So I've got a question guys.

Yesterday my exhaust pipe cracked and, as you can imagine, it sounds wonderful to have what is essentially a straight pipe. This is the third exhaust this car has gone through, but I don't plan on having it anymore. Only replaced the last two to pass inspection. Interestingly, the last two pipes went towards the back of the vehicle, right before the muffler. This time, however, it seems to have broken extremely close to the engine (engine noise comes clearly coming from somewhere in front of me now) and I was wondering if this could pose any kind of risks (besides the fact that there's a useless muffler just waiting to fall off) and if it will have any real effect on the cars performance (someone told me my mileage will go to shit, but I doubt it)?

can affect performance and mpg negatively. won't necessarily damage the engine but won't do it much good. about time you upgrade to a stainless steel it sounds like?

Poisonous gas WILL enter your car and make you die while driving, probably causing you to crash and kill someone else too!

This is what happens when i get bored and have free time on my hands.
http://youtu.be/UMYooBBz2W0
It's sort of car related, i guess. I mean it was in my car at one point.

Quote from Rappa Z :

So I've got a question guys.

Yesterday my exhaust pipe cracked and, as you can imagine, it sounds wonderful to have what is essentially a straight pipe. This is the third exhaust this car has gone through, but I don't plan on having it anymore.

When you say it has cracked do you mean it has rusted through or that good metal has failed due to fatigue (most commonly around a weld)? If it's good metal that has failed it is probably due to a combination of poor mounting (missing support stays/worn out rubbers, or over stiff replacements) or a poor quality replacement part. If you don't intend to keep it long and the metal around the point of failure is good you can just get it welded up, mind it will fail again after a while if you don't fix the source of the problem.

As to what will happen when the exhaust pipe is removed, who knows? Random people on a forum certainly can't advise you, the chances are it'll run much the same. A moron would tell you that it produces more power because it sounds louder. What is happening to the flow through the exhaust ports is a complex thermo-fluid dynamics problem, maybe contact the engine designer and wait a few months.

The chances are you're not going to damage anything, most industrial engines work on the principal that the customer can do pretty much whatever they like with the exhaust after the manifold and the engine won't be affected too badly.

Quote from S14 DRIFT :

can affect performance and mpg negatively. won't necessarily damage the engine but won't do it much good. about time you upgrade to a stainless steel it sounds like?

Stainless steel is a terrible choice of material for an exhaust and whilst people have traditionally got away with using it on low performance engines it is still a stupid choice. It will make fatigue from both vibrations and especially thermal cycles far worse. Welding stainless steel is not always straight forward and bear in mind the number of mild steel exhausts that fall apart due to dodgy welding...

EDIT - What KiRmelius said is very important to remember, make sure the exhaust is vented away from the underbody of your car. A typical exhaust mounted under a central tunnel down the car will find its way into the cockpit, even a small leak is very dangerous, if you have to drive a car with a leaking exhaust open all the windows and stop if you can smell/feel the effects of exhaust fumes. They're really not fun.

Quote from R3DMAN :

Quite literally awesome! However... Looking at your youtube, you've had nothing but problems!

Looks and sounds the nuts though!

Quote from ajp71 :

Stainless steel is a terrible choice of material for an exhaust and whilst people have traditionally got away with using it on low performance engines it is still a stupid choice. It will make fatigue from both vibrations and especially thermal cycles far worse. Welding stainless steel is not always straight forward and bear in mind the number of mild steel exhausts that fall apart due to dodgy welding...

Yeah unfortunately most people can't afford titanium or anything fancy such as that so stainless steel works fine. had stainless steel exhaust systems before on my motorcycles and all been fine. if it's ok on a bike revving to 14000rpm it's ok on my car revving to 5. it's fine miltek, piper, scorpion, akropovic, etc, it's fine for you and me and bob up the road.
hopefully should be getting my free exhaust system soon..

Yeah, first problems with my Fiesta came. Engine control just started lighting up, so we went to a workshop to get it checked. Not only was an ignition cable completely bitten through, but after changing that and driving a few KMs it lit up again. Went to let it check again, and appearently the lambda sensor is broken. Only thing I hope, is that it's really that, and not, that the catalyzer is broken. Otherwise it'll be expensive as sh!t. :/

Quote from S14 DRIFT :

Yeah unfortunately most people can't afford titanium or anything fancy such as that so stainless steel works fine. had stainless steel exhaust systems before on my motorcycles and all been fine. if it's ok on a bike revving to 14000rpm it's ok on my car revving to 5. it's fine miltek, piper, scorpion, akropovic, etc, it's fine for you and me and bob up the road.
hopefully should be getting my free exhaust system soon..

Good old mild steel (any random grade) is a far better material for an exhaust than stainless steel (except possibly unobtanium type grades). If you're consuming mild steel exhausts at a rate that isn't financially viable then you're either driving a boat (a lot of which do not use stainless steel exhausts) or have some very strange exhaust products (sticking stuff in your fuel again?). An exhaust should rust from the inside out, especially if it has got a decent protective coating on the outside of it.

Stainless steel exhausts are typically sold to three types of people:
1. Classic car enthusiasts who want an exhaust that'll last forever.
2. People who like shiny things.
3. Idiots who believe marketing material.

It'll probably surprise you to learn that the order of preference for race car/very high performance exhausts is titanium/Inconel/other unobtanium > high strength steel > mild steel

Mild steel exhausts with 4 figure price tags are common place in lower level motorsport competition and where exotic materials are banned.

A stainless steel exhaust could be made lighter and last longer (in an extreme environment) if it was made from just about anything else.

If you're really obsessed about rust then use a water called aluminium exhaust.

Quote from ajp71 :

What KiRmelius said is very important to remember, make sure the exhaust is vented away from the underbody of your car. A typical exhaust mounted under a central tunnel down the car will find its way into the cockpit, even a small leak is very dangerous, if you have to drive a car with a leaking exhaust open all the windows and stop if you can smell/feel the effects of exhaust fumes. They're really not fun.

usually as long as you keep the car moving theres enough airflow to pull the exhaust fumes away from the cars ventilation intakes (friend of mine drove around with a golf that had completely disintegrated its flex tube right behind the exhaust manifold for a couple of weeks... usually flooring it cause quite frankly it did sound awesome)
also while certainly dangerous its not like youll instantly die if you inhale a bit of exhaust gasses

Quote from Shotglass :

usually as long as you keep the car moving theres enough airflow to pull the exhaust fumes away from the cars ventilation intakes (friend of mine drove around with a golf that had completely disintegrated its flex tube right behind the exhaust manifold for a couple of weeks... usually flooring it cause quite frankly it did sound awesome)
also while certainly dangerous its not like youll instantly die if you inhale a bit of exhaust gasses

I've seen someone loose consciousness of a tin top race car within 20 minutes of trying to put up with a leaking exhaust. Even on a race track he was damn lucky to end up coasting to a stop without hitting anything surrounded by the best help possible.

Admittedly a race car will be putting out far more emissions and generally has less sealing between the underbody and cockpit, but they also don't normally have shut windows and a nice cosy engine bay fed heater for hours on end down the motorway...

Quote from ajp71 :

Good old mild steel (any random grade) is a far better material for an exhaust than stainless steel (except possibly unobtanium type grades). If you're consuming mild steel exhausts at a rate that isn't financially viable then you're either driving a boat (a lot of which do not use stainless steel exhausts) or have some very strange exhaust products (sticking stuff in your fuel again?). An exhaust should rust from the inside out, especially if it has got a decent protective coating on the outside of it.

Stainless steel exhausts are typically sold to three types of people:
1. Classic car enthusiasts who want an exhaust that'll last forever.
2. People who like shiny things.
3. Idiots who believe marketing material.

It'll probably surprise you to learn that the order of preference for race car/very high performance exhausts is titanium/Inconel/other unobtanium > high strength steel > mild steel

Mild steel exhausts with 4 figure price tags are common place in lower level motorsport competition and where exotic materials are banned.

A stainless steel exhaust could be made lighter and last longer (in an extreme environment) if it was made from just about anything else.

If you're really obsessed about rust then use a water called aluminium exhaust.

well, i'm not doubting what you're saying but speaking from my personal opinion. i had a bike which was an fzs600 fazer which had mild steel exhausts from the factory. they had a paint type finish but this chipped easily. rust quickly consumed them, it was a common problem. it was replaced with stainless steel downpipes and they gave no problems to the previous owner and was fine for me after 14,000 miles, rain, sun or puddles for that matter.

you'd need to stick more than a bit of 2 stroke oil (which is not a corrosive, you should now that) however my golf exhausts seems fine. i'll only find out when the exhaust company have it in to develop the new one on and say "yeah you've got loads of holes".

now the most important part in exhaust design for performance is not material but flow and you can achieve the same flow with a mild steel, stainless steel or titanium exhaust. the only difference is weight which is where the titanium comes in handy as it's light.

now i'm not doubting your knowledge here but when miltek, piper, venom, akropovic, arrow, mtc, beowulf, hks, scorpion, etc, all are using stainless steel as a minimum rather than mild steel, certainly says something.

use of stainless steel isn't amazingly costly compared to mild but means it won't rust regardless of what happens (within reason) - i've never come across a corroded stainless steel exhaust. they are good because they are durable and fairly cheap. if you want to spend double the price on a titanium exhaust which won't do anything other than have a blue tinge to it when it gets hot and weighs a bit less save the money!

also many boat exhausts are made of a cast iron which does not rust when submergered as it's not exposed to air as must. there are also many types of coating (usually ceramic) which are applied. to be fair a thick layer of paint would protect a boat because generally they are not subjected to impact force such as stones, speedbumps, stonechips, etc .

Quote from S14 DRIFT :

now the most important part in exhaust design for performance is not material but flow and you can achieve the same flow with a mild steel, stainless steel or titanium exhaust. the only difference is weight which is where the titanium comes in handy as it's light.

True in essence, although heat transfer characteristics, mass and tolerance to vibration are all pretty critical and bother a car manufacturer far more than the tuning crowd.

Quote :

now i'm not doubting your knowledge here but when miltek, piper, venom, akropovic, arrow, mtc, beowulf, hks, scorpion, etc, all are using stainless steel as a minimum rather than mild steel, certainly says something.

Those companies produce exhausts that produce noise and look shiny, performance is not a requirement, merely convincing the customer there is a performance improvement is enough.

It is true that exhausts for idiots (kindly listed above) or exhausts for a specialist application where the cost of mild steel replacements isn't viable can be made of stainless steel. They won't be as good as a mild steel exhaust, but I acknowledge it takes a far deal of commitment (be it financial or time) to go for the better material that is only slightly cheaper but has to be replaced routinely. There's good reason though that there are still a lot of high value cars that 'need' an upgrade to stainless steel, why aren't manufacturers fitting it as standard? As you point out it's not just due to cost...

Quote from S14 DRIFT :

you'd need to stick more than a bit of 2 stroke oil (which is not a corrosive, you should now that) however my golf exhausts seems fine. i'll only find out when the exhaust company have it in to develop the new one on and say "yeah you've got loads of holes".

...and the products of partially combusted 2 stroke oil are?

Fuel isn't meant to be corrosive but its products still do a jolly good job of making a mess of mild steel...

Took a look under the car and the pipes have held up well, but the welds haven't. Pipes are clean as could be but every weld has rusted almost all the way through, as well as all the brackets holding up the exhaust. My dad's going to help me pull of all the useless exhaust tomorrow and we're going to try and divert what's left to the side. Illegal straight pipe FTW.

Also, it turns out the break wasn't as far forward as I figured. It's right underneath the gear lever so I believe that most of the exhaust is bypassing me. That said, I still have the windows open in December because it sounds ****ing wonderful.

Quote from ajp71 :

I've seen someone loose consciousness of a tin top race car within 20 minutes of trying to put up with a leaking exhaust. Even on a race track he was damn lucky to end up coasting to a stop without hitting anything surrounded by the best help possible.

Admittedly a race car will be putting out far more emissions and generally has less sealing between the underbody and cockpit, but they also don't normally have shut windows and a nice cosy engine bay fed heater for hours on end down the motorway...

well the car certainly did let quite a bit of the fumes inside
the smell was very very noticeable while standing still
no idea why he never experienced any health issues although it might be related to it happening in the summer and hum driving around with the windows down going as fast and full throttle as he can while enjoying the incredible racket a 75hp golf engine is capeable of

Well, this might actually be true, my driving instructor told he was once driving in Russia, got tired and stopped to have some sleep. Since it was freezing cold outside, he left the engine turned on. Exhaust was okay, but the rear of a car (and exhaust pipe) was against the wind direction. Wind blew all the gases under the car. He was lucky enough to be waken up by some noise about half an hour later. He had massive headache, felt dizzy, vision was blurry and he felt shitty in general. So death from gas poisoning while standing in traffic jam with broken exhaust pipe seems plausible.

Ive parked up for hours with my engine running and I've never died. Even slept for 2 hours with my engine running no problems!!

Sounds a bit of a myth...then again you can be blown up by a Meteor who knows.....

there are people that has worse reaction to exhaust gases than others.for example my mom has headache in my car(i have straight pipe,and stinks a bit.i dont even smell it..) and she wanna pass out,but thats from the g-force

Suggest to mythbusters, anyone?

As I said, wind direction counts also.

Carbon monoxide poisoning is well documented medical science, not some wacky theory. Breathing car exhaust fumes is a classic suicide method!

There's a serious danger associated with breathing exhaust fumes and by the time you become aware it is time to act, not wilfully ignore it. What's next investigate the myth that air crashes are dangerous because not everybody gets killed in them?

Quote from ajp71 :

Carbon monoxide poisoning is well documented medical science, not some wacky theory. Breathing car exhaust fumes is a classic suicide method!

There's a serious danger associated with breathing exhaust fumes and by the time you become aware it is time to act, not wilfully ignore it. What's next investigate the myth that air crashes are dangerous because not everybody gets killed in them?

But a healthy-running engine doesn't put out carbon monoxide, it puts out carbon dioxide, which isn't lethal, but it's not the best, it's what we exhale. it's when the engine begin to run out of oxygen to burn that it begins to produce Carbon monoxide, such as in an enclosed area i.e. a garage. So, when the fuel/air mixture isn't right, yes, it's dangerous, but when you have plenty of oxygen to burn and a good mixture, you should be fine...at least that's what I remember from school.

Quote from roadrash17 :

But a healthy-running engine doesn't put out carbon monoxide, it puts out carbon dioxide, which isn't lethal, but it's not the best, it's what we exhale. it's when the engine begin to run out of oxygen to burn that it begins to produce Carbon monoxide, such as in an enclosed area i.e. a garage. So, when the fuel/air mixture isn't right, yes, it's dangerous, but when you have plenty of oxygen to burn and a good mixture, you should be fine...at least that's what I remember from school.

rubbish on so many counts
first of all any engine produces carbonmonoxide when its running which is the whole point of having a catalysator which converts that into comparably harmless co2 (amoung other poisonous gases that also get catalysed into less dangerous forms in it)
secondly co2 is deadly in concentrations above about 8%

Haha, mmk. well perhaps I was taught rubbish xD