Generally speaking from what I have seen on my vehicles as well as othersadding the correctperformance modscan give you a much better mpgwhen drivennormally (and by normally I do not mean racing it up and down the highway tring to set land speed records or gunning it at every light/stopsignyou come accross).

 

In theory, a lot of performance mods will increase fuel economy. More HP means you can drive at a given speed with less effort (and gas). However, I've found that the weight of my right foot increases in direct proportion to the increase in HP my mods attain...[&:]

 

Hammer not always, look at high perf cars, they're gas guzzlers.

 

But the question is still out there...Will everyday city driving in the tow/haul mode have any long term negitive effects to the tranny????

 

no, its a truck, some trucks ne we have their trailer removed and will always be in tow haul.
Now if yer using tow haul to get a boost and hitting the pedal a bit harder the. Yeah it'll be bad.

 

For those of you that are interested I found a gear ratio calculator online and ran a few numbers.

3.55 gears at 2100RPM with .75 trans. ratio (4th gear) = 71.5 MPH with my tire size

3.98 gears at 2100RPM with .67 trans. ratio (5th gear) = 71.4 MPH with my tire size

So it looks like I can use the Tow / Haul and it would be like changing to 3.98 gears. It will not be as good as 4.10's or 4.56's but it is the push of a button and does not cost me the $1200+ for new gears. Again this is my daily driver and I am not interested in racing it or I would go for the gears. Since I am only interested in MPG right now and I can buy alot of gas for the price of gears I am going to continue this way and add a CAI and exhaust and see how that helps. Right now it looks to have added about 2MPG for me but it has only been a few days.

 

Keep us posted and do the numbers by hand next time so we can see the real deal and not off the lie-o-meter that the truck gives us.

 

I will be doing actual MPG calculations by hand before any mods go on it. Right now I have reset the electronic meter about every 500-1000 miles and it has never been more than 15.5 and the average has been about 15.The lowest it has been was 13.4.I have 56K on my truck so that is pretty consistent. If the computer keeps showing the gains I will do a few tanks by hand and give the actual MPG.

 

I just bought a 08 Ram 1500 with the 4.7. I am getting 5-8 miles per gallon with a 2800lb load. WTF is wrong. The dealership says it needs to break in. So when it breaks in am I going to get 10 or 11 miles per gallon. What the hel do I do?

 

There is plenty of data out there, so let's separate fact from fiction.

(1) The lower the rear ratio, the better the gas mileage on the highway. The manufacturer would not put in a 3.21 if there was not benefit they could claim. Most of today's engines run at the best fuel consumption at the 1800-2100 rpm range. This is due to the relationship of piston speed and friction.

(2) The higher the ratio, better the fuel consumption in stop and go (city) due to the required horsepower needed to accelerate a 5500-6500 vechicle. The torque doesn't start building seriously until about 1500 rpms. RamItOne was spot on the comparision to a bicycle. Additionally, if you are hauling or towing heavy loads, the higher ratio is even more important that it will improve drivability and save the transmission plus improving mileage even more.

(3) The tow/haul versus the OD lockout holds each gear longer. The effect on gas mileage would be so small not to make a measurable difference. Yes, by shifting up at a lower rpm should have atheorical benefit. Here in northwest Jersey mountains, the tow/haul button is used when going up or down. Going up it reduces the transmission from wandering, keeps the engine in the power band longer and should save you a few drops of fuel. To me, using it going down is more important in that the increased engine braking saves the brakes and the overheating the rotors and the related warpage.

(4) A free flowing exhaust "can" increase horsepower in the higher rpm band. Great, but it comes at the expense of lower torque at the lower rpms. That is where most gas is used trying to get our 3 ton brick moving (item 2)

(5) The most efficient methods are the tried and true. Proper maintenance, correct or superior lubicants (not the stuff that you used to see only on late night TV), narrower tires with lower rolling resistence and drive like you don't have a license and you are scared of getting caught.

It's just like taking care of yourself, if it feelsor tastes too good, it's most likey is not good for you.I got the hemi for a reason and I am going to do it "once in a while."