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MPG questions


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Hey guys,

So with moving lately I've had the chance to make more long trips with my truck, and also done a good bit of lower speed back road driving. Also done a good bit of trailer towing lately. Some empty car trailer, some loaded car trailer with a tractor like in my thread about first time towing, and some loaded 6x12 enclosed trailer. Nothing too heavy, I would say 8k max and around 3k average. Anyway I've been noticing my average MPG numbers with all this driving and they aren't where I'd like them to be. Unloaded on the highway doing 65 mph with 3:54 rear, best incan get with the edge is a little under 19. With the smarty I used to have I could almost hit 22! Now I never towed with the smarty so I don't have a comparison, but I would say mixed around town driving and towing I'm getting around 15-16. After my trip from PA to VA yesterday the scangauge is showing about 15 and that was with the 6x12 enclosed trailer loaded on the way, unloaded on the way back, which isn't all that bad, I'm just trying to figure out why my numbers with the smarty were better and why I can't do even close to as well as @Mopar1973Man? I still think my injectors aren't the best, but after seeing mikes videos, I don't think I'm smoking more than he was with his edge comp. why can't I hit low 20s unloaded on the highway? I have stock size tires. All maintenance is caught up on, no brakes dragging or anything, all fresh fluids. Should I switch injectors and see what that does? Maybe try more or less 2 stroke(I'm using about and oz per gallon right now)? Maybe try optilube instead? Quadzilla? What are your thoughts? What would explain the drop in mileage going from smarty to comp? Bye I always run with the MPG fooler turned on even in summer because my iat temps are only around 100° even when it's hot out. Could that be hurting me?

Edited by leathermaneod
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Are you hand calcing hte numbers or using hte scan gauge?  

 

Honestly I struggle to break 20 unless I am under 60 mph.  

 

55 mph = 24-25 easy

60 mph = 21 maybe

65 mph = 18 mpg

75 ,mph = laughable

 

 

Tires make a unbelivable difference.  I recently went from heavy 235/85/16's to a lighter 235/85/16 and I picked up nearly 1 mpg.  

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Thanks for the replies guys!

I usually hand calc everything to be as accurate as possible and just use the scan gauge to get the most accurate odometer reading(gps calculated) and to estimate mpgs. I have not found the scan gauge to be very accurate except on long trips, haven't figured out why. Maybe I am just expecting too much then. Your numbers at 65 are right what mine are when empty. I haven't check at lower speeds, though I was able to watch it rapidly go down on the scan gauge above 65 mph. I know what you mean about tires, and my current setup is definitely not optimal for milage. I have heavy stock chrome 3rd gen wheels and 265/70/17's with a fairly aggressive tread pattern right now. I do have a bed topper though so that probably helps some. As for injectors, they may have around 50k on them, but not sure. PO put them in and just told me they are BD Diesel 75hp. I always assumed they weren't the greatest because I have read, in one or two places, that BD's run hot and dirty, not sure how true that is, but I believed it based on the smoke. However, now that I've seen Mike's smoke with the comp, I don't know that they are that bad. I just thought when I got the comp I'd be able to get numbers closer to Mike(low 20's) with it, but I've had the opposite experience lol. I'd also like to be able to add timing without using the max power setting and be less laggy. I miss the smarty for the mpgs and the zero lag experience, but I like the comp for the ability to change on the fly and the fact that I don't need to be reflashing the ecm all the time. Need that quadzilla! 

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If money ran free like the salmon of Capistrano I would tell you.

 

do some 245/75/17 tires with the alumninum 3rd gens

ditch the BD injectors for some 7 x .009 DFI or DAP injectors

get a quad and mess with your timing unitl mileage comes up.

slow down to 55 and enjoy the roses.  :smart:

 

 

But we live in the real world so I would say slow down, and get some different tires next time you need them. beyond that it is hard to justify the cost of mods for the small return on investment. 

 

 

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I certainly appreciate the advice! I have been wanting to swap out injectors and pretty much decided on DFI when the time comes, not sure if I wanna go quite that big though....maybe 7x.008 or .0085?....anyway, I'd also like to do the quad, I'm working on selling the comp first lol. Then there are the wheels and tires, I always wanted the alloy 3rd gens, but I didn't find anywhen I needed them, so I had to settle for the chrome clads. I actually like their looks, but they sure are heavy! Hopefully I can find a good deal on some alloys sometime before I next need tires. When the time comes I will do as you suggest and look into some 254/75/17's. In the mean time, what are your opinions on optilube? I've been reading about it some lately and wondering if it would be better for me than 2 stoke, especially since I don't tow very heavy that often. Then there are the different kinds, any opinions on them? 

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If you are planning to get a quad get at least  7 x .009 injectors.  you can control the canbus tuning a lot easier than wiretap.  Since you can canbus tune you can use your injector size for power and the quad for tuning.  

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One thing you want to do is weigh you wheel and tire. Like right now I'm at 62 pounds for one wheel and tire assembly. Ever 1 pound of rotational mass you remove is like taking 8 pounds off the frame. So going from the factory wheels to 16x7 and dropping from 265s to 235s drop about 25 pounds from one wheel assembly. Basically dropped 100 pounds for rotational mass also like dropping 800 pounds off the frame.

Edited by Mopar1973Man
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  • 2 weeks later...

Just returned from 2000 mile trip. Lots of wind, lots of grades in the eastern sierras, GCW 20,150 with loaded 27ft 5r and a quad trailer on back of that. Speed 65 mph. NO tuner. New rv275s from Vulcan performance. 13.5 mpg on paper. My around town went up 1 mpg to 18.5 over stock injectors. My past mpg was 12.5 with a 18,500 gcw over 12000 miles to AK. All of Canada and most of AK is 55mph. I would recommend rv275s for a nice stocker upgrade.

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