View Poll Results: Public Vote - Which size?
Voters: 18. You may not vote on this poll
I am confused and need some input............
Record Breaker
Joined: Dec 2005
Posts: 1,998
Likes: 1
From: Shreveport Louisiana
I agree Froggy, for the most part. But there are many more factors that effect exhaust performance and how well it reacts to differing situations. Not the least of which are Thermal dynamics, as they apply to any given materiel, valve size, design and construction materiel, and exhaust port design and size, header design and construction materiel and individual cylinder exhaust pulse.
Whenever an engine modification increases the average area of the airflow paths into and out of an engine, there is a chance the velocity of the flow will decrease. Most of the time the factor of velocity decrease is very small compared to the area increased, so flow is generally increased. If modifications are taken too far, the velocity will decrease more than the area increases, so flow is adversely affected. This is why 2.25 inch pipe works well in our individual applications.
This explains it quite well.
Air flow is not just influenced by the size (area) of the paths it takes into and out of the engine. It is also influenced by the speed at which it moves.
Specific Port Flow (cubic meter/sec) = Flow Velocity (m/s) x Average Path Area (m2)
So in short, As mentioned before, if the diameter (and hence cross-sectional area) of the pipe is increased too much, the velocity of the air flow will decrease more than the area increases, so flow would be adversely affected and power would be lost.
Whenever an engine modification increases the average area of the airflow paths into and out of an engine, there is a chance the velocity of the flow will decrease. Most of the time the factor of velocity decrease is very small compared to the area increased, so flow is generally increased. If modifications are taken too far, the velocity will decrease more than the area increases, so flow is adversely affected. This is why 2.25 inch pipe works well in our individual applications.
This explains it quite well.
Air flow is not just influenced by the size (area) of the paths it takes into and out of the engine. It is also influenced by the speed at which it moves.
Specific Port Flow (cubic meter/sec) = Flow Velocity (m/s) x Average Path Area (m2)
So in short, As mentioned before, if the diameter (and hence cross-sectional area) of the pipe is increased too much, the velocity of the air flow will decrease more than the area increases, so flow would be adversely affected and power would be lost.
Record Breaker
Joined: Dec 2005
Posts: 1,998
Likes: 1
From: Shreveport Louisiana
Sorry, I got carried away.
Use 2.25in pipe and an "X" pipe, you will be fine Dogg!
http://www.autoanything.com/exhausts...A2672A0A0.aspx
Use 2.25in pipe and an "X" pipe, you will be fine Dogg!
http://www.autoanything.com/exhausts...A2672A0A0.aspx
Thread Starter
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Record Breaker
Joined: Mar 2008
Posts: 1,437
Likes: 0
From: North Carolina
Sorry, I got carried away.
Use 2.25in pipe and an "X" pipe, you will be fine Dogg!
http://www.autoanything.com/exhausts...A2672A0A0.aspx
Use 2.25in pipe and an "X" pipe, you will be fine Dogg!
http://www.autoanything.com/exhausts...A2672A0A0.aspx
Professional
Joined: Feb 2008
Posts: 227
Likes: 0
From: Cairo, Egypt
Funny, I just responded to a very similar post on another forum. It had the same erroneous misconception it.
Think back to basic geometry. Remember, the area of a circle is Πr².
The area of a 2.25" pipe is 3.14 * 1.125 *1.125= 3.97. *2 pipes= 7.95 square inches.
The area of a 4.5" pipe is 3.14 * 2.25 * 2.25= 15.9 square inches. Not even close. Two 2.25" pipes are NOT the same as a single 4.5" pipe.
Comparing a si/so to a si/do.
The area of a 3" pipe is 3.14 * 1.5 * 1.5= 7.06 square inches.
So at first glance, the the 2 pipes at 2.25" are better. A closer look reveals the increased drag from the extra sidewall of the pipes. This negates the small increase in area.
A 3" single exhaust provides similar flow characteristics to a 2.25" dual exhaust. No one would ever dream of going to a single exhaust larger than 3", therefore, the only logical conclusion is that a properly flowing dual exhaust will built with 2.25" pipe.
As I said previously, there are a lot of FAST trucks out there running 2.25" duals. I reccomend you give a call to magnaflow or flowmaster and get their profesional opinion. You will waste a LOT of money by going with too big of a diameter. And your truck will be slower as a result.
Think back to basic geometry. Remember, the area of a circle is Πr².
The area of a 2.25" pipe is 3.14 * 1.125 *1.125= 3.97. *2 pipes= 7.95 square inches.
The area of a 4.5" pipe is 3.14 * 2.25 * 2.25= 15.9 square inches. Not even close. Two 2.25" pipes are NOT the same as a single 4.5" pipe.
Comparing a si/so to a si/do.
The area of a 3" pipe is 3.14 * 1.5 * 1.5= 7.06 square inches.
So at first glance, the the 2 pipes at 2.25" are better. A closer look reveals the increased drag from the extra sidewall of the pipes. This negates the small increase in area.
A 3" single exhaust provides similar flow characteristics to a 2.25" dual exhaust. No one would ever dream of going to a single exhaust larger than 3", therefore, the only logical conclusion is that a properly flowing dual exhaust will built with 2.25" pipe.
As I said previously, there are a lot of FAST trucks out there running 2.25" duals. I reccomend you give a call to magnaflow or flowmaster and get their profesional opinion. You will waste a LOT of money by going with too big of a diameter. And your truck will be slower as a result.