Improving mpg.... - Diesel Forum

hoseclamp · 02-24-2013, 04:28 PM

Thinking of the afe intake with a dry pro7 filter and a DPF-back pipe with muffler, no programming. Thoughts on if there would be mpg improvements? Trying to gain some mpg back with ssr's installed, lost approx 1.5mpg with bigger tires and lugs. It just looks awesome with them! Thx.

ShumpH15 · 02-24-2013, 06:16 PM

IMO I don't think you will see anything that will come near recouping the investment.

hoseclamp · 02-24-2013, 06:39 PM

Total cost will be around $800 installed for intake and exhaust. Even a .5mpg improvement is almost 20 miles a tank. If I can gain 1-2mpg I would be happy for sure. I love the ssr's

Hdslider · 02-25-2013, 06:17 AM

Your not going to see mpg gains. You will hear the turbo a bit more. And like said you will see a lose in the pocket book.

hoseclamp · 02-25-2013, 01:55 PM

Well that blows.

TXF-250 · 02-25-2013, 05:10 PM

you'll definitely be wasting your money on the air intake. it's been proven that the stock intake flows enough air far in excess of the horsepower a chipped motor is capable of producing.

the exhaust...maybe...but it would be minimal. you're really not removing that much restriction by taking out the muffler. The real restriction is the cat and the dpf...but to remove that you've got to get a tuner to reprogram the computer

keep in mind...you tamper with emissions equipment, you're dacing with danger on keeping your warranty.

hoseclamp · 02-25-2013, 07:49 PM

No way I'm tampering with the emissions, I don't want to deal with that. I did another run on the highway again, comparing tires and mpg returns. 235/70-17 winter tires, 31.9" tall, were 15.8-16.0mpg, 35/10.50-17 ssr swampers were 14.4mpg, 285/75-17 nitto terra grapplers, 33.86" tall, 14.7mpg. That really surprised me. I might do a dpf back and intake anyway, just to see. Tune not important, has gobs of power anyway.

mmomega · 02-25-2013, 08:06 PM

I'm wanting to say the last time I did the math, that IF I spent $1,000 on a programmer + intake and IF I could gain +2mpg (which is a lot) I would have to fill up 71 times gaining 2mpg /tank to even break even on the money I spent.

...and you aren't guaranteed any mileage gains

hoseclamp · 02-25-2013, 08:26 PM

Quote:

Originally Posted by mmomega

I'm wanting to say the last time I did the math, that IF I spent $1,000 on a programmer + intake and IF I could gain +2mpg (which is a lot) I would have to fill up 71 times gaining 2mpg /tank to even break even on the money I spent.

...and you aren't guaranteed any mileage gains

Agreed, but my calculations are a bit different as are costs for fuel, regardless It really isn't the savings, much like spending huge bucks on led and fluorescent lighting at home, it's just to use less.

ViperKiller · 02-26-2013, 07:16 AM

By adding a intake and DPF back exhaust, the maximum MPG improvement that you "could" achieve will be statistically unresolvable.

i.e. if your mods produce a .10 MPG improvement (which is generous IMO) you will have that much fluctuation in your MPG from other variables (such as seasonal climate changes, quality of fuel, driving characteristics, etc)

I would like to see one of our 6.7s put on a engine dyno, holding all the other factors constant, to see what efficiency an intake and DPF back exhaust would actually produce.
Even then, I think the error in the testing equipment would be greater than any realizable gain.

Sorry, i'm a little cynical towards the aftermarket vendors claims of "increased MPG" based on biased and statistically indeterminate data.

gearhead1011 · 02-26-2013, 09:35 AM

Something to think about. I don't see any mention of correcting for speedometer error for the tire size change. The speedometer and odometer are going to be off because of the tire size change. There is roughly a 6.5% difference in the tire size which means the odometer and fuel economy is going to be off by 6.5%. The way I figure it the actual MPG if you allow for a 6.5% odometer error you are actually getting about 15.4 with the bigger tires. So you have only lost about 1/2 MPG for the increased drag and gear ratio change for those tires.

TXF-250 · 02-26-2013, 01:21 PM

Quote:

Originally Posted by gearhead1011

Something to think about. I don't see any mention of correcting for speedometer error for the tire size change. The speedometer and odometer are going to be off because of the tire size change. There is roughly a 6.5% difference in the tire size which means the odometer and fuel economy is going to be off by 6.5%. The way I figure it the actual MPG if you allow for a 6.5% odometer error you are actually getting about 15.4 with the bigger tires. So you have only lost about 1/2 MPG for the increased drag and gear ratio change for those tires.

VERY good point. I completely forgot about this. If you really want to calibrate it correctly, you'd have to go and get the computer reprogrammed (which a dealer might be able to do?) or buy a little add on that compensates for it.

Your mileage might not have suffered as much as you think?

hoseclamp · 02-26-2013, 03:29 PM

I have calibrated for all tire sizes, and verified with GPS.

Willie77 · 02-26-2013, 04:59 PM

Earlier in the post, several people mentioned possibly installing a DPF back exhaust.

Is there any possibility that the installation of the aftermarket exhaust, even tho it is DPF back, would/could void the warranty? Could the dual tip w/ cooling cut-outs be considered emissions, and thus removing it could void the warranty?

Ty1 · 02-27-2013, 08:05 PM

It depends on your dealer. The dual tip with the cooling cutouts is considered at least in the 6.4 owners manual a "functioning" part of the DPF system. I'll leave that to you to think about, but if it's called "functioning", chances are that if the dealer isn't easy going that it could void the warranty.....chances are that it would affect the DPF in slight ways.