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bigger injectors=better fuel economy?

19K views 17 replies 10 participants last post by  twoicebergs 
#1 ·
so ive been reading alot of "build" threads lately because i plan on studding my truck in the near future. alot of guys are sending injectors out to be serviced and upgraded while they are in there and are picking up some mpg. why is this? im relatively new to diesels (this one is my only one but have been doing all work myself for the past 3 years). my injectors have about 105k on them so getting serviced is in the plans but should i have them opened up to say 155s while im at it? im not after every last hp from this truck, but if i gain some that wouldnt hurt either. so can someone explain why you would get a fuel increase with more fuel flow? thanks
 
#2 ·
More power or HP/Torque = better Mileage.

The thought behind that equation is that with more power you need to use less throttle (or "fuel") to get the same result.

Like with stock injectors, if you use about 40% throttle to enter the freeway, then with a larger injectors you should only need about 35% throttle applied... Does that make sense?
 
#7 ·
I think it's more a sum of all the new parts that show a gain in MPG.
This is the best answer. There are so many variables to improving fuel consumption, but the goal of bigger injectors is HP and torque. Both of those use more fuel. However, if you are gentle on the pedal and have "new injectors with efficient nozzles" your fuel economy should go up when compared to dirty and worn nozzles. The biggest gain to fuel economy without changing aerodynamics is in the tune. The tune that can extract the largest power from smallest amount of fuel in the cylinder without grenading it, will also improve mileage, but may actually create an emission problem. :doh:
 
#8 ·
so if i upgrade injectors what is the best route to take with a stock turbo, 155s 175s? again im not doing a performance build just updating parts with more reliable ones but if i can get a little more power for a few bucks than so be it. the turbo in this truck will most likely never be changed unless it craps out and then i would just put a mtw stage one at most.
 
#11 ·
#10 ·
Anyone ever put thier truck back to stock and drive it? Rarley I bet but, notice how loud the exhaust is? Rpm's are high. Like mentioned more power, especially down low, less required to move the truck.
 
#16 ·
Yes Jwsland!! I Have Put My Truck Back To Stoc, It Takes Alot More Throttle To Get Her Rolling!!!
 
#18 ·
You guys are killing me! Pedal position is a function of your foot. Fuel metering is a function of the PCM reading all the sensors, including the APS (fuel pedal) and coming up with a fuel schedule to feed to the FICM so it can give instructions to the IPR along with fuel metering (injector timing and PW). If you have a tune, it may place more emphasis on early APS movement, which will only affect your foot to seat of the pants feedback. If you produce 200 hp fuel metering at 1/4 APS position it is the same as 200 hp fuel metering at 1/2 APS position. It also might make it more drivable and give you better fuel economy, as you are less likely to over-fuel the acceleration. I can almost guarantee that if you drive with your ballet slippers on, you will get better MPGs!
 
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