Muffler rusted out and hanging so I broke it off. Should I leave it this way? - Fuel Economy, Hypermiling, EcoModding News and Forum

Bdorion1 · 07-31-2011, 12:23 AM

So I've lurked around here for a long time and finally have a question I haven't seen anything on. So here's the story:

I went out one day to see my muffler hanging off and touching the ground. It had been rusting out and the midpipe looked like swiss cheese so i just snapped it off temporarily until I could have it fixed. Long story short, I never did fix it. My car has a relatively small engine and it isn't loud by any means relative to many other cars/motorcycles on the road. I have driven this way for months now and never had a problem with the police. I even renewed my inspection this way.

So my reasoning now is that less weight, less aerodynamic drag and possibly reduced back pressure (questionable?) would lead to a small mpg boost. Are there other factors i'm not accounting for here that could negate the benefits?

Btw A-B-A isn't practical because the "A" stands for a $250+ repair job.

deathtrain · 07-31-2011, 12:34 AM

if you got no issues, you dont care, and renewed your inspection that way then go back to sleep and dont worry about it.

Vekke · 07-31-2011, 05:22 AM

If louder noises dont bother you and you were able to inspect the car you are good to go. Taking muffler out makes:'
- car lighter
- reduses the back pressure
- increses engine noises
- Aerodynamic wise it depends did the muffler smooth the underside of the car or not. I would also put some pipe to extend the pipe to the rear part of the car. If there is pipe under the car you can get fumes inside the when being stationary...

oil pan 4 · 07-31-2011, 06:02 AM

Free flowing exhaust always showed the least of improvements for me on N/A vehicle.
The only vehicles where straight pipe showed improvements was with a turbo. That is only because the turbo is sensitive to back pressure, where the diesel and gas engines are not so sensitive.

toc · 07-31-2011, 08:47 AM

Fix up the muffler with some pipe to route the gases back to the rear of the vehicle, if they enter the cabin they can be very dangerous for those inside the car.

Shouldn't take much more than some correctly sized pipe and a bit of welding, I would think (that is, without the muffler, but then if you 'fix' it, could be issues later when the car is inspected)?

SentraSE-R · 07-31-2011, 10:04 AM

It depends on your engine management system and scavenging. If you're running a primitive system (carburetor or can't adjust fuel delivery ), you may burn valves from going lean. Also depending on design of the exhaust manifold, you my lose torque w/o adequate backpressure.

Bdorion1 · 07-31-2011, 02:45 PM

Ah the fumes I didn't even think of that. The pipe goes to underneath the trunk so hopefully its good. Probably should do something to extend it. I have a 98 cavalier z24 convertible so its fuel injection so I don't think running lean would be a problem. Also the muffler stuck out below other components so I'm pretty sure it gives aerodynamic savings having it gone.

Frank Lee · 07-31-2011, 03:34 PM

Are you sure it's really quiet, or does it just seem quiet to you while you are in the car?

Bdorion1 · 07-31-2011, 04:38 PM

Quote:

Originally Posted by Frank Lee

Are you sure it's really quiet, or does it just seem quiet to you while you are in the car?

Its actually pretty loud but not as loud as I expected. Its quieter than your typical motorcycle. Its quieter even then your typical stock V8 or large truck. That being said, you can still clearly tell there is a muffler problem when accelerating or going uphill. Maybe they think I'm just some dumb kid who put a noisy exhaust on his car.

Thymeclock · 07-31-2011, 11:28 PM

Quote:

Originally Posted by Bdorion1

Its actually pretty loud but not as loud as I expected. Its quieter than your typical motorcycle. Its quieter even then your typical stock V8 or large truck. That being said, you can still clearly tell there is a muffler problem when accelerating or going uphill. Maybe they think I'm just some dumb kid who put a noisy exhaust on his car.

Your car won't pass a State inspection without it. Your MPG won't improve any. It will annoy everyone within earshot, including possibly some cops who have nothing better to do but detain you for it.

Why be so cheap? Buy a replacement muffler and some clamps and DIY.

But perhaps your entire exhaust system may also be rotted out...