Sensible upgrades

I have an 03 1500 quad-cab 5.7 4x4. As all know, it gets crap gas mileage. It also has ~50 HP less than some newer model 5.7s.
1. What did Dodge do to bump the HP on the 5.7?
2. Typically, I add headers, larger exhaust, and a cold air intake to bump performance AND mileage. Any recommendations as to other upgrades that will increase HP while also increasing gas mileage?
3. Will underbody panels decrease wind drag (thus increasing economy)?

My goal is to see if I can pass the 400 HP mark while increasing gas mileage to 20+ hwy.

I've seen a dodge magnum with a stroker kit with over 400hp and get almost 26mpg on the highway. But that car weighs a bunch less than or trucks. You're going to have a hard time getting that much Hp with decent gas mileage. Eventually, as hp goes up, ur mpg will start going down since you'll need more fuel to get that motor going.

Things like proper tune up and weight reduction will help your mpg. Going easy on the mods MAY help, but there's no guarantee. Better flowing exhaust, a warm air intake, and a tuner would possibly increase your mpg. I say warm air intake, because as I understand it, warmer air takes less fuel to ignite while in the combustion chamber, therefore less fuel. Cold air intakes theoretically require more fuel, thus more HP. That being said, air intakes on our trucks are hardly anything more that aesthetic mods, at least on anything not highly modified.

Good luck with your endeavors! If I forgot something, or messed up on my facts (entirely possible lol), someone please correct me!

HP/TQ gains were largely made from refinements to heads/intake. Someone ought to be along to detail the fine points of the changes.

Other mods? Don't know, as my truck is just for work. If you haven't already, you *might* eke out a tiny gain with synthetic fluids.

An underbody pan? I don't think it's going to give back anything, especially when compared to cost/time for fitment. A deeper air dam might give some of that effect, I'd think. Our trucks sit tall, so lowering ought to help.

I think it might help to clean up the front, though. The center of the bumper with the insert that most use for lights or extra cooling would probably flow air across the front better if it was convex. I read a story about the 2G Chargers of the late '60s getting their butts handed to them on racetracks due to the recessed grille opening. Charger 500s brought the grille flush with the leading edges of the fenders and did away with the "flying buttress" roofline via a smooth back window. Later, it was determined that still wasn't good enough and then came the Charger Daytona with pointed front cap and rear wing.

I put a full exhaust and a tune on my 03 Hemi, got some more power but mpg didn't move. Still at almost exactly 11.8


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Teligence said:

I have an 03 1500 quad-cab 5.7 4x4. As all know, it gets crap gas mileage. It also has ~50 HP less than some newer model 5.7s.
1. What did Dodge do to bump the HP on the 5.7?
2. Typically, I add headers, larger exhaust, and a cold air intake to bump performance AND mileage. Any recommendations as to other upgrades that will increase HP while also increasing gas mileage?
3. Will underbody panels decrease wind drag (thus increasing economy)?

My goal is to see if I can pass the 400 HP mark while increasing gas mileage to 20+ hwy.

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1. VVT (variable valve timing), heads (eagle heads are more like 6.1 heads valve size and port config wise), more cam timing with tuning to match, more compression and an active intake manifold (internally switches between long and short runners). The intake works because the same engine (390/395 in trucks) in an LX/LC car is rated 370/375.
2. Tuning, whether it be canned or custom will work well with all of that.
3. Not really, especially on a truck lol

You can easily hit the 400 mark with your stock heads, but after your good exhaust (to include headers) you will need a cam. With the double OD in the trans as long as you keep you foot out of the firewall you will still get ok mileage. Remember, this is a truck, a heavy truck lol. Not a much lighter car.

Just put a K&N on this weekend - much noisier under medium to heavy acceleration. I'm assuming that it's mostly due to the removal of the "resonator" box between the throttle body and the air filter?

I've yet to get it on the highway to determine any noticeable improvement in mileage...

Teligence said:

Just put a K&N on this weekend - much noisier under medium to heavy acceleration. I'm assuming that it's mostly due to the removal of the "resonator" box between the throttle body and the air filter?

I've yet to get it on the highway to determine any noticeable improvement in mileage...

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From what I've read you are correct about the resonator but as far as an increase in mpgs you won't really see anything. At least I and a lot of other people haven't. The noise you get out of it is nice though.

Easy question what size wheels and tires do you have on it? People do not realize how much these will suck down fuel mileage.

When was the last tune up, plugs and such?

WilliamS said:

Easy question what size wheels and tires do you have on it? People do not realize how much these will suck down fuel mileage.

When was the last tune up, plugs and such?

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This is true! I lost around 1 mpg after getting new tires put on.