My Experience With Backpressure

chakis24 · September 20, 2010

well, as some of you know a few months ago i lost one of my exhaust pipes due to it literally rotting away. i had a custom shop redo my exhaust about 3 or so years ago and well now its gone- as is the shop the did it (which may explain a thing or two). that thread is here: http://www.gm-trucks.com/forums/index.php?...xhaust+fell+off

that was about a month and a half ago. to summarize: i was glad it did. my mpg's went up, and the truck seemed more responsive. i credit this to the crappy custom shop doing a terrible design on my exhaust- the pipe that fell had 10 bends in it, a few of them 90 degrees to make it fit around the spare tire.

fast forward a few weeks and the second fell off. go figure. on my way camping upstate (with the quad in back) all of a sudden i hear this banging- and i think its the front end. look under and nothing, so we get there and the next morning i see the tip isnt really aligned the way it usually is, so i give a touch with my foot and the whole thing pivots. great. so now i have no pipes, and it rotted off weird so i have a 3.5 inch outlet (because the first fell off right at the muffler) and a 2.5 inch out (because the second fell off after the adapter that was welded on to bring down the pipe size).

at first i thought things were cool- but then i started noticing mpg numbers....12-13 highway!!! my responsiveness and passing power was gone, i just couldnt believe the effect. now, with both pipes i was averaging 13.3 mpg per the DIC (which is low because i never calibrated with the bigger tires) overall over an extended period of every type of driving. with the one pipe gone i was up to 14.8 on my daily commute...but with both out under 13. terrible.

so, i couldnt let this be. so i bought some of that exhaust aluminum and tape at auto zone and patched up the end of the 2.5 inch outlet as a temporarily permanent fix. my mpg's are now over 16 highway, high 14s on my commute, passing power is back and i couldnt be happier. its only been a few days- but im quite happy with the way things are turning out.

lesson learned, finding the right amount of backpressure is key.

Eddie 70 · September 20, 2010

Hmmmm

chakis24 · September 20, 2010

Hmmmm

haha, its not that ghetto. and its at the muffler so you cant see it unless you get underneath.

tanked_darren · September 20, 2010

I've had some cars in the past where the muffler rots or falls off or the pipe after the cats rots, its amazing the difference it makes when you replace it all, even on a 4cyl.

Eddie 70 · September 20, 2010

Hmmmm

haha, its not that ghetto. and its at the muffler so you cant see it unless you get underneath.

Sorry I couldn't resist. I have been saving that picture for most of the summer.

When I was a teenager I was out on a date with a new girl I really liked. I had an old car but it ran pretty good and looked nice. While on the way home, the exhaust broke just after the muffler and the pipe drug the ground. It sounded like the car was coming apart. The muffler would bounce off the pavement and hit the bottom of the car and back to the pavement. I don't remember how far it was to get her home but I can remember thinking I it seemed forever. The next morning I took a hacksaw and cut the muffler off and made it straight pipe on one side. LOL!! It really was loud then. New exhaust and the car ran and felt like new. The girl went out with me again, for about 3 years!!