What are the gains of exhaust
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Joined: Jan 2002
Posts: 1,078
Originally posted by Dave B
Bigger is not always better
Some people aren't doing a good job of explaining themselves. The true goal of a good flowing exhaust is to keep exhaust velocity to the maximum. Exhaust velocity has a lot to do with heat. The more heat you have in the exhaust, the better the flow will be (to a point). If the exhaust is allowed to cool too much (low velocity), a turbulence occurs in the pipe (kinda like in weather when a cold front meets a warm front). Pipe diameter is related to this goal of keeping in the heat, but bigger pipes won't always yield the best gains. If the pipe is too big, the exhaust velocity slows down, therefore the motor can't breath as well. NA cars can make do with smaller pipes because they don't move a lot of air. A turbo charged car will move lots of air under boost therefore you see some of the biggest diameter pipes on a relatively small turbo motor. The VQ Max does fine with a good mandrel 2.5" exhaust. No more than that will be needed. A strong running 2.0 liter turbo Talon/Eclipse can make full use of a 3" system, possibly even a 3.5" system depending on mods. If you understand the basic function of "pie", you'd know a 3.5" system will flow gobs more air than a 2.5" system.
The "popping" people hear is mostly due to a lack of velocity. Usually this popping occurs on engine deceleration. The popping is the combustion of air/fuel in the exhaust pipe. I'm not exactly clear on the concept, but the air/fuel mixture coming in contact with the hot/cold spots in the exhaust causes a kind of detonation in exhaust pipe therefore you get the popping.
Dave
Bigger is not always better
Some people aren't doing a good job of explaining themselves. The true goal of a good flowing exhaust is to keep exhaust velocity to the maximum. Exhaust velocity has a lot to do with heat. The more heat you have in the exhaust, the better the flow will be (to a point). If the exhaust is allowed to cool too much (low velocity), a turbulence occurs in the pipe (kinda like in weather when a cold front meets a warm front). Pipe diameter is related to this goal of keeping in the heat, but bigger pipes won't always yield the best gains. If the pipe is too big, the exhaust velocity slows down, therefore the motor can't breath as well. NA cars can make do with smaller pipes because they don't move a lot of air. A turbo charged car will move lots of air under boost therefore you see some of the biggest diameter pipes on a relatively small turbo motor. The VQ Max does fine with a good mandrel 2.5" exhaust. No more than that will be needed. A strong running 2.0 liter turbo Talon/Eclipse can make full use of a 3" system, possibly even a 3.5" system depending on mods. If you understand the basic function of "pie", you'd know a 3.5" system will flow gobs more air than a 2.5" system. The "popping" people hear is mostly due to a lack of velocity. Usually this popping occurs on engine deceleration. The popping is the combustion of air/fuel in the exhaust pipe. I'm not exactly clear on the concept, but the air/fuel mixture coming in contact with the hot/cold spots in the exhaust causes a kind of detonation in exhaust pipe therefore you get the popping.
Dave
in other words its backfiring??? or am i safe and this is normal?
Well there goes the incentive to use the search feature.
Originally posted by Dave B
Bigger is not always better Some people aren't doing a good job of explaining themselves. The true goal of a good flowing exhaust is to keep exhaust velocity to the maximum. Exhaust velocity has a lot to do with heat. The more heat you have in the exhaust, the better the flow will be (to a point). If the exhaust is allowed to cool too much (low velocity), a turbulence occurs in the pipe (kinda like in weather when a cold front meets a warm front). Pipe diameter is related to this goal of keeping in the heat, but bigger pipes won't always yield the best gains. If the pipe is too big, the exhaust velocity slows down, therefore the motor can't breath as well. NA cars can make do with smaller pipes because they don't move a lot of air. A turbo charged car will move lots of air under boost therefore you see some of the biggest diameter pipes on a relatively small turbo motor. The VQ Max does fine with a good mandrel 2.5" exhaust. No more than that will be needed. A strong running 2.0 liter turbo Talon/Eclipse can make full use of a 3" system, possibly even a 3.5" system depending on mods. If you understand the basic function of "pie", you'd know a 3.5" system will flow gobs more air than a 2.5" system.
The "popping" people hear is mostly due to a lack of velocity. Usually this popping occurs on engine deceleration. The popping is the combustion of air/fuel in the exhaust pipe. I'm not exactly clear on the concept, but the air/fuel mixture coming in contact with the hot/cold spots in the exhaust causes a kind of detonation in exhaust pipe therefore you get the popping.
Dave
Bigger is not always better
Some people aren't doing a good job of explaining themselves. The true goal of a good flowing exhaust is to keep exhaust velocity to the maximum. Exhaust velocity has a lot to do with heat. The more heat you have in the exhaust, the better the flow will be (to a point). If the exhaust is allowed to cool too much (low velocity), a turbulence occurs in the pipe (kinda like in weather when a cold front meets a warm front). Pipe diameter is related to this goal of keeping in the heat, but bigger pipes won't always yield the best gains. If the pipe is too big, the exhaust velocity slows down, therefore the motor can't breath as well. NA cars can make do with smaller pipes because they don't move a lot of air. A turbo charged car will move lots of air under boost therefore you see some of the biggest diameter pipes on a relatively small turbo motor. The VQ Max does fine with a good mandrel 2.5" exhaust. No more than that will be needed. A strong running 2.0 liter turbo Talon/Eclipse can make full use of a 3" system, possibly even a 3.5" system depending on mods. If you understand the basic function of "pie", you'd know a 3.5" system will flow gobs more air than a 2.5" system. The "popping" people hear is mostly due to a lack of velocity. Usually this popping occurs on engine deceleration. The popping is the combustion of air/fuel in the exhaust pipe. I'm not exactly clear on the concept, but the air/fuel mixture coming in contact with the hot/cold spots in the exhaust causes a kind of detonation in exhaust pipe therefore you get the popping.
Dave
ha ha stupid search!!
but seriously though, sx7r is running 3" dual exhaust and its just a straight pipe. no muffler or nothing is that a bit overkill, would he be better off with smaller pipes? given hes running lots more hp than i ever will be but still 3" is big and 3" duals is huge.
Not DAVEB the parts guy
Joined: Aug 2000
Posts: 8,549
Re: ha ha stupid search!!
Originally posted by Justin95SE
but seriously though, sx7r is running 3" dual exhaust and its just a straight pipe. no muffler or nothing is that a bit overkill, would he be better off with smaller pipes? given hes running lots more hp than i ever will be but still 3" is big and 3" duals is huge.
but seriously though, sx7r is running 3" dual exhaust and its just a straight pipe. no muffler or nothing is that a bit overkill, would he be better off with smaller pipes? given hes running lots more hp than i ever will be but still 3" is big and 3" duals is huge.
Dave
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