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TRV1 · 01-08-2016, 07:50 AM

We recently added a 2007 38' Fleetwood Expedition to our "toy list". It has a 300 hp Cat engine. Allison 6 speed transmission .We plan to be on the road by May for a six month voyage.
I am thinking we may be a bit underpowered for toading and would like to get some input.
Thanks all.

budwilson · 01-08-2016, 08:20 AM

You will be ok. You won't break any speed records in the mountains but you will make it. I have a Cat c7 330 hp in my Discovery and have had no problems towing my CRV.

jondrew55 · 01-08-2016, 08:44 AM

We pulled our 3800 pound Murano thru the mountains of Tenessee last year with our 300HP Excursion 35C with no problems. Like the other poster said, your not going to win any races up hills, but no strain at all. Flat ground you hardly realize you're towing anything.

navigator336 · 01-08-2016, 12:46 PM

A Caterpillar service center can reprogram (rerate) your 300 hp C7 to 350 hp. The cost is about $500. The peak torque remains the same, but the torque curve following peak torque is much flatter meaning you'll be able to pull grades faster. I had mine done a couple of years ago and it clearly improves climbing ability. The Cat dealer told me people report improved mileage as well ranging from 0.25 MPG to 1.5 MPG improvement. In my opinion, the people reporting 1.5 MPG improvement are dreaming. The 0.25 MPG improvement is about what I've seen. I can pull a 4500 lb. toad up a long 7% grade at about 38 to 40 MPH. On grades in the 5 to 6% range I can generally hold 45 to 50 MPH.

Notlad · 01-08-2016, 05:49 PM

Quote:

Originally Posted by navigator336

A Caterpillar service center can reprogram (rerate) your 300 hp C7 to 350 hp. The cost is about $500. The peak torque remains the same, but the torque curve following peak torque is much flatter meaning you'll be able to pull grades faster. I had mine done a couple of years ago and it clearly improves climbing ability. The Cat dealer told me people report improved mileage as well ranging from 0.25 MPG to 1.5 MPG improvement. In my opinion, the people reporting 1.5 MPG improvement are dreaming. The 0.25 MPG improvement is about what I've seen. I can pull a 4500 lb. toad up a long 7% grade at about 38 to 40 MPH. On grades in the 5 to 6% range I can generally hold 45 to 50 MPH.

There aren't any issues with the transmission handling the additional 50hp? I am asking because I have seen posts about the Cummins 300 hp where people say that although you can flash it to 330 hp some of the transmissions on the 300 hp can't handle the additional HP / torque.

navigator336 · 01-08-2016, 06:13 PM

Quote:

Originally Posted by Notlad

There aren't any issues with the transmission handling the additional 50hp? I am asking because I have seen posts about the Cummins 300 hp where people say that although you can flash it to 330 hp some of the transmissions on the 300 hp can't handle the additional HP / torque.

No, no issue with the trans which is an Allison MH3000 series for all three version of the 2004 EPA C7 (300, 330 and 350 HP). The three versions are identical and only the program varies. The biggest concern would be the cooling, but at least for all rear radiator Fleetwood's in that time frame using the C7 they all have a surface area of 1050 square inches.

stuhly · 01-08-2016, 06:31 PM

You have to remember it is rocket scientists and brain surgeons telling you that the Allison won't stand a reflash to 350 horse. Best thing to do is ignore the nay sayers and talk to Allison.

kmx888 · 01-09-2016, 10:00 AM

I towed a 5,000 lb. trailer all over the US including extensive driving in the mountains with a 275 HP Cummins and a 4 speeds Allison. I had NO trouble at all. In the mountains not the fastest but not the slowest. I would buy one again and not worry about it.

Triker56 · 01-09-2016, 10:50 AM

Quote:

Originally Posted by stuhly

You have to remember it is rocket scientists and brain surgeons telling you that the Allison won't stand a reflash to 350 horse. Best thing to do is ignore the nay sayers and talk to Allison.

The Allison 3000 transmission by their printed info.
Can handle up to a max 450HP and 1250 lb-ft torque

Over that then the 4000 is needed that will take 650HP and 1950 lb-ft torque.

navigator336 · 01-09-2016, 10:51 AM

The original poster's comment may be in reference to an Allison 1000 or 2000 series transmission. They are more limited in torque and horsepower inputs. Attached is Allison's specs on page 6 of the document.

http://www.allisontransmission.com/d...df?sfvrsn=4%20

TRV1 · 01-10-2016, 10:20 AM

Thanks all
I am the op. Trans is Allison 3000 6spd.

navigator336 · 01-10-2016, 01:45 PM

TRV1,

Sorry, when I wrote "original poster" I should have put "NATLAD" who posted the comment about the transmission perhaps not capable of withstanding the additional horsepower. I knew you have the Allison MH3000 series based on your 2007 Expedition. I have a 2006 Expedition 34H which has three slides (two living room) so it is very close to the same weight as yours. You'll have no problem pulling grades with a toad. Without rerating the engine to 350 HP your speeds on the 5 to 7% grades will be roughly 3 MPH slower, but still perfectly acceptable. Below is a link to the torque curves of the three versions of the engine. You'll see how much flatter the 350 HP version is past peak torque.

http://www.rvtechlibrary.com/engine/Cat_C7_Specs.pdf

Mr_D · 01-10-2016, 01:53 PM

Quote:

Originally Posted by navigator336

TRV1,

Sorry, when I wrote "original poster" I should have put "NATLAD" who posted the comment about the transmission perhaps not capable of withstanding the additional horsepower. I knew you have the Allison MH3000 series based on your 2007 Expedition. I have a 2006 Expedition 34H which has three slides (two living room) so it is very close to the same weight as yours. You'll have no problem pulling grades with a toad. Without rerating the engine to 350 HP your speeds on the 5 to 7% grades will be roughly 3 MPH slower, but still perfectly acceptable. Below is a link to the torque curves of the three versions of the engine. You'll see how much flatter the 350 HP version is past peak torque.

http://www.rvtechlibrary.com/engine/Cat_C7_Specs.pdf

And there in lies the "problem" with some peoples perception of HP and torque. You have to look at the plotted curve of both to understand the differences in performance, not just the peaks!

navigator336 · 01-10-2016, 02:15 PM

Mr.D,

Well said. Looking at just the torque or horsepower of an engine won't tell you anywhere near the complete picture of its performance. A good common sense way of thinking about horsepower and torque is, "torque is the ability of the engine to do a quantity of work", while horsepower is the ability of the engine to do that quantity of work at a different speeds". Therefore the more torque an engine has, the heavier the load it can push/pull up a hill. The more horsepower it has with the same torque, the faster it can push/pull that same load up the hill.