Fuel Mileage

[jlwelding]

Ok so my sons early 04 is getting 20 mpg and he drives it like he stole it. He is running a bully dog. My 05 auto is getting 15 bearly, I average more like 13.75. Is it in the cam, injectors or what? Why cant this 05 get better fuel mileage? I am thinking of getting a Smarty Jr. or a jet eng. that way I can just fly there and back.

[CSM]

Same weight between the two trucks?

[AH64ID]

Is it getting 20 on the overhead or on the calculator?Early 04 or 04.5?The 03-04's are better on fuel, the pistons and tuning are different. Being an 04 the cam should be the same.

[jlwelding]

His is a 3/4 ton mine is a 1 ton. I know there is some weight diff. but if he would drive it normal there's no telling what it would get. And both trucks are auto's. And yes it's hand cal. I just got off the phone with him and it is a late 03. So I got to ask what the h--- were the manufactor thinking when they changed pistons? And they changed the cam also?

[AH64ID]

Emissions, emissions, emissions..The cam is a debate. I have heard from several knowledgeable cam companies that they have always been the same. I have heard other say they changed in the early 04 trucks. There is only one cam offered from Dodge now. The 03-04's are easier on fuel, but 20 when driving aggressive still sounds too good to be true.

[cajflynn]

03-04 two injection events. 05- up three injection events.

[jlwelding]

yep sure does, I forgot that

[AH64ID]

03-04 two injection events. 05- up three injection events.

Hopefully not for long! EFI already has the ability to take away the 3rd event on the 06-07, and rumor is Marco is madly working it for 04.5-07.

[dorkweed]

I've read in numerous forums that the "3" injections events do not occur all the time. I don't remember when or where it shuts down though................whether at speed, or idle. I just don't recallI wonder how shuting down the 3rd event will work with the 04.5-07 piston design. Didn't they go to that design for the 3rd injection event to help with the emissions???

[AH64ID]

The 3rd event doesn't happen all the time, but enough that EFIlive tuned trucks are seeing about 3mpg increase when it's deleted!It's mostly emissions, with some power.. just deleting it will result in a loss of power, you have to up the main event duration to get that power back.

[dorkweed]

It's mostly emissions, with some power.. just deleting it will result in a loss of power, you have to up the main event duration to get that power back.

Now that you say that, IIRC, it was Marco (Smarty) that was able to eliminate the 3rd event in some beta tests, but did nothing to the 1st or 2nd event, but it had huge effects on performance...........HP and Torque. It makes sense that if you eliminate the 3rd totally and rearrange the parameters of the 1st and 2nd events it would increase mileage. Which is exactly why the '03 and early '04's tend to get better mileage and "less black oil"!!!!!

[AH64ID]

I don't think Marco's testing ever left the dyno, at least not from what I was told... But that was a few years ago, and now there is a new drawing board (and finally some good competition). The power produced by the 3rd event is very inefficient based on the supreme retardation of the timing.

[dorkweed]

I the reason to the multiple events is to lower peak combustion chamber pressures and temperatures for emission purposes. With a single event, you get a huge spike in temp and pressure. If you graph it out it essentially looks like the letter A without the cross part. The area under the "A" being total power.With multiple events, the peak pressures and temps are lower, the the graph would essentially look like the upper half of a circle. The top part of being lower than the top of the "A" on the single event graph. However, the area under the circle is greater than the A, so more power was produced.That's how it was "splained" to me in a nutshell.I'll see if I can find that somewhere.

[AH64ID]

The multiple events do lower cylinder pressure and temp, which decreases emissions. A properly timed pilot and main event can make more power on less fuel than a single event, but the 3rd event just isn't efficient and burns a bit more fuel per hp.