3" exhaust pipe

[CompOrangeSN95]

I asked in my build thread but I think that's dying haha Anyone know a good way to flare the end of 3" exhaust pipe?

 

[AaRoN]

Why?

 

[MustangChris]

^+1

 

[CompOrangeSN95]

I am running a new exhaust due to the new engine and mac long tube headers and I need to flare the end so it will mount up properly... I can't seem to find any pre flared pieces... all I can find is the flange itself but that wont do much if it doesn't have anything to clamp on

 

[mygreengt]

try a diesel exhaust store

 

[AaRoN]

Is your engine N/A or FI?

 

[CompOrangeSN95]

try a diesel exhaust store

not a bad idea, I'll see what I can find... if nothing else I'll bring the pipe to a local metal working shop and have them do it

Is your engine N/A or FI?

it is N/A why do you ask?

 

[AaRoN]

I ask because a 3" exhaust will do nothing but reduce exhaust scavenging and rob power.

 

[CompOrangeSN95]

I ask because a 3" exhaust will do nothing but reduce exhaust scavenging and rob power.

too late, I was worried about not having any back pressure but I wanted to go big enough that when I upgrade I don't have to upgrade the exhaust

 

[MustangChris]

you can always weld in a washer somewhere in the middle ;-)

 

[CompOrangeSN95]

you can always weld in a washer somewhere in the middle ;-)

haha you got a point, a removable baffle isn't a bad idea

 

[MustangChris]

see. im the smartest guy ever... its all good. thats what im here for.

 

[ryclef331]

Are you trying to weld it together or clamp it all together? I don't see why you need flare anything?

 

[cantbuytime]

I say use the slip couplings or band clamps. pretty easy to find.

I dont think he needs 3" pipe but shouldnt hurt anything. I also think only the MOD motors suffer power loss due to overflowing exhaust?

Please enlighten me??

I am going 3" myself, but I have 2 extra cylinders. LOL

 

[CompOrangeSN95]

haha the 2 extra cylinders will help you out. These are the headers I am getting, should be at my house in a few days MAC TF3945... if you look at the collectors they are set up to except the MAC pro chamber which I am not buying.... I need to make the end of my exhaust the same as the end of the MAC pro chamber which is flared. Yes I am welding it, everything will be welded together as 1 assembly so all I need to do to remove it is unbolt it from the headers and drop it down

 

[SVTurbo 98]

I ask because a 3" exhaust will do nothing but reduce exhaust scavenging and rob power.

Prove it.

 

[CompOrangeSN95]

I ask because a 3" exhaust will do nothing but reduce exhaust scavenging and rob power.

Prove it.

+1

 

[AaRoN]

I ask because a 3" exhaust will do nothing but reduce exhaust scavenging and rob power.

Prove it.

Sure thing:

First of all when it comes to modifying a car, bigger is not always better. In this case, it holds true to my point. Larger diameter exhaust piping does increase flow but decreases velocity. Velocity equals torque and flow equals horsepower (when speaking of induction and exhaust). Too large of an exhaust also reduces the scavenging effect. The general rule for a car with a 250-300 cu. in. engine making around 300HP (n/a) with dual exhaust should have a 2.5" exhaust for optimum performance and scavenging. When the piping is too big it also has more heat transfer. Meaning the exhaust gases are cooler, thus moving slower. This is the purpose of header wraps. The thermal barrier on the headers reduces the amount of escaping heat which speeds up the exhaust gases inside the header. Scavenging is important to help remove all exhaust gases from each cylinder. Without that, what's the point of the exhaust system?

 

[SVTurbo 98]

I ask because a 3" exhaust will do nothing but reduce exhaust scavenging and rob power.

Prove it.

Sure thing:

First of all when it comes to modifying a car, bigger is not always better. In this case, it holds true to my point. Larger diameter exhaust piping does increase flow but decreases velocity. Velocity equals torque and flow equals horsepower (when speaking of induction and exhaust). Too large of an exhaust also reduces the scavenging effect. The general rule for a car with a 250-300 cu. in. engine making around 300HP (n/a) with dual exhaust should have a 2.5" exhaust for optimum performance and scavenging. When the piping is too big it also has more heat transfer. Meaning the exhaust gases are cooler, thus moving slower. This is the purpose of header wraps. The thermal barrier on the headers reduces the amount of escaping heat which speeds up the exhaust gases inside the header. Scavenging is important to help remove all exhaust gases from each cylinder. Without that, what's the point of the exhaust system?

Well you didn't really prove anything with that response but rather repeat what you've read on the web or read in a magazine. I was looking for tests that you have done (or someone else) that prove too big of an exhaust after the collector will hurt performance with tuning involved.

How exactly is velocity measured in an exhaust system?
What happens to exhaust gases as they cool down?
Where in the exhaust system do the gases cool down and is it farther down the system as you increase rpm?
Where is the pulse based exhaust scavenging concentrated at?

I'm really not trying to be an ass i'm just looking for hard facts that support your claim...

 

[AaRoN]

I ask because a 3" exhaust will do nothing but reduce exhaust scavenging and rob power.

Prove it.

Sure thing:

First of all when it comes to modifying a car, bigger is not always better. In this case, it holds true to my point. Larger diameter exhaust piping does increase flow but decreases velocity. Velocity equals torque and flow equals horsepower (when speaking of induction and exhaust). Too large of an exhaust also reduces the scavenging effect. The general rule for a car with a 250-300 cu. in. engine making around 300HP (n/a) with dual exhaust should have a 2.5" exhaust for optimum performance and scavenging. When the piping is too big it also has more heat transfer. Meaning the exhaust gases are cooler, thus moving slower. This is the purpose of header wraps. The thermal barrier on the headers reduces the amount of escaping heat which speeds up the exhaust gases inside the header. Scavenging is important to help remove all exhaust gases from each cylinder. Without that, what's the point of the exhaust system?

Well you didn't really prove anything with that response but rather repeat what you've read on the web or read in a magazine. I was looking for tests that you have done (or someone else) that prove too big of an exhaust after the collector will hurt performance with tuning involved.

How exactly is velocity measured in an exhaust system?
What happens to exhaust gases as they cool down?
Where in the exhaust system do the gases cool down and is it farther down the system as you increase rpm?
Where is the pulse based exhaust scavenging concentrated at?

I'm really not trying to be an a*s i'm just looking for hard facts that support your claim...

Lol...I'm almost offended. First, let me tell you that this information is not something I read on the interwebz or in a car-porn magazine. I am a Ford Certified Technician and I graduated from the Universal Technical Institute with honors. If you feel you need some kind of proof of that too, I'd be happy to snap a pic of my certs.

How exactly is velocity measured in an exhaust system? Velocity isn't really "measured" in an exhaust system. It's merely a law of physics. Think of a large diameter straw versus a small diameter straw. When you drink from a large diameter straw, you get more of what you're drinking but it doesn't go very far inside of your mouth. A smaller diameter straw moves the liquid quicker and farther into your mouth.

What happens to exhaust gases as they cool down? As exhaust gases cool, they slow down. Think about what happens when the you are running and exhale slower. Takes you longer to catch your breath. Right?

Where in the exhaust system do the gases cool down and is it farther down the system as you increase rpm? Gases begin to cool almost immediately. Not by a significant amount and yes, it is always further down the exhaust system that they cool the most. A larger exhaust system (more surface area) will cool the gases more quickly.

Where is the pulse based exhaust scavenging concentrated at? The scavenging depends on the entire exhaust system (pipe diameter and length, header design, muffler design, back pressure, etc.).

An exhaust system has to be matched to an engine. Do you think that manufacturers just pull pipe sizes, lengths, bends and muffler designs out of a hat and say " that looks good"? It's all engineered based on formulas. Formulas which I'd be happy to share with the SN95 community and if you still feel this is all "stuff I read on the internet".