When discussing Cat Back systems and air intake options, all everyone talks about are hp performance gains and the better sound quality. I am planning on installing a Cat back, air intake, and throttle body spacer, but for the reason of mpg gains. I drive 120 miles round trip to work everyday . I have a 2003 Supercrew, 5.4L, 4x2. I've checked many, many web sites and local shops, but they all promote the products they have in stock and don't have comparative info. on the mileage gains of the various makes (Flows/Gibson/MAC/Magnaflow/Borla/Bassani/etc.).
Do any of you know where I can find this information? Can any of you share your experiences related to mpg gains of various systems? I am currently getting 15 to 15 1/2 mpg. Is it realistic to think I can get 18 mpg?

Also, I've learned that the some makes deliver their peak performance at very high rpm (5K - 6K) and others at lower rpm (2K - 4K). If I have to mash the gas to reach the performance gain, I'll probably end up burning more fuel than I do now. Any one know which cat backs provide their gains at the lower r's?

All replies are appreciated. Thanks!

Supercrewser

 

Supposedly the Gibson is made for mid to lower RPM's. That is what they claim in their advertising anyways. I just put mine on today so I don't know the mileage yet, but I will be keeping track. I can't really tell if there is a performance gain at all, mainly because it has been raining all day and the rear tires want to spin. It does seem like they are breaking free with less effort than I was used to which would be a good sign that any power gain might be at the lower RPMs. Will need a few days to be albe to tell though. The sound is great though. Low rumble sounds like a V-8, but not too loud.

 

AG, thanks for the reply. It sounds like you might have something there. Once you've had time to make a valid comparison, I'd really appreciate the feedback. I'm not in any hurry... I'd rather wait and get it right the first time. Thanks again!

 

When discussing Cat Back systems and air intake options, all everyone talks about are hp performance gains and the better sound quality. I am planning on installing a Cat back, air intake, and throttle body spacer, but for the reason of mpg gains.

I still have my stock exhaust system. I'd upgrade in a minute if I thought it would give me anywhere close to an extra 3MPG. Although I understand the appeal of "deep throaty" sound,, I don't really need it on my van. For 3 MPG I'd gladly live with it, but it ain't gonna happen. That is the conclusion I've come to after reading these boards for over two years.

If I knew for sure I'd get 1 to 1.5 more MPG on the HWY + more power in the 1500 to 2500 RPM range I'd spend the money. But I havn't seen the proof. So here I am stuck in "stockville".

As far as throttle body spacers.... an expensive paperweight at best. That is the consensus of the many posts I've read.

I'm putting together an electric fan system and considering opening up my air intake to try to free up some ponies and improve my MPG. When I get it done I'll post my experience. Good luck with your truck.

Bill

 

Bill, 2 years huh? I'm patient, but not that patient .

Yeah, I've heard the same thing about the throttle body spacers. I've heard they can create an annoying howling sound as well. I will probably wait until I have installed all other components to decide if I want to attempt the paperweight.

Currently (stock), I can get 15 1/2 mpg if I keep it at 70 on the freeway on my long commute to work. The trip is mostly freeway with some surface streets. Most of the time, however, I look down and the speedo is nearer 80 (oops).

On a recent camping trip the truck was loaded w/ 4 adults and a piled-high bed. The first 275 mile leg yielded 17.5 mpg's. It was all freeway miles @ 75 mph. The mountain driving didn't fair as well... 13.5 mpg.

So anyway, I'm hoping to increase from 15 1/2 to 18 with the addition of 3 components. Like you, I'll open up the air intake, and then let it breath out the back with a Cat back. And then I'll add a tonneau cover for areodynamics. Unfortunately that won't help your van.

18 or bust!

I'll continue my research into a Cat back system that achieves it's performance boost in the lower rpm range and post anything exciting I find back here.

What's with the electric fan system you're tinkering with? Are there performance gains to be had?

Bye for now.

 

The electric fans reduce the load on the motor, freeing up a bit of HP, underdrive pulleys are another wat to do that. I don't have any experience with either but from what I've heard the performance and mileage gains are noticeable since they directly relate to the load on the motor.

 

If I don't hit 18 mpg with the first 3 add-ons, I might try the underdrive pulleys. I've heard that you need to be careful though with the alternater pulley, as a significant change could cause your electrical system to be under charged. I would most llikely leave that one stock and change the others.

 

I fell for the claims in the magazines when I bought my previous truck (96' Chev, 305, tonneau cover). I added the FIPK and Gibson cat back and I too noticed that the rear tires would break loose easier at stop signs, but the only way I could break 20mpg was to drive 50 mph. There is a tendency to want to romp it more often, which doesn't help mileage. Bottom line: add the K&N filter-don't buy the FIPK, add the cat back and a bed cover/topper and slow down. My current ride: 01' screw: 4x2, 4.6, K&N, 2" lower at rear, is averaging 18.5 in mixed driving. Am going to add a topper and running boards/ground effects. The topper people are claiming 13% mileage gain, but I need the extra space anyway.