I am in the process of installing my 4.10 regeared differentials so I am not able to comment on the effect on mileage yet.
Right now with my larger tires and stock 3.55 gearing I am averaging 17-18 MPG with mostly highway driving. I have some long hills in my area so getting up to highway speed and maintaining it seems to have the greatest effect on my mileage compared to the smaller stock tires I ran. With the stock tires I would see 19-21 mpg or better under the same driving conditions. It is my hope that I can achieve 20 mpg or better with the new gears installed.
I have not dynoed my truck and really don't have any intention to in the near future; my greater concern is obtaining the best fuel economy I can with the larger tires. I will be doing some mileage testing that will compare different intake configurations. I plan to do it during the month of July once my new gears have been broken in properly.
I would be interested in seeing your dyno results with the KKM. Being that it is exposed to underhood heat (especially in your climate) I suspect it may result in a loss in power due to the air charge being less dense. However, t is my hope that the heated air charge will also have the effect in improving fuel economy (heated air = less dense air = less fuel needed), provided the vehicle's computer does not reduce ignition timing to compensate for the higher intake air temperatures.
My observations so far indicate that at highway speeds, the KKM results in intake air temperatures being up to 10 degrees F above ambient temperature. At slower speeds or driving in traffic, that temperature rises substantially.
My testing that I mentioned will involve driving the same route (around 25 miles per trip) to and from work on highway and surface streets with various intake configurations. I plan to perform 10 trips with each configuration to try and get a rough average so that I can get an idea as to which configuration offers the best fuel economy improvements. I will refill the fuel tank and reset the computer between testing each configuration.
The configurations I will test will be:
-Stock setup and a new stock filter (as a baseline)
-Stock setup with a K&N panel filter
-Stock setup with a K&N panel filter and the headlight intake duct removed
-Stock airbox with a K&N panel filter, headlight duct removed, and replacing the stock intake tube with a smooth metal one of about the same diameter
-KKM with the stock intake tube
-KKM with the smooth metal intake tube
Hopefully this will show some trends that indicate how these modifications might impact fuel economy.
If you have suggestions on this testing I would welcome your input.
Hay Ronin8002 I would like ask you,
how is your mileage with the 4.10?
and did you dyno your truck?
my dyno with all mods and torque tuning (before KKM and hi flow cat)
91 octane = Max power 182 HP and max torque 239 ft-lbs
and the same tuning
87 octane = Max power 179 HP and max torque 236 ft-lbs
the stock dyno
87 octane = Max power 168 HP and max torque 201 ft-lbs
I'll make another dyno tuning with the KKM and hi-flow cat soon