A lot of interesting comments here about performance and sounds, but has anyone kept track of the before and after mileage when a performance exhaust is installed?

I'm looking at installing 3 chamber Flowmasters along with a second 2 1/2" diameter tailpipe.
Both pipes terminating at the rear and pointing to the side similar to the stock tailpipe.

Mainly for the mileage improvement in my 02 Supercrew with 5.4L, automatic and 3.55 gears.

As it is, it does quite well in towing.
Pulling a tandem axle car trailer over California's I-5 Ridge Route grades from the San Joaquin Valley into L.A.
Once with about 3600# total car and trailer and the next with about 4200# car and trailer.
Both times in hot weather fwiw.
First time, 101 F. at the bottom of the grade, second time during a heat wave and 107 F. at the bottom of the grade.
I did turn off the A/C prior to the grade and had no overheating problems.

Each time it was able to maintain 60 mph and could have gone faster.
It was also able to recover from 25 mph after getting caught behind a couple of slow trucks.

Mileage is not really too bad as it is, but a bit more wouldn't hurt my feelings.

 

I am on my third tank of gas since installing a flowmaster 40 si/do on my 2002 F-150 5.4L 4X4. I use mid grade and get 14 mpg as of now. I suspect it might increase to 16 mpg but thats all. All city driving with minimal hwy.
I know by installing performance mods the engine is not going to run as efficiant but I guess that the price to pay.
It's also very worth it. I love the way my flowmaster sounds

Future engine mods include an air intake system and possibly a superchip.

 

Considering how simple and insignificant to the OEM manufacturing costs associated with restriction elimination to an exhaust system must be -- and adding that to how much Ford would stand to lose by not providing a truck with the absolute best all around fuel economy (for CAFE/EPA/Noise, etc reasons) -- does it follow that you could see any significant fuel mileage increase with an exhaust system that wasn't obnoxious to your neighbors?

 

Good points Y2K and why I'm asking.

Information from the muffler shops is a touch less than objective and information from other owners can be subjective as well.

The Ford exhaust system as it is doesn't look too bad, but looking at some other brand pickups - and slightly older ones - single exhaust systems it's easy to see that with some of them there's considerable restriction.

What I was hoping was that someone could point me to some dyno tests somewhere.
Tests that were a little objective, but realizing that magazines generally want to please their advertisers, that may be a stretch.

I'll go along with you on the noise bit as well.
Additional noise is not what I'm after.

You sound very much like a Ford engineer.
And if so, congrats on being part of a team that builds a very nice truck.
And if not - the engineer bit anyway - your answer does make me think.

Thanks.

 

I have more questions than I have answers -- and I'd like to know the answer to your question too.

 

I was getting 14.5 mpg when I was using the stock muffler, I added a raven z33 (and left everything else stock) and now I am getting about 17 mpg average (thats a 2.5 mpg increase just from taking the restrictive muffler off, I also noticed a fair increase in power.. how much .. probably only about 3 to 5 HP but the throttle responce also increased so if feels like more.) this is based on in town driving to work and back.. I towed my trailer over the moutian and back and got 21 mpg for that trip so I can say yes I picked up some fuel milage.

Steve

 

That's a very happy story.

Based upon your experience, would you care to offer an opinion as to why Ford hasn't discovered (or provided) that solution?

 

well as far as asteits, it is a little louder (not much) but when you get on the throttle is gets quite loud. the in cab noise is higher (especialy around 2000 rpm) so I would guess that is about 80% of it.. all so you have to look at engin longevity, by restricting the flow you lower exhaust gas temps, so the engin "should" last a little longer, and also with higher back pressure I think it will alow the "cats" and "O2 sensor" to work better as the flow through them will be slower (I am not sure about this one so if some one knows for sure they can chime in). but I think 80% of it is because of the noise issues.. the average person doesent want to hear there mufflers..

Steve