CUMMINS 6.7 340HP WITH ALLISON 2500 5 SPEED PERFORMANCE?

[jbpack1]

Does anyone have experience with the subject power and tranny in a DIESEL PUSHER? I am considering buying 2008 Forest River Berkshire 39'.
If so, please reply with GVWR, GCWR and weight of your toad, and that all-important fuel mileage.

[jbpack1]

Does anyone have experience with the subject power and tranny in a DIESEL PUSHER? I am considering buying 2008 Forest River Berkshire 39'.
If so, please reply with GVWR, GCWR and weight of your toad, and that all-important fuel mileage.

[Gary RVRoamer]

This is a pretty broad question rather than a "problem" so I moved your post to General Discussion and added a shortcut to the "Towing & Toads" section as well.

[Norm Payne]

That engine will be a little weak on torque, but my major concern would be the Allison 2500 5-speed transmission in a 39' diesel pusher. If it was me I would pass on this motorhome and keep looking.

[Pusherman]

The Cummins 6.7L 340HP engine is rated at 660 lb-ft of torque. As others have stated, this engine might be a little under-rated for a 39'MH. I would opt for at a minimum comparable specs to the CAT C-7, which is 350 hp and 860 lb-ft of torque. Either brand engine is fine, but compare the specs. Torque is in many ways more important than horse power for pulling grades, etc.

I also would go for the 6-speed Allison 3000MH series transmissions in a coach of this size.

[FleetMan]

Take the coach for an extensive test drive and put it through as much as you think you'll encounter in "your" normal use. The manufacturers will not install a power train that will not perform adequately and safely, think liability. Does that mean it will perform like a sports car and climb the steepest mountain under full load towing a heavy toad and keep accelerating, heck no. There are many who will never have enough horsepower and torque no matter what they drive while others are content to chug along legally and safely, smell the roses and wave as the "sports cars" go by.

You have to be the final judge.

[Ecker]

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by jbpack1:
Does anyone have experience with the subject power and tranny in a DIESEL PUSHER? I am considering buying 2008 Forest River Berkshire 39'.
If so, please reply with GVWR, GCWR and weight of your toad, and that all-important fuel mileage. </div></BLOCKQUOTE>

You don't mention engine model but its stated as ISB in earlier message. If so, I think you'll get better mileage on ISB than any other engine in use today but at the cost of some reduced performance on mountain grades. It would appear that if it has as described in same message a Allison 5 speed this unit is probably designed for a lower price point i.e for more money one could get a 6 speed and an ISC Cummins or CAT C7 - its all ways a trade off between price and features.

[rmmpe]

That power-train, in my opinion, is less than marginal for the vehicle and something you'll kick yourself for later.

It's not like set of tires in that you can change them later. Once you buy the MH, you're stuck with the power.

We have an ISC(330 HP/950 lbs. feet of Torque) and Allison 3060 transmission. A good combination. But there have been a few times I've had to shift to 2nd to maintain 20 MPH on a steep grade (without a TOAD).

If it were me, I'd opt for a more acceptable power-train.

Actual road weight: 26,000 lbs.
GVWR: 28,000 lbs.
GCWR: 33,000 lbs.
Avg. MPG: 9.2 (state and county highway driving in the NE states).
Best Interstate MPG: 10.6 by Silverleaf and 10.4 with arithmetic (Milford, PA to Watertown, NY & return on I-81).
Note: I have not yet towed but will on our next trip.

[Ecker]

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by rmmpe:
That power-train, in my opinion, is less than marginal for the vehicle and something you'll kick yourself for later
It's not like set of tires in that you can change them later. Once you buy the MH, you're stuck with the power.

We have an ISC(330 HP/950 lbs. feet of Torque) and Allison 3060 transmission. A good combination. But there have been a few times I've had to shift to 2nd to maintain 20 MPH on a steep grade (without a TOAD).

If it were me, I'd opt for a more acceptable power-train.

Actual road weight: 26,000 lbs.
GVWR: 28,000 lbs.
GCWR: 33,000 lbs.
Avg. MPG: 9.2 (state and county highway driving in the NE states).
Best Interstate MPG: 10.6 by Silverleaf and 10.4 with arithmetic (Milford, PA to Watertown, NY & return on I-81).
Note: I have not yet towed but will on our next trip. </div></BLOCKQUOTE>
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You need to have engine checked if you lug down to 20 on steep incline. I had Cummins ISB275 and 3060 tranny with same weight as you and pulling a toad and never had such a problem. I lived at 7000 ft in the mountains and drove the worst of them for seven years 90,000 miles. Even if I did, I would trade off an occassional slow climb for 50% better fuel economy i.e. 10.5 vs 7 for larger engines like ISC/ISL/C7

[rmmpe]

Hi Leo.
As I said, it was only a few times and 1 was on an 11% grade on a 2-lane county highway in New England. Also, I was not pushing the power. When needed, Silverleaf indicates a full 950 of torque. Overall, the engine/trans combo operates very well.

And, as you also said, my MPG more than satisfies me and for the few times I may experience the climb issue, I'll live with it.
However, I did, briefly, consider bumping the power to 350HP/1050T. But, I laid down 'til the impulse passed.

But, I stand by what I said in my original post; the power package originally questioned is a bit on the light side for a large MH.