Can you Tell Me About Exhaust Systems ?
#1
11-30-2007, 02:45 PM
Can you Tell Me About Exhaust Systems ?
[align=center]Can You Tell Me About Exhaust Systems?[/align][align=center][:-][/align][align=center]I think the below is good information `if you[/align][align=center]are considering any exhaust work.[/align][align=center]Knowledge is Power : )[/align][align=center][:-][/align][align=center]Exhaust Theory
From: www.overboost.com[/align][align=center][:-][/align][align=center]We've seen too much misinformation regarding exhaust theory. What kind of misinformation? For starters, there are a lot of people in the "Bigger is Better" camp. We're talking about exhaust pipe diameters. Even the big magazine editors are boldly smattering statements like, "For a turbo car, you can't get an exhaust pipe that's too big." Also, terms like "back pressure" and the statement, "An engine needs back pressure to run properly!" really rub us the wrong way. [/align][align=center]Let's start from the beginning. What is an exhaust system? Silly question? Not hardly. Exhaust systems carry out several functions. Among them are: (1) Getting hot, noxious exhaust gasses from your engine to a place away from the engine compartment; (2) Significantly attenuating noise output from the engine; and (3) In the case of modern cars, reduce exhaust emissions. [/align][align=center]Hardware[/align][align=center][:-][/align][align=center]In order to give you a really good idea of what makes up an exhaust system, let's start with what exhaust gas travels through to get out of your car, as well as some terms and definitions: [/align][align=center]After your air/fuel mixture (or nitrous/fuel mixture) burns, you will obviously have some leftovers consisting of a few unburned hydrocarbons (fuel), carbon monoxide, carbon dioxide, nitrogen oxides, sulfur dioxide, phosphorus, and the occasional molecule of a heavy metal, such as lead or molybdenum. These are all in gaseous form, and will be under a lot of pressure as the piston rushes them out of the cylinder and into the exhaust manifold or header. They will also be hotter 'n Hades. (After all, this was the explosion of an air/fuel mixture, right?) An exhaust manifold is usually made of cast iron, and its' primary purpose is to funnel several exhaust ports into one, so you don't need four exhaust pipes sticking out the back of your Civic. [/align][align=center]Exhaust manifolds are usually pretty restrictive to the flow of exhaust gas, and thus waste a lot of power because your pistons have to push on the exhaust gasses pretty hard to get them out. So why does virtually every new automobile sold have exhaust manifolds? Because they are cheap to produce, and easy to install. Real cheap. Real easy. Like me. [/align][align=center][b]"Ok," you ask, "so now what?" Ah, good thing you asked. The performance alternative to the exhaust manifold is a header. What's the difference? Where a manifold usually has several holes converging into a common chamber to route all your gasses, a header has precisely formed tubes that curve gently to join your exhaust ports to your exhaust pipe. How does this help? First of all, as with any fluid, exhaust gasses must be treated gently for maximum horsepower production. You don't want to just slam-bang exhaust gas from your engine into the exhaust system. No way, Jo-se'! Just as the body of your '94 Eclipse is
From: www.overboost.com[/align][align=center][:-][/align][align=center]We've seen too much misinformation regarding exhaust theory. What kind of misinformation? For starters, there are a lot of people in the "Bigger is Better" camp. We're talking about exhaust pipe diameters. Even the big magazine editors are boldly smattering statements like, "For a turbo car, you can't get an exhaust pipe that's too big." Also, terms like "back pressure" and the statement, "An engine needs back pressure to run properly!" really rub us the wrong way. [/align][align=center]Let's start from the beginning. What is an exhaust system? Silly question? Not hardly. Exhaust systems carry out several functions. Among them are: (1) Getting hot, noxious exhaust gasses from your engine to a place away from the engine compartment; (2) Significantly attenuating noise output from the engine; and (3) In the case of modern cars, reduce exhaust emissions. [/align][align=center]Hardware[/align][align=center][:-][/align][align=center]In order to give you a really good idea of what makes up an exhaust system, let's start with what exhaust gas travels through to get out of your car, as well as some terms and definitions: [/align][align=center]After your air/fuel mixture (or nitrous/fuel mixture) burns, you will obviously have some leftovers consisting of a few unburned hydrocarbons (fuel), carbon monoxide, carbon dioxide, nitrogen oxides, sulfur dioxide, phosphorus, and the occasional molecule of a heavy metal, such as lead or molybdenum. These are all in gaseous form, and will be under a lot of pressure as the piston rushes them out of the cylinder and into the exhaust manifold or header. They will also be hotter 'n Hades. (After all, this was the explosion of an air/fuel mixture, right?) An exhaust manifold is usually made of cast iron, and its' primary purpose is to funnel several exhaust ports into one, so you don't need four exhaust pipes sticking out the back of your Civic. [/align][align=center]Exhaust manifolds are usually pretty restrictive to the flow of exhaust gas, and thus waste a lot of power because your pistons have to push on the exhaust gasses pretty hard to get them out. So why does virtually every new automobile sold have exhaust manifolds? Because they are cheap to produce, and easy to install. Real cheap. Real easy. Like me. [/align][align=center][b]"Ok," you ask, "so now what?" Ah, good thing you asked. The performance alternative to the exhaust manifold is a header. What's the difference? Where a manifold usually has several holes converging into a common chamber to route all your gasses, a header has precisely formed tubes that curve gently to join your exhaust ports to your exhaust pipe. How does this help? First of all, as with any fluid, exhaust gasses must be treated gently for maximum horsepower production. You don't want to just slam-bang exhaust gas from your engine into the exhaust system. No way, Jo-se'! Just as the body of your '94 Eclipse is
#2
12-08-2007, 10:13 AM
RE: Can you Tell Me About Exhaust Systems ?
Hey space we are gettin a little wind from the west surfs up!
Nice post I tend to agree with the article I do have one thing to say in my experience headers do nothing for a stock vehicle and any backpressure at all will disrupt the headers ablity to let the gases flow any smoother or faster than stock manifolds. While I agree every little thing helps build HP headers are useless unless you have a unrestricted exhaust.
I work for a aerospace company as a test mechanic I have tested engines from reciprocal to rockets for the past 30 years and there is one thing that has never change with the internal combustion engine It's all about getting as much cold air in and getting as much hot air out as fast as you can. This is the Key to HP. One huge thing that will make a differance is U-bend delete thats a big restriction.
Nice post I tend to agree with the article I do have one thing to say in my experience headers do nothing for a stock vehicle and any backpressure at all will disrupt the headers ablity to let the gases flow any smoother or faster than stock manifolds. While I agree every little thing helps build HP headers are useless unless you have a unrestricted exhaust.
I work for a aerospace company as a test mechanic I have tested engines from reciprocal to rockets for the past 30 years and there is one thing that has never change with the internal combustion engine It's all about getting as much cold air in and getting as much hot air out as fast as you can. This is the Key to HP. One huge thing that will make a differance is U-bend delete thats a big restriction.
#3
12-08-2007, 10:26 AM
RE: Can you Tell Me About Exhaust Systems ?
Ty, Thanks for your post, and feedback. You have a very interesting career. Sounds like a lot of fun.
[hr]
I seen on the morning news the Waves on the West Coast 
WoW 
WoW We only get Kidd'ie Waves in FLorida, unless it's hurricane season. : )
[:-]
#5
12-08-2007, 07:10 PM
RE: Can you Tell Me About Exhaust Systems ?
no need for 4 pipes on ur civic? i say no need for a civic lol but neways can u buy a u bend delete for the stock exhaust...or is this a waste of money and one should go with the full exhaust
#6
12-09-2007, 07:22 AM
RE: Can you Tell Me About Exhaust Systems ?
I've been told a full dual exhaust system from the factory is good for 400HP+, as long as you get rid of the U-bend pipe, and have a good cat' in the system, either high flow, or just a functioning properly factory cat'.
Hasn't some of you added bigger pipes and hurt performance?
One of my next performance items will probably be the Power Log front exhaust manifold, as that seems to be a restriction, also. ZZPerformance.com has it, but I can't connect to their server right now for the link to it.
Hasn't some of you added bigger pipes and hurt performance?
One of my next performance items will probably be the Power Log front exhaust manifold, as that seems to be a restriction, also. ZZPerformance.com has it, but I can't connect to their server right now for the link to it.
#7
12-09-2007, 08:25 AM
RE: Can you Tell Me About Exhaust Systems ?
Kweef nice handle! I think with a stock engine the best you can do is Hi flow cat and ( which will delete the U bend) and a set of low restiction mufflers of your choice, anything after that is a waste of money on a stock engine. But the more you do to get air into your motor (forced induction, bigger TB, cam, ect) the more you have to do to get it out. (headers , NO cat, true dauls, glasspacks ect)
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