Any truck drivers willing to do an exhaust experiment?
 

Weight and backpressure generally is what i'm curious about here

It'd be great if you had a scan gauge or something to add to the test

I was just wondering about if any of these will change fuel economy

1) Stock Exhaust
2)Stock exhaust with turndown at axle
3) Aftermarket muffler with turndown

This might not make much of a difference but it'd be different to see if it makes ANY

I'm thinking it probably would on a newer Dodge truck since they have that second big resonator at the end

But once again would anyone with a truck be willing to do this expirement

Why truck?

Please stop dude. We've established this stuff already. Lower weight will get better gas mileage, but you won't lose that much with exhaust. And the stock exhaust flows fine.

How you gonna do a turndown at the rear axle unless its like an older style mustang or something like my el camino where the muffler is before the axle. I was just saying truck because almost all trucks exhuast are like this

mustangs up to 2004 use the same set up, and I can hardly call them old, as a matter of fact, I am using aftermarket muffler and a turn down on my 00 stang as of right now. Stock muffler was maybe 2lbs heavier, and stock tail pipe was another 3lbs or so. 5lbs wouldn't make a difference in a 3000lb car/truck

i was just wondering the exact effect it's like flat pan hubcaps and wheels it was a 4.6 % difference on the metro on here at 56MPH but that's still registered as a big accomplishment . Same as blocking offf small areas like lower grilles and areas where fog lights etc. are

That's why i said old ER ;)
Did the turndown with the new muffler affect your mileage at all or did it stay the same?

the turn don't matter today.
a tiny engine and carbed is something to notice, but today? who cares. It will do nothing.

I did affect the mileage, I lost 1-2mpg in the city, car felt like it lost some bottom end, I got little more power on the top end ( not much), but loss of bottom end torque makes the car feel more sluggish, which requires more throttle feedback. I kind of knew that I was going to get which higher flowing muffler, but listened to some people that said, less pumping losses, sure:rolleyes:. That's ok, I am working on another exhaust set up that should put me where I was before and than some, can't wait for more bottom end torque.

Exhaust sizing and backpressure makes a big difference.
The better non-Harley motorcycle sites will have lots of info.
To put it briefly, "drag" shorty pipes on a bike give great top end but are beyond sluggish off the line. Ever notice how crappy a bike sounds with them around town?
There are several online exhaust calculators that will easily show you the changes. Bigger dia. pipes can actually hurt your power and economy due to slowed velocity of the exhaust gas. Then theres the whole pressure wave timing calculations to play with, trust me thats what computers are for!
For the street, stick with a good muffler, stock size exhaust, and non-drag headers and you will be fine.