I recently got some new goodies on my truck. I added some 40 horse power over stock injectors, ARP head studs, EGR delete, and an SCT custom tuner.

I was wondering if the injectors would lower my fuel economy since they are bigger than stock. So far I have had it on my performance tune which adds about 135hp to the truck. I drove about 60 miles and used a quarter tank about 40 miles was highway and the rest in town. I have a 29 gallon tank in my truck.

Is this normal or should i be getting better fuel milage ?


Thanks for your help

 

from my math that seems to be around 8 mpg. How hard do you drive it? and what highway speeds? And you should prolly do the whole tank before trying to figure it out.

 

on the highway i was doin about 75 maybe 80 and i dont drive it too hard ill just give it a few stomps every now and then. i just turned down the tune to my economy tune which is an 85hp add vs the 135 for the performance tune. so im gonna see how that runs for a bit.

 

From just about everyone on here that talks about what tune to run and mpg, they have said that they get some of the best fuel mileage out of the performance tune. Im sure mike will be here to answer this more in depth here pretty soon.

 

I have bigger injectors on mine will that affect the mpg ?

 

the bigger injectors should probably help out the mileage, if driven properly. need to do a full tank test to figure out mileage, if I top my 29 gallon tank off I can go for 100 miles before I even see the needle move, I normally go 500 miles before fill up and still have about an 1/8th tank left.

 

I recently toped off the tank and wrote down the miles I'm gonna see how many mile I can put on the truck till I have to fill up again. So far its on the street tune which is my mild tune and I'm gonna see how many miles I get with this tune then I guess I'll try the economy tune. Then maybe my performance tune which is my highest.

I guess I'll just have to mess with it for a while

 

How are you topping the tank off here? You can't just run the pump til it clicks, do you know this? It's not exactly widely known.

Who's tunes are you running?

Who's injectors? What size? Most good 6.0 injector builders don't advertise with HP ratings they give the CC size (body size of the injector) and the nozzle % size over stock. So stock injectors are 135cc/stock and an upgrade would be a 155/50 meaning 155 cc's vs the stock 135cc's and 50% larger nozzles than stock. Etc etc...

With a GOOD set of injectors, and proper tuning, as long as you keep your foot out of it, and you have a decently matched turbo, mileage should increase. You should be making more power earlier, so it should be easier for the truck to get up to speed etc, so less throttle required means better mileage usually, but I wouldn't mod it expecting to get it... if it stays the same or increases a touch, be happy.

So we really need to know about the injectors/tuning/turbo here... Who did the work?

8mpg means something is wrong. I'm going to chalk it up to not calculating mileage correctly for the time being.

 

The injectors are from Pensacola Injection they'er 40 hp over stock the tuning was done by sinister diesel i bought all the stuff from mkm customs and the turbo is the original stock turbo.
And when i topped off the tank I have a gauge on my pump at home that tells me how many gallons of fuel i have pumped and i mad sure i put as close to 29 gallons as i could without it pouring everywhere

 

Ok to properly check milage on a superduty, here's what you need to do:

Fill the tank. Pump clicks off, slowly keep pouring. You've got another 3-5 gallons to go bud. The fuel foams up in the tank and causes it to click off at weird intervals. So you have to slowly pour in the tank until you can see fuel resting in the filler neck, this is the ONLY way to ensure you have the same amount of fuel in there each time. Just because your pump has a counter on it, how do you know how much was left in the tank? Plus you really didn't drive many miles right? Hard to tell on that short of a trip. You've also got 35's according to your sig, has your speedo been updated to reflect that? If not, you're traveling farther than your odometer says, so it's better than what your calculating. So, again, fill up to the neck, drive for a WHOLE tank, then fill up to the neck again, take the miles driven, divide the gallons you put in the tank into miles driven and bam... that is the most accurate way to do it on these trucks. Do it a few tanks, avg it out.

I've heard not one good thing about Pensacola injectors. Usually the stories I read about them are something like "I did all 8 injectors, then 2 weeks later had all 8 replaced again, then two weeks later 6 more, finally scrapped them all and went with OEM Ford injectors".... hopefully not the case, but my heart literally sank when I read Pensacola up there.

Next time, don't buy injectors for a 6.0 that come with a HP rating. It's absurd.

Anyways, lets try and move forward here, "40hp" luckily I know isn't a large injector, but it's still "larger" than stock. What size? Who knows. I would try and ask the guys who sold you the injector. Ask them how you're supposed to get custom tunes for your new bigger sticks if you don't know what size they are, or how big the nozzles are.

You will need an SCT with custom tunes, I'm assuming you don't have them because you ignored that question on me, or just missed it. Either way, you should really be working with a tuner to get your potential out of those injectors (or any larger injector for that matter) in order to harness the new power, and make the trans live with it. Big injectors and no tuning will kill a trans in a hurry.