dual exhaust question
10-30-2005, 06:24 PM
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dual exhaust question
I am just wondering why dual exhausts are not good for 4 cylinder cars. I've heard this a lot while surfing h-t but never really understood why and am curious to why it is not good. Also if it is not good why do some 4 cylinder cars have them such as s2k or mr2. I am not planning on getting any dual exhaust systems, I just want a better understanding of why. Thanks in advance.
10-30-2005, 06:27 PM
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Re: dual exhaust question (flipp117)
i dont really know either. ive heard that its too much back pressure for a 4 cyl. i dunno. but if you notcie the acuras with 6 cylinders and the v6 accords have dual..also a s2k is a 6 cylinder i think
10-30-2005, 06:33 PM
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Re: (00CivicGirl)
yeah i've noticed that too that the v6 accords have dual. I've also noticed that maybe since mr2 turbos have dual it may help them? but then again the n/a mr2s still have dual so I am a little confused.
10-30-2005, 06:48 PM
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its not to much back pressure...its to little back pressure thats bad for 4 cylinders...to much back pressure decreases power nd to much back pressure can bend valves in the head...so if u put dual exhaust on a 1.6 or 1.8 it isnt such a good idea...now the 2.4 wich the s2000 nd mr2's have its ok to have dual exhaust on since the motor isnt so small like 1.6 nd 1.8 nd if u dont have enoughf back pressure the engine can stall....my automotive teacher taught all this stuff so im not makin it up cuz i asked the same question
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10-30-2005, 07:20 PM
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the MR2 is one muffler with two outlets, if you have an inline 4, with a header to a collector, from there back its all how restrictive it is, no matter what pipes go where and what splits off how.
true duals are on a V engine like a V8 where there are 2 collectors and 2 whole exhaust systems. they have dual outlets mainly just because they have 2 headers start out with. Many of them put the 2 pipes togeather into a big one, or even put in an X or H pipe to make sure the pressure is the same in both systems (in case one is a little more restrictive.
The bad way to do duals on an inline 4 would be to have a header that had 2 collectors (2 cylinders per collector) then keep two totally separate systems with two mufflers.
If you just have a header and pipe and a Y and two mufflers, that might just be cooler to you, and it will be less restrictive than just a single muffler, and probably quieter (since there is more baffling / glasspack per amount of exhaust)
hope that helps.
true duals are on a V engine like a V8 where there are 2 collectors and 2 whole exhaust systems. they have dual outlets mainly just because they have 2 headers start out with. Many of them put the 2 pipes togeather into a big one, or even put in an X or H pipe to make sure the pressure is the same in both systems (in case one is a little more restrictive.
The bad way to do duals on an inline 4 would be to have a header that had 2 collectors (2 cylinders per collector) then keep two totally separate systems with two mufflers.
If you just have a header and pipe and a Y and two mufflers, that might just be cooler to you, and it will be less restrictive than just a single muffler, and probably quieter (since there is more baffling / glasspack per amount of exhaust)
hope that helps.
10-30-2005, 08:17 PM
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Re: dual exhaust question (flipp117)
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by flipp117 »</TD></TR><TR><TD CLASS="quote">I am just wondering why dual exhausts are not good for 4 cylinder cars. I've heard this a lot while surfing h-t but never really understood why and am curious to why it is not good. Also if it is not good why do some 4 cylinder cars have them such as s2k or mr2. I am not planning on getting any dual exhaust systems, I just want a better understanding of why. Thanks in advance.</TD></TR></TABLE>
answer me this...why are they good?
..theres your answer for why they arent good.
answer me this...why are they good?
..theres your answer for why they arent good.
10-30-2005, 09:24 PM
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Re: (moosepoop21)
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by moosepoop21 »</TD></TR><TR><TD CLASS="quote">its not to much back pressure...its to little back pressure thats bad for 4 cylinders...to much back pressure decreases power nd to much back pressure can bend valves in the head...so if u put dual exhaust on a 1.6 or 1.8 it isnt such a good idea...now the 2.4 wich the s2000 nd mr2's have its ok to have dual exhaust on since the motor isnt so small like 1.6 nd 1.8 nd if u dont have enoughf back pressure the engine can stall....my automotive teacher taught all this stuff so im not makin it up cuz i asked the same question </TD></TR></TABLE>
sorry, but your automotive teacher is an idiot.
first of all, the backpressure issue has been brought up thousands of times. back pressure is bad BOTTOM LINE. i'll say this for those who still dont understand. 4 STROKE ENGINES DO NOT NEED BACKPRESSURE WHATSOEVER what engines do rely on is exhaust gas velocity, which is the basis of exhaust pipe sizing (too big of pipe causes low velocity and therefore affects scavenging of exhaust gasses from the combustion chamber)
if running dual exhaust made the car "have too little back pressure" then cutting off your muffler would do the same since the pipe just splits after the rear suspension.
the reason dual exhaust isnt good, is because it does nothing for performance. in some cases it can hinder performance because of where the pipe splits into 2, it creates a restriction, also known as BACKPRESSURE which hinders exhaust gas velocity.
the reason some factory 4 cylinders come wth dual exhaust is for asthetics only. it LOOKS sporty.
sorry, but your automotive teacher is an idiot.
first of all, the backpressure issue has been brought up thousands of times. back pressure is bad BOTTOM LINE. i'll say this for those who still dont understand. 4 STROKE ENGINES DO NOT NEED BACKPRESSURE WHATSOEVER what engines do rely on is exhaust gas velocity, which is the basis of exhaust pipe sizing (too big of pipe causes low velocity and therefore affects scavenging of exhaust gasses from the combustion chamber)
if running dual exhaust made the car "have too little back pressure" then cutting off your muffler would do the same since the pipe just splits after the rear suspension.
the reason dual exhaust isnt good, is because it does nothing for performance. in some cases it can hinder performance because of where the pipe splits into 2, it creates a restriction, also known as BACKPRESSURE which hinders exhaust gas velocity.
the reason some factory 4 cylinders come wth dual exhaust is for asthetics only. it LOOKS sporty.
10-30-2005, 09:29 PM
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Re: dual exhaust question (00CivicGirl)
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by 00CivicGirl »</TD></TR><TR><TD CLASS="quote">also a s2k is a 6 cylinder i think</TD></TR></TABLE>
The Honda S2000 is NOT a 6 cylindar. It has an inline 4 cylindar motor.
The Honda S2000 is NOT a 6 cylindar. It has an inline 4 cylindar motor.
10-30-2005, 10:54 PM
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Re: (91civicDXdude)
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by 91civicDXdude »</TD></TR><TR><TD CLASS="quote">sorry, but your automotive teacher is an idiot.
first of all, the backpressure issue has been brought up thousands of times. back pressure is bad BOTTOM LINE. i'll say this for those who still dont understand. 4 STROKE ENGINES DO NOT NEED BACKPRESSURE WHATSOEVER what engines do rely on is exhaust gas velocity, which is the basis of exhaust pipe sizing (too big of pipe causes low velocity and therefore affects scavenging of exhaust gasses from the combustion chamber)
if running dual exhaust made the car "have too little back pressure" then cutting off your muffler would do the same since the pipe just splits after the rear suspension.
the reason dual exhaust isnt good, is because it does nothing for performance. in some cases it can hinder performance because of where the pipe splits into 2, it creates a restriction, also known as BACKPRESSURE which hinders exhaust gas velocity.
the reason some factory 4 cylinders come wth dual exhaust is for asthetics only. it LOOKS sporty.</TD></TR></TABLE>
This is the only guy that's replied that knows what he's talking about, listen up kids, school is in session.
Exhaust is full of energy, thermal, kinetic, and sound, reduce any of these things and the energy is lost, thus is flow. Dual exhaust causes thermal energy to be lost, think of a heat soak, it is a larger area for heat to be dispersed. Every ricer knows colder air is more dense, dense air flows more slowly.
Backpressure like stated is never wanted on a 4 stroke engine, smaller piping, smaller ports, etc. flow better at low RPMs giving better low end power. The opposite is true for high end power, however, this will cause loss of low end power, for a street car, you need to decide what you can tolerate to drive on the streets and sacrifice some horsepower.
Sacrifice some horsepower you say? How is that?
Horsepower is made from torque over time, 300ft/lbs at 2,000rpms is going to make alot less power than 300ft/lbs at 5,000rpms. It's alot more 300ft/lbs being made over a cetain time, i hope that makes sense, i suck at explaining things.
I'm no expert at this, but i know enough to understand what's going on, if anyone would like to add to this do so.
first of all, the backpressure issue has been brought up thousands of times. back pressure is bad BOTTOM LINE. i'll say this for those who still dont understand. 4 STROKE ENGINES DO NOT NEED BACKPRESSURE WHATSOEVER what engines do rely on is exhaust gas velocity, which is the basis of exhaust pipe sizing (too big of pipe causes low velocity and therefore affects scavenging of exhaust gasses from the combustion chamber)
if running dual exhaust made the car "have too little back pressure" then cutting off your muffler would do the same since the pipe just splits after the rear suspension.
the reason dual exhaust isnt good, is because it does nothing for performance. in some cases it can hinder performance because of where the pipe splits into 2, it creates a restriction, also known as BACKPRESSURE which hinders exhaust gas velocity.
the reason some factory 4 cylinders come wth dual exhaust is for asthetics only. it LOOKS sporty.</TD></TR></TABLE>
This is the only guy that's replied that knows what he's talking about, listen up kids, school is in session.
Exhaust is full of energy, thermal, kinetic, and sound, reduce any of these things and the energy is lost, thus is flow. Dual exhaust causes thermal energy to be lost, think of a heat soak, it is a larger area for heat to be dispersed. Every ricer knows colder air is more dense, dense air flows more slowly.
Backpressure like stated is never wanted on a 4 stroke engine, smaller piping, smaller ports, etc. flow better at low RPMs giving better low end power. The opposite is true for high end power, however, this will cause loss of low end power, for a street car, you need to decide what you can tolerate to drive on the streets and sacrifice some horsepower.
Sacrifice some horsepower you say? How is that?
Horsepower is made from torque over time, 300ft/lbs at 2,000rpms is going to make alot less power than 300ft/lbs at 5,000rpms. It's alot more 300ft/lbs being made over a cetain time, i hope that makes sense, i suck at explaining things.
I'm no expert at this, but i know enough to understand what's going on, if anyone would like to add to this do so.
10-30-2005, 11:09 PM
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Re: (O16581724 5 2 5)
f*** it, if anyone wants dual exhaust on their car just add a 90 degree onto your already existing exhaust, like the guy I bought my car from. 
F***ing idiot!!!! Anyone wanna buy a fake dual exhaust?? 
F***ing idiot!!!! Anyone wanna buy a fake dual exhaust??
10-30-2005, 11:53 PM
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Re: (O16581724 5 2 5)
Ok I just want to make sure I have this correct. Dual exhaust basically causes the air to not flow as well because when it splits at the Y part it causes restriction. The size of the piping on single exhausts will affect the type of power you get. I.E. smaller piping means lower end power and larger piping means more top end power. Is this correct?
Edit: No I'm not thinking of getting a dual exhaust I am simply just curious because I have been reading on this forum that they are bad. I just wanted to know why and the basic principle of it.
Edit: No I'm not thinking of getting a dual exhaust I am simply just curious because I have been reading on this forum that they are bad. I just wanted to know why and the basic principle of it.
10-31-2005, 04:36 AM
#18
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Re: dual exhaust question (flipp117)
Not gonna hurt or gain performance. It is much easier to run one pie then 2.
K.I.S.S-keep it simple stupid
Sure you could run a dual exhaust off your 4 cyclinger but it's much easier to run a single pipe. You would need to also make custom headers also. Basicaly alot of work for not a bit of gain.
Also most car that have 2 pipes sticking out the back don't really have dual exhaust.
K.I.S.S-keep it simple stupid
Sure you could run a dual exhaust off your 4 cyclinger but it's much easier to run a single pipe. You would need to also make custom headers also. Basicaly alot of work for not a bit of gain.
Also most car that have 2 pipes sticking out the back don't really have dual exhaust.
10-31-2005, 06:31 AM
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Re: dual exhaust question (turboman)
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by turboman »</TD></TR><TR><TD CLASS="quote"> Also most car that have 2 pipes sticking out the back don't really have dual exhaust.</TD></TR></TABLE>
haha. i bet that looks real good on those cold days. one muffler blowing out smoke, the other one isnt. lol
flipp117 - congrats. you're the first person under 300 posts that actually makes sense and understands wtf they want answered
take notes newbs!
haha. i bet that looks real good on those cold days. one muffler blowing out smoke, the other one isnt. lol
flipp117 - congrats. you're the first person under 300 posts that actually makes sense and understands wtf they want answered
take notes newbs!
10-31-2005, 06:37 AM
#20
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Re: dual exhaust question (niann)
all that extra metal fron the y to your extra muffler adds weight too. I wouldn't run a dual exhaust unless i had 2 exhaust banks on my motor, or the car came stock that way. IMO, it looks dumb as hell on any econbox car.
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