MPG increase? What worked for me. - Diesel Truck Forum - TheDieselGarage.com
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post #1 of 18 (permalink) Old 12-27-2007, 03:29 AM Thread Starter
 
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MPG increase? What worked for me.

I have been trying to get the most MPG out of my truck the last couple of weeks. I have a 2008 6.4L crew cab short bed F350 SRW. I also have a KEM Performance DPF delete with a superchips programmer, programmed by KEM. My truck had 16000 miles on it when I started the testing. I went to see the family for Christams. before I left I installed a Job #2 front air dam. I also added the deisel fuel additive from Ford for ULSD engines to my Fuel. I saw about a 1.5MPG increase at highway speeds From the addition of these two products. I drive a stretch of highway about 80 miles long and pretty much flat the whole way to see the Family. I set the cruise at 70MPH as soon as I got on the highway. When I reached my destination I had averaged 16.5 MPG. While I was there for a few days I changed my oil with Amsoil. They have came out with a new synthetic formula for ULSD engines. I drove around town back in my home town for about 2 days put about 150 miles on the truck. When I returned home today, I reset my average MPG meter on the truck and drove down the same strecth of highway returning home at the exact same speed. Never taking it off of cruise the whole time, either time. When I got back tonight I had averaged 18.7 MPG. I did all of this according to the computer so I know it might not be perfect but I think that when I calculate it by hand it should be close. I will try that next.

Both times I was running the exact same tune from the KEM programmed Superchips. Performance, which is the highest.

One thing I did notice is that the MPG is effected greatly by speed. I drove down some highways after I changed the oil and set the cruise at 65MPH for about 10 miles and got an average of 21MPG. I know that doesn't sound right compared to all the other trucks on this forum but I have done alot to my truck to increase the MPG. Pretty much everything you can do, other than changing the gear ratio. Plus I have no reason to Lie. :thanks:
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post #2 of 18 (permalink) Old 12-27-2007, 05:04 AM
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Sounds like these engines are pretty picky about the oil. 65 VS. 70 isn't TOO much of a difference it seems like, i mean 18.7 is great but 21 only 5mph slower? Thats really good.

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post #3 of 18 (permalink) Old 12-27-2007, 11:46 AM
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Wow, bro that is awesome mileage! I had planned on switching to amsoil at 5,000 miles. I only have 1500 on mine and overall I'm up to and average mpg of 14.00. I've seen as hi as 17mpg average on a flat stretch of highway. I do use the ford diesel addative and my truck is a job #2 truck. F-250 6.4 Crew Cab Lariat etc... The dpf delete system sounds great, but I just don't want to void the warranty on this thing so early on in it's life, I'm sure everything is expensive to fix, considering Ford is replacing my chrome grille under warranty and that has a retail of $980.00. Well good luck and keep me posted on your mileage. If you could pm me with the details of the superchip program and the dpf delete, I would like to research them a bit. Thanks

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post #4 of 18 (permalink) Old 12-27-2007, 01:04 PM
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Holy cow!!
Does the oil REALLY make that much of a difference??
Diesel Pro's, would REALLY like to hear from you on this............
I do know that I am getting about 12 1/2 with the "stubby pencil method" but for the last month it has been (no tow and mostly highway)
Thoughts please:bow:
~Mike~

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post #5 of 18 (permalink) Old 12-27-2007, 01:49 PM
 
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Thanks for that info. If we didn't stock delo cj-4 oil at my shop I (unlimited free oil) I would be running synthetic. But the problem I have with sythn. I really don't like running the same oil in my truck over 5,000miles. I have a pretty good oil change routine at my shop - but if you are seeing that much of an increase with synthetic I'm thinking about switching.
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post #6 of 18 (permalink) Old 12-27-2007, 01:57 PM
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I'm not doubting the oil makes some difference but I'm willing to bet the dpf delete made the biggest difference.

to the original poster.. what kind of mileage were you getting before you got rid of the dpf?

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post #7 of 18 (permalink) Old 12-27-2007, 02:25 PM
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With the DPF removed (and your warranty voided I might add), the PCM does not need to regen... EVER. This means no "extra" fuel is ever injected, that alone will significantly improve mileage especially in light use applications.

The formula for aerodynamic drag is 1/2 x A x Cd x V^2 {One half the area times the coefficient of drag times the speed SQUARED). So, take a truck say 6' tall and 6.5' wide, that's an area of (6 x 6.5 = 39 sq-ft). Say the Cd is 0.45 (typical truck), and the speed for test #1 is 70, for #2 it's 65.

#1: 1/2 x 39 x 0.45 x 70^2 = 18.5 x 0.45 x 4,900 = 40,792.50
#2: 1/2 x 39 x 0.45 x 65^2 = 18.5 x 0.45 x 4,225 = 35,173.125

So #2 has 86.22% as much drag as #1 (13.88% less drag), for only a 5 mph slower speed. Putting this another way, you increased drag by 16% for a 7.6% increase in speed going from 65 to 70 MPH.

Even more telling is when you consider 40 MPH to 80 MPH...

40 MPH = 1/2 x 39 x 0.45 x 40^2 = 18.5 x 0.45 x 1600 = 13,320
80 MPH = 1/2 x 39 x 0.45 x 80^2 = 18.5 x 0.45 x 6400 = 53,280

53,280/13,320 = 4! You have FOUR TIMES the aerodynamic drag for only doubling the speed!

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post #8 of 18 (permalink) Old 12-27-2007, 02:57 PM
 
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Awesome Information John.:Thumbup: :thanks:
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post #9 of 18 (permalink) Old 12-27-2007, 03:22 PM
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wow john awesome info !!

I add this when my truck was bone stock from the time it had 3miles to the time it had 1300miles I drove from denver to new orleans after I picked my truck up from randy and I saw 17 to 18.5 mpgs "hand calculated" on all high way driving this is with a job2 lower valence. Now since I change the valence, use amsoil 5w-40 and use optilube xpd fuel treatment the best I get is 15 to 16 on the highway.I also always let my truck do a full 30min regen once a week. Granted I have not driven for long periods of time and I probably drive faster now. but its just an observation I still can't see how the lower valence makes that much difference.
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post #10 of 18 (permalink) Old 12-27-2007, 05:33 PM
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Another worthy note is that the idea of a chin spoiler is the get the air to move out around the vehicle or over it, and NOT under it! There are LOTS of things under a vehicle that add to drag (turbulance). The two most effective methods of reducing drag (assuming you are going to drive say 70 no matter what) are:

Lowering the vehicle - this makes it "shorter", therfore the Area is less...(a chin spoiler is a way to get this and maintain necessary ground clearance).
and
Covering the undrebelly - this means the air does not "catch" on stuff like transfer cases, mufflers, pipes, axles etc., smooth underbellies reduce drag.

'93 F-250 HD, 7.3L IDI, 5spd - FARM TRUCK
I Support: Trailer brakes an every axle over the towing vehicle's GVW; CDLs for RVers; Safety inspections for ALL vehicles and 6 axle trucks (97K GVW proposal).

Democracy is two wolves and a lamb voting on what to have for lunch. Liberty is a well-armed lamb contesting the vote - Benjamin Franklin

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