catback exhaust ques
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Joined: Oct 2002
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From: NY/ CT
catback exhaust ques
Can someone xplain to me why I have been reading that when you put a catback exhast on you car you lose torque. I may be reading wrong but I have been reading some of that in the honda forums. I persanliy drive a 96 accord vtec. which I am trying to make faster lol but dont have much money. all i have right now is a Cold air waiting on some headers and i was going to put an exhaust but i have been reading the whole torque thing. can someone explain
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Joined: Oct 2002
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From: LA, CALI
you lose low end torque due to the fact that the aftermarket exhaust system has a bigger piping than the stock piping. The bigger piping will push out more air that the engine is exhaling than stock piping, therefore taking away a little bit of torque and giving you some high end horsepower gain. Stock piping was designed for the right mixture of low end torque and horsepower, which is for everyday drivability. However, the high end gain that you get with an after market catback system is significantly more than the little torque you lose at the low end.
Example, get a narrow straw and a wide straw. Blow on both straws. The narrow one is the stock exhaust piping, and the wide one is an aftermarket system. If you blow hard on the narrow one, you will feel a lot of pressure. This is backpressure, which translates into torque. However, you will notice that not a lot of air can be pushed out with the small diameter of the straw. The wider straw on the other hand does not have so much pressure when you blow hard into it, but more air can pass thru than the small straw, which translates into horsepower.
hope it helpd.
Example, get a narrow straw and a wide straw. Blow on both straws. The narrow one is the stock exhaust piping, and the wide one is an aftermarket system. If you blow hard on the narrow one, you will feel a lot of pressure. This is backpressure, which translates into torque. However, you will notice that not a lot of air can be pushed out with the small diameter of the straw. The wider straw on the other hand does not have so much pressure when you blow hard into it, but more air can pass thru than the small straw, which translates into horsepower.
hope it helpd.
Lurker
Joined: Mar 2002
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From: NoVA
Originally posted by F23A4_AcCoRdude
you lose low end torque due to the fact that the aftermarket exhaust system has a bigger piping than the stock piping. The bigger piping will push out more air that the engine is exhaling than stock piping, therefore taking away a little bit of torque and giving you some high end horsepower gain. Stock piping was designed for the right mixture of low end torque and horsepower, which is for everyday drivability. However, the high end gain that you get with an after market catback system is significantly more than the little torque you lose at the low end.
Example, get a narrow straw and a wide straw. Blow on both straws. The narrow one is the stock exhaust piping, and the wide one is an aftermarket system. If you blow hard on the narrow one, you will feel a lot of pressure. This is backpressure, which translates into torque. However, you will notice that not a lot of air can be pushed out with the small diameter of the straw. The wider straw on the other hand does not have so much pressure when you blow hard into it, but more air can pass thru than the small straw, which translates into horsepower.
hope it helpd.
you lose low end torque due to the fact that the aftermarket exhaust system has a bigger piping than the stock piping. The bigger piping will push out more air that the engine is exhaling than stock piping, therefore taking away a little bit of torque and giving you some high end horsepower gain. Stock piping was designed for the right mixture of low end torque and horsepower, which is for everyday drivability. However, the high end gain that you get with an after market catback system is significantly more than the little torque you lose at the low end.
Example, get a narrow straw and a wide straw. Blow on both straws. The narrow one is the stock exhaust piping, and the wide one is an aftermarket system. If you blow hard on the narrow one, you will feel a lot of pressure. This is backpressure, which translates into torque. However, you will notice that not a lot of air can be pushed out with the small diameter of the straw. The wider straw on the other hand does not have so much pressure when you blow hard into it, but more air can pass thru than the small straw, which translates into horsepower.
hope it helpd.
AH that was MY philosophy to teach n00bs about Intake/Headers/Exhausts!
I guess I'm not the only that used that terminology
WaSsuP?
Joined: Jun 2002
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From: Garland, TX
Originally posted by Accordacer
After a long research the conclusion that I made was there is no point of getting cat exhaust if you dont have forced induction. Just get some muffler tip thats it.
After a long research the conclusion that I made was there is no point of getting cat exhaust if you dont have forced induction. Just get some muffler tip thats it.
Honda Biased
Joined: Mar 2002
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From: Kennesaw, GA
ok..good explanation....BUT...can you please explain that if you help your engine get rid of its "breathed" air quicker(catback/wider straw), that it looses ANYTHING(low end or high)? It just isnt making sense to me. Please explain in fine detail if u can! thanx!
Dave
Dave
WaSsuP?
Joined: Jun 2002
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From: Garland, TX
It's all about exhaust velocity. Okay, at 2 rpms there are minimal exhaust gases, so let's say you have like a 3" exhaust piping and your stock was 1.5". The velocity of the exhaust gases exiting the car on your stock piping will be faster then the 3" piping at low rpm, therefore losing torque. The reason you gain more top end horsepower is that let's say you're at 11 rpm or so 
. Okay now, on your 1.5" stock piping, the exhaust gases are more congested in the piping and can't be released as quick as a 3" exhuast piping would.
Hope this helps.
. Okay now, on your 1.5" stock piping, the exhaust gases are more congested in the piping and can't be released as quick as a 3" exhuast piping would.Hope this helps.
Faster than your Geo
Joined: Jun 2002
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lol, if you need it explained in detail, its likely to take more physics than you are likely to know. . .
If you know anyone who's at least a sophomore in mechanical engineering and has taken classes in thermodynamics and fluids, or are interested in going to school or that yourself, its a good start, but as far as a good explanation in a reasonable timeframe, id stick with the straw analogy. . .
If you know anyone who's at least a sophomore in mechanical engineering and has taken classes in thermodynamics and fluids, or are interested in going to school or that yourself, its a good start, but as far as a good explanation in a reasonable timeframe, id stick with the straw analogy. . .
Faster than your Geo
Joined: Jun 2002
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note: what i mean in my previous post is this, everyone here can tell you that backpressure is directly related to torque, but most of them probably couldn't give you a mathematical relationship or a detailed mechanical reasoning, im not trying to offend anyone here, but if this is the gap of information you are looking for, this may not be the place to ask the question. . .
Honda Biased
Joined: Mar 2002
Posts: 1,076
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From: Kennesaw, GA
well..if nobody is agreeing with me, i'll just trust you guys.
But if you could....could you tell me how much hp you gain at say 6-7k rpm...and how much you loose at 2-5? Those are low/high in an accord engine correct? Whats the redline in the f22 and h22? How much of a difference?
Dave
But if you could....could you tell me how much hp you gain at say 6-7k rpm...and how much you loose at 2-5? Those are low/high in an accord engine correct? Whats the redline in the f22 and h22? How much of a difference?
Dave