Jump to content

DC Sports True Dual Exhaust ...


ChrisUUC

Recommended Posts

Actually, there is slight misconception in terminology that needs to be cleared up. It is not that a certain amount of backpressure is needed for optimum performance. A well designed exhaust system should not only relieve backpressure, but go one step further and create a vacuum in the system. When the next cylinder's exhaust valve opens, the vacuum in the

system pulls the exhaust out of the cylinder. This is what's termed "scavenging". It just easier to call it as needing a little backpressure than it is to explain a balanced airflow system to the average guy on the street.

 

The physics of airflow dynamics dictate that the pipe should be only be big enough to handle a given volume of air or in this case exhaust gases. Whether it be an exhaust system or a A/C duct in your home first consideration is the proper tube diameter. Many people think "Bigger is Better", but this is not the case. The smallest diameter that will handle the airflow of a given volume of air at a given air velocity should be used. This small diameter will generate the velocity (air speed) needed to "Scavenge" or create a vacuum in the pipe. In the case of a internal combustion engine, if the pipe diameter is to small for the engine it will pull hard at low rpm's but at some point in the higher rpm's the tube will not be able to flow as much air

as the engine is pumping out, and the engine will "clock out " early, not reaching its potential peak rpm. In this situation it would require going one size larger in tube diameter. This is why the general rule of thumb is that the maximum exhaust pipe for a normally aspirated multi valve engine operating under 8000rpm should only be .75 to 1 time the displacement of the engine in litres.

 

This vacuum in the exhaust system also has a big effect on the intake side as well. Because the vacuum is pulling the exhaust out of the cylinder this creates a stronger vacuum pulse on the intake side that pulls a stronger air/ fuel charge into the cylinder. If the pipe diameter is to big the Air ( Exhaust) become lazy and wants the intake side to push it out so in the case of an engine the intake charge gets contaminated with exhaust gases. If the pipe is to big for an application this can also cause restriction in airflow because it is moving to slow and will actually start to back up in the pipe.

 

This is an over simplified overview in airflow dynamics but you should get the general idea.

Link to comment
Share on other sites

Actually, there is slight misconception in terminology that needs to be cleared up. It is not that a certain amount of backpressure is needed for optimum performance. A well designed exhaust system should not only relieve backpressure, but go one step further and create a vacuum in the system. When the next cylinder's exhaust valve opens, the vacuum in the

system pulls the exhaust out of the cylinder. This is what's termed "scavenging". It just easier to call it as needing a little backpressure than it is to explain a balanced airflow system to the average guy on the street.

 

The physics of airflow dynamics dictate that the pipe should be only be big enough to handle a given volume of air or in this case exhaust gases. Whether it be an exhaust system or a A/C duct in your home first consideration is the proper tube diameter. Many people think "Bigger is Better", but this is not the case. The smallest diameter that will handle the airflow of a given volume of air at a given air velocity should be used. This small diameter will generate the velocity (air speed) needed to "Scavenge" or create a vacuum in the pipe. In the case of a internal combustion engine, if the pipe diameter is to small for the engine it will pull hard at low rpm's but at some point in the higher rpm's the tube will not be able to flow as much air

as the engine is pumping out, and the engine will "clock out " early, not reaching its potential peak rpm. In this situation it would require going one size larger in tube diameter. This is why the general rule of thumb is that the maximum exhaust pipe for a normally aspirated multi valve engine operating under 8000rpm should only be .75 to 1 time the displacement of the engine in litres.

 

This vacuum in the exhaust system also has a big effect on the intake side as well. Because the vacuum is pulling the exhaust out of the cylinder this creates a stronger vacuum pulse on the intake side that pulls a stronger air/ fuel charge into the cylinder. If the pipe diameter is to big the Air ( Exhaust) become lazy and wants the intake side to push it out so in the case of an engine the intake charge gets contaminated with exhaust gases. If the pipe is to big for an application this can also cause restriction in airflow because it is moving to slow and will actually start to back up in the pipe.

 

This is an over simplified overview in airflow dynamics but you should get the general idea.

 

 

I have heard of scavenging on a type of 2 stroke before but never knew it works like this. Cheers for clearing that up :thumbs:

Link to comment
Share on other sites

The DC system just seems to cause a drop in midrange torque we have found ( I actually run one of these on my JDM car) I have cars with indentical mods as cars with DC systems on and they all give more mid range torque.

 

The HKS super sound master isnt full true dual is connects to a stock Y pipe so you get the full scavenging effect from the connected headers, The copies thou we have found have inferior silencers causing bad flow, I think the pipework Diameter is smaller as well than the genuine HKS systems.

 

 

I still think you cant be a set of de-cats ( resonated or not ) XYZ with race cat and a stock UK system and a remap, this sounds real nice without being raspy or loud.

 

Mark

Link to comment
Share on other sites

Hmmmm If i got one cheap enough id maybe go with it but failing that .,,

 

HFC's ... stock system ... panel filters ... remap (in time)

 

Ill maybe open this also up to any exhaust if theres any nice second hand ones out there ... No nismos though as the price wont allow me :(

Link to comment
Share on other sites

Hmmmm If i got one cheap enough id maybe go with it but failing that .,,

 

HFC's ... stock system ... panel filters ... remap (in time)

 

Ill maybe open this also up to any exhaust if theres any nice second hand ones out there ... No nismos though as the price wont allow me :(

 

tannabe ;) sounds great

 

motordyne exhaust is good, think it makes good gains as well. Team Lizard have it fitted to his race car.

Link to comment
Share on other sites

I love the sound of the tanabe medalion touring?? ... Whats the price on them?

 

From what I understand you also need a Tanabe Y-pipe as well else it wont fit :thumbs: The Medalion on its own does not come with one.

 

Sounds nice though B)

Link to comment
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

×
×
  • Create New...