High flow exhaust cause a loss of...?
That One Guy
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High flow exhaust cause a loss of...?
So I hear claims here and there that running with a straight high flow exhaust on NA cars, most likly with no cat, can lead to a loss of low end, and mid-range power, all your daily drive ablity basically.
Is this true? I dont think theres a big number difference, maybe more of an opinion. Or maybe depends on each situation. Any general thoughts to this?
But I'm not too sure, so any input on this.
Is this true? I dont think theres a big number difference, maybe more of an opinion. Or maybe depends on each situation. Any general thoughts to this?
But I'm not too sure, so any input on this.
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Last edited by edmel89; 11-04-2009 at 05:46 AM.
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Big exhaust = no backpressure = honda = no torque = no low end(well even less than before anyways.)
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When you say Honda, do you mean only Honda's, or do you mean 4cyl's
Straight through "big" exhaust only benefit turbo engines, and larger displacments?
Straight through "big" exhaust only benefit turbo engines, and larger displacments?
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Last edited by edmel89; 11-04-2009 at 05:47 AM.
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Backpressure isn't the goal...
The goal is to get the exhaust gas out as quickly as possible. That is ahcieved through maximum exhaust velocity, which also aids with exhaust gas scavenging.
If you go with a larger diameter pipe than your engine can fill to maximum velocity, the exhaust gas density lowers, allowing temperatures to drop; colder gasses are more dense, thus harder to push.
The goal is to get the exhaust gas out as quickly as possible. That is ahcieved through maximum exhaust velocity, which also aids with exhaust gas scavenging.
If you go with a larger diameter pipe than your engine can fill to maximum velocity, the exhaust gas density lowers, allowing temperatures to drop; colder gasses are more dense, thus harder to push.
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So to answer your question, no, actually.
Torque delivery is more shaped by exhaust manifold design. A lot of people complain of losing torque with large diameter exhaust, but they usually installed a header at the same time.
Another thing to consider is the psychological aspect. People claim to "feel" lost torque with large diameter exhaust, but dyno charts often read otherwise.
Torque delivery is more shaped by exhaust manifold design. A lot of people complain of losing torque with large diameter exhaust, but they usually installed a header at the same time.
Another thing to consider is the psychological aspect. People claim to "feel" lost torque with large diameter exhaust, but dyno charts often read otherwise.
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If anyone ever tells you back pressure is necessary they have no idea how an exhaust works. Back pressure is terrible, and to be avoided at all costs.
The goal of an exhaust is actually scavenging exhaust gasses during the overlap period. Though EGVs are definitely a huge part of this. Headers do have the biggest impact on the torque curve, and can move the curve to the higher or lower end of the power band. You can lose low end torque, but you will gain top end torque, so header design is a compromise. OE exhausts are designed with many variables in mind, if you change diameter, you need to change temperature or length to get the same effects if you're not altering your header.
Backpressure isn't the goal...
The goal is to get the exhaust gas out as quickly as possible. That is ahcieved through maximum exhaust velocity, which also aids with exhaust gas scavenging.
If you go with a larger diameter pipe than your engine can fill to maximum velocity, the exhaust gas density lowers, allowing temperatures to drop; colder gasses are more dense, thus harder to push.
The goal is to get the exhaust gas out as quickly as possible. That is ahcieved through maximum exhaust velocity, which also aids with exhaust gas scavenging.
If you go with a larger diameter pipe than your engine can fill to maximum velocity, the exhaust gas density lowers, allowing temperatures to drop; colder gasses are more dense, thus harder to push.
The goal of an exhaust is actually scavenging exhaust gasses during the overlap period. Though EGVs are definitely a huge part of this. Headers do have the biggest impact on the torque curve, and can move the curve to the higher or lower end of the power band. You can lose low end torque, but you will gain top end torque, so header design is a compromise. OE exhausts are designed with many variables in mind, if you change diameter, you need to change temperature or length to get the same effects if you're not altering your header.
Offset-----Less is MORE!!
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boostin-Nice info, I can't rep you yet but it's good to see someone post quality info
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