Do you loose power with an open exaust
Do you loose power with an open exaust
03-21-2009, 04:39 PM
#3
2nd Gear Member
Join Date: Feb 2008
Location: Ohio
Posts: 306
I'm guessing you mean just straight pipes from the manifold back with no X or H pipe, and no mufflers? Yes, I'm pretty sure you would lose some power, but I can't really explain why. I think it has to do with Bernoulli's Principle when applied to a gas, versus a liquid.
03-22-2009, 05:39 PM
#5
2nd Gear Member
Join Date: Dec 2008
Location: WI
Posts: 172
Exhaust systems are part of a chain of factors that affect performance. Carburetors or injectors, cams, and other components comprise the rest of the chain.
When everything is in sync, the chain burns the gas/air combination to give maximum horsepower. The air/fuel mixture is burned in the combustion chamber, and the valves are timed so that the exhaust valve opens at just the right time, and the spent gasses are released to the exhaust.
When the exhaust back pressure is reduced without making modifications to the cams, carburetor, etc, the gasses are scavenged from the combustion chamber before they're completely burned. This results in a loss of horsepower.
Open exhausts ("drag pipes") work, but only if the other components are changed as well.
When everything is in sync, the chain burns the gas/air combination to give maximum horsepower. The air/fuel mixture is burned in the combustion chamber, and the valves are timed so that the exhaust valve opens at just the right time, and the spent gasses are released to the exhaust.
When the exhaust back pressure is reduced without making modifications to the cams, carburetor, etc, the gasses are scavenged from the combustion chamber before they're completely burned. This results in a loss of horsepower.
Open exhausts ("drag pipes") work, but only if the other components are changed as well.
03-22-2009, 06:41 PM
#6
Deputy CatDog - To Purr'tect and Explode
Join Date: Jun 2007
Location: NM
Posts: 1,900
Exhaust systems are part of a chain of factors that affect performance. Carburetors or injectors, cams, and other components comprise the rest of the chain.
When everything is in sync, the chain burns the gas/air combination to give maximum horsepower. The air/fuel mixture is burned in the combustion chamber, and the valves are timed so that the exhaust valve opens at just the right time, and the spent gasses are released to the exhaust.
When the exhaust back pressure is reduced without making modifications to the cams, carburetor, etc, the gasses are scavenged from the combustion chamber before they're completely burned. This results in a loss of horsepower.
Open exhausts ("drag pipes") work, but only if the other components are changed as well.
When everything is in sync, the chain burns the gas/air combination to give maximum horsepower. The air/fuel mixture is burned in the combustion chamber, and the valves are timed so that the exhaust valve opens at just the right time, and the spent gasses are released to the exhaust.
When the exhaust back pressure is reduced without making modifications to the cams, carburetor, etc, the gasses are scavenged from the combustion chamber before they're completely burned. This results in a loss of horsepower.
Open exhausts ("drag pipes") work, but only if the other components are changed as well.
We have people with the "straight pipe" question every day it seems.
03-22-2009, 08:12 PM
#7
4th Gear Member
Join Date: Jan 2007
Location:
Posts: 1,999
Less backpressure equals more power. Open exhaust will enable you to make more power than a restrictive exhaust.
The minor exception would be a lean running engine. Opening the exhaust may make it more lean which will make less power. If you were to keep the fuel/air mixture the same then open will be more. Especially with a radical overlap camshaft.
The minor exception would be a lean running engine. Opening the exhaust may make it more lean which will make less power. If you were to keep the fuel/air mixture the same then open will be more. Especially with a radical overlap camshaft.
03-29-2009, 05:40 PM
#9
2nd Gear Member
Join Date: Dec 2008
Location: WI
Posts: 172
Jfsram, are you saying that simply swapping the factory exhaust for open pipes will result in a power increase, or are you saying that adjustments/modifications are needed to increase the HP after going to open pipe?
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