Open Header
01-20-2008, 02:43 AM
#26
* B A N N E D *
Join Date: Jan 2008
Posts: 174
Likes: 0
Received 0 Likes
on
0 Posts
Re: Open Header (h22chilton)
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by h22chilton »</TD></TR><TR><TD CLASS="quote">my open header backfiring, flame throwing earth rumblin chassis shaking goodness, even the crotch-rockets complain.
</TD></TR></TABLE>
why don't you frind off the tab on the stock header, then tack it to your header, and install the intake manifold supprt so your header won't be clunking around all the time?
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Day_Walker »</TD></TR><TR><TD CLASS="quote">I remember a thread on here where some guy made some kind of valve that he could open by pulling on a wire in the cabin that would open up the valve to make it into a open header.</TD></TR></TABLE>
its called a cutout, they are really cheap, and on hmt we use old broken throttle bodies on ghetto hinges to hold them open.
the cutouts are pretty common for the street car/ weekend drag car thing
</TD></TR></TABLE>why don't you frind off the tab on the stock header, then tack it to your header, and install the intake manifold supprt so your header won't be clunking around all the time?
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Day_Walker »</TD></TR><TR><TD CLASS="quote">I remember a thread on here where some guy made some kind of valve that he could open by pulling on a wire in the cabin that would open up the valve to make it into a open header.</TD></TR></TABLE>
its called a cutout, they are really cheap, and on hmt we use old broken throttle bodies on ghetto hinges to hold them open.
the cutouts are pretty common for the street car/ weekend drag car thing
01-20-2008, 05:43 AM
#27
EPIC TUNING
Join Date: Sep 2002
Location: WA
Posts: 10,285
Likes: 0
Received 0 Likes
on
0 Posts
Re: (skilly)
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by skilly »</TD></TR><TR><TD CLASS="quote">
Try it on your truck
When I bought my Work ram, lets just say it was nowhere near as clean as yours 
I drove from Fredrick back to my house, about 1-1/2 hours on an open dp due to rust. I seriously couldn't hear anything for about 3 hours after I got back.</TD></TR></TABLE>
LOL, its loud enough as it is, I can only imagine what it would be like with open DP.
Well, I remember we ran my dads ram with no muffler to see what it sounded like while we installing the DP and exhaust. expletiveing rediculous.
Try it on your truck
When I bought my Work ram, lets just say it was nowhere near as clean as yours I drove from Fredrick back to my house, about 1-1/2 hours on an open dp due to rust. I seriously couldn't hear anything for about 3 hours after I got back.</TD></TR></TABLE>LOL, its loud enough as it is, I can only imagine what it would be like with open DP.
Well, I remember we ran my dads ram with no muffler to see what it sounded like while we installing the DP and exhaust. expletiveing rediculous.
01-20-2008, 08:38 AM
#28
* B A N N E D *
Join Date: Mar 2004
Location: WTB CA. . ., ky, us
Posts: 465
Likes: 0
Received 0 Likes
on
0 Posts
Re: Open Header (ninethree-civic)
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by ninethree-civic »</TD></TR><TR><TD CLASS="quote">
why don't you frind off the tab on the stock header, then tack it to your header, and install the intake manifold supprt so your header won't be clunking around all the time?
</TD></TR></TABLE>
your kidding right??
race header clunking around? intake manifold support??
I just put an $800 suspension on instead, keeps it off the ground
why don't you frind off the tab on the stock header, then tack it to your header, and install the intake manifold supprt so your header won't be clunking around all the time?
</TD></TR></TABLE>
your kidding right??
race header clunking around? intake manifold support??
I just put an $800 suspension on instead, keeps it off the ground
01-20-2008, 12:02 PM
#29
Night Owl
Join Date: Dec 2005
Location: the restaurant at the end of the universe
Posts: 4,199
Likes: 0
Received 1 Like
on
1 Post
Re: (ninethree-civic)
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by ninethree-civic »</TD></TR><TR><TD CLASS="quote">
ya thats an old rat rod myth, thus why you see skinny *** pipes in some of the older hot rods ( they thought it made more power)
and it's also horrible for a forced induction car, IE why people run blow off valves, and waste gates. otherwise they wouldnt bother. if they WANTED back pressure then remove the blow off valve and remove the wastegate..........
and if you take the theory of back pressure, then shoving a tennis ball in your exhaust or running an O-loop would be the greatest modification ever </TD></TR></TABLE>
Back pressure is not a myth. You're correct about restrictions on FI cars, but most of your assumptions are incorrect. Stock Honda exhaust systems produce a gob of low-end torque due to the restrictions producing low pressure at the tail end and effectively "sucking" the next exhaust pulse along. However, this doesn't apply for every make/model. Any newer BMW will detect that the engine is running lean if you have aftermarket exhaust, and adjust accordingly.
ya thats an old rat rod myth, thus why you see skinny *** pipes in some of the older hot rods ( they thought it made more power)
and it's also horrible for a forced induction car, IE why people run blow off valves, and waste gates. otherwise they wouldnt bother. if they WANTED back pressure then remove the blow off valve and remove the wastegate..........
and if you take the theory of back pressure, then shoving a tennis ball in your exhaust or running an O-loop would be the greatest modification ever </TD></TR></TABLE>
Back pressure is not a myth. You're correct about restrictions on FI cars, but most of your assumptions are incorrect. Stock Honda exhaust systems produce a gob of low-end torque due to the restrictions producing low pressure at the tail end and effectively "sucking" the next exhaust pulse along. However, this doesn't apply for every make/model. Any newer BMW will detect that the engine is running lean if you have aftermarket exhaust, and adjust accordingly.
01-20-2008, 01:21 PM
#30
Member
Join Date: Jun 2005
Location: Southern, MD, USA
Posts: 1,323
Likes: 0
Received 0 Likes
on
0 Posts
Re: (ninethree-civic)
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by ninethree-civic »</TD></TR><TR><TD CLASS="quote">and it's also horrible for a forced induction car, IE why people run blow off valves, and waste gates. otherwise they wouldnt bother. if they WANTED back pressure then remove the blow off valve and remove the wastegate..........
and if you take the theory of back pressure, then shoving a tennis ball in your exhaust or running an O-loop would be the greatest modification ever </TD></TR></TABLE>
Hold up homeslice.
Blow off valves are to let pressure out of the system so it doesn't blow back through the compressor wheel when you close the throttle body. A BOV has nothing to do with the exhaust.
A wastegate is there to let exhaust gases go through it instead of being forced through the exhaust housing of the turbo so it can maintain a certain level of boost. W/out a wastegate the turbo would continue to push a greater & greater volume of air out of it, which would eventually put the turbo out of it's efficiency range.
and if you take the theory of back pressure, then shoving a tennis ball in your exhaust or running an O-loop would be the greatest modification ever </TD></TR></TABLE>
Hold up homeslice.
Blow off valves are to let pressure out of the system so it doesn't blow back through the compressor wheel when you close the throttle body. A BOV has nothing to do with the exhaust.
A wastegate is there to let exhaust gases go through it instead of being forced through the exhaust housing of the turbo so it can maintain a certain level of boost. W/out a wastegate the turbo would continue to push a greater & greater volume of air out of it, which would eventually put the turbo out of it's efficiency range.
01-20-2008, 03:00 PM
#31
* B A N N E D *
Join Date: Jan 2008
Posts: 174
Likes: 0
Received 0 Likes
on
0 Posts
Re: (Everyones Hero)
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Everyones Hero »</TD></TR><TR><TD CLASS="quote">Hold up homeslice.
Blow off valves are to let pressure out of the system so it doesn't blow back through the compressor wheel when you close the throttle body. A BOV has nothing to do with the exhaust.
A wastegate is there to let exhaust gases go through it instead of being forced through the exhaust housing of the turbo so it can maintain a certain level of boost. W/out a wastegate the turbo would continue to push a greater & greater volume of air out of it, which would eventually put the turbo out of it's efficiency range.</TD></TR></TABLE>
right i went 2 steps ahead, my bad.
if backpressure was useful, then you'd want compressor surge would you not?
take the BOV off of the charge pping close the throttle
now your compressor is starting to want to back peddle CREATING back pressure in the manifold
then you remove the waste gate so it will not open up letting that exta pressure vent out or you allow it to open up way later in terms of pressure
but we do know (most of us) this is a horrid idea.
in fact back pressure does not allow all of the exhuast gas to exit the cylinder allowing the a/f mixture not compress as much as it should, effectivly reducing fuel milage, power and longevity of the compressor.
and in fact IF back pressure was a law of engine theory then, why would such a silly thing as valve overlap exist?
honda uses the exhuast to meet the restrictive standards of ULEV, after all their company is based around "safe for the enviorment" why would they not run restrictive exhuasts, huge EGR's (ever seen an R18 egr is larger than the exhaust), and other smog related devices not present on "performance" cars
Blow off valves are to let pressure out of the system so it doesn't blow back through the compressor wheel when you close the throttle body. A BOV has nothing to do with the exhaust.
A wastegate is there to let exhaust gases go through it instead of being forced through the exhaust housing of the turbo so it can maintain a certain level of boost. W/out a wastegate the turbo would continue to push a greater & greater volume of air out of it, which would eventually put the turbo out of it's efficiency range.</TD></TR></TABLE>
right i went 2 steps ahead, my bad.
if backpressure was useful, then you'd want compressor surge would you not?
take the BOV off of the charge pping close the throttle
now your compressor is starting to want to back peddle CREATING back pressure in the manifold
then you remove the waste gate so it will not open up letting that exta pressure vent out or you allow it to open up way later in terms of pressure
but we do know (most of us) this is a horrid idea.
in fact back pressure does not allow all of the exhuast gas to exit the cylinder allowing the a/f mixture not compress as much as it should, effectivly reducing fuel milage, power and longevity of the compressor.
and in fact IF back pressure was a law of engine theory then, why would such a silly thing as valve overlap exist?
honda uses the exhuast to meet the restrictive standards of ULEV, after all their company is based around "safe for the enviorment" why would they not run restrictive exhuasts, huge EGR's (ever seen an R18 egr is larger than the exhaust), and other smog related devices not present on "performance" cars
01-20-2008, 11:56 PM
#32
Honda-Tech Member
Join Date: Sep 2004
Location: so cal, USA
Posts: 4,516
Likes: 0
Received 0 Likes
on
0 Posts
Re: (ninethree-civic)
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by ninethree-civic »</TD></TR><TR><TD CLASS="quote">
right i went 2 steps ahead, my bad.
if backpressure was useful, then you'd want compressor surge would you not?
take the BOV off of the charge pping close the throttle
now your compressor is starting to want to back peddle CREATING back pressure in the manifold
then you remove the waste gate so it will not open up letting that exta pressure vent out or you allow it to open up way later in terms of pressure
but we do know (most of us) this is a horrid idea.
in fact back pressure does not allow all of the exhuast gas to exit the cylinder allowing the a/f mixture not compress as much as it should, effectivly reducing fuel milage, power and longevity of the compressor.
and in fact IF back pressure was a law of engine theory then, why would such a silly thing as valve overlap exist?
honda uses the exhuast to meet the restrictive standards of ULEV, after all their company is based around "safe for the enviorment" why would they not run restrictive exhuasts, huge EGR's (ever seen an R18 egr is larger than the exhaust), and other smog related devices not present on "performance" cars </TD></TR></TABLE>
sigh..
the BOV sits between the turbo and the intake manifold. It's to prevent back pressure to your turbo by releasing air through the blow-off valve when you take your foot off the gas pedal which closes the throttle body valve. You don't want back pressure here because it damages your turbo. Having a BOV prevents back pressure to your turbo thus extending the life of your turbo.
Removing a wastegate would be stupid because it controls the amount of boost. It also prevents your turbine from spinning indefinitely and faster than it's supposed to.
The first reason why people say "backpressure is good" is because they believe that increased backpressure by itself will increase torque, particularly with a stock exhaust manifold. Granted, some stock manifolds act somewhat like performance headers at low RPM, but these manifolds will exhibit poor performance at higher RPM. This, however does not automatically lead to the conclusion that backpressure produces more torque. The increase in torque is not due to backpressure, but to the effects of changes in fuel/air mixture. If your car has the ability to adjust a/f ratio on it's own, then you wouldn't want back pressure.
right i went 2 steps ahead, my bad.
if backpressure was useful, then you'd want compressor surge would you not?
take the BOV off of the charge pping close the throttle
now your compressor is starting to want to back peddle CREATING back pressure in the manifold
then you remove the waste gate so it will not open up letting that exta pressure vent out or you allow it to open up way later in terms of pressure
but we do know (most of us) this is a horrid idea.
in fact back pressure does not allow all of the exhuast gas to exit the cylinder allowing the a/f mixture not compress as much as it should, effectivly reducing fuel milage, power and longevity of the compressor.
and in fact IF back pressure was a law of engine theory then, why would such a silly thing as valve overlap exist?
honda uses the exhuast to meet the restrictive standards of ULEV, after all their company is based around "safe for the enviorment" why would they not run restrictive exhuasts, huge EGR's (ever seen an R18 egr is larger than the exhaust), and other smog related devices not present on "performance" cars </TD></TR></TABLE>
sigh..
the BOV sits between the turbo and the intake manifold. It's to prevent back pressure to your turbo by releasing air through the blow-off valve when you take your foot off the gas pedal which closes the throttle body valve. You don't want back pressure here because it damages your turbo. Having a BOV prevents back pressure to your turbo thus extending the life of your turbo.
Removing a wastegate would be stupid because it controls the amount of boost. It also prevents your turbine from spinning indefinitely and faster than it's supposed to.
The first reason why people say "backpressure is good" is because they believe that increased backpressure by itself will increase torque, particularly with a stock exhaust manifold. Granted, some stock manifolds act somewhat like performance headers at low RPM, but these manifolds will exhibit poor performance at higher RPM. This, however does not automatically lead to the conclusion that backpressure produces more torque. The increase in torque is not due to backpressure, but to the effects of changes in fuel/air mixture. If your car has the ability to adjust a/f ratio on it's own, then you wouldn't want back pressure.
01-21-2008, 01:30 AM
#33
Honda-Tech Member
Join Date: Apr 2005
Location: Lincoln, Ne, USA
Posts: 1,895
Likes: 0
Received 0 Likes
on
0 Posts
Re: (eMpAtHy)
backpressure=bad in all situations. However, you have to balance the mass flow and velocity of the exhaust in order to optimize the design...And like everything there are compromises.
01-21-2008, 05:57 AM
#34
EPIC TUNING
Join Date: Sep 2002
Location: WA
Posts: 10,285
Likes: 0
Received 0 Likes
on
0 Posts
Re: (ninethree-civic)
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by ninethree-civic »</TD></TR><TR><TD CLASS="quote">
right i went 2 steps ahead, my bad.
if backpressure was useful, then you'd want compressor surge would you not?
take the BOV off of the charge pping close the throttle
now your compressor is starting to want to back peddle CREATING back pressure in the manifold
then you remove the waste gate so it will not open up letting that exta pressure vent out or you allow it to open up way later in terms of pressure
but we do know (most of us) this is a horrid idea.
in fact back pressure does not allow all of the exhuast gas to exit the cylinder allowing the a/f mixture not compress as much as it should, effectivly reducing fuel milage, power and longevity of the compressor.
and in fact IF back pressure was a law of engine theory then, why would such a silly thing as valve overlap exist?
honda uses the exhuast to meet the restrictive standards of ULEV, after all their company is based around "safe for the enviorment" why would they not run restrictive exhuasts, huge EGR's (ever seen an R18 egr is larger than the exhaust), and other smog related devices not present on "performance" cars </TD></TR></TABLE>
LOL @ your attempt to sound smart
right i went 2 steps ahead, my bad.
if backpressure was useful, then you'd want compressor surge would you not?
take the BOV off of the charge pping close the throttle
now your compressor is starting to want to back peddle CREATING back pressure in the manifold
then you remove the waste gate so it will not open up letting that exta pressure vent out or you allow it to open up way later in terms of pressure
but we do know (most of us) this is a horrid idea.
in fact back pressure does not allow all of the exhuast gas to exit the cylinder allowing the a/f mixture not compress as much as it should, effectivly reducing fuel milage, power and longevity of the compressor.
and in fact IF back pressure was a law of engine theory then, why would such a silly thing as valve overlap exist?
honda uses the exhuast to meet the restrictive standards of ULEV, after all their company is based around "safe for the enviorment" why would they not run restrictive exhuasts, huge EGR's (ever seen an R18 egr is larger than the exhaust), and other smog related devices not present on "performance" cars </TD></TR></TABLE>
LOL @ your attempt to sound smart
01-21-2008, 12:15 PM
#35
Honda-Tech Member
Re: (k24em2)
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by k24em2 »</TD></TR><TR><TD CLASS="quote">backpressure=bad in all situations. However, you have to balance the mass flow and velocity of the exhaust in order to optimize the design...And like everything there are compromises.</TD></TR></TABLE>
Exactly.
In a performance application, back pressure is never desired. However, it can be useful for a street driven car since it reduces exhaust noise.
Exactly.
In a performance application, back pressure is never desired. However, it can be useful for a street driven car since it reduces exhaust noise.
01-21-2008, 01:28 PM
#36
Im not Banned
Join Date: Apr 2007
Posts: 1,347
Likes: 0
Received 0 Likes
on
0 Posts
Re: (E-Rok)
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by E-Rok »</TD></TR><TR><TD CLASS="quote">
LOL @ your attempt to sound smart</TD></TR></TABLE>
He's lucky I can't be bothered going through all his threads and posting all the stupid **** he's said lol
LOL @ your attempt to sound smart</TD></TR></TABLE>
He's lucky I can't be bothered going through all his threads and posting all the stupid **** he's said lol
01-23-2008, 11:50 AM
#38
Honda-Tech Member
Join Date: Oct 2001
Location: Eindhoven, Netherlands
Posts: 1,756
Likes: 0
Received 0 Likes
on
0 Posts
Re:
When I swapped a B16 into my Civic, it still seemed just as slow as before. I figured out it was because the stock exhaust was not up to the task of the greater air flow.
So, I used to unbolt it at the track and it would straight up make over a half second difference in my 1/4 mile time. Hell, even later on when I unbolted an upgraded exhaust, it would still make a significant difference.
Point is, don't underestimate the difference an open header can do for your power output. That said, don't underestimate what it can do for your ricer status, either.
So, I used to unbolt it at the track and it would straight up make over a half second difference in my 1/4 mile time. Hell, even later on when I unbolted an upgraded exhaust, it would still make a significant difference.
Point is, don't underestimate the difference an open header can do for your power output. That said, don't underestimate what it can do for your ricer status, either.
01-23-2008, 11:52 AM
#39
Honda-Tech Member
Re: Re: (Lsos)
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Lsos »</TD></TR><TR><TD CLASS="quote">When I swapped a B16 into my Civic, it still seemed just as slow as before. I figured out it was because the stock exhaust was not up to the task of the greater air flow.
So, I used to unbolt it at the track and it would straight up make over a half second difference in my 1/4 mile time. Hell, even later on when I unbolted an upgraded exhaust, it would still make a significant difference.
Point is, don't underestimate the difference an open header can do for your power output. That said, don't underestimate what it can do for your ricer status, either.</TD></TR></TABLE>
What was your "upgraded" exhaust?
So, I used to unbolt it at the track and it would straight up make over a half second difference in my 1/4 mile time. Hell, even later on when I unbolted an upgraded exhaust, it would still make a significant difference.
Point is, don't underestimate the difference an open header can do for your power output. That said, don't underestimate what it can do for your ricer status, either.</TD></TR></TABLE>
What was your "upgraded" exhaust?
01-23-2008, 12:26 PM
#40
Honda-Tech Member
Join Date: May 2006
Location: NB, Canada
Posts: 2,788
Likes: 0
Received 0 Likes
on
0 Posts
Re: Re: (ddd4114)
Please, I may be understanding the terminology wrong, but if someone can explain to me how "backpressure" ie: any restriction or reversion is good, I would like to know.
If I can get my exhaust gas velocity high enough, during valve overlap at TDC, It's possible to promote scavenging of the exhaust gases, or in other words, the exhaust actually exiting faster out than the piston is moving up, creating some small amount of vacuum in the cylinder, and therefore potentially sucking a small amount of air/fuel into the cylinder before the piston even starts moving down on the intake stroke.
That's my understanding of the theoretical application. Whether or not it actually is effective, well, I'd like to hear some input from any engine builders.
If I can get my exhaust gas velocity high enough, during valve overlap at TDC, It's possible to promote scavenging of the exhaust gases, or in other words, the exhaust actually exiting faster out than the piston is moving up, creating some small amount of vacuum in the cylinder, and therefore potentially sucking a small amount of air/fuel into the cylinder before the piston even starts moving down on the intake stroke.
That's my understanding of the theoretical application. Whether or not it actually is effective, well, I'd like to hear some input from any engine builders.
01-23-2008, 03:27 PM
#41
Join Date: Jan 2008
Location: Lexington, SC
Posts: 37
Likes: 0
Received 0 Likes
on
0 Posts
Re: Re: (gibsanez)
Not an engine builder, I am a jet engine mechanic if that counts.
Everytime I hear that backpressure argument I cringe.
you want the pressure inside the exhaust pipes, header, ports to be low as possible in relation to the exhaust gasses inside cylinder before the exhaust valve(s) open. The greater the pressure differences in pressure the quicker and more thurough the waste gasses will be scavanged from the cylinder.
If the gasses on each side of the valve were same pressure there would be no flow when it open (well maybe diffusion)
So what benefit would if be to keep the exhaust gases after the valve at higher pressure?
The higher the velocity of a gas the lower the pressure and temperature.
The lower the velocity of a gas the higher the pressure and temperature.
The best exhaust would be one that varied its size in relation the amount of gasses and temperature of the gasses to maximize velocity of the gasses to decrease the pressure. Since our technology/wallets are insufficent, we are stuck with fixed exhausts.
Ideally with a fixed exhaust you want the pipes to converge in the direction of the exhaust flow to increase the exhausts velocity. So a pipe that starts out big and slowly gets smaller as it reaches the exit is good. The ideal exhaust wouldn't want anything to obstuct the flow of the gas so no mufflers, no cats and no edges.
Here is something from my other forum relating to this
http://www.hyundaiperformance....rgent
Everytime I hear that backpressure argument I cringe.
you want the pressure inside the exhaust pipes, header, ports to be low as possible in relation to the exhaust gasses inside cylinder before the exhaust valve(s) open. The greater the pressure differences in pressure the quicker and more thurough the waste gasses will be scavanged from the cylinder.
If the gasses on each side of the valve were same pressure there would be no flow when it open (well maybe diffusion)
So what benefit would if be to keep the exhaust gases after the valve at higher pressure?
The higher the velocity of a gas the lower the pressure and temperature.
The lower the velocity of a gas the higher the pressure and temperature.
The best exhaust would be one that varied its size in relation the amount of gasses and temperature of the gasses to maximize velocity of the gasses to decrease the pressure. Since our technology/wallets are insufficent, we are stuck with fixed exhausts.
Ideally with a fixed exhaust you want the pipes to converge in the direction of the exhaust flow to increase the exhausts velocity. So a pipe that starts out big and slowly gets smaller as it reaches the exit is good. The ideal exhaust wouldn't want anything to obstuct the flow of the gas so no mufflers, no cats and no edges.
Here is something from my other forum relating to this
http://www.hyundaiperformance....rgent
01-23-2008, 04:26 PM
#43
Honda-Tech Member
Re: Re: (Coal_forge)
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Coal_forge »</TD></TR><TR><TD CLASS="quote">you want the pressure inside the exhaust pipes, header, ports to be low as possible in relation to the exhaust gasses inside cylinder before the exhaust valve(s) open. The greater the pressure differences in pressure the quicker and more thurough the waste gasses will be scavanged from the cylinder.
If the gasses on each side of the valve were same pressure there would be no flow when it open (well maybe diffusion)
So what benefit would if be to keep the exhaust gases after the valve at higher pressure?
The higher the velocity of a gas the lower the pressure and temperature.
The lower the velocity of a gas the higher the pressure and temperature.
The best exhaust would be one that varied its size in relation the amount of gasses and temperature of the gasses to maximize velocity of the gasses to decrease the pressure. Since our technology/wallets are insufficent, we are stuck with fixed exhausts.
Ideally with a fixed exhaust you want the pipes to converge in the direction of the exhaust flow to increase the exhausts velocity. So a pipe that starts out big and slowly gets smaller as it reaches the exit is good. The ideal exhaust wouldn't want anything to obstuct the flow of the gas so no mufflers, no cats and no edges.
Here is something from my other forum relating to this
http://www.hyundaiperformance....rgent</TD></TR></TABLE>
I agree with everything except that last part. Wouldn't a pipe that is gradually reduced in diameter facilitate reversion? I guess it depends on the gradualness of the CSA reduction.
If the gasses on each side of the valve were same pressure there would be no flow when it open (well maybe diffusion)
So what benefit would if be to keep the exhaust gases after the valve at higher pressure?
The higher the velocity of a gas the lower the pressure and temperature.
The lower the velocity of a gas the higher the pressure and temperature.
The best exhaust would be one that varied its size in relation the amount of gasses and temperature of the gasses to maximize velocity of the gasses to decrease the pressure. Since our technology/wallets are insufficent, we are stuck with fixed exhausts.
Ideally with a fixed exhaust you want the pipes to converge in the direction of the exhaust flow to increase the exhausts velocity. So a pipe that starts out big and slowly gets smaller as it reaches the exit is good. The ideal exhaust wouldn't want anything to obstuct the flow of the gas so no mufflers, no cats and no edges.
Here is something from my other forum relating to this
http://www.hyundaiperformance....rgent</TD></TR></TABLE>
I agree with everything except that last part. Wouldn't a pipe that is gradually reduced in diameter facilitate reversion? I guess it depends on the gradualness of the CSA reduction.
01-23-2008, 06:25 PM
#44
Honda-Tech Member
Join Date: Oct 2001
Location: Eindhoven, Netherlands
Posts: 1,756
Likes: 0
Received 0 Likes
on
0 Posts
Re: Re: (ddd4114)
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by ddd4114 »</TD></TR><TR><TD CLASS="quote">
What was your "upgraded" exhaust?</TD></TR></TABLE>
It was just wider. 2 1/4 in muffler shop piping if I remember. I tossed a supertrapp muffler on the back. Later I threw a cherry bomb resonator in the center somewhere just so it sounds a little less horrible.
What was your "upgraded" exhaust?</TD></TR></TABLE>
It was just wider. 2 1/4 in muffler shop piping if I remember. I tossed a supertrapp muffler on the back. Later I threw a cherry bomb resonator in the center somewhere just so it sounds a little less horrible.
Thread
Thread Starter
Forum
Replies
Last Post
EM2ABOO
Honda Civic (2001 - 2005)
7
10-25-2009 10:07 AM
