Bounder, Beaver
  de N8GGG

muskoka guy

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  • 2000 Coachmen Santara 370 isb cummins diesel
Re: feedback on 5.9L Cummins with Allison trans.?
« Reply #8 on: November 18, 2017, 09:09:06 PM »
For sure. My coach has a gross vehicle weight of around 26000 lbs. Im sure I weigh less than that, but with your ratio of 1 hp per 100 lbs, my 5.9 comes in pretty good with 300 hp. As stated, its all dependent on how much your rig weighs in relation to the hp it has.
« Last Edit: November 18, 2017, 09:10:46 PM by muskoka guy »

oldryder

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Re: feedback on 5.9L Cummins with Allison trans.?
« Reply #9 on: November 19, 2017, 01:35:36 PM »
Everyone; thx for replies.  Now I know to ask about the HP for the specific motor and also ask about HP vs. weight.  Good info.

Best Regards;
Mark in MN

TonyDtorch

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Re: feedback on 5.9L Cummins with Allison trans.?
« Reply #10 on: November 19, 2017, 08:36:55 PM »
People never really have anything bad to say about the 5.9...except it's a small motor.  (likely the best small diesel)
« Last Edit: November 19, 2017, 08:41:56 PM by TonyDtorch »

gravesdiesel

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Re: feedback on 5.9L Cummins with Allison trans.?
« Reply #11 on: November 20, 2017, 12:56:25 PM »
I have two 5.9s and have owned four others also.  Never a bit of problem out of them and I run them hard. More important than the horsepower numbers are the torque numbers.  That is what you need for hauling and pulling.
2016 KZ Spree 262 RKS
2003 Dodge 3500 4 door flatbed 4x4 diesel, 6 speed
1996 Dodge 3500 extra cab flatbed 4x4 diesel 5 speed
2006 Arctic Cat TRV diesel 4x4 ATV
(2) 1981 Yamaha G1 2 cycle golf carts
Many other diesels on the farm!

Gary RV_Wizard

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Re: feedback on 5.9L Cummins with Allison trans.?
« Reply #12 on: November 20, 2017, 02:18:14 PM »
Since horsepower and torque are inextricably tied together, if you get one, you get the other.  Only the rpms at which each is delivered varies much.
Gary
--------------
Gary Brinck
Summers: Black Mountain, NC
Home: Ocala National Forest, FL

A Traveler

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Re: feedback on 5.9L Cummins with Allison trans.?
« Reply #13 on: November 22, 2017, 06:24:07 PM »
...More important than the horsepower numbers are the torque numbers.  That is what you need for hauling and pulling.

This is a very common - and incorrect - perception. You need HORSEPOWER for hauling and pulling. As Gary said, torque and horsepower are linked, but the key number is the horsepower number, not the torque. 300 hp is 300 hp, whether it's being produced by a big diesel at 1,800 rpm or a small gas engine at 5,000 rpm.

TonyDtorch

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Re: feedback on 5.9L Cummins with Allison trans.?
« Reply #14 on: November 22, 2017, 07:17:40 PM »
uh oh...that always tics off every internet engineer on this forum.    :)

taoshum

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Re: feedback on 5.9L Cummins with Allison trans.?
« Reply #15 on: November 22, 2017, 11:00:45 PM »
This is a very common - and incorrect - perception. You need HORSEPOWER for hauling and pulling. As Gary said, torque and horsepower are linked, but the key number is the horsepower number, not the torque. 300 hp is 300 hp, whether it's being produced by a big diesel at 1,800 rpm or a small gas engine at 5,000 rpm.

Or, an electric motor with full torque at zero RPM so it can start moving the cable on a ski lift?  Once it starts moving, then it becomes HP.
07 Itasca Meridian 34SH.  '08 Jeep Sahara.
Taos, NM.

taoshum

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Re: feedback on 5.9L Cummins with Allison trans.?
« Reply #16 on: November 22, 2017, 11:09:19 PM »
First what year? I have  one of those little 5.9 Cummins engines in a 38 ft. coach that has ben over every major pass and grade in the US. NO PROBLEM, You need to learn to drive any large coach it isn't like driving your car. Nothing sadder than watching some one with a 330hp and up coach that can't get over hills easily because they don't know  how to drive.
If you have any questions just ask.
Bill

We've been running a "little" 5.9/300 for years as well... up/down one Rocky Mt pass after another for years pulling a JK.  I have to say that on the high passes, with a 6% grade, it won't hold much more than 45 MPH.
07 Itasca Meridian 34SH.  '08 Jeep Sahara.
Taos, NM.

WILDEBILL308

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Re: feedback on 5.9L Cummins with Allison trans.?
« Reply #17 on: November 23, 2017, 09:24:55 AM »
 "I have to say that on the high passes, with a 6% grade, it won't hold much more than 45 MPH."
What gear and what rpm? If you can't accelerate in a gear on a hill you need to down shift till you can. Then keep your rpm near peak hp.
Bill
2003 Bounder 38N
300 HP 5.9 Cummins
Allison 3000MH Trans.
Towing 2014 Honda CRV
Home base Fort Worth, Texas
A man who carries a cat by the tail learns something he can learn in no other way.
-Mark Twain-

Larry N.

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  • Westminster, CO
Re: feedback on 5.9L Cummins with Allison trans.?
« Reply #18 on: November 23, 2017, 10:09:03 AM »
"I have to say that on the high passes, with a 6% grade, it won't hold much more than 45 MPH."
What gear and what rpm? If you can't accelerate in a gear on a hill you need to down shift till you can. Then keep your rpm near peak hp.
Bill

Bill, on those steeper mountain grades, it's often the case that if you downshift, you'll slow down, rather than speed up, at least with a diesel. So I usually let the transmission decide -- it sets shift limits, anyway, no matter which gear I select -- though I'll occasionally downshift a tad early if it'll let me) just to reduce the rate of slowing. There just isn't enough power/torque to accelerate once you've slowed, regardless of gear chosen, on the 5%+ grades. It's not as if it were a manual transmission, or even one with no computer control (rare these days).
Larry and Mary Ann N.
2016 Newmar Ventana 3709 -ISB6.7 XT 360HP
2015 Wrangler Sahara Unlimited toad
Formerly: Trailmanor 2720SL, Bounder, Beaver
  de N8GGG

TonyDtorch

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Re: feedback on 5.9L Cummins with Allison trans.?
« Reply #19 on: November 23, 2017, 10:23:55 AM »
Many of the new semi trucks with have 11-13 speed automatic transmissions so they can maintain effective speeds up hills.

That technology should be coming to motorhomes soon.

docj

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Re: feedback on 5.9L Cummins with Allison trans.?
« Reply #20 on: November 23, 2017, 11:03:58 AM »
Or, an electric motor with full torque at zero RPM so it can start moving the cable on a ski lift?  Once it starts moving, then it becomes HP.

There's a real simple explanation of the relationship between horsepower and torque.  HP governs the speed you can maintain going up a mountain.  HP is a "power" measurement and power is defined as energy per unit time.  The small engine will have to turn faster than the big diesel but 400HP is the same in both.

Torque is a bit of a different story.  It's the rotational analog of force in Newton's Second Law.  In simple terms it's how quickly you can change the rotation rate of a motor which, in turn, governs how quickly the vehicle powered by the engine can accelerate.  The electric motor example is a good one--big diesels (for example, C-12, C-15, ISM, ISX) develop enormous amounts of torque (>1500 lb-ft) at very low rpm's (~1100-1300rpm).  That means that full torque is developed as the vehicle starts moving from a stop.  The 5.9L or 6.7 ISB has a max torque output of ~800-1,000 lb ft. but can achieve more through gearing but, as with horsepower, it has to spin faster to do that.  Starting from a stop it accelerates more slowly than will the big diesel. 

With an automatic transmission, torque multiplication occurs in the "torque converter" but the maximum amount of torque multiplication produced by a converter is highly dependent on the size and geometry of the turbine and stator blades, and is generated only when the converter is at or near the stall phase of operation. Typical stall torque multiplication ratios range from 1.8:1 to 2.5:1 for most automotive applications.  So the ISB can achieve torque equal to that the base torque output of a larger engine, but that large engine will also experience significant torque multiplication from its torque converter.

For the old-timers here, this is the same situation we saw when imported cars with small, high-revving engines first began to compete against the big American V-8's we grew up with.  Those little engines were rated at the same HP as our Ford and Chevy 8's but they weren't able to produce the same wheel-spinning starts as were the cars we grew up with. The difference was that the small engines achieved their max performance at higher rpm's (and usually developed much less torque). Therefore, they couldn't spin their wheels unless you were prepared to pop their clutches at some pretty high rpm's.

Since you can't pop a clutch with an automatic transmission, with a smaller, lower torque engine you will accelerate more slowly until you have enough engine speed to get into your max torque zone.  By way of comparison my ~34,000 lb Beaver with a C-12 producing 1,550 lb-ft of torque at ~1200 rpm is virtually in its max torque zone as it moves off the line.  Therefore, it accelerates more like a car than a MH.

Before people start reacting, I'm not dissing anyone's MH or engine.  I'm simply pointing out that there are real differences between the performance of large-block, high torque diesels and smaller ones with lower torque outputs even when both are rated at the same HP. At(Caution--I'm a retired physics teacher with a Ph.D in physics, so let's not debate the science.)
« Last Edit: November 23, 2017, 11:06:11 AM by docj »
Sandie & Joel

2000 40' Beaver Patriot Thunder Princeton--425 HP/1550 ft-lbs CAT C-12
2014 Honda CR-V AWD EX-L with ReadyBrute tow bar/braking system
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WILDEBILL308

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Re: feedback on 5.9L Cummins with Allison trans.?
« Reply #21 on: November 23, 2017, 11:04:18 AM »
Bill, on those steeper mountain grades, it's often the case that if you downshift, you'll slow down, rather than speed up, at least with a diesel. So I usually let the transmission decide -- it sets shift limits, anyway, no matter which gear I select -- though I'll occasionally downshift a tad early if it'll let me) just to reduce the rate of slowing. There just isn't enough power/torque to accelerate once you've slowed, regardless of gear chosen, on the 5%+ grades. It's not as if it were a manual transmission, or even one with no computer control (rare these days).
There is some fallacy out there that you should be able to drive over hills like you were driving a car. That is not going to happen even if you have a 650 HP coach. The weight to HP is about the same.
Not down shifting will drive EGT temp through the roof. You are dumping more fuel with less air than you really need to burn it efficiently. This produces extra hot exhaust gas. What are your EGT temps running?
You need to know what your max governed rpm is. Manually down shift till you can accelerate then hold close to your max rpm. once you have your rpm up you may be able to go back up one gear. You want to stay above max torque. If you can't accelerate drop back down and hold your rpm at a safe rpm.
I have never not ben able to accelerate on a hill. That includes some over 10% in the Smokey's. :))
Bill
   
2003 Bounder 38N
300 HP 5.9 Cummins
Allison 3000MH Trans.
Towing 2014 Honda CRV
Home base Fort Worth, Texas
A man who carries a cat by the tail learns something he can learn in no other way.
-Mark Twain-

taoshum

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Re: feedback on 5.9L Cummins with Allison trans.?
« Reply #22 on: November 23, 2017, 11:09:59 AM »
"I have to say that on the high passes, with a 6% grade, it won't hold much more than 45 MPH."
What gear and what rpm? If you can't accelerate in a gear on a hill you need to down shift till you can. Then keep your rpm near peak hp.
Bill

Usually settles in 3rd gear at 2900 RPM on the really steep, long grades; if I slow down and drop into 2nd gear, it will accelerate and shift up to 3rd but that's about it;  in 4th or higher it will slow down and downshift, so (as someone mentioned) we just let the computer handle the engine.  I don't really care as long as I make it over the pass...  Once coming up into Leadville from the north, the computer shut us down warning about a "low coolant level" so we pulled over and let it cool and added some anti-freeze coolant (not much, like 1/4th of a quart).  No problems after that.  Much later I found a very small leak on one of the hoses so I tightened the hose clamp and have never had a problem since.  I'm not sure about the location of the coolant level sensor but it must be very sensitive.  I do watch the engine and transmission temperatures more carefully on long grades. 
« Last Edit: November 23, 2017, 11:37:29 AM by taoshum »
07 Itasca Meridian 34SH.  '08 Jeep Sahara.
Taos, NM.

TonyDtorch

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Re: feedback on 5.9L Cummins with Allison trans.?
« Reply #23 on: November 23, 2017, 01:02:35 PM »
one big issue with a diesel engine it has a relatively small rpm power band (usually about 1200 rpm.) 

and if you have very few gears to choose from,  the torque converter will not fully lock. essentially slipping the clutch and wasting power.

WILDEBILL308

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Re: feedback on 5.9L Cummins with Allison trans.?
« Reply #24 on: November 23, 2017, 06:08:30 PM »
Interring, as my Allison will lock the torque converter in every gear but first. What are you driving?
taoshum, If you manually down shift it will run cooler on hills.
Bill
2003 Bounder 38N
300 HP 5.9 Cummins
Allison 3000MH Trans.
Towing 2014 Honda CRV
Home base Fort Worth, Texas
A man who carries a cat by the tail learns something he can learn in no other way.
-Mark Twain-

Larry N.

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  • Westminster, CO
Re: feedback on 5.9L Cummins with Allison trans.?
« Reply #25 on: November 24, 2017, 06:49:43 AM »
There is some fallacy out there that you should be able to drive over hills like you were driving a car. That is not going to happen even if you have a 650 HP coach. The weight to HP is about the same.
Not down shifting will drive EGT temp through the roof. You are dumping more fuel with less air than you really need to burn it efficiently. This produces extra hot exhaust gas. What are your EGT temps running?
You need to know what your max governed rpm is. Manually down shift till you can accelerate then hold close to your max rpm. once you have your rpm up you may be able to go back up one gear. You want to stay above max torque. If you can't accelerate drop back down and hold your rpm at a safe rpm.
I have never not ben able to accelerate on a hill. That includes some over 10% in the Smokey's. :))
Bill
 

I wasn't trying (or expecting) to make it through like a car, Bill. On those grades, no matter what you do, you slow and slow and slow until it will finally hold the speed. There are several automatic downshifts in there, built in to the transmission/engine control module(s). It's often at the high end of the power band, so downshifting (only six gears, remember) from there is very often counter-productive, IF it will let you shift -- you can select anything you want, but it won't let you actually downshift until you get to a point where the programming deems it safe for the engine/transmission.

It's hard to believe your final statement about accelerating on a 10% grade, unless you first slow to (perhaps) first gear, in which case you are very slow indeed, and this would happen automatically on a steep enough grade, but I'm not sure either the Beaver (CAT 525 HP governed at 1800 RPM) or the Ventana would keep going (up) on a 10% grade of any length (never been on one that steep in the coach), given what I see on 8%.

All that being said, there are times when I'll manually downshift (once it will let me do so), select actually, to be able to hold just three or four more mph.

Quote
What are your EGT temps running?
They didn't provide a gauge for that, nor did they provide a mixture control such as many aircraft have (computer does that). Engine and transmission temps are the only ones I have for temp, and they're both where they belong, even on steep grades several miles long (of course they're not directly affected by fuel burn or mixture).

All the above notwithstanding, traffic often affects what speed you can maintain on those steep grades, since traffic may be heavy enough that you can't change lanes, but have a truck ahead of you that forces a slowdown to 15-20 mph, even on a 4% or 5% grade.

Larry and Mary Ann N.
2016 Newmar Ventana 3709 -ISB6.7 XT 360HP
2015 Wrangler Sahara Unlimited toad
Formerly: Trailmanor 2720SL, Bounder, Beaver
  de N8GGG

taoshum

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Re: feedback on 5.9L Cummins with Allison trans.?
« Reply #26 on: November 24, 2017, 07:28:14 PM »
Interring, as my Allison will lock the torque converter in every gear but first. What are you driving?
taoshum, If you manually down shift it will run cooler on hills.
Bill


It always holds the same temperature on long grades.  Like I mentioned, we had a low coolant alarm once but the temp was fine.
07 Itasca Meridian 34SH.  '08 Jeep Sahara.
Taos, NM.