Why Does Exhaust Leak = Less Power?
04-08-02 | 08:44 PM
#1
Thread Starter
WTB S5 N/A FC
Joined: Oct 2001
Posts: 2,778
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From: College Station, Tx
Why Does Exhaust Leak = Less Power?
I have a huge one around my header, and I am just wondering why this causes a lack of power. I am gonna fix it tomorrow, cuz this is NOT gonna fly!!
04-08-02 | 09:28 PM
#2
Rotary Freak
Joined: Dec 2001
Posts: 2,941
Likes: 1
From: sandiego, ca
h
I would think that if the leak was before your oxygen sensor that it would sense too much air and send too much fuel. I guess. Also mabey the leak would create turbulense or lose pressure and reduce scaveging and velocity the exaust needs to shoot it out. Sounds logical too me.
04-08-02 | 10:59 PM
#4
Rotary Freak
Joined: Dec 2001
Posts: 2,941
Likes: 1
From: sandiego, ca
Re: h
Originally posted by von
I would think that if the leak was before your oxygen sensor that it would sense too much air and send too much fuel. I guess. Also mabey the leak would create turbulense or lose pressure and reduce scaveging and velocity the exaust needs to shoot it out. Sounds logical too me.
I would think that if the leak was before your oxygen sensor that it would sense too much air and send too much fuel. I guess. Also mabey the leak would create turbulense or lose pressure and reduce scaveging and velocity the exaust needs to shoot it out. Sounds logical too me.
04-08-02 | 11:25 PM
#7
I came, I saw, I boosted.
Joined: Apr 2001
Posts: 1,921
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From: Windsor, Ontario, Canada
Naw...it's not about backpressure... damn. It's unbelievable how many people, including WAY too many bonehead certified mechanics don't understand exhaust systems.
Backpressure happens when an ehxuast is exeeding it's tuned flow limit.
Backpressure itself will NEVER increase power.. only decrease it.
Backpressure is an unfortunate side effect of reducing tubing diameter, to cause FASTER exhuast flow. Therefore, at lower RPM's, when there ins't a low of gas flowing though the exhaust, it can flow through fast, and pull the next exhaust pulse out better, =more power.
However, as RPM's increase, more gas is flowing, so the smaller exhaust becomes a restriction, and plulses start to back up. So a bigger exhaust is better for higher RPM's, because it allows the pulses to escape freely, but still be able to pull the next one beyhind it out.
But at lower RPM's this big exhaust won't make as much power, because the exhaust pulses aren't fast enough to effectively draw the following one out.
Now- you go TOO big for your engine, and you lose exhaust velocity, so yoy lose power everywhere.
This is what's happening to you. Your exhaust pulses are escaping out the leak, and not through the legth of the pipe. It's essentially acting like a 5" exhaust pipe or something.
Dan
Backpressure happens when an ehxuast is exeeding it's tuned flow limit.
Backpressure itself will NEVER increase power.. only decrease it.
Backpressure is an unfortunate side effect of reducing tubing diameter, to cause FASTER exhuast flow. Therefore, at lower RPM's, when there ins't a low of gas flowing though the exhaust, it can flow through fast, and pull the next exhaust pulse out better, =more power.
However, as RPM's increase, more gas is flowing, so the smaller exhaust becomes a restriction, and plulses start to back up. So a bigger exhaust is better for higher RPM's, because it allows the pulses to escape freely, but still be able to pull the next one beyhind it out.
But at lower RPM's this big exhaust won't make as much power, because the exhaust pulses aren't fast enough to effectively draw the following one out.
Now- you go TOO big for your engine, and you lose exhaust velocity, so yoy lose power everywhere.
This is what's happening to you. Your exhaust pulses are escaping out the leak, and not through the legth of the pipe. It's essentially acting like a 5" exhaust pipe or something.
Dan
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04-09-02 | 01:17 AM
#10
I wish I was driving!
Joined: Dec 2001
Posts: 5,241
Likes: 84
From: BC, Canada
WRONG!
If you read, you'll see hee has a 1991 blaze red coupe, which uses the air pump to open the auxilary ports.
Backpressure is only used on S4 cars, not S5 cars.
C'mon, ppl. This thread is full of posts that are out and out wrong... don't post inaccurate information.
Sean Cathcart
If you read, you'll see hee has a 1991 blaze red coupe, which uses the air pump to open the auxilary ports.
Backpressure is only used on S4 cars, not S5 cars.
C'mon, ppl. This thread is full of posts that are out and out wrong... don't post inaccurate information.
Sean Cathcart
04-09-02 | 01:20 AM
#11
Senior Member
Joined: Mar 2001
Posts: 301
Likes: 0
From: Grafton WV
Why does my turbo 2 run like **** with no exhaust on it other than that downpipe on it? it didnt have any power to it at all. didnt even boost high i got the exhaust back on now but for a day i drove it with nothing on it
04-09-02 | 02:07 AM
#12
Thread Starter
WTB S5 N/A FC
Joined: Oct 2001
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From: College Station, Tx
Ok, 1 more question. If I have a exhaust leak, will flames shoot out it? Basically, would it be safe to drive it to a store to get new bolts to rectify the leak, or would flames shoot out the leak in the engine, possibly causing a fire? I need to go to the parts store tomorrow to fix this, I am just a little nervous. I am glad I have a fuel cut switch and a fire extinguisher!!!
04-09-02 | 03:08 AM
#16
I wish I was driving!
Joined: Dec 2001
Posts: 5,241
Likes: 84
From: BC, Canada
Actually, just lay off the throttle and you should be fine no matter what. Really, there is a lot of air flowing through the engine bay, and without wideopen throttle, you shouldn't be seeing any temps too ridiculous in the exhaust.
Due to the things around the exhaust, being really only aluminum intake, coolant hose, and oil pan, I doubt any damage could occur.
There is no real rubber lines in close proximity to the header.
You should be fine. After all, and exhaust leak won't do any damage to undercoating if it leaks up onto the floor, so I don't see any possible damage being done to aluminum parts.
Good luck with the fix and the damn high legal bill, brotha!
Sean
Due to the things around the exhaust, being really only aluminum intake, coolant hose, and oil pan, I doubt any damage could occur.
There is no real rubber lines in close proximity to the header.
You should be fine. After all, and exhaust leak won't do any damage to undercoating if it leaks up onto the floor, so I don't see any possible damage being done to aluminum parts.
Good luck with the fix and the damn high legal bill, brotha!
Sean
04-09-02 | 04:22 AM
#17
Senior Member
Joined: Mar 2002
Posts: 666
Likes: 1
From: Memphis, Japan
Backpressure happens when an ehxuast is exeeding it's tuned flow limit.
Backpressure itself will NEVER increase power.. only decrease it.
Backpressure is an unfortunate side effect of reducing tubing diameter, to cause FASTER exhuast flow. Therefore, at lower RPM's, when there ins't a low of gas flowing though the exhaust, it can flow through fast, and pull the next exhaust pulse out better, =more power.
However, as RPM's increase, more gas is flowing, so the smaller exhaust becomes a restriction, and plulses start to back up. So a bigger exhaust is better for higher RPM's, because it allows the pulses to escape freely, but still be able to pull the next one beyhind it out.
But at lower RPM's this big exhaust won't make as much power, because the exhaust pulses aren't fast enough to effectively draw the following one out.
Now- you go TOO big for your engine, and you lose exhaust velocity, so yoy lose power everywhere.
This is what's happening to you. Your exhaust pulses are escaping out the leak, and not through the legth of the pipe. It's essentially acting like a 5" exhaust pipe or something.
Dan
Backpressure itself will NEVER increase power.. only decrease it.
Backpressure is an unfortunate side effect of reducing tubing diameter, to cause FASTER exhuast flow. Therefore, at lower RPM's, when there ins't a low of gas flowing though the exhaust, it can flow through fast, and pull the next exhaust pulse out better, =more power.
However, as RPM's increase, more gas is flowing, so the smaller exhaust becomes a restriction, and plulses start to back up. So a bigger exhaust is better for higher RPM's, because it allows the pulses to escape freely, but still be able to pull the next one beyhind it out.
But at lower RPM's this big exhaust won't make as much power, because the exhaust pulses aren't fast enough to effectively draw the following one out.
Now- you go TOO big for your engine, and you lose exhaust velocity, so yoy lose power everywhere.
This is what's happening to you. Your exhaust pulses are escaping out the leak, and not through the legth of the pipe. It's essentially acting like a 5" exhaust pipe or something.
Dan
One guy gives you the answer to the question yet you keep babbling. This should be the end of this thread I honestly can't see what other questions you would have.
04-09-02 | 04:42 AM
#18
I wish I was driving!
Joined: Dec 2001
Posts: 5,241
Likes: 84
From: BC, Canada
Originally posted by Ranzo
One guy gives you the answer to the question yet you keep babbling. This should be the end of this thread I honestly can't see what other questions you would have.
One guy gives you the answer to the question yet you keep babbling. This should be the end of this thread I honestly can't see what other questions you would have.
The answer given in your quote does NOT answer all of the questions in this thread.
This thread is filled with technical questions, and the only babble I see in this thread is from you.
Yet another disrespectful newbie to add to my list of people I will not help.
Sean
04-09-02 | 11:15 AM
#19
Despise Enmity
Joined: May 2001
Posts: 2,420
Likes: 0
From: Richmond, VA
Originally posted by scathcart
Shutup! Who the hell do you think you are?
The answer given in your quote does NOT answer all of the questions in this thread.
This thread is filled with technical questions, and the only babble I see in this thread is from you.
Yet another disrespectful newbie to add to my list of people I will not help.
Sean
Shutup! Who the hell do you think you are?
The answer given in your quote does NOT answer all of the questions in this thread.
This thread is filled with technical questions, and the only babble I see in this thread is from you.
Yet another disrespectful newbie to add to my list of people I will not help.
Sean
04-09-02 | 11:21 AM
#20
Thread Starter
WTB S5 N/A FC
Joined: Oct 2001
Posts: 2,778
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From: College Station, Tx
Of course he does, and since he is my big bro, his list is also mine!! Thanks Sean, and the court has me doin $50 a month payments till DECEMBER!!! 
So I should be able to scrape enough together for some n20 soon enough!!! I got some bolts today, now to just install em!! Man, this header is LOUD!!!!!
Thanks Sean, and the court has me doin $50 a month payments till DECEMBER!!! So I should be able to scrape enough together for some n20 soon enough!!! I got some bolts today, now to just install em!! Man, this header is LOUD!!!!!
04-09-02 | 08:47 PM
#21
I wish I was driving!
Joined: Dec 2001
Posts: 5,241
Likes: 84
From: BC, Canada
Originally posted by Josepi
You keep a list?
You keep a list?
Just a mental list. Surprisingly, all of the people on it, save one, are people with less than 100 posts.
How do people come on here and just think they can boss people around, tell us to **** off if we don't help them right away, etc.?
Like, look at this guy. 25 posts and he has now come on here and told us what we can and can't write in this forum. What a load of BS.
Ranzo, you have offered no real help to anyone here in your short time, and if you had, you would realize that people can ask MORE THAN ONE question in their threads.
If you don't wanna read the ramble then don't, otherwise, **** off and mind your own business.
Rico05 has been far more helpful than you have in this forum, and if he wants to ask 2 questions, who are you to call it rambling?
Anyway, bro, I hope all went well today with getting your header straightened out. Pretty cool of the court to cut it down to payments, but shitty to have to pay none the less.
Sean Cathcart
04-09-02 | 09:35 PM
#22
I came, I saw, I boosted.
Joined: Apr 2001
Posts: 1,921
Likes: 0
From: Windsor, Ontario, Canada
Ya, the header will be DAMN loud, I hope you are prepared for it... it's really hard to get a "nice" sound from a header. You can keep the volume down by some big mufflers, but it'll always be kindof tinkly and weedwhaker'y. It's not horrible at all, but some people don't like it...
I REALLY hope that you don't actually have a leak, and you are just now hearing exhaust noise coming THOUGH the pipes! This is what paceshitter's do. I have mine wrapped to kill that.
Anyways- my main point to help ya-
**DRIVE THE CAR AS LITTLE AS POSSIBLE WITH AS LITTLE THROTTLE AS POSSIBLE!**
It isn't really much of a fire hazard, BUT the heat at that part of exhaust. combined with the manifold that isn't mounted flat, can warp the **** out of the flange.
This thing actually happened to me, even after I've been warned.
I had a stud break on a header install. I put the header on anyways and drove it for a week or more.. it had a tiny leak at the beginning. By the end, it was 1/4" MINIMUM away form the block!!
It had to be machined flush! $$$!
Be really carefull with that!
I REALLY hope that you don't actually have a leak, and you are just now hearing exhaust noise coming THOUGH the pipes! This is what paceshitter's do. I have mine wrapped to kill that.
Anyways- my main point to help ya-
**DRIVE THE CAR AS LITTLE AS POSSIBLE WITH AS LITTLE THROTTLE AS POSSIBLE!**
It isn't really much of a fire hazard, BUT the heat at that part of exhaust. combined with the manifold that isn't mounted flat, can warp the **** out of the flange.
This thing actually happened to me, even after I've been warned.
I had a stud break on a header install. I put the header on anyways and drove it for a week or more.. it had a tiny leak at the beginning. By the end, it was 1/4" MINIMUM away form the block!!
It had to be machined flush! $$$!
Be really carefull with that!
04-09-02 | 09:53 PM
#23
Originally posted by seveninphilly
Lack of back pressure
Lack of back pressure
Originally posted by Bambam7
Naw...it's not about backpressure... damn. It's unbelievable how many people, including WAY too many bonehead certified mechanics don't understand exhaust systems.
Backpressure happens when an ehxuast is exeeding it's tuned flow limit.
Backpressure itself will NEVER increase power.. only decrease it.
Backpressure is an unfortunate side effect of reducing tubing diameter, to cause FASTER exhuast flow. Therefore, at lower RPM's, when there ins't a low of gas flowing though the exhaust, it can flow through fast, and pull the next exhaust pulse out better, =more power.
However, as RPM's increase, more gas is flowing, so the smaller exhaust becomes a restriction, and plulses start to back up. So a bigger exhaust is better for higher RPM's, because it allows the pulses to escape freely, but still be able to pull the next one beyhind it out.
But at lower RPM's this big exhaust won't make as much power, because the exhaust pulses aren't fast enough to effectively draw the following one out.
Now- you go TOO big for your engine, and you lose exhaust velocity, so yoy lose power everywhere.
This is what's happening to you. Your exhaust pulses are escaping out the leak, and not through the legth of the pipe. It's essentially acting like a 5" exhaust pipe or something.
Dan
Naw...it's not about backpressure... damn. It's unbelievable how many people, including WAY too many bonehead certified mechanics don't understand exhaust systems.
Backpressure happens when an ehxuast is exeeding it's tuned flow limit.
Backpressure itself will NEVER increase power.. only decrease it.
Backpressure is an unfortunate side effect of reducing tubing diameter, to cause FASTER exhuast flow. Therefore, at lower RPM's, when there ins't a low of gas flowing though the exhaust, it can flow through fast, and pull the next exhaust pulse out better, =more power.
However, as RPM's increase, more gas is flowing, so the smaller exhaust becomes a restriction, and plulses start to back up. So a bigger exhaust is better for higher RPM's, because it allows the pulses to escape freely, but still be able to pull the next one beyhind it out.
But at lower RPM's this big exhaust won't make as much power, because the exhaust pulses aren't fast enough to effectively draw the following one out.
Now- you go TOO big for your engine, and you lose exhaust velocity, so yoy lose power everywhere.
This is what's happening to you. Your exhaust pulses are escaping out the leak, and not through the legth of the pipe. It's essentially acting like a 5" exhaust pipe or something.
Dan
EDIT> the exhaust leak at header=less back pressure
Last edited by seveninphilly; 04-09-02 at 09:56 PM.
04-09-02 | 10:26 PM
#24
Senior Member
Joined: Mar 2002
Posts: 666
Likes: 1
From: Memphis, Japan
Just a mental list. Surprisingly, all of the people on it, save one, are people with less than 100 posts.
How do people come on here and just think they can boss people around, tell us to **** off if we don't help them right away, etc.?
Like, look at this guy. 25 posts and he has now come on here and told us what we can and can't write in this forum. What a load of BS.
Ranzo, you have offered no real help to anyone here in your short time, and if you had, you would realize that people can ask MORE THAN ONE question in their threads.
If you don't wanna read the ramble then don't, otherwise, **** off and mind your own business.
Rico05 has been far more helpful than you have in this forum, and if he wants to ask 2 questions, who are you to call it rambling?
Anyway, bro, I hope all went well today with getting your header straightened out. Pretty cool of the court to cut it down to payments, but shitty to have to pay none the less.
Sean Cathcart
How do people come on here and just think they can boss people around, tell us to **** off if we don't help them right away, etc.?
Like, look at this guy. 25 posts and he has now come on here and told us what we can and can't write in this forum. What a load of BS.
Ranzo, you have offered no real help to anyone here in your short time, and if you had, you would realize that people can ask MORE THAN ONE question in their threads.
If you don't wanna read the ramble then don't, otherwise, **** off and mind your own business.
Rico05 has been far more helpful than you have in this forum, and if he wants to ask 2 questions, who are you to call it rambling?
Anyway, bro, I hope all went well today with getting your header straightened out. Pretty cool of the court to cut it down to payments, but shitty to have to pay none the less.
Sean Cathcart
Do you wanna compare FC3S knowledge?? I fear you would lose. I have stayed away from forums because of **** like this. I was before a member of the Team FC3S list and the big rx7 list and stopped both because of people like you.
Do not tell people in a public forum to **** Off!! I never told anyone that. All I was insinuating is that people stay on subject. It seems that you guys ask some questions that are very elementary.....that is fine nobody knows everything. I see all these things talking about cars shooting flames and ****......go buy a flamethrower.... If Rico5 is so helpful why he does not know these things already. I am not picking on Rico5, I don' t know him and I am not here to start fights but I will finish any that are started with me! If I am wrong I will admit I am wrong and use it as a lesson, You should do the same.
Randy....
04-09-02 | 10:40 PM
#25
I wish I was driving!
Joined: Dec 2001
Posts: 5,241
Likes: 84
From: BC, Canada
You can have all the knowledge you want, but if you keep it to yourself and only have posts telling people they can't ask questions, then indeed, you should **** Off. What a great guy: Absolute Genius when in comes to these cars, and instead of helping people, only takes the time to give a post to tell them to shutup.
Thank-you ever so much for you wise words of wisdom, oh-rotary-lord.
I know quite a bit about these cars, but I would be an ******* to just come one here and only tell people to stop asking questions.
Like I said before, if you don't like the way the discussion is going, keep it to yourself. There is no need to discourage rotary enthusiasts from asking for help, be it from the most basic problem to the most complex theoretical question.
You say you stay away from places like this? I am relieved. I should hope that you would never have kids, and tell them to stop rambling for asking questions that seem simple to you.
As well, fact is fact: You can claim to have all this knowledge on these cars, but if you don't share it, your point is moot. I think that b/c of this, we can all agree that currently I have displayed much more knowledge on these cars than you have.
Sean Cathcart
Thank-you ever so much for you wise words of wisdom, oh-rotary-lord.
I know quite a bit about these cars, but I would be an ******* to just come one here and only tell people to stop asking questions.
Like I said before, if you don't like the way the discussion is going, keep it to yourself. There is no need to discourage rotary enthusiasts from asking for help, be it from the most basic problem to the most complex theoretical question.
You say you stay away from places like this? I am relieved. I should hope that you would never have kids, and tell them to stop rambling for asking questions that seem simple to you.
As well, fact is fact: You can claim to have all this knowledge on these cars, but if you don't share it, your point is moot. I think that b/c of this, we can all agree that currently I have displayed much more knowledge on these cars than you have.
Sean Cathcart