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Old 04-28-2010, 09:14 PM   #1
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Back Pressure?

I have long tube headers with true dual exhaust and hi-flo cats. Ive been told to get like Flowmaster mufflers to help with "back pressure" on the hemi model engines. Can some explain to me what this "back pressure" is? Thanks for your knowledge.

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Old 04-28-2010, 11:04 PM   #2
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Back Pressure?

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quote:Can some explain to me what this "back pressure" is?
the need for it is a myth IMHO. Plenty of others will argue.
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Old 04-29-2010, 09:05 AM   #3
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Back Pressure?

I dont believe in the back pressure thing either. But I have become a bit of a believer regarding exhaust temperature affecting overall performance. I found some talk on another forum about it regarding HEMI's and had talked to a few others about maintaining a certain temperature range. Diameter pipe obviously allows different flows and temps causing a resistance of sorts. Resistance creates temperature. Something to that affect.

Too large a diameter of piping you may experience a bit of lag down low. To small a diameter you may adversely affect the overall performace.

Combine that with CAI, Thermostat, headers, blah blah...I believe I look for a certain package for overall performance and efficiency. My experience with engines (80's) and older, I could see a difference with the total package. When I lived in FL I yanked out my thermostat (always friggin warm outside), ran a larger radiator, and of course ignition and a bunch of other mods and wow a huge difference in performance and smoothness.

But hell everybody has their theory. This one made the most sense to be. Now if you stick a few bananas up the rear pipe and clog it sure thats back pressure
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Old 04-29-2010, 09:14 AM   #4
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Back Pressure?

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quote:the need for it is a myth IMHO. Plenty of others will argue.
That is why I have never entered into a discussion on back pressure. It is a myth! How many pure race cars have you seen with any kind of device for back pressure?
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Old 04-29-2010, 10:47 AM   #5
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Back Pressure?

Agreed!
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Old 04-29-2010, 09:40 PM   #6
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Back Pressure?

Thanks for clearing it up guys!!!
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Old 04-29-2010, 11:17 PM   #7
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Back Pressure?

I'm real big on the entire backpressure thing myself but I do know that on my true duals when I went from a pair of 1 chamber mufflers to a pair of 3 chamber mufflers I gained a little bit of low end.

At some point I will be changing to straight thru mufflers and we will see what happens then.
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Old 04-29-2010, 11:27 PM   #8
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Back Pressure?

Back Pressure, a mans excuse to conforming to emissions codes! </3 Catalytic Converters
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Old 04-30-2010, 10:48 AM   #9
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Old 05-04-2010, 12:36 AM   #10
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Back Pressure?

IMO, back pressure is a myth. My step dad used to race open wheel modified's and was always harpin' on me about my back pressure when I made exhaust mod's on my first vehicles, but I straight piped both my first cars, ran over 100,000 miles and never had a single valve train problem, which is the common said result of running low back pressure since the supposed loss of "back pressure" of your exhaust doesn't let the exhaust valve(s) close smoothly. Instead they sort of "slam shut", but guess what... that's what valve springs are for.

I did drop a valve in a Nissan I straight piped, but that was due to red-lining it way way way too long in a race. Anyhow, best of luck.
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