need help with my straight pipes ( ANYBODY )
06-08-2012, 02:18 PM
#21
5th Gear Member
Join Date: Nov 2005
Location: MN
Posts: 4,412
When picking the appropriate sized exhaust you're basically trying to find the sweet spot between volume and velocity.
You never want back pressure, you always want full evacuation of the combustion chamber. Otherwise with your next intake stroke, you're not bring in as much fresh air because the combustion chamber is currently being occupied with by-product. Thus lowering the engines volumetric efficiency.
Everything from your intake filter to your tail pipe plays into the mix here. When you remove restriction in your exhaust by increasing the diameter of your exhaust piping, you will be increasing volume while lowering velocity which can have a negative effect on exhaust scavenging. If the air is traveling through the system at x rate of speed but then is forced to slow down because of an improperly sized exhaust, this will promote poor scavenging.
This is why you will see people who put 3" exhaust systems on an otherwise stock cars not gain nearly the power you should with a 2.5" system. The engine is not producing enough exhaust flow to necessitate the larger pipe diameter, thus the velocity of the exhaust slows down.
You never want back pressure, you always want full evacuation of the combustion chamber. Otherwise with your next intake stroke, you're not bring in as much fresh air because the combustion chamber is currently being occupied with by-product. Thus lowering the engines volumetric efficiency.
Everything from your intake filter to your tail pipe plays into the mix here. When you remove restriction in your exhaust by increasing the diameter of your exhaust piping, you will be increasing volume while lowering velocity which can have a negative effect on exhaust scavenging. If the air is traveling through the system at x rate of speed but then is forced to slow down because of an improperly sized exhaust, this will promote poor scavenging.
This is why you will see people who put 3" exhaust systems on an otherwise stock cars not gain nearly the power you should with a 2.5" system. The engine is not producing enough exhaust flow to necessitate the larger pipe diameter, thus the velocity of the exhaust slows down.
06-08-2012, 06:59 PM
#22
4th Gear Member
Join Date: Nov 2006
Location:
Posts: 1,229
When picking the appropriate sized exhaust you're basically trying to find the sweet spot between volume and velocity.
You never want back pressure, you always want full evacuation of the combustion chamber. Otherwise with your next intake stroke, you're not bring in as much fresh air because the combustion chamber is currently being occupied with by-product. Thus lowering the engines volumetric efficiency.
Everything from your intake filter to your tail pipe plays into the mix here. When you remove restriction in your exhaust by increasing the diameter of your exhaust piping, you will be increasing volume while lowering velocity which can have a negative effect on exhaust scavenging. If the air is traveling through the system at x rate of speed but then is forced to slow down because of an improperly sized exhaust, this will promote poor scavenging.
This is why you will see people who put 3" exhaust systems on an otherwise stock cars not gain nearly the power you should with a 2.5" system. The engine is not producing enough exhaust flow to necessitate the larger pipe diameter, thus the velocity of the exhaust slows down.
You never want back pressure, you always want full evacuation of the combustion chamber. Otherwise with your next intake stroke, you're not bring in as much fresh air because the combustion chamber is currently being occupied with by-product. Thus lowering the engines volumetric efficiency.
Everything from your intake filter to your tail pipe plays into the mix here. When you remove restriction in your exhaust by increasing the diameter of your exhaust piping, you will be increasing volume while lowering velocity which can have a negative effect on exhaust scavenging. If the air is traveling through the system at x rate of speed but then is forced to slow down because of an improperly sized exhaust, this will promote poor scavenging.
This is why you will see people who put 3" exhaust systems on an otherwise stock cars not gain nearly the power you should with a 2.5" system. The engine is not producing enough exhaust flow to necessitate the larger pipe diameter, thus the velocity of the exhaust slows down.
06-08-2012, 10:22 PM
#23
5th Gear Member
Join Date: Nov 2005
Location: MN
Posts: 4,412
Because straight pipes sound like clapped out pick up trucks.... So we made the discussion more interesting.
06-13-2012, 03:11 PM
#26
also i do have mods done to my car so its not stock so thats why i have the xpipe no cats i have put blast packs on and that helped out a lot it is still loud but that stock car sound has went away and it sounds aggressive now. and my neighbors are happier since its not that stock car sound now.
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