Mpg
Posting Guru
Joined: Sep 2003
Posts: 1,211
Likes: 0
Originally Posted by one4speed
[color=black][size=2]The guy with the Dodge is full of it. Most aftermarket chips skew the overhead calculations.
Posting Guru
Joined: Sep 2003
Posts: 1,211
Likes: 0
you're getting better mpg after the reflash?
Originally Posted by kimminau2
I had to take a short trip this morning to the dealer for the first LOF and the reflash. So I decided to do an mpg test. It is all hwy pretty close to 50% 65 mph and 50% 75 mph, those are the posted speed limits. I set the cruise on the speed limit both ways. When I got to the dealer the service advisor asked me if I had any turbo lag, there is not very much, it is pretty responsive which is what I told him. He then told me that the reflash should also help with the turbo lag. I was surprised but said OK. The other thing I was interested in is that someone else on this forum mentioned that they had the reflash done and seemed to get better mpg afterward. So to make a short story long this is what I got, unloaded.
F450 4.88's.
Going 66.6 miles / 6.9 gallons = 9.65 mpg
Coming 67.5 miles / 6.04 gallons = 11.18 mpg
BTW there are some hills between here and there but overall the elevation is about the same. Also the lie-o-meter was accurate going but I did not reset it for the trip back.
F450 4.88's.
Going 66.6 miles / 6.9 gallons = 9.65 mpg
Coming 67.5 miles / 6.04 gallons = 11.18 mpg
BTW there are some hills between here and there but overall the elevation is about the same. Also the lie-o-meter was accurate going but I did not reset it for the trip back.
Cargo Master
Joined: Nov 2003
Posts: 2,585
Likes: 1
From: Duluth, Mn.
Originally Posted by mattebury
Let's do the math on that one.
Assumptions:
Cost of a GV unit ~$4k (includes labor guess and drive shaft mod)
Cost of a gallon of diesel, $3.10 (San Diego, CA on April 14)
Current average MPG 12.5 (for arguments sake, your results may vary)
15,000 miles per year
2.5 MPG improvement with GV to 15 MPG (another WAG - wild a guess)
Results:
1,200 gallons per year current setup
1,000 gallons per year with GV unit
200 gallons per year savings = $620 savings per year = 6.5 year payback
Given that set of assumptions, a GV unit does not make much sense, so there must be some other performance benefit, or you just want one. If I were to do a more sophisticated analysis that took into account Present Value and the expected cost of fuel over time (Increase in the cost of diesel), I don't think that I'd come up with much of a different decision.
FYI, this is my daily job to do these types of cash flow anaysis. Drives my wife nuts.
Assumptions:
Cost of a GV unit ~$4k (includes labor guess and drive shaft mod)
Cost of a gallon of diesel, $3.10 (San Diego, CA on April 14)
Current average MPG 12.5 (for arguments sake, your results may vary)
15,000 miles per year
2.5 MPG improvement with GV to 15 MPG (another WAG - wild a guess)
Results:
1,200 gallons per year current setup
1,000 gallons per year with GV unit
200 gallons per year savings = $620 savings per year = 6.5 year payback
Given that set of assumptions, a GV unit does not make much sense, so there must be some other performance benefit, or you just want one. If I were to do a more sophisticated analysis that took into account Present Value and the expected cost of fuel over time (Increase in the cost of diesel), I don't think that I'd come up with much of a different decision.
FYI, this is my daily job to do these types of cash flow anaysis. Drives my wife nuts.
$2400 for the unit. I was quoted $215 from a local driveline shop to shorten/balance a driveshaft. Install shouldn't be more than $500? 5 Hrs @ $85/Hr = $425
$0, If you DIY.
So, Even with install, $3500 is prolly the high end of the unit.
If you see a 500 RPM difference at cruising speed (which is stated on GV 's site) you should see a 30% increase in MPG. Which at 12.5 MPG, is + 3.75 MPG.
The fuel savings might even be more. It seems most of the guys w/450's run over 2K RPM's @ +70 MPH. So if they can drop down below 2K RPM's @ 70 MPH. It might save more than 30%??
Try those numbers?
I don't know where to draw the line as far as payback. But I'd think if you could get it anywhere near 2-3 years. It'd be worth it?
Junior User
Joined: Feb 2007
Posts: 66
Likes: 0
From: Silver Spring, Md
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Cargo Master
Joined: Nov 2003
Posts: 2,585
Likes: 1
From: Duluth, Mn.
Posting Guru
Joined: Jun 2006
Posts: 2,096
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IMO unless you bought a F450 to use as lightly loaded turnpike cruiser I doubt many would find the pay back for the GV unit to be practical. I doubt trying to operate the engine below peak torque rpm while towing or loaded will be pleasant or practical.
I also would wonder if the below 2,000 rpm cruising might cause more fuel assisted regenerations to clean out the DPF offsetting to an extent any fuel economy improvement.
But I guess we won't really know until someone steps up and tries one.
I also would wonder if the below 2,000 rpm cruising might cause more fuel assisted regenerations to clean out the DPF offsetting to an extent any fuel economy improvement.
But I guess we won't really know until someone steps up and tries one.
Elder User
Joined: Jan 2006
Posts: 684
Likes: 2
From: Tucson, AZ
Originally Posted by origcharger
IMO unless you bought a F450 to use as lightly loaded turnpike cruiser I doubt many would find the pay back for the GV unit to be practical. I doubt trying to operate the engine below peak torque rpm while towing or loaded will be pleasant or practical.
I also would wonder if the below 2,000 rpm cruising might cause more fuel assisted regenerations to clean out the DPF offsetting to an extent any fuel economy improvement.
But I guess we won't really know until someone steps up and tries one.
I also would wonder if the below 2,000 rpm cruising might cause more fuel assisted regenerations to clean out the DPF offsetting to an extent any fuel economy improvement.
But I guess we won't really know until someone steps up and tries one.
Elder User
Joined: Feb 2006
Posts: 759
Likes: 0
From: Central Massachusetts
Kimminau,Mattebury,Fonefiddy,Strut, I drive my family crazy sometimes when I get with other Truck owners at campgrounds. I can imagine you four together it would probably be a marathon till the next morning. All kidding aside, it is great to read all the input you guys put into this thread, I’m learning a lot.
Thread Starter
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Senior User
Joined: Apr 2006
Posts: 349
Likes: 0
From: San Diego, CA
Originally Posted by fonefiddy
I think some of your costs/savings are just a bit off.
$2400 for the unit. I was quoted $215 from a local driveline shop to shorten/balance a driveshaft. Install shouldn't be more than $500? 5 Hrs @ $85/Hr = $425
$0, If you DIY.
So, Even with install, $3500 is prolly the high end of the unit.
If you see a 500 RPM difference at cruising speed (which is stated on GV 's site) you should see a 30% increase in MPG. Which at 12.5 MPG, is + 3.75 MPG.
The fuel savings might even be more. It seems most of the guys w/450's run over 2K RPM's @ +70 MPH. So if they can drop down below 2K RPM's @ 70 MPH. It might save more than 30%??
Try those numbers?
I don't know where to draw the line as far as payback. But I'd think if you could get it anywhere near 2-3 years. It'd be worth it?
$2400 for the unit. I was quoted $215 from a local driveline shop to shorten/balance a driveshaft. Install shouldn't be more than $500? 5 Hrs @ $85/Hr = $425
$0, If you DIY.
So, Even with install, $3500 is prolly the high end of the unit.
If you see a 500 RPM difference at cruising speed (which is stated on GV 's site) you should see a 30% increase in MPG. Which at 12.5 MPG, is + 3.75 MPG.
The fuel savings might even be more. It seems most of the guys w/450's run over 2K RPM's @ +70 MPH. So if they can drop down below 2K RPM's @ 70 MPH. It might save more than 30%??
Try those numbers?
I don't know where to draw the line as far as payback. But I'd think if you could get it anywhere near 2-3 years. It'd be worth it?
But, fair enough ...
With a 3.75 MPG improvement over 12.5 MPG
GV installed cost = $3,500
Gallons @ 15,000 / year @ 16.25 MPG = ~925 gallons
= ~275 gallons saved from 12.5 MPG base case
= ~$860 saved at $3.10 per gallon
= ~4 year payback
Cheers
