vertical exhausts

[CanadaLT]

A guy I know has two Ford ranger trucks and he tracked the fuel economy of both for a few months. He then made a vertical exhaust, like the big rigs, for one truck and his economy went up about 4%. Has anyone else done this?

[euromodder]

Did he maybe cut down the back pressure as well while doing so ?
Remove the catalyst, silencer or stuff like that ?

[Daox]

Changing the exhaust can and will alter fuel economy. Making the pipes vertical has nothing to do with it.

[RobertISaar]

i might be able to believe it. designed properly, the air running past it while driving at a significant speed could generate enough of a vacuum in the exhaust to relieve some load on the engine during the exhaust stroke.

4%.... not a huge change, that would be the difference between 25 and 26MPG, if the average ranger(and driver) is used for an example.

[spacemanspif]

May have reduced back pressure. Many posts about Rangers doing better with a more free flowing exhaust. Depending on the way the tips are cut, there may be some scavenging from the air passing over it, thus removing even more back pressure.

[cRiPpLe_rOoStEr]

Did he delete the silencer when he stacked the exhaust?

[freebeard]

Signal lost in the noise. Needs A-B-A testing.

[Frank Lee]

Needs a-b-a to make that claim. Also need to see logs to see if fe was steadier than +_ 2% before. Otherwise, we know unless the exhaust system was really messed up to begin with, changes to it really don't amount to much fe wise, even though the added noise provides so much pleasure that it alone is worth it. Let's hope the next mod is to cut the stacks off at about driver's ear level, or better yet turn the pipes in towards the cab.

[markweatherill]

I always liked those hinged caps on the tops of big truck exhausts. Or were they on steam trains?
I expect the exhaust system has lost a fair few feet of piping anyway.

[Fat Charlie]

Aha! It's a weight savings move.