Back-pressure good or bad?
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Senior User
Joined: Apr 2006
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From: In a small Canadian town
Back-pressure good or bad?
Well I've have had this question in my head for a long time and have been debating it with a buddy of mine. He says that if you can eliminate back pressure in the exhaust your better off, free'er flowing. But I have heard that lower back pressure is good but vehicals work better with a little back pressure. Now his truck is stright piped and runs like a top no problems, but it a 5.9 CTD, so the turbo would create the right amount of back pressure right? What is really better little back-pressure or none.
Posting Legend
Joined: Sep 2001
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Moved to proper forum.
I think you will find this has been debated often here. Back pressure is a misnomer. The exhaust system should be properly designed to increase performance by scavenging the cylinders at the optimum RPM for cam operation. It must be matched to the cam which must be matched to the application...
I think you will find this has been debated often here. Back pressure is a misnomer. The exhaust system should be properly designed to increase performance by scavenging the cylinders at the optimum RPM for cam operation. It must be matched to the cam which must be matched to the application...
Posting Guru
Joined: Feb 2006
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Backpressure is not good anytime as it is caused by a restriction in the exhaust system which causes burned exhaust gasses to "back up" in the combustion chamber. This not only dilutes the incoming fuel/air charge, but has to be pumped out of the combustion chamber and exhaust system. Pumping losses of as much as 8 hp have been measured due to backpressure.
Many confuse backpressure with flow velocity. They are not the same. It usually comes up when discussing pipe size. A larger pipe can cause a loss of low end torque, and a smaller pipe increase the torque. This is where the tuning of the exhaust system comes in. By changing pipe size, length, location, configuration, the power band can be optimized for the engine rpm desired. jim d
Many confuse backpressure with flow velocity. They are not the same. It usually comes up when discussing pipe size. A larger pipe can cause a loss of low end torque, and a smaller pipe increase the torque. This is where the tuning of the exhaust system comes in. By changing pipe size, length, location, configuration, the power band can be optimized for the engine rpm desired. jim d
