MPG ?

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BracketNova
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MPG ?

#1 Post by BracketNova » Sun Oct 10, 2010 6:57 pm

Hey gents. I have a 99 dodge 2wd w/ a cummins. I recently switched from 4.10s to 3.55s and picked up a whopping 1 mpg putting me at 12.5 mpg. I thought I should see closer to 16. I am pulling a total weight of 8000 lbs behind me in an enclosed trailer. Anyone else have a similar setup (cummins and enclosed)? if so what are your mpgs. Anything I should check. I'm not much of a diesel guy. Truck has 350,000 on it :roll:
"I always compare drag racing to lighting $100 bills on fire, only it's more expensive." - Craig W.

Check out my website...
http://www.findmoneyraces.com


'71 Nova E85
6.69 @ 100.2 MPH 9/6/14
1.4257 60'
1700' DA

13:1 439 BBC
3330 lbs

DOTracer
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Re: MPG ?

#2 Post by DOTracer » Mon Oct 11, 2010 7:04 am

I have an '03 Ram Cummins HO and it gets 16 to 17 mpg around town. With my old open trailer it got 14 to 14.5 mpg towing. The new 28' enclosed typically gets around 11 mpg towing at approx 9 to 10k lbs loaded.

If you can get 12 mpg or more with an enclosed, your doing better than me.

Keep in mind your new gears are likely putting even more load and stress on an already weak Dodge transmission assuming an automatic.

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Re: MPG ?

#3 Post by John_Heard » Mon Oct 11, 2010 7:16 am

I think it's unlikely to see the kind of mileage you're wanting when pulling. Lot of things are going to affect that, especially wind and how hard you're running it. On mine if we were bucking a head wind pulling the enclosed it would really kill the mpg.

DOTracer
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Re: MPG ?

#4 Post by DOTracer » Mon Oct 11, 2010 7:19 am

With the Cummins diesel you'll get the best mileage at a steady state speed, minimal throttle movement, 65 mph, 1850 rpm on the tach. Starts/stops and hills really kill mileage as your hard on the throttle getting up to speed or trying to maintain speed.

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Moparious Maximus
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Re: MPG ?

#5 Post by Moparious Maximus » Mon Oct 11, 2010 8:33 am

You are doing alright at 12.5, we used to get that with a 30' trailer, now with the 48' gooseneck we are down to 10.0 but its very heavy.

Is this a stock truck? The cummins will usually get better milage with a few toys, fueling boxes, bigger injectors, and if you have gobs of $$$$, compound turbos.

Our towing truck is an 2001 cummins and over 400hp it pulls like a dream, warning though diesel performance is another expencive addiction.
'63 Plymouth, Straight axle, Leaf springs, Drum brakes, 31x10.5wx15 Rears 3215lbs
Best time to date 7.99 @ 170 mph
572" Wedge 8-71 @ 28% OD, ALKY, Glide, Dana

http://www.youtube.com/watch?v=vq-xzFWHtFk
http://www.youtube.com/watch?v=JfyZSw59R_o

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BracketNova
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Re: MPG ?

#6 Post by BracketNova » Mon Oct 11, 2010 6:19 pm

It has a VanAaken box on it. It got worse mpg when I took it off. It also has a BHAF, I was told bigger injectors, a higher stall converter and a beefed up trans. With the small gears it runs at 1900 RPM at 70MPH. EGTs at 700°, any slower or faster they rise to 800°. At 70MPH it is at 10 PSI boost. With the 4.10s I could maintain 550° at 65MPH and 6/7 PSI of boost. This is all in overdrive. I kicked it out of overdrive for a bit this weekend, the egts dropped by 100° but the RPMs at 65 were something like 2700. I really didn't feell very safe at that RPM :shock: .

I guess I'm trying to figure out what the better gear is. It does get significantly better mileage unloaded than it did with the 4.10s. I am sposed to send my 4.10s back to the guy who sent me these 3.55s. I just want to be absolutely sure it's what I want to do. Especially since my 4.10 carrier is a limited slip, and I got an open from him. :?


Oh ya...it's a dually too
"I always compare drag racing to lighting $100 bills on fire, only it's more expensive." - Craig W.

Check out my website...
http://www.findmoneyraces.com


'71 Nova E85
6.69 @ 100.2 MPH 9/6/14
1.4257 60'
1700' DA

13:1 439 BBC
3330 lbs

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Moparious Maximus
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Re: MPG ?

#7 Post by Moparious Maximus » Tue Oct 12, 2010 8:21 am

I've never pulled anything heavy with my 4.10 geared truck just the 3.55, but with both trucks empty they get the exact same milage, 18-19. You will almost always get better milage the slower you tow, but if you are like us and always in a hurry thats hard to do, we do keep the rpm under 1900 all the time. Another problem, if our rpm is under say 1650 we have to work pretty hard to pull the big hills, and the egt's climb to 1200* or so, but we never let it out of OD. Kinda limits us to between 60 and 72 mph.
'63 Plymouth, Straight axle, Leaf springs, Drum brakes, 31x10.5wx15 Rears 3215lbs
Best time to date 7.99 @ 170 mph
572" Wedge 8-71 @ 28% OD, ALKY, Glide, Dana

http://www.youtube.com/watch?v=vq-xzFWHtFk
http://www.youtube.com/watch?v=JfyZSw59R_o

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BracketNova
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Re: MPG ?

#8 Post by BracketNova » Wed Oct 13, 2010 2:42 pm

Ya, I always SAY I'm going to pull slow but end up doing 70/75 all the time :)
"I always compare drag racing to lighting $100 bills on fire, only it's more expensive." - Craig W.

Check out my website...
http://www.findmoneyraces.com


'71 Nova E85
6.69 @ 100.2 MPH 9/6/14
1.4257 60'
1700' DA

13:1 439 BBC
3330 lbs

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