Only 12mpg with dpf and black maxx?

[Michael220]

I have an 08 f250 4x4 with 373 gears I just got the truck it has dpf delete but still has the cat. It has a h&s black maxx. Still stock air box. Any ideas why it's so low I know other guys are getting way better. It's just leveled with 35s I've gone thru 2 tanks and haven't seen anything over 13 hand calculated driving mixed a lot of highway the last tank I didn't even get a heavy foot

 

[webb06]

I you delete the dpf then the cat also comes out with it. Not aware of any kits that leave the cat intact.

 

[Michael220]

I you delete the dpf then the cat also comes out with it. Not aware of any kits that leave the cat intact.

That's what I thought I asked the guy I got it from and he said that an exhaust shop did it

 

[MINK]

Actually sounds about right. I get 13-15 mixed and 17-19 on the freeway trips, hand calculated. Heavy tires dont help at all.

 

[RedRice589]

Well they have just the dpf delete pipe. Or you can get the dpf/doc delete or dpf/cat same thing. If you're doing one just do the other. My 2wd gets a tad better i average 16-17 but its rural driving. In the city its crap usually. Any big motor gets sthat around town its normal.

 

[Twinjracing]

Mine got 14mpg on high hwy. In town got around 11. Pulling my camper I got got 10 mpg. So far my 6.7 is better untouched

SCT tuned and deleted with air intake.
Sent in my sleep @ work

 

[seeyalater5.9]

I would get a true CAI on it and full exhaust. Should help a little

 

[golfer]

I'll reply simply to add data...

2008 2WD regular cab... @ 150k miles. 13.0-13.6mpg hand calculated in mixed 50/50

DPF/Cat delete...stock injection system/turbo hardware..has minor tweaks (MCC) to H&S tuning.

**

I was stunned at how poor the fuel economy is..hell my 7.3L 4WD Excursion with BIG injectors & turbo, etc get's better mpg than the little/light 6.4L.

though....

we have been doing a LOT of R&D work on our cylinder head flow bench..and there is a HUGE loss in flow...from just a dirty used OEM intake manifold...and a brand new/untouched/non-EGR-dirtied intake manifold...

I'll update later, but I suspect that a new intake manifold (new stock or new ported) is going to translate into a fair amount of efficiency gained.

off the top of my head, I think we gained 30+ CFM flow in going from stock dirty to stock clean...

 

[RedRice589]

Good to know! Thx ported could even be a tad better....?

 

[WILD_PHIL]

I'll reply simply to add data...

2008 2WD regular cab... @ 150k miles. 13.0-13.6mpg hand calculated in mixed 50/50

DPF/Cat delete...stock injection system/turbo hardware..has minor tweaks (MCC) to H&S tuning.

**

I was stunned at how poor the fuel economy is..hell my 7.3L 4WD Excursion with BIG injectors & turbo, etc get's better mpg than the little/light 6.4L.

though....

we have been doing a LOT of R&D work on our cylinder head flow bench..and there is a HUGE loss in flow...from just a dirty used OEM intake manifold...and a brand new/untouched/non-EGR-dirtied intake manifold...

I'll update later, but I suspect that a new intake manifold (new stock or new ported) is going to translate into a fair amount of efficiency gained.

off the top of my head, I think we gained 30+ CFM flow in going from stock dirty to stock clean...

Any updates Golf?

 

[Motostroker]

I get 10-11. Sitting on 37s. Deleted, tuned, and tow powers. And every air upgrade known to man kind

 

[WILD_PHIL]

And suddenly im rethinking the 6 inch lift and 37s on mine. Lol

 

[Motostroker]

Haha touché. It's personal preference I guess. I like the look WAY better. So to me it's worth it

 

[golfer]

Any updates Golf?

negatron...

my 6.4 is in the body shop (nothing major, someone hit the fender while I was parked)...

once it get's back, cab's coming off, and the intake (as well as other parts) will be installed...

I've thought about this a LOT...

and aside from the (dirty) intake 'theory'...I think it's equally..and honestly MUCH more likely that the poor fuel economy is simply from these things running 10psi of boost tooling down the hwy...

an equivalently powered (single turbo) 7.3L or 6.0L would be running less than 3-4psi if annnny under those same conditions..

lots of parasitic loss 'driving' a turbo, compressing the air, the pistons' working against that boost (and drive pressure)...to make what...70rwhp to run a steady state 75mph on flat ground??

if I have time before the cab get's yanked..I might start messing with the VGT controls in the MCC software...open those beetches up.

 

[TyCorr]

Thats good Dave because that smaller motor with a state of the art injection system should.be knocking down better fuel economy than its overweight, drooling injection systemed brother.

 

[golfer]

yeah..no chit...

part of the reason I bought it...just a 'commuter' that I can still play with..

 

[WoodBoy]

negatron...

my 6.4 is in the body shop (nothing major, someone hit the fender while I was parked)...

once it get's back, cab's coming off, and the intake (as well as other parts) will be installed...

I've thought about this a LOT...

and aside from the (dirty) intake 'theory'...I think it's equally..and honestly MUCH more likely that the poor fuel economy is simply from these things running 10psi of boost tooling down the hwy...

an equivalently powered (single turbo) 7.3L or 6.0L would be running less than 3-4psi if annnny under those same conditions..

lots of parasitic loss 'driving' a turbo, compressing the air, the pistons' working against that boost (and drive pressure)...to make what...70rwhp to run a steady state 75mph on flat ground??

if I have time before the cab get's yanked..I might start messing with the VGT controls in the MCC software...open those beetches up.

I said something to matt about this. I unplugged my vgt and watched my fuel mileage on the dash go up dramastically. Of course I'm not going to run a whole tank through it with the vgt undone so I can hand calculate it just food for thought

 

[Gearhead]

I said something to matt about this. I unplugged my vgt and watched my fuel mileage on the dash go up dramastically. Of course I'm not going to run a whole tank through it with the vgt undone so I can hand calculate it just food for thought

It is being looked into....

 

[WoodBoy]

It is being looked into....

:thumbup:I didnt figure you would let us down

 

[Strokersace]

Subbing this one as I'm going to be going to a 6.4 within the next year. Coming from a 7.3 I'm used to poor fuel economy. Pulled my horse trailer about a month ago with a bone stock 6.4 and it pulled like my modded 7.3 but was majorly disappointed in how bad the fuel mileage was in the 6.4.

When I get one, it will not be stock, but won't be over the top either. But want better fuel economy or I'm going to keep my modded 7.3.