Turbo v non-turbo mileage?

[Selahdoor]

I have the non-turbo 7.3 idi.

Backed by a C6.

1988 f250.

I am averaging about 10 miles per gallon.


My question... If I put turbo on the engine, will I get better fuel mileage? Or am I stuck with what I have, because of the C6?

 

[FORDF250HDXLT]

your suspensions are right about the majority of your issue being the old school 3 speed auto.when i installed a turbo,i saw a reduction in fuel economy,not an increase.

your largest and imho only worthwhile gain will be swapping the c6 out for a zf5 or even just a manual 4 speed would do better.an e40d swap is costly and probably would cheaper to just buy a newer truck with one already instead of doing that if you prefer auto's.
if you don't drive it much,just run 'er.if you do,ask yourself if you need to.perhaps get a little beater 4cyl car to go with it.
this is what i do.i don't prefer driving little 4cyl cars but i like having $ for other things more so i deal with it lol.
it's nice to hop in something when a truck isn't required with my little honda because really it just feels like driving for free when getting over 30 mpg all the time with it.feels free to drive all week for 15 bucks or so.this isn't worthwhile to tag and insure two vehicles if you don't drive enough to make it worthwhile of course.all trucks suck when it comes to fuel economy.it's just the way it is really.gotta face that.

 

[Shadetreemechanic]

You didn't tell us what axle ratio you have or what type of driving you do, but unless you are flying all the time with 4.10s, that mileage sounds a little low. I would start by making sure your injection system is in good shape and timing is correct. That should pick up a couple mpgs. Beyond that transmission swap, rear axle ratio swap, or gear vendors would all likely be more effective than turbo. Turbo will theoretically improve efficiency and MPGs, but only if you can keep your foot out of it.

 

[no mufflers]

my mileage stayed about the same when I put the turbo on. an overdrive transmission will help.

 

[dunk]

'86 6.9 with C6 and Banks turbo, 3.55:1 gears 4x4 crew cab. Prior to new pump and injectors it was averaging 11-12.5 MPG the previous few months, the two tanks since it has done 10.19 and 10.91. I suspect because I'm using the additional power as it was terrible gutless previously, basically could use the pedal as an on/off switch and it was still ridiculously slow.

Over 21k miles I've seen:
Worst of 8.25 (gained 2-3 MPG since that first measured tank by advancing pump timing from 6*-8.5*)
Best of 15.22 (on 45-55 MPH two lane blacktop)
Average of 11.85.
The key here is most of my driving is either around town stop and go or highway 65-70 MPH. The slip of the slushbox torque converter and lack of overdrive kill MPG in those conditions. ZF5 is currently in the works and I expect highway MPG to improve to mid teens.

IMO a turbo probably won't make a huge difference in MPG but may help a little. You'll notice improvement in power and EGT though. What you really need is a ZF5 if you want more MPG.

On the econobox, even when fuel was $3.50-$4.00/gal is would take a LOT of miles for a decent econobox to reach ROI particularly when factoring insurance costs (NJ is very high primarily resultant from socialist laws), taxes, and maintenance. Crunch the numbers and see how far off ROI is. I restore classic bikes as a hobby and primarily ride for half the year. I don't consider TCO, ROI as it's not there for the time and money involved in a restoration and the miles I travel, but riding costs $.04/mi in fuel these days while the IDI costs $.15/mi. Cost of restoration, maintenance, taxes, insurance for the bike would exist either way but every mile I ride instead of drive saves me $.11 these days. Varies based on fuel prices... Average cost per mile since I've been tracking is $.26.

Point is, if your goal is to save an appreciable amount of money, crunch the numbers and weigh your options. I always laugh when people at work go out and buy a new $30k econobox with payments and interest and brag to me about how much money they're saving. I tell 'em stop right there unless you want to hang around for a bit while I crunch the numbers on how money you're losing per month and over the time you expect to own the vehicle. Perfectly fine if they just want a nice new luxury, we all have things we value, but it annoys me when they try to mask their extravagant luxury purchase (which they usually can't afford, hence the loan) as some sort of great frugal endeavor.

Rant over... Overdrive will get you the most bang for the buck on MPG improvement with a fairly short number of miles to ROI.

 

[jayro88]

Mine is a c6+DNE2 with 3.54's in an e250. Before the OD I would get 13-14mpg mixed driving depending on fuel, terrain, wind etc etc etc. with a best of 16.5 on an all hwy trip with the cruise set at 65mph. I replaced the torque converter with a low stall diesel one and added the OD. Now I am averaging 15-16mpg in the winter time mixed and 16-18mpg in the summer mixed.

Best has been 18.8mpg on a long trip loaded with 10 people in the van and pulling a 4x8 trailer full of luggage. Planning a trip south this summer......hoping to be able to hit 20mpg with less people and no trailer. I eventually may swap in an e4od.

 

[Clb]

My 88 suxed, sucked, sucks ***, banks c-6 4:10
11 max
The 93 maxed 13-14 empty on the i-5 from la north running 60.
Pulling 10.

 

[FORDF250HDXLT]

On the econobox, even when fuel was $3.50-$4.00/gal is would take a LOT of miles for a decent econobox to reach ROI particularly when factoring insurance costs (NJ is very high primarily resultant from socialist laws), taxes, and maintenance. Crunch the numbers and see how far off ROI is.

but from a savers viewpoint,the ecobox is the primary vehicle.the truck would be the secondary since they are far more expensive to drive.
so imo,it's crunching the numbers time to see if you can also afford the truck,not to see if you can also afford the car.
you can always a rent a truck for a day when needed.another viewpoint is,the cheap car saves putting ware and tare on the truck too.this is worth a lot as well.

 

[dunk]

Good point, I should have mentioned that but I assumed the audience here need a truck for one reason or another. For those who only need a truck rarely you are comparing to additional costs and ROI of having a truck vs renting or throwing a friend with a truck a few bucks or some beer. For those who need a truck regularly you are using the scenario of ROI on the additional cost of a small car.

Personally I need a truck just about every weekend 6-8 months of the year to tow my boat, and haul some large and heavy stuff pretty regularly throughout the year for projects and hobbies. Yes, a boat is a luxury but I live for watersports. Can't tow a 5500 lbs boat with a Falcon. I loved my Falcon while I had it, $700 for 30+ MPG in a cool classic car. Wanted to swap the three on the tree for a T5 and shoot for 40+ MPG. Woulda been a fun project, wasn't sure the 144 would have the torque down low though. Nothing some more compression and some port work couldn't fix though. Economics of spending money for more than 30 MPG are questionable though, particularly now that I've got a bike that gets 42+ MPG.

For me the insurance cost is the deal breaker, whether it'll reach ROI in any reasonable amount of time. If government got out of the insurance racket and drivers were insured for liability rather than vehicles then a second (or third, fifth, tenth) vehicle wouldn't have a huge continual cost associated with it. In NJ we pay through the nose for insurance, particularly if you ride a bike and want no part of the liberal no fault insurance racket so you can retain the right to file suit against someone who has caused you injury and be made financially whole. Unfortunately to exempt myself from that system I switched from having very high liability and uninsured limits to having bare minimum legal limits on my truck as that's what's required to be able to seek compensation if injured while riding my bike. Fortunately bike insurance is relatively cheap, even for agreed value policies and high limits.

The other thing that ****** me off is in this ****** state they used to charge registration fees and tolls based on vehicle class (weight). A bike was $15/yr for road tax, tolls were a fraction of what cars cost. Now they charge the same for all. The lie of road tax being for road maintenance is clearly over as there's no way a 500 lbs bike puts the same wear on the roads as a 6000 lbs truck, yet I pay the same for both.

 

[Hydro-idi]

My rig consistently averaged 16mpg highway with c6 & 3:55's (going about 60-65). I'm assuming gas mileage will go up a little with the 3.08's now but haven't checked. Maybe I will find out soon if I ever get this damn engine straightened out one day :/.
I don't think the turbo will help your mileage unless you swap out rear end gears &/or go with a different transmission setup.

 

[chris142]

I can get 16mpg if I really try by not powering up hills. More like 14 if I do.

 

[The_88_lariat]

My 88 with a zf5 old style banks tubro and 4.10 cruising at 2k rpm on the highway with no hills and a loaded bed no trailer 24.32 miles a gallon before i turned up the pump last weekend

 

[burt]

It's beyond me how people get 20's with an idi. Over many years and many trucks breaking 16 has been very rare. I always get worse mpg with a turbo because it's imposible for me to not use the power. Almost all of my driving would be hills. Keep an eye on ebay ect. For a gear vendors that has the right adaptor for your truck. Easy to install if you are at all inclined to wrench. Usually go for about $1000 plus getting your driveshaft shortened. They are very nice to drive with splitting gears as well. That said I still don't get past 14mpg to much with a gv zf5 f350 4x4 7.3. Same truck with an old motor no turbo no gear vendors I used to get 15.5 consistently with a load in the hills.

 

[FORDF250HDXLT]

It's beyond me how people get 20's with an idi.

2wd's driving them empty like cars on flat land locations like here in the midwest and even then,it makes you wonder if it's based on 10 consecutive tanks or just an estimate.

that said,i know chip truck can get (doesn't mean it does) 17 mpg.because i ran it empty on the interstate before.that's a 4wd dually stake body dump.so you take a 2wd,srw,a normal bed and run it empty on flat land all the time.i can see it.

 

[burt]

I've never had a 2wd or driven long flat distances empty and I don't recall ever hitting 17 mpg. Close tho. All these numbers sound like a far cry from the 10mpg the op is getting. I'd have a real hard time living with that. What kinda rpm are you cruising at?