Yes, I know that we don't buy and drive trucks for the great gas mileage. I just want to make sure that I don't keep doing things that make it keep going down.

My first mod was the exhaust. I put on a cat back Magnaflow. I chose magnaflow because I read many times that it was the one to get for towing power and increased gas mileage. My gas mileage before that mode was about 14.5. After that it was 13.9

My next mod was changing out my 305/50/20 wheels and tires for 295/70/17 all with a level kit. I "thought" that by going from a heavy 20" rim to a lighter 17" I'd be doing better. I also thought that by going from the 32" height of the 305's to the 33" (closer to stock) height of the 295/70/17 I would be getting better mileage. Now I'm looking at about 12.5mpg.

I will want to do more to the truck as time passes, but I don't want to keep killing my MPG.

Mods I want include: Superchip, CAI, e-fan and possibly gears (have 3:92.. not sure if it's worth it.)

Most of what I've read suggests that all of those will not kill (and possibly improve) MPG.

I'm not doing any of this FOR the increased MPG. I'm doing it to get better response out of the truck. I just don't want to keep going backwards.

Thanks,

 

e-fan will be the most noticeable gain

 

that and gears but coming from a 4.7l i have done all of the above and im still beating down 14.5 all day when i straight get after it of coarse it goes down but what do you expect...im sure the reason you see a drop on mpg's after an exhaust is the fact that you gun it a lil more than you prolly realize just hear that roaring sound.....

 

Did your computer get reprogrammed to recognize the new, larger diameter tire size? If not, your odometer will be slightly under-reporting your actual distance and you'll be computing your mileage from a false number. It isn't much but every little bit helps.

 

stock size is 33in so he is fine...

 

Good point. But that means that his odometer with the smaller non-stock tires was overstating his driving distance and so that skewed the mileage to calculate slightly higher than it actually was. Now he's back to normal.

Wouldn't hurt to check the odometer against a GPS or the measured highway mileage markers. Do it over about 10 miles or more so that you can see any small error that might exist.

 

hmmm... so perhaps I never REALLY was getting 14.5? I'll do the mile marker check next time I jump on the highway.

 

are you hand calc the mpg's or watching the overhead, some say the overhead is wrong...i myself have never hand calc the mpgs i just watch it to see how much it changes if any....

 

Yes, those numbers that I quoted are from hand calculating several takes of gas before and after each mod. My overhead now says that I am averaging 13.8, but I know that is for all time since I bought the truck. I reset it when I bought it and am letting it play out.

 

i reset mine after each oil change and mod and when i got it it said 12.3 so i think im doing good, dont let anything stop you from doing these mods all combined together im very pleased with my 4.7l and btw i have a club in the club section called the 287crew come join just click the link in my sig its for us 4.7l owners....