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Discussion Starter #1
Hey Everyone,
I have a 2007 Commander Hemi and recently started towing a 26ft travel trailer. Haven't gone on any real big trips yet but I will be going on a 1500 mile trip and I have some concerns to ask. Gross Trailer Weight is 6k on the scales found it to be about 5600lbs loaded. So long story short I have the hitch all setup fine and everything is level but First: I want to know what gear I really should be towing in on the highway. I do use tow haul mode but have been just leaving it in 5th but seems to really bog on hills and will down shift every time and then take forever to shift back into 5th. 2nd: I'm only getting about 8-9mpg as well which seems low. In the past with other larger campers and similar size vehicle (tahoe) I use to get anywhere from 11-13mpg. Is it typical that the hemi's do this poorly on fuel? (Vehicle has 60k miles and in the spring had new spark plugs, air filters, transmission fluids/filters, t-care fluid and differentials) I usually try to do about 65mph on the highway but no matter how big or small of a hill vehicle won't hold speed. I would think with all the hemi power It should be able to hold this speed pretty easily. So I guess I wanna know if I hold 4th instead of 5th will it do better on both power on hills/fuel or will the rpms be to high and fuel mileage will just drop more? Any insight will be appreciated good or bad. I know some of this may be common sense stuff but just really want to get other peoples opinions.

Thanks,
Sam
 

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I would imagine that the gas mileage would go down a little more because if you held it in 4th the rpm's would be higher therefore consuming more fuel. However i think you will have more power due to the higher rpm's.
 

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Discussion Starter #3
So I guess the question is and I'll just have to try is that with higher rpms will I have better power and strain the motor less and potentially get better fuel economy. I used to mountain bike race and when I first got into it I learned keeping a higher/steady rpm pedaling actually saved personal energy and allowed me to go farther while racing rather then using a higher gear and pedaling harder/slower. I'm hoping this same thought works with mechanical engines. Have higher rpms allowing for less strain and potentially get a better burn per cylinder and make each spray go farther. Here's hoping :)
 

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2007 Hemi, 21 ft toy hauler (7000lbs) cross country trip from CA to DE.
I have a flashpaq with trans tuning option.

Best I got was 8 mpgs, I tried messing with the shift points and it got me no where for extra mpgs. I ran with 4 showing most of the time on the shifter read out because anytime it would drop into 5th I'd actually get worse gas milage. The reason being to maintain the same speed it was a higher throttle position (flashpaq readout) so I could run 55 in 4th (actually 3rd) with 22% TP, or 55 in 5th (actually 4th) with 38% TP. Which should be the same as you explained in your mountainbiking experience.

I averaged closer to 7.5mpgs, an only went 55-59mph the most of the trip, I messed with speeds, and shift points and everything and couldn't squeeze any more milage out. Granted I'm lifted with 32" tires also, but my speedo is corrected for the tire size.
 

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Pulled a 23' Layton at about 5k lbs loaded out 2500 miles rount trip. Couldnt get over 10mpg so thats about right. Do you have a brake controller?

Smoothe acceleration curve from stop, brake early, lightly accelerate on downhill and coast as much up hill, constant speeds....and enjoy your trip!!!!!
 

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The extra weight and extra drag will kill your fuel economy.

I have not towed much with the Commander yet but with our old Grand Cherokee we would pull a pop-up that was maybe 2000 lbs loaded. Fuel economy went from 19 to about 14 avg with that small of a trailer.

As far as what gear to tow in. I would suspect you just need to turn on the tow/haul button which will basically drop out the overdrive. Gearing, I say leave it in D which will give you the full range of gearing except O/D with the tow/haul button depressed. Downshifting in the hills is normal for any vehicle towing a heavier trailer.

With the GC we were able to keep 65 - 70 MPH most of the time but by slowing down in hilly areas it allowed the trans to hunt for a gear less often. Sometimes I would drop out the cruise control and sacrifice a little speed going up hill to avoid downshifting.

My current motorhome has the same issues as well.
 

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Discussion Starter #7
Thanks for all the input. I do have a brake controller and as far as control of the vehicle/trailer I haven't had any issues. Sounds like I need to just get use to the difference between what I use to tow with and this vehicle. I will say I think I'm going to just hold 4th to keep the rpms up so it doesn't bog on the hills and see where the mileage sits. If I see a drop I will return to 5th but I have a feeling it will do better in 4th both power wise and possibly fuel economy wise. If it stays the same fuel economy wise that's fine as long as the power is there.

Thanks,
Sam
 

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I tow a travel trailer with my 4.7 Commander. Trailer weighs in a about 6,000 lbs. full and total length is about 31 ft. Mileage depends on whether you are towing on flat road or hilly terrain. Either way you mileage will SUCK! If you get 10 miles per gallon average, you should be happy! If you do a lot of towing, your water pump will get extra wear. Be prepared for early replacement. I use the "Tow/Haul mode for any time I tow.
 

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Thanks for all the input. I do have a brake controller and as far as control of the vehicle/trailer I haven't had any issues. Sounds like I need to just get use to the difference between what I use to tow with and this vehicle. I will say I think I'm going to just hold 4th to keep the rpms up so it doesn't bog on the hills and see where the mileage sits. If I see a drop I will return to 5th but I have a feeling it will do better in 4th both power wise and possibly fuel economy wise. If it stays the same fuel economy wise that's fine as long as the power is there.

Thanks,
Sam
Keep in mind that 4th and 5th gear on the Commander are both overdrive. 3rd gear is 1:1. Max torque (which is the only # that matters for towing) comes quite high at 4350RPM. When towing a big load up any incline you probably want to keep the RPMs @3000 minimum.

I have a small trailer I tow for the scouts (7 X 12 and packed to the roof with gear) in a hemi commander and I don't even know it's there .... except when crossing railroad tracks.
 

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Discussion Starter #10
I'll keep that in mind for 3rd gear. I really don't think I want to hold that high of a rpm but probably will drop it to 3rd on a the larger hills. One other question I have is why would the water pump wear more? The water pump spins with the same amount of tension whether your towing or not?
 
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