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  #1  
Old 09-26-2014, 04:10 PM
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nberry1954 nberry1954 is offline
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Default General Exhaust Question

Ok, I don't know much about exhaust, but I have a question about back pressure. I always hear people talking about how you need a certain amount of back pressure to maintain low end power. I was under the impression that any back pressure is a bad thing, and the loss of power when exhaust systems are upgraded are due to the exhaust pulses losing velocity and not being able to vaccum out the following pulses of exhaust. If someone could clear this up, or share some knowledge I would be grateful. Thanks!
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Old 09-27-2014, 08:51 AM
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subed and a bump
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Old 09-27-2014, 12:51 PM
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Alittle bit of back pressure is always good. As you stated above. You can find such info on racing sites. Or even verify with the exhaust manufacturer.
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Old 09-27-2014, 02:54 PM
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I'm not exactly sure how it all works, but my understanding is that up to a certain point, back pressure contributes to torque, while a reduction in back pressure contributes to horsepower.
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Old 09-27-2014, 07:49 PM
huntergreen huntergreen is offline
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i thought the cats would provide all th needed back pressure.
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Old 09-28-2014, 02:05 AM
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Cats are for emissions. It converts Hydrocarbon, Carbon Monoxide, and Nitrogen Oxide. Hydrocarbon (unburned Gas) is what produces Acid Rain and Smog. Carbon Monoxide and Nitrogen Oxide is what can kill air breathing folks. So, it does not effect Zombies. (at least I don't think so)
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Old 09-28-2014, 05:56 PM
huntergreen huntergreen is offline
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rdm, tks, but they are restrictive as compared to the trucks i had pre cat. wouldn't they at least contribute to to back pressure?
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Old 09-28-2014, 07:31 PM
TJC.geotech TJC.geotech is offline
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Back pressure theories are nonsense. A properly designed system will provide scavenging which will aid in the evacuation of the cylinder and actually draw some of the next cycles charge into the chamber. Go too large on the primary tube, or too short and you will kill this effect. That's why virtually every street oriented header is about 30" long and sized to the port.
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Old 09-28-2014, 07:32 PM
TJC.geotech TJC.geotech is offline
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And modern cats are not a restriction.
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Old 09-28-2014, 11:50 PM
huntergreen huntergreen is offline
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ok tj.
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