Notices
Pre-Power Stroke Diesel (7.3L IDI & 6.9L) Diesel Topics Only

MPG Question. IDI vs non

Thread Tools
 
Search this Thread
 
Old Aug 27, 2016 | 10:55 PM
  #1  
Resendiz's Avatar
Resendiz
Thread Starter
|
Laughing Gas
15 Year Member
Photogenic
Photoriffic
Shutterbug
Joined: Sep 2010
Posts: 1,027
Likes: 2
From: USA
MPG Question. IDI vs non

I get my pick up truck back Monday (just bought it, went straight to mechanics). I have been wondering what MPG I can expect to get out of it. 6.9 turbo.

Ive heard that turbo helps with MPG, then I've heard that it does the exact opposite.

I have a e40d. The psi goes up to 8psi and when i did drive it home after purchasing it, it cruises at 1-2psi. Don't know if that means anything.

Its a longbed, 4 door. dually.

The registration says it weighs 4600lbs, which i think is low for some reason but hey im used to 8000lbs uhauls. Does this sound about right to you guys?

Does anyone here have a similar set up that can give me an idea of what MPG i can expect? I would be happy with 15mpg+. Ive heard people getting 20+ but i can't believe it for some reason




Now i know what its like being away from your child for too long.
 
Reply
Old Aug 27, 2016 | 11:16 PM
  #2  
Macrobb's Avatar
Macrobb
Postmaster
Joined: Dec 2011
Posts: 3,860
Likes: 7
You've got a big rig; I'd say anywhere in the 14-17 range.
The problem is that 'fuel mileage' depends on a number of factors.
The first is that, as a mechanical engine, we have no computer that can tell us 'instant' economy, so the economy is simply tank to tank.
This means that your economy includes:
1. startups
2. Idling, including warming up
3. low speed driving - probably lower economy if you have lots of stops
4. Medium speed driving, like 45. Probably fairly good economy
5. Highway driving - 60-ish will be higher economy than 70+.

As that mix changes, your fuel economy numbers will change... though the truck is no more or less efficient than it ever was.

For example, a couple years back I took a trip of about 600 miles one-way, all highway. I basically filled up just before I hit the highway, and filled up when near empty, right along the highway. I averaged 17.5 MPG, despite going 75 the whole way(ZF5 + GV overdrive = 2K RPM at 75)
On the other hand, in my daily commute, I average somewhere in the 14.5 range... mainly because I have a 10 mile commute, 8 of it is highway... and it barely gets warmed up fully by the end. Lots of cold starts involved.
 
Reply
Old Aug 28, 2016 | 06:38 AM
  #3  
tjc transport's Avatar
tjc transport
i ain't rite
Joined: Mar 2005
Posts: 65,507
Likes: 5,563
From: Marlboro Mental Hospital.
Club FTE Gold Member
being it is a dually, that rite there is going to take about 2MPG off the top of the mileage. but with the overdrive trans, 15 does not sound out of the question.
turbo can increase mileage, but it can decrease it also because you tend to have a heavier foot when driving a turbocharged truck.
as for the 4600 lbs deal, make sure it is not registered for 4600. if so, it is overweight as is. my bet is that rig is closer to 8000 empty.
 
Reply
Old Aug 28, 2016 | 06:45 AM
  #4  
hturner12's Avatar
hturner12
Postmaster
Joined: Oct 2014
Posts: 3,914
Likes: 9
From: Thomaston
Good looking truck. My 90 super cab is 6300. Mix in town and highway I am getting 16
 
Reply
Old Aug 28, 2016 | 07:22 AM
  #5  
Shawn MacAnanny's Avatar
Shawn MacAnanny
Elder User
Joined: Dec 2005
Posts: 776
Likes: 3
From: Felton, Delaware
My truck in my signature has my fuelly for it. I drove it 200 miles daily and got 14.5 to 15.6 in a crew cab long bed dually with utility body weighed 8900lbs empty. With a trailer it would get 13 to14.

It was totaled a few weeks ago so I have been using my 1996 single cab f350 dually 4x4 which I put the same bed on and it weighs 8600lbs empty, has 4 inch exhaust, kn intake and cts 2 tuner with about a 60hp tune. First fill up was 18.7mpg.
 
Reply
Old Aug 28, 2016 | 01:57 PM
  #6  
genscripter's Avatar
genscripter
Cargo Master
10 Year Member
Photogenic
Liked
Loved
Joined: Oct 2012
Posts: 3,072
Likes: 48
From: California
I've done A LOT to make my IDI run as efficiently as possible.

I bought my turbo to save MPG. Instead, it is too much fun to drive so I get about hte same MPG as before. But I guess that's a savings in a sense because now I can drive 15mph faster and get the same MPG.

But if you are looking to add a turbo to increase MPG, good luck. It's all about managing the accellerator pedal.
 
Reply
Old Aug 28, 2016 | 08:11 PM
  #7  
Festus Hagen's Avatar
Festus Hagen
Methanoholic
Joined: Mar 2009
Posts: 6,442
Likes: 8
From: Maine (NorCal Native)
Club FTE Gold Member
Originally Posted by genscripter
I've done A LOT to make my IDI run as efficiently as possible.

I bought my turbo to save MPG. Instead, it is too much fun to drive so I get about hte same MPG as before. But I guess that's a savings in a sense because now I can drive 15mph faster and get the same MPG.

But if you are looking to add a turbo to increase MPG, good luck. It's all about managing the accellerator pedal.
Blue ... Amen!
Red ... Key words!

-Enjoy
fh : )_~
 
Reply
Old Aug 28, 2016 | 11:44 PM
  #8  
Resendiz's Avatar
Resendiz
Thread Starter
|
Laughing Gas
15 Year Member
Photogenic
Photoriffic
Shutterbug
Joined: Sep 2010
Posts: 1,027
Likes: 2
From: USA
Thanks for the replies. So about 14-16. More like 14. I will definitely enjoy the turbo
 
Reply
FTE Stories

Ford Trucks for Ford Truck Enthusiasts

story-0

Rezvani's Latest Post-Apocalytic Monster Is a Ford F-150 Raptor Underneath

 Verdad Gallardo
story-1

Top 10 Most Expensive Ford Trucks Ever Sold on Bring a Trailer

 Joe Kucinski
story-2

2027 Ford Super Duty Buyer's Guide (Every Model, Engine, & Package)

 Brett Foote
story-3

Top 10 Ford Truck Tragedies

 Joe Kucinski
story-4

AEV FXL Super Duty - the Super Duty Raptor Ford Doesn't Make

 Brett Foote
story-5

Lobo Vs Lobo: Proof the F-150 Lobo Should Be Even Lower!

 Michael S. Palmer
story-6

Ford's 2001 Explorer Sportsman Concept Looks For a New Home

 Verdad Gallardo
story-7

10 Best Ford Truck Engines We Miss the Most!

 Joe Kucinski
story-8

2026 Shelby F-150 Off-Road: Better Than a Raptor R?

 Brett Foote
story-9

2027 Super Duty Carhartt Package First Look: 12 Things You NEED to Know!

 Michael S. Palmer
Old Sep 3, 2016 | 04:38 PM
  #9  
Ethan Robinson's Avatar
Ethan Robinson
Freshman User
Joined: Mar 2016
Posts: 45
Likes: 0
My 88 7.3 NA 2wd 3/4 ton with zf5 gets 12.3. And I don't really have a heavy foot. But I think i may have other issues
 
Reply
Old Sep 3, 2016 | 04:43 PM
  #10  
Shawn MacAnanny's Avatar
Shawn MacAnanny
Elder User
Joined: Dec 2005
Posts: 776
Likes: 3
From: Felton, Delaware
After a few thousand miles the 4x4 psd is only getting 15.6 to.15.8 so not much better than the idit I had
 
Reply
Old Sep 4, 2016 | 12:13 AM
  #11  
genscripter's Avatar
genscripter
Cargo Master
10 Year Member
Photogenic
Liked
Loved
Joined: Oct 2012
Posts: 3,072
Likes: 48
From: California
My van gets around 19-20mpg if I keep it at 55mph. 17-18mpg if I give 'er hell. But I have done lots of eco mods.

GVOD, Hypermax Turbo, hi flow exhaust, aluminum driveshaft, LRR maximum size tires, e-pump, 3G alternator, pv panels, hughes torque converter, and other things to try to save fuel. And I did several timing tests to optimize for the best fuel ratio relative to degrees TDC. I think I've reached the upper end of what an IDI with my gear ratio and tranny can get. I'm contemplating going e-fan and making a front air dam like Jayro did to gain a half mpg, maybe. So when I hear someone claim they get 25 mpg in their IDI with an auto just by changing the oil, I always call BS.

Recently, I've been looking into installing a front axle on my van but not installing the transfer case and front drive shaft. Instead, I have been looking at the Tesla motor assembly, which is mounted on their driveshafts. Maybe with enough undermounted batteries being simultaneously charged by my 3G alternator(s), perhaps I can write a controller that would make my IDI van a semi-hybrid for city driving. Even if I could get enough juice to get 50 miles on one charge, that would be solid for some of my day-to-day LA driving. IDK. Still really early in the planning stages.
 
Reply
Old Sep 4, 2016 | 12:23 AM
  #12  
Macrobb's Avatar
Macrobb
Postmaster
Joined: Dec 2011
Posts: 3,860
Likes: 7
Just feel good that your 25 year old truck is getting 14-18, where this guy's 2013 F-150 is getting 13-14 with an EcoBoost engine: https://www.ford-trucks.com/forums/1...-34-tires.html
(Note: This topic came up in the "Similar Threads" box...)

Even if you don't get 25 MPG, you more than make up the difference in simply lack of operating costs, and that's not even accounting for how much less it cost to buy one of these old trucks vs a new one. And it can do more...
 
Reply
Old Sep 4, 2016 | 06:26 AM
  #13  
Shawn MacAnanny's Avatar
Shawn MacAnanny
Elder User
Joined: Dec 2005
Posts: 776
Likes: 3
From: Felton, Delaware
Originally Posted by genscripter
My van gets around 19-20mpg if I keep it at 55mph. 17-18mpg if I give 'er hell. But I have done lots of eco mods.

GVOD, Hypermax Turbo, hi flow exhaust, aluminum driveshaft, LRR maximum size tires, e-pump, 3G alternator, pv panels, hughes torque converter, and other things to try to save fuel. And I did several timing tests to optimize for the best fuel ratio relative to degrees TDC. I think I've reached the upper end of what an IDI with my gear ratio and tranny can get. I'm contemplating going e-fan and making a front air dam like Jayro did to gain a half mpg, maybe. So when I hear someone claim they get 25 mpg in their IDI with an auto just by changing the oil, I always call BS.

Recently, I've been looking into installing a front axle on my van but not installing the transfer case and front drive shaft. Instead, I have been looking at the Tesla motor assembly, which is mounted on their driveshafts. Maybe with enough undermounted batteries being simultaneously charged by my 3G alternator(s), perhaps I can write a controller that would make my IDI van a semi-hybrid for city driving. Even if I could get enough juice to get 50 miles on one charge, that would be solid for some of my day-to-day LA driving. IDK. Still really early in the planning stages.

How much does you van weigh?

Look at others people's fuel economy on fuelly, you browse and see diesel mpg vs gas for all years. These are hand calculated real wold mpg. I use it for all of my vehicles. Newer f350s don't get any better. Both my trucks weigh almost 9k which is pretty heavy. My old duramax used to average 15mpg h best ever as 17mpg. My 2001 suburban averages 13 to 15, best ever 16mpg. My 2012 passat tdi averaged 41mpg over its 85k life best of 49mpg on a 1600 mile trip


Ford F-350 Super Duty MPG - Actual MPG from 743 Ford F-350 Super Duty owners
 
Reply
Old Sep 4, 2016 | 06:59 AM
  #14  
jayro88's Avatar
jayro88
Fleet Mechanic
Joined: Oct 2012
Posts: 1,943
Likes: 21
Originally Posted by genscripter
My van gets around 19-20mpg if I keep it at 55mph. 17-18mpg if I give 'er hell. But I have done lots of eco mods.

GVOD, Hypermax Turbo, hi flow exhaust, aluminum driveshaft, LRR maximum size tires, e-pump, 3G alternator, pv panels, hughes torque converter, and other things to try to save fuel. And I did several timing tests to optimize for the best fuel ratio relative to degrees TDC. I think I've reached the upper end of what an IDI with my gear ratio and tranny can get. I'm contemplating going e-fan and making a front air dam like Jayro did to gain a half mpg, maybe. So when I hear someone claim they get 25 mpg in their IDI with an auto just by changing the oil, I always call BS.

Recently, I've been looking into installing a front axle on my van but not installing the transfer case and front drive shaft. Instead, I have been looking at the Tesla motor assembly, which is mounted on their driveshafts. Maybe with enough undermounted batteries being simultaneously charged by my 3G alternator(s), perhaps I can write a controller that would make my IDI van a semi-hybrid for city driving. Even if I could get enough juice to get 50 miles on one charge, that would be solid for some of my day-to-day LA driving. IDK. Still really early in the planning stages.
Interesting idea on the electric front axle.

Your MPG numbers sound inline with mine. I am about about 1-1.5mpg lower than yours, but you have a few efficiency mods I don't. I do think the vans suffer in the aero department. I am currently about half way through wrapping my air dam with some scrap sheet metal I have so it doesn't look quite as hillbilly as it did. I was hoping to be able to test it on my trip this summer, but time ran out.

So are you against a transmission swap? For the $ of the electric motor you could swap in a e40d or 4r100. With the upgrades available to them their durability issues are much less and using a stand alone controller gets rid of the funky electrical/sensor issued they seem to have with the stock wiring/computer. Combined with your GVOD you could have the best of both worlds. 4.10's (or even 4.56's if you wanted) for towing and more efficient stop and go driving......while you would have lower hwy cruising rpm's than you currently do with the benefit of the locking torque converter. This is the route I am looking at.

With the right mods, I think that 20-25mpg hwy would be achievable in the right model ID truck.

Sorry for the tangent.....I think that OP would be able to see 16 or maybe 17 mpg on the hwy with slower cruising speeds and the optimal terrain/conditions. Probably 14-16mpg is more realistic.
 
Reply
Old Sep 4, 2016 | 10:56 AM
  #15  
genscripter's Avatar
genscripter
Cargo Master
10 Year Member
Photogenic
Liked
Loved
Joined: Oct 2012
Posts: 3,072
Likes: 48
From: California
After I get my short block and I reinstall the engine, I'm looking to fab up some kind of a long thing innercooler above where my trans cooler is mounted in front of my condenser. We'll see. Maybe that'll give me a little more HP, thus a little better fuel economy.

I considered goin with the E4OD with a GV, but I'd have to source a new GV tailshaft housing, the reviews for the E4OD are pretty awful, I already have some decent C6 upgrades (deep sump, better filter, E350 cooler, etc), and I think my Hypermax up- and down-pipes won't work from a C6 to E4OD.

If I can run the Aerostar e-fan and delete the fan clutch, that'll help a little with the drain on the engine. I already have the 3G alt, so i'm good on the amps. Plus removing the fan clutch should afford me more room to route the piping for the innercooler.

The aerodynamics is a prob. A friend of mine suggested I use my access to these vac formers I have, and make an acrylic nose cone. IDK.

In the end, I'm leaning toward doing the first IDI hybrid. It's not as exotic as it seems. people are making conversion kits for cars for a while now. The motor mounts to the existing axle, and is belt driven to where the driveshaft yoke applies. Obviously those split-axles won't work, but a fixed shaft would.



I've only seen it on things like crown vics and whatnot, because trucks and vans are too heavy to get a decent range on a single charge. But all I'm looking for is something like 50 miles per charge. That'd be nice for my day-driving in Los Angeles. Plus with my solar array on top, i'd get a trickle charge when the van sits for days in the Calif sun.

The other BIG problem with this plan is to get enough room for the motor on the axle with the van. it already has a major issue with clearance for the 4x conversions, so adding that motor could be tough. I know the van will need to be raised at least 3 inches, thus aero becomes a prob again. But then i could have more clearance for batteries and possibly build a flat panel for the underside of the van, thus helping aero. lots of work to do....
 
Reply



All times are GMT -5. The time now is 06:02 PM.

story-0
Rezvani's Latest Post-Apocalytic Monster Is a Ford F-150 Raptor Underneath

Slideshow: Called the Fortress, the 850-horsepower pickup combines Raptor underpinnings with military-inspired features, survival equipment, and a starting price of $285,000.

By Verdad Gallardo | 2026-05-30 18:33:59


VIEW MORE
story-1
Top 10 Most Expensive Ford Trucks Ever Sold on Bring a Trailer

Slideshow: 10 most expensive Ford trucks ever sold on Bring a Trailer.

By Joe Kucinski | 2026-05-27 16:24:34


VIEW MORE
story-2
2027 Ford Super Duty Buyer's Guide (Every Model, Engine, & Package)

Here's everything that has changed for the latest model year.

By Brett Foote | 2026-05-27 16:17:28


VIEW MORE
story-3
Top 10 Ford Truck Tragedies

Slideshow: Top 10 Ford truck tragedies.

By Joe Kucinski | 2026-05-18 19:34:33


VIEW MORE
story-4
AEV FXL Super Duty - the Super Duty Raptor Ford Doesn't Make

And it might be even better than that.

By Brett Foote | 2026-05-18 19:26:42


VIEW MORE
story-5
Lobo Vs Lobo: Proof the F-150 Lobo Should Be Even Lower!

Slideshow: Does lowering an F-150 Lobo RUIN the ride quality?

By Michael S. Palmer | 2026-05-18 19:20:37


VIEW MORE
story-6
Ford's 2001 Explorer Sportsman Concept Looks For a New Home

Slideshow: Ford's bizarre fishing-themed Explorer concept has resurfaced after spending decades largely forgotten.

By Verdad Gallardo | 2026-05-12 18:07:46


VIEW MORE
story-7
10 Best Ford Truck Engines We Miss the Most!

Slideshow: The 10 best Ford truck engines we miss the most.

By Joe Kucinski | 2026-05-12 13:09:47


VIEW MORE
story-8
2026 Shelby F-150 Off-Road: Better Than a Raptor R?

Slideshow: first look at the 810 hp 2026 Shelby F-150 Off-Road!

By Brett Foote | 2026-05-12 12:50:07


VIEW MORE
story-9
2027 Super Duty Carhartt Package First Look: 12 Things You NEED to Know!

Slideshow: Everything You Need to Know about the 2027 Super Duty Carhartt Package!

By Michael S. Palmer | 2026-05-07 17:51:06


VIEW MORE