rusted exhuast

[eishiba]

So on my 91 corolla has gotten louder. I did some searching and found that the exhuast, where it connects with the exhuast manifold which is held on by two peg bolts has rusted. There is an inch or two wide hole. Thats what has made the car sound louder and like its farting. The car feels like it hasn't got the power it had before. It could be cause as it farts it just feels more sluggish than it already is. Does the exhuast need a certain compression amount like the engine on the inside needs to make the engine run at its best?

[SCT]

I'm not sure if the engines require any exhaust pressures...But I've noticed sluggishness when I had leaks before the catalytic converter.

[RobMilkshakes]

I dont think its from a lack of back pressure, there engines do not need back pressure, they're not two strokes. there's a chance the leak could be causing more back pressure though dpending on the size and location of the leak. It could be causing turbulence inside the pipe and slowing exhaust flow.

Of course like usual I am basing this on no facts that I have observed, just a few things I remember from a fluid dynamics class.



You said it is rusted on the down pipe, where? is it the flange, actually on the pipe itself, or the two studs rusted out?

[freakinbox]

Yeah I honestly have no idea on this either for sure. Experience tells me just the manifold and no exhaust makes the car seem weak and sluggish. Even taking out the cat (had to repair the breather pipe on it, it's a 4af thing if you are lost. 4afe didn't have them) and only having a down pipe connected has a similar effect.

With mine there was no rust, I guess the hot and cold transitions on the metal causes it to weaken and it completely broke off at the flange for the manifold while on the hwy. The whole drive home even at slower speeds after I got off the hwy, the car just felt like it had NOTHING to give.

Also don't ask me why but I do know that if you leave it like that to long you can eventually blow the head gasket. Didn't happen to my car (probably because I replaced it after I got home), but I have known many it has. It's also loud and you can get pulled over for it.

[Donald]

Back pressure is not the issue. It is velosity of scavenging.
The exhaust works like a syphon, and it helps scavenging the burnt gasses from the combustion chamber, and allow the in-flow of fresh oxygen and fuel.

If you have a leak in your exhaust system in the wrong place, it can work the same way as a leak in a syphon. It upsets the operation.

Changing the diameter of the pipe can help or spoil the scavenging effect, depending on the volume and velocity of the engine's pumping capacity.

That is what a tuned exhaust system is all about.

This is an extremely simplified discription.