Backpressure Myth and destroying it
06-09-2007, 02:57 PM
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Backpressure Myth and destroying it
I found this on Prelude power its kind of old but explains alot and will clear up alot of misconceptions. This was taken directly from Preludepower.com. Thanks poet for the info.
Back pressure, Exhaust velocity and scavenging.
The myth: “engines need some backpressure.”
One of the most misunderstood concepts in exhaust theory is backpressure. People love to talk about backpressure on message boards with no real understanding of what it is and what its consequences are. I'm sure many of you have heard or read the phrase "engines need some backpressure" when discussing exhaust upgrades. That phrase is in fact completely inaccurate and a wholly misguided notion.
How the myth came about:
It is easy to see how this misunderstanding arises. Lets’ say that Max puts a 3-inch system on his normally aspirated car. He soon realizes that he has lost power right through the power band. The connection is made in his throbbing brain….
Put on 3" pipe = loss of backpressure = loss of power.
Max erroneously concludes that you need backpressure to retain performance. He has ignored the need for exhaust gas velocity to get that scavenge effect.
The other myth: “engines can get burned valves from not enough backpressure”
How this myth came about:
The other reason why people say "backpressure is good" is because they hear that cars (or motorcycles) that have had performance exhaust work done to them would then go on to burn exhaust valves. Now, it is true that such valve burning has occurred as a result of the exhaust mods, but it isn't due merely to a lack of backpressure.
The internal combustion engine is a complex, dynamic collection of different systems working together to convert the stored power in gasoline into mechanical energy to push a car down the road. Anytime one of these systems are modified, that mod will also indirectly affect the other systems, as well.
Now, valve burning occurs as a result of a very lean-burning engine. In order to achieve a theoretical optimal combustion, an engine needs 14.7 parts of oxygen by mass to 1 part of gasoline (again, by mass). This is referred to as a stochiometric (chemically correct) mixture, and is commonly referred to as a 14.7:1 mix. If an engine burns with less oxygen present (13:1, 12:1, etc...), it is said to run rich. Conversely, if the engine runs with more oxygen present (16:1, 17:1, etc...), it is said to run lean. Today's engines are designed to run at 14.7:1 for normally cruising, with rich mixtures on acceleration or warm-up, and lean mixtures while decelerating.
Getting back to the discussion, the reason that exhaust valves burn is because the engine is burning lean. Normal engines will tolerate lean burning for a little bit, but not for sustained periods of time. The reason why the engine is burning lean to begin with is that the reduction in backpressure is causing more air to be drawn into the combustion chamber than before. Earlier cars (and motorcycles) with carburetion often could not adjust for his.
Once these vehicles received performance mods that reduced backpressure, they tended to burn valves because of the resulting over-lean condition. This, incidentally, also provides a basis for the "torque increase" seen if backpressure is maintained. As the fuel/air mixture becomes leaner, the resultant combustion will produce progressively less and less of the force needed to produce torque.
Some basic exhaust theory
Your exhaust system is designed to evacuate gases from the combustion chamber quickly and efficiently. Exhaust gases are not produced in a smooth stream; exhaust gases originate in pulses. A 4 cylinder motor will have 4 distinct pulses per complete engine cycle; a 6 cylinder has 6 pulses and so on. The more pulses that are produced, the more continuous the exhaust flow. Backpressure can be loosely defined as the resistance to positive flow - in this case, the resistance to positive flow of the exhaust stream.
Backpressure and velocity.
Some people operate under the misguided notion that wider pipes are more effective at clearing the combustion chamber than narrower pipes. It's not hard to see how this misconception is appealing - wider pipes have the capability to flow more than narrower pipes. So if they have the ability to flow more, why isn't "wider is better" a good rule of thumb for exhaust upgrading? In a word - VELOCITY. I'm sure that all of you have at one time used a garden hose w/o a spray nozzle on it. If you let the water just run unrestricted out of the house it flows at a rather slow rate. However, if you take your finger and cover part of the opening, the water will flow out at a much, much, faster rate.
The astute exhaust designer knows that you must balance flow capacity with velocity. You want the exhaust gases to exit the chamber and speed along at the highest velocity possible - you want a FAST exhaust stream. If you have two exhaust pulses of equal volume, one in a 2" pipe and one in a 3" pipe, the pulse in the 2" pipe will be traveling considerably FASTER than the pulse in the 3" pipe. While it is true that the narrower the pipe, the higher the velocity of the exiting gases, you want make sure the pipe is wide enough so that there is as little backpressure as possible while maintaining suitable exhaust gas velocity.
Backpressure in its most extreme form can lead to reversion of the exhaust stream - that is to say the exhaust flows backwards, which is not good. The trick is to have a pipe that that is as narrow as possible while having as close to zero backpressure as possible at the RPM range you want your power band to be located at. Exhaust pipe diameters are best suited to a particular RPM range. A smaller pipe diameter will produce higher exhaust velocities at a lower RPM but create unacceptably high amounts of backpressure at high rpm. Thus if your power band is located 2-3000 RPM you'd want a narrower pipe than if your power band is located at 8-9000RPM.
Many engineers try to work around the RPM specific nature of pipe diameters by using setups that are capable of creating a similar effect as a change in pipe diameter on the fly. The most advanced is Ferrari's which consists of two exhaust paths after the header - at low RPM only one path is open to maintain exhaust velocity, but as RPM climbs and exhaust volume increases, the second path is opened to curb backpressure - since there is greater exhaust volume there is no loss in flow velocity. BMW and Nissan use a simpler and less effective method - there is a single exhaust path to the muffler; the muffler has two paths; one path is closed at low RPM but both are open at high RPM.
So why is exhaust velocity so important?
The faster an exhaust pulse moves, the better it can scavenge out all of the spent gasses during valve overlap. The guiding principles of exhaust pulse scavenging are a bit beyond the scope of this doc but the general idea is a fast moving pulse creates a low pressure area behind it. This low pressure area acts as a vacuum and draws along the air behind it. A similar example would be a vehicle traveling at a high rate of speed on a dusty road. There is a low pressure area immediately behind the moving vehicle - dust particles get sucked into this low pressure area causing it to collect on the back of the vehicle. This effect is most noticeable on vans and hatchbacks which tend to create large trailing low pressure areas - giving rise to the numerous "wash me please" messages written in the thickly collected dust on the rear door(s).
Conclusion.
SO it turns out that engines don't need backpressure, they need as high a flow velocity as possible with as little backpressure as possible.
Back pressure, Exhaust velocity and scavenging.
The myth: “engines need some backpressure.”
One of the most misunderstood concepts in exhaust theory is backpressure. People love to talk about backpressure on message boards with no real understanding of what it is and what its consequences are. I'm sure many of you have heard or read the phrase "engines need some backpressure" when discussing exhaust upgrades. That phrase is in fact completely inaccurate and a wholly misguided notion.
How the myth came about:
It is easy to see how this misunderstanding arises. Lets’ say that Max puts a 3-inch system on his normally aspirated car. He soon realizes that he has lost power right through the power band. The connection is made in his throbbing brain….
Put on 3" pipe = loss of backpressure = loss of power.
Max erroneously concludes that you need backpressure to retain performance. He has ignored the need for exhaust gas velocity to get that scavenge effect.
The other myth: “engines can get burned valves from not enough backpressure”
How this myth came about:
The other reason why people say "backpressure is good" is because they hear that cars (or motorcycles) that have had performance exhaust work done to them would then go on to burn exhaust valves. Now, it is true that such valve burning has occurred as a result of the exhaust mods, but it isn't due merely to a lack of backpressure.
The internal combustion engine is a complex, dynamic collection of different systems working together to convert the stored power in gasoline into mechanical energy to push a car down the road. Anytime one of these systems are modified, that mod will also indirectly affect the other systems, as well.
Now, valve burning occurs as a result of a very lean-burning engine. In order to achieve a theoretical optimal combustion, an engine needs 14.7 parts of oxygen by mass to 1 part of gasoline (again, by mass). This is referred to as a stochiometric (chemically correct) mixture, and is commonly referred to as a 14.7:1 mix. If an engine burns with less oxygen present (13:1, 12:1, etc...), it is said to run rich. Conversely, if the engine runs with more oxygen present (16:1, 17:1, etc...), it is said to run lean. Today's engines are designed to run at 14.7:1 for normally cruising, with rich mixtures on acceleration or warm-up, and lean mixtures while decelerating.
Getting back to the discussion, the reason that exhaust valves burn is because the engine is burning lean. Normal engines will tolerate lean burning for a little bit, but not for sustained periods of time. The reason why the engine is burning lean to begin with is that the reduction in backpressure is causing more air to be drawn into the combustion chamber than before. Earlier cars (and motorcycles) with carburetion often could not adjust for his.
Once these vehicles received performance mods that reduced backpressure, they tended to burn valves because of the resulting over-lean condition. This, incidentally, also provides a basis for the "torque increase" seen if backpressure is maintained. As the fuel/air mixture becomes leaner, the resultant combustion will produce progressively less and less of the force needed to produce torque.
Some basic exhaust theory
Your exhaust system is designed to evacuate gases from the combustion chamber quickly and efficiently. Exhaust gases are not produced in a smooth stream; exhaust gases originate in pulses. A 4 cylinder motor will have 4 distinct pulses per complete engine cycle; a 6 cylinder has 6 pulses and so on. The more pulses that are produced, the more continuous the exhaust flow. Backpressure can be loosely defined as the resistance to positive flow - in this case, the resistance to positive flow of the exhaust stream.
Backpressure and velocity.
Some people operate under the misguided notion that wider pipes are more effective at clearing the combustion chamber than narrower pipes. It's not hard to see how this misconception is appealing - wider pipes have the capability to flow more than narrower pipes. So if they have the ability to flow more, why isn't "wider is better" a good rule of thumb for exhaust upgrading? In a word - VELOCITY. I'm sure that all of you have at one time used a garden hose w/o a spray nozzle on it. If you let the water just run unrestricted out of the house it flows at a rather slow rate. However, if you take your finger and cover part of the opening, the water will flow out at a much, much, faster rate.
The astute exhaust designer knows that you must balance flow capacity with velocity. You want the exhaust gases to exit the chamber and speed along at the highest velocity possible - you want a FAST exhaust stream. If you have two exhaust pulses of equal volume, one in a 2" pipe and one in a 3" pipe, the pulse in the 2" pipe will be traveling considerably FASTER than the pulse in the 3" pipe. While it is true that the narrower the pipe, the higher the velocity of the exiting gases, you want make sure the pipe is wide enough so that there is as little backpressure as possible while maintaining suitable exhaust gas velocity.
Backpressure in its most extreme form can lead to reversion of the exhaust stream - that is to say the exhaust flows backwards, which is not good. The trick is to have a pipe that that is as narrow as possible while having as close to zero backpressure as possible at the RPM range you want your power band to be located at. Exhaust pipe diameters are best suited to a particular RPM range. A smaller pipe diameter will produce higher exhaust velocities at a lower RPM but create unacceptably high amounts of backpressure at high rpm. Thus if your power band is located 2-3000 RPM you'd want a narrower pipe than if your power band is located at 8-9000RPM.
Many engineers try to work around the RPM specific nature of pipe diameters by using setups that are capable of creating a similar effect as a change in pipe diameter on the fly. The most advanced is Ferrari's which consists of two exhaust paths after the header - at low RPM only one path is open to maintain exhaust velocity, but as RPM climbs and exhaust volume increases, the second path is opened to curb backpressure - since there is greater exhaust volume there is no loss in flow velocity. BMW and Nissan use a simpler and less effective method - there is a single exhaust path to the muffler; the muffler has two paths; one path is closed at low RPM but both are open at high RPM.
So why is exhaust velocity so important?
The faster an exhaust pulse moves, the better it can scavenge out all of the spent gasses during valve overlap. The guiding principles of exhaust pulse scavenging are a bit beyond the scope of this doc but the general idea is a fast moving pulse creates a low pressure area behind it. This low pressure area acts as a vacuum and draws along the air behind it. A similar example would be a vehicle traveling at a high rate of speed on a dusty road. There is a low pressure area immediately behind the moving vehicle - dust particles get sucked into this low pressure area causing it to collect on the back of the vehicle. This effect is most noticeable on vans and hatchbacks which tend to create large trailing low pressure areas - giving rise to the numerous "wash me please" messages written in the thickly collected dust on the rear door(s).
Conclusion.
SO it turns out that engines don't need backpressure, they need as high a flow velocity as possible with as little backpressure as possible.
06-09-2007, 04:13 PM
#2
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So why would a 3" exhaust cause power loss on an underpowered 4cyl?
Im not saying its wrong.....Never been on the Dyno with it. I know my friends Civic ran like **** after we installed the Thermal 3" compared to the 2.36" Apex. Who knows though, butt dyno is good for only so much.
Im not saying its wrong.....Never been on the Dyno with it. I know my friends Civic ran like **** after we installed the Thermal 3" compared to the 2.36" Apex. Who knows though, butt dyno is good for only so much.
06-09-2007, 04:56 PM
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Re: (:=:NirVTEC:=:)
basically its saying you want an exhaust with as close to zero backpressure as possible and you want to go with the smaller diameter tubing in order to acheive that near 0 number in order to increase exhaust velocity. If your power band is located 2-3000 RPM you'd want a narrower pipe than if your power band is located at 8-9000RPM.
06-09-2007, 06:01 PM
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Re: (lude98SH)
exactly. your 100 % correct! 
I have silencer in stock 2.37? back with vibrant axle over i reach 207 whp 166 tq
2.5 collector, 2.5 back with same axle over, but w/silencer out, 4", i reach 196 whp 162 tq (sounds better though lol)
I reach peak powers between 3500-5500 rpm so having larger piping was actually hurting my numbers. Put silencer back, reverted back to stock collector and piping (slightly moded motor) and re dyno'ed with 207 / 166
Larger piping almost for turbo or FI applications Im starting to think. Or larger motors in general of course, but in relation to preludes, i would think stock motors or even slightly modded I/H, motors benifit best off stock lower diameter exhaust systems with open cat ofcourse rather than aftermarket 2.5 and 4" open mufflers.
Or what else would explain dramatic number variance?. both same Dyno machine/shop and everything!
Also, i guess a perfectly straight pipe right back from collector would be the best efficient way to run exhaust???!
Modified by mattsnooz at 7:15 PM 6/9/2007
I have silencer in stock 2.37? back with vibrant axle over i reach 207 whp 166 tq
2.5 collector, 2.5 back with same axle over, but w/silencer out, 4", i reach 196 whp 162 tq (sounds better though lol)
I reach peak powers between 3500-5500 rpm so having larger piping was actually hurting my numbers. Put silencer back, reverted back to stock collector and piping (slightly moded motor) and re dyno'ed with 207 / 166
Larger piping almost for turbo or FI applications Im starting to think. Or larger motors in general of course, but in relation to preludes, i would think stock motors or even slightly modded I/H, motors benifit best off stock lower diameter exhaust systems with open cat ofcourse rather than aftermarket 2.5 and 4" open mufflers.
Or what else would explain dramatic number variance?. both same Dyno machine/shop and everything!
Also, i guess a perfectly straight pipe right back from collector would be the best efficient way to run exhaust???!
Modified by mattsnooz at 7:15 PM 6/9/2007
06-10-2007, 05:45 AM
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Re: (ECX)
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by ECX »</TD></TR><TR><TD CLASS="quote">Conclusion.
SO it turns out that engines don't need backpressure, they need as high a flow velocity as possible with as little backpressure as possible.</TD></TR></TABLE>
What you should have concluded is that the kids and some of the "adults" on this board need to stay in school and get a f*cking education.
No matter what you friends uber l33t civic may or may not have done on the dyno the laws of physics are just that.... LAWS
I've stated this numerous times, as have a few other h-t members, but there is no convincing the ignorant.
SO it turns out that engines don't need backpressure, they need as high a flow velocity as possible with as little backpressure as possible.</TD></TR></TABLE>
What you should have concluded is that the kids and some of the "adults" on this board need to stay in school and get a f*cking education.
No matter what you friends uber l33t civic may or may not have done on the dyno the laws of physics are just that.... LAWS
I've stated this numerous times, as have a few other h-t members, but there is no convincing the ignorant.
06-10-2007, 05:57 AM
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Re: (Silver Surfer)
well hopefully this little write explains everything alittle more and lets ppl see more in depth why you dont need backpressure.
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06-10-2007, 08:46 AM
#8
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its just like how water flows.... say you're flowing 2 gallons per minute of water through a pipe. you take that same volume of water and flow it through a larger pipe and it will slow down, it works the same with exhaust. you just have to find the medium, where the pipe is not to small too restrict and its not too large to slow you down.
06-10-2007, 09:06 AM
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It's also worth mentioning that backpressure can sometimes make an engine with lots of cam overlap run better, as it keeps the intake charge from going straight through the combustion chamber and out the exhaust valves. In this case, it's the cams that are the issue, not the exhaust. However, some will point to this as proof that engines "need" some sort of back pressure. 
06-13-2007, 01:57 PM
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Re: (96Civic_Coupe)
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by 96Civic_Coupe »</TD></TR><TR><TD CLASS="quote">ok so should i do 2.3" or 2.5" straight pipe on a stock 97 sh</TD></TR></TABLE>
3.2". I did some dyno tests awhile ago, and that's the size that made the most torque.
3.2". I did some dyno tests awhile ago, and that's the size that made the most torque.
06-13-2007, 02:40 PM
#15
Re: (The Phil)
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by The Phil »</TD></TR><TR><TD CLASS="quote">
3.2". I did some dyno tests awhile ago, and that's the size that made the most torque.</TD></TR></TABLE>
I would agree.
Most people just like to read the dumb *** bullshit they post up on random websites about what they think a good size should be. The fact of the matter is that it has been proven numerous amounts of times that honda engines making more power open header, so if the best exhaust is no exhaust, then wtf are you thinking choking it through tiny tubes bc you read something on a page opposite an ad for color changing neons with an ugly blonde girl wearing black latex and high boots.
3.2". I did some dyno tests awhile ago, and that's the size that made the most torque.</TD></TR></TABLE>
I would agree.
Most people just like to read the dumb *** bullshit they post up on random websites about what they think a good size should be. The fact of the matter is that it has been proven numerous amounts of times that honda engines making more power open header, so if the best exhaust is no exhaust, then wtf are you thinking choking it through tiny tubes bc you read something on a page opposite an ad for color changing neons with an ugly blonde girl wearing black latex and high boots.
06-13-2007, 10:33 PM
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Re: (117)
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by 117 »</TD></TR><TR><TD CLASS="quote">It's also worth mentioning that backpressure can sometimes make an engine with lots of cam overlap run better, as it keeps the intake charge from going straight through the combustion chamber and out the exhaust valves. In this case, it's the cams that are the issue, not the exhaust. However, some will point to this as proof that engines "need" some sort of back pressure. </TD></TR></TABLE>
If you could get a vacuum charge on the back side of the exhaust valve that would draw so much intake into the cylinder that it would draw clean intake out of the exhaust..Then your header is really working and or you have one big *** camshaft.
</TD></TR></TABLE>If you could get a vacuum charge on the back side of the exhaust valve that would draw so much intake into the cylinder that it would draw clean intake out of the exhaust..Then your header is really working and or you have one big *** camshaft.
06-14-2007, 04:15 AM
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Re: (RMF Headers)
its not just size, its restrictions, bends (FLOW mostly) so yeah if you ran open cat-back you'd see the best possible efficiency (NO restrictions), but we can't cause of noise/emissions so we need cat-back.
I'd go 2.5 back minimum for any of our 2.2 2.3 L preludes.
Stock is too restrictive. go bigger with FI or turbo
So i guess true best option would be a diaphragm operated exhaust that would open to a secondary exhaust route at upper rpms to help facilitate the higher velocity of exhaust gas?? almost like stock intake diaphragm maybe? who knows, I'm still learning but that's my hypothesis
would having the exhaust routed straight back with no bends or cat (no restrictions) yield good performance? (just wondering though. Please keep flaming to minimum if they are dumb questions or statements)
I'd go 2.5 back minimum for any of our 2.2 2.3 L preludes.
Stock is too restrictive. go bigger with FI or turbo
So i guess true best option would be a diaphragm operated exhaust that would open to a secondary exhaust route at upper rpms to help facilitate the higher velocity of exhaust gas?? almost like stock intake diaphragm maybe? who knows, I'm still learning but that's my hypothesis
would having the exhaust routed straight back with no bends or cat (no restrictions) yield good performance? (just wondering though. Please keep flaming to minimum if they are dumb questions or statements)
06-14-2007, 04:55 AM
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Re: (mattsnooz)
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by mattsnooz »</TD></TR><TR><TD CLASS="quote">
So i guess true best option would be a diaphragm operated exhaust that would open to a secondary exhaust route at upper rpms to help facilitate the higher velocity of exhaust gas?? almost like stock intake diaphragm maybe? who knows, I'm still learning but that's my hypothesis
</TD></TR></TABLE>
newer superbikes use this kind of exhaust technology.
So i guess true best option would be a diaphragm operated exhaust that would open to a secondary exhaust route at upper rpms to help facilitate the higher velocity of exhaust gas?? almost like stock intake diaphragm maybe? who knows, I'm still learning but that's my hypothesis
</TD></TR></TABLE>
newer superbikes use this kind of exhaust technology.
06-14-2007, 05:09 AM
#23
Re: (mafia)
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by mafia »</TD></TR><TR><TD CLASS="quote">So i dont get it.... Is it better to have a big piping (3") Or small (2.3") On a NA stock H22? with bolt ons</TD></TR></TABLE>
If I had a bone stock H22 or H23, I would have 2.5" piping. For a built engine I would have 3.0" piping.
If I had a bone stock H22 or H23, I would have 2.5" piping. For a built engine I would have 3.0" piping.
06-14-2007, 05:39 AM
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Re: (mattsnooz)
This is very very interesting. Too bad I haven't taken my flows class yet, or I would have known this..That is if Auburn trys to teach me this when time comes, next semester.....
Anywho, I am one that never thought about it as in 0 backpressure with maximum flow. When I finished my turbo setup on my f22a I went with a 2.5" dp connected to a 3" exhaust to retain "backpressure" to keep my torque up since it is mostly a torquey engine. But, the fact from this statement is that the 2.5" dp can release all of my exhaust with a faster velocity than the 3" can on my engine, thus being the higher results on dyno. Since my operating range is lesser than that of a h22 the 2.5" dp benefits me where it would restrict a boosted h22. Kidstylz, here on HT, and I both live here in Auburn and have similiar setups but his being on h22 and mine being f22, I see boost a lot sooner than he does which is obvisouly lower by rpms.
I always related our different situations as he benefited from 3" dp because his boost enters more on the hp side of the graph where mine is on the torque side....me<5252rpm him>5252rpm. Both of us, being FI, need to flow best when positive pressure is achieved internally. Now, I see why the 2.5" dp benefits me with my application and the 3" does the same for him.
Conclusion
Everyone that reads this can now speak with some wisdom about this subject and refer any stubborn minds back to this page
This should go in the FAQ's for just very good, valuable bits of information.
Thanks for sharing this!
Thomas
Anywho, I am one that never thought about it as in 0 backpressure with maximum flow. When I finished my turbo setup on my f22a I went with a 2.5" dp connected to a 3" exhaust to retain "backpressure" to keep my torque up since it is mostly a torquey engine. But, the fact from this statement is that the 2.5" dp can release all of my exhaust with a faster velocity than the 3" can on my engine, thus being the higher results on dyno. Since my operating range is lesser than that of a h22 the 2.5" dp benefits me where it would restrict a boosted h22. Kidstylz, here on HT, and I both live here in Auburn and have similiar setups but his being on h22 and mine being f22, I see boost a lot sooner than he does which is obvisouly lower by rpms.
I always related our different situations as he benefited from 3" dp because his boost enters more on the hp side of the graph where mine is on the torque side....me<5252rpm him>5252rpm. Both of us, being FI, need to flow best when positive pressure is achieved internally. Now, I see why the 2.5" dp benefits me with my application and the 3" does the same for him.
Conclusion
Everyone that reads this can now speak with some wisdom about this subject and refer any stubborn minds back to this page
This should go in the FAQ's for just very good, valuable bits of information.
Thanks for sharing this!
Thomas
06-14-2007, 06:24 AM
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Re: (mgags7)
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by mgags7 »</TD></TR><TR><TD CLASS="quote">
I would agree.
Most people just like to read the dumb *** bullshit they post up on random websites about what they think a good size should be. The fact of the matter is that it has been proven numerous amounts of times that honda engines making more power open header, so if the best exhaust is no exhaust, then wtf are you thinking choking it through tiny tubes bc you read something on a page opposite an ad for color changing neons with an ugly blonde girl wearing black latex and high boots.</TD></TR></TABLE>
Well that is the exhaust or better yet the collector back you are talking about. What about before that in the header....ive only heard talk about collector size never really about the size of the primaries.
I would agree.
Most people just like to read the dumb *** bullshit they post up on random websites about what they think a good size should be. The fact of the matter is that it has been proven numerous amounts of times that honda engines making more power open header, so if the best exhaust is no exhaust, then wtf are you thinking choking it through tiny tubes bc you read something on a page opposite an ad for color changing neons with an ugly blonde girl wearing black latex and high boots.</TD></TR></TABLE>
Well that is the exhaust or better yet the collector back you are talking about. What about before that in the header....ive only heard talk about collector size never really about the size of the primaries.