Chromeshadow

In my experience, a tune can increase both power and mileage by advancing the timing a little. One or two degrees will improve both. I've tuned plenty of cars with adjustable distributors and driven over 500,000 miles on them before and after.
The reason I do not have a tune on my 2013 3.7 is that I trust that Ford used the parameters that give the best performance and best longevity for my engine. I drive my cars about 200,000 miles and I do not want engine troubles. I would consider a dyno tune-only if I can watch and see what changes are being made. Btw, I've tried premium and regular, mileage seems to be the same.
I have a tune in my 2009 Solstice GXP 2.0 turbo. The tune came from GM and did not affect the factory warranty. I can only run premium in this car now tho-so any increase in mileage(if any) is offset by the cost of the gas. It did add 30 hp and a few surprised looks from people who don't know what it is and try to pass or cut me off.

I do run K&N filters in all of my vehicles, I did notice a little improvement in mileage in the 3.7. I believe the car will always pull in the proper amount of air, but the easier it is to pull the air( less work for the engine) the better the mileage. I saved the original filter and put it in for a few days when I clean the K&N. I think Ford (inho) might think using an oil type air filter might create problems with owners who put too much oil on them and mess up the sensors. I wash mine and let it dry one day, oil it and let it set another day and look for runs.

I am very impressed with the 3.7, I get over 30 mpg on the highway and my best 0-60 is about 5.5 seconds. I don't baby it, I usually have a couple of good burn outs on each drive. Whats not to like? 305 hp and 30 mpg on the highway?

cruisin5268d

This x10000000

CAIs are a waste 99% of the time...especially if someone is just going to be putt putting around town

Chromeshadow

Am I missing something? Does this mean I never need to clean or replace my air filter cause there are other losses? If driving with a dirty air filter loses mileage, why wouldn't using a better-easier flowing air filter improve mileage?

Btw, I tried a bunch of tricks on my old 2000 3.8 auto, advancing the timing by rotating the crank shaft positioner sprocket, under drive pulleys, dual exhaust, and K&N cold air kit, my best mileage was 31.6 on two consecutive tanks,calculated manually, driving 80 mph through Iowa. This model was rated at 27 on the highway, probably at 60 or 65 mph, not at 80 mph, so this is a pretty big improvement.

yourmom6990

Agree 100%. Some people are simply bigots.

Art161

I could be wrong here. If so, I hope someone comes along to correct me.

I don't think a somewhat dirty air filter reduces your gas mileage on a modern car. The computer adjusts the air/fuel mixture to optimum.

Obviously, you have to replace the filter at some point. You don't want chunks of dirt getting sucked into the engine.

Performance is a slightly different story. In "normal" driving, a somewhat dirty air filter doesn't matter. It does matter if you live at WOT. The reduced maximum air flow will reduce performance.

jz78817

Strawman. try to be reasonable, and preferably respond to the things I actually said and not what you wish I said. yes, eventually the air filter can get dirty and clogged to the point where the pressure drop across it will start to negatively affect performance and economy. It's got to get really dirty to get to that point, though.

if the stock parts flow well enough where they don't present a significant restriction to the engine, making them freer-breathing isn't going to get you anything. at wide-open-throttle (WOT) and at redline of about 6,000 rpm, the 4.0 needs about 424 cfm of airflow. But if you're cruising down the interstate at 2200 rpm in 5th gear with the throttle open only a little, the engine only needs at most 155 cfm of airflow- probably less than that due to lower % cylinder fill. so if the stock airbox/filter/duct setup can easily flow 424 cfm, it's not going to be a noticeable restriction when the engine's only demanding 150.

where a CAI can help you is if you're trying to make more peak power. once you're at or near WOT the pumping losses of the throttle are pretty much gone, so now the upstream stuff is worth modifying.

yeah, but there are still uncontrolled variables in play. you don't account for wind speed/direction, road grade, temperature, etc. I would expect any car rated at 27 hwy to do better than that at a steady cruise. The EPA ratings that go on the sticker aren't measured at a steady cruise. My '12 5.0 is rated at 26 highway but at a steady 65-70 mph on relatively level roads it can turn out 28-29.

Chromeshadow

JZ, this may come as a shock to you, but most of us on this site believe we can improve almost every aspect of our Mustangs, speed, handling, appearance, exhaust and sound systems. I think you should loosen up and have fun with your cars or sell your Mustang, if you actually own one and get a Volvo.

PNYXPRESS

I will say from experience with my 3.8l and with my 4.6l that adding a k&n filter WILL increase the fuel mileage by 1-3 mpg. I also know that when I went to the BBK CAI with 93 dyno tune I lost mpg with the 4.6L

Also going duals on my 3.8l. Caused a slight loss of mpg due to loss of back pressure.

Not sure if the 4.0l reacts the same way though

jz78817

where have I said you can't? I'm only saying that in this specific situation, the proposed modifications probably won't help. You really have a knack for putting words in my mouth.

that's original. I'm actually looking for a motorcycle; I don't think Volvo makes those.

highly unlikely the filter gave you that. With all of the CAFE pressure on automakers, if a slightly more expensive air filter would return a real 1-3 mpg improvement, they'd be on all production cars already. we as humans are prone to "confirmation bias;" if we expect an action to have a certain outcome, we'll unconsciously do things to try to reach that outcome. In the case of trying to get better fuel economy, if we change or add something to our cars in hopes of better mpg, we often subtly change our driving habits, almost always without realizing it. It's the change in driving style that gets you the improvement in fuel economy.

PNYXPRESS

Oh I didnt know you were an all knowing, all seeing mustang god. Have you ever owned a 3.8L new edge mustang or a 4.6L with only a K&N filter and no other mod.

If you actually knew anything about CAFE standards then you would know it isnt just about gas mileage and power. Cars are tuned for optimal emissions at the sacrifice of fuel mileage.