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Old 08-23-2012, 02:06 PM   #1
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Open headers!

S it bad to run open headers or not? I am outing on my LTs soon and I don't yet have the money saved for my slp loudmouths but I don't want to just out my flow masters back on. Can I run open headers or wil it be bad? And do need an x or h pipe with the slps?
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Old 08-23-2012, 02:16 PM   #2
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its fine just dnt rpm brake
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Old 08-23-2012, 02:27 PM   #3
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its fine just dnt rpm brake
Explain what rpm braking is
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Old 08-23-2012, 02:32 PM   #4
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Rpm breaking?
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Old 08-23-2012, 02:51 PM   #5
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I also heard tht u loose some hp if u open em up idk if thts true or not
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Old 08-23-2012, 03:19 PM   #6
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Back pressure is a good thing.
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Old 08-23-2012, 06:32 PM   #7
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going to 5 grand on you're tach letting off the gas while staying in gear letting rpms drop. with will cause little vacum may suck in dirt cause valve float

---------- Post added at 05:32 PM ---------- Previous post was at 05:27 PM ----------

its call scavenge. sorry my spelling sucks
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Old 08-23-2012, 08:49 PM   #8
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Quote:
Originally Posted by 2003mustangGT
S it bad to run open headers or not? I am outing on my LTs soon and I don't yet have the money saved for my slp loudmouths but I don't want to just out my flow masters back on. Can I run open headers or wil it be bad? And do need an x or h pipe with the slps?


---------- Post added at 08:49 PM ---------- Previous post was at 08:49 PM ----------

[/COLOR]
Quote:
Originally Posted by 2003mustangGT
S it bad to run open headers or not? I am outing on my LTs soon and I don't yet have the money saved for my slp loudmouths but I don't want to just out my flow masters back on. Can I run open headers or wil it be bad? And do need an x or h pipe with the slps?
You will burn up your valves

You need back pressure just wait and do it right.
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Old 08-23-2012, 09:01 PM   #9
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Yeah will screw up valves wait till you get money
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Old 08-26-2012, 05:05 PM   #10
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Re: Open headers!

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Originally Posted by 01bullitt View Post
its fine just dnt rpm brake
You do know that a good way to burn a valve? Not only that the engine needs the back pressure for efficient operations.

---------- Post added at 05:05 PM ---------- Previous post was at 04:49 PM ----------

Quote:
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going to 5 grand on you're tach letting off the gas while staying in gear letting rpms drop. with will cause little vacum may suck in dirt cause valve float

---------- Post added at 05:32 PM ---------- Previous post was at 05:27 PM ----------

its call scavenge. sorry my spelling sucks
So wrong

Scavenging is the action of drawing in air and exhausting that air, in an uninterrupted manner. The use of a header or manifold is to cause the air to speed up in a focused manner. An Exhaust pipe adds to this event, in helping the air speed up upon exit.

Valve float is when the valve(s) do not remain in contact with the camshaft lobe during operation, when engine rpm exceeds the valve train tolerance.

Hope it helps you on your quest.
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Old 08-26-2012, 05:08 PM   #11
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Quote:
Originally Posted by Venomouz831
I also heard tht u loose some hp if u open em up idk if thts true or not
Had a friend tell me its better top end power when open
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Old 08-26-2012, 05:20 PM   #12
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Re: Open headers!

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Originally Posted by Butch View Post
Had a friend tell me its better top end power when open
And yet a Stock car has exhaust pipes, indy cars have exhaust pipes. here's a way to look at it. Think of a leaf blower, there is more air speed and force with a tube blowing air then there would be taking the tube off and trying to blow leaves without it. Or better yet a gun. Short barrel more initial blast but no sustained speed and distance, you put a long barrel on it and not you have increase bullet speed and distance. Open your mouth wide and blow then blow again but with your lips focused. BACKPRESSURE.
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Old 08-26-2012, 08:13 PM   #13
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Quote:
Originally Posted by 32vNomad

And yet a Stock car has exhaust pipes, indy cars have exhaust pipes. here's a way to look at it. Think of a leaf blower, there is more air speed and force with a tube blowing air then there would be taking the tube off and trying to blow leaves without it. Or better yet a gun. Short barrel more initial blast but no sustained speed and distance, you put a long barrel on it and not you have increase bullet speed and distance. Open your mouth wide and blow then blow again but with your lips focused. BACKPRESSURE.
+1
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Old 08-26-2012, 08:19 PM   #14
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Re: Open headers!

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Originally Posted by 32vNomad View Post
And yet a Stock car has exhaust pipes, indy cars have exhaust pipes. here's a way to look at it. Think of a leaf blower, there is more air speed and force with a tube blowing air then there would be taking the tube off and trying to blow leaves without it. Or better yet a gun. Short barrel more initial blast but no sustained speed and distance, you put a long barrel on it and not you have increase bullet speed and distance. Open your mouth wide and blow then blow again but with your lips focused. BACKPRESSURE.
I tried to explained that to my ex wife,,but she didnt get..lol,,jk
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Old 08-26-2012, 10:19 PM   #15
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Quote:
Originally Posted by 32vNomad

And yet a Stock car has exhaust pipes, indy cars have exhaust pipes. here's a way to look at it. Think of a leaf blower, there is more air speed and force with a tube blowing air then there would be taking the tube off and trying to blow leaves without it. Or better yet a gun. Short barrel more initial blast but no sustained speed and distance, you put a long barrel on it and not you have increase bullet speed and distance. Open your mouth wide and blow then blow again but with your lips focused. BACKPRESSURE.
Ah I see. And I totally just tried that jaja.
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Old 08-26-2012, 10:41 PM   #16
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I don't agree fully with everything explained. I do agree that some scavenging/backpressure is good. But what a lot of people think is somewhat of myth.And I wouldn't run open headers. But once you get enough hp this does change. That's why most drag cars run open headers or straight pipes. And I believe that you would gain top end. But really lose on the bottom end. To the best way to create a perfect flowing exhaust would be to create a funnel type shape. With the largest pipe being the tail pipes. For example. 3 1/2" tail pipes, 3" mufflers, 2 1/2" x pipe. This type of setup is dyno proven and is the way I would go.
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Old 08-26-2012, 11:20 PM   #17
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Re: Open headers!

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Originally Posted by dreamstang View Post
I don't agree fully with everything explained. I do agree that some scavenging/backpressure is good. But what a lot of people think is somewhat of myth.And I wouldn't run open headers. But once you get enough hp this does change. That's why most drag cars run open headers or straight pipes. And I believe that you would gain top end. But really lose on the bottom end. To the best way to create a perfect flowing exhaust would be to create a funnel type shape. With the largest pipe being the tail pipes. For example. 3 1/2" tail pipes, 3" mufflers, 2 1/2" x pipe. This type of setup is dyno proven and is the way I would go.
The pipe is what helps create backpressure. A NA motor it needs Backpressure and Savaging both to make efficient power. A drag car for the most has a FORCED inducted engine. With FI backpressure is not needed as much as the air is being forcefully pulled in and pushed out. Running open headers is cool in the garage on a first start up. But in no way a performance benefit on a street car, your only looking to damage your engine.
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Old 08-26-2012, 11:44 PM   #18
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How much do the slp loudmouth cams cost?
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Old 08-27-2012, 12:40 AM   #19
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What about cutouts?
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Old 08-27-2012, 04:53 AM   #20
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Quote:
Originally Posted by 32vNomad

The pipe is what helps create backpressure. A NA motor it needs Backpressure and Savaging both to make efficient power. A drag car for the most has a FORCED inducted engine. With FI backpressure is not needed as much as the air is being forcefully pulled in and pushed out. Running open headers is cool in the garage on a first start up. But in no way a performance benefit on a street car, your only looking to damage your engine.
I never said it doesn't help and I would run open headers. Everyone here seems misunderstood about the backpressure theory.

Myths about "back-pressure"

http://www.carforum.net/exhaust-syst...-pressure.html

http://my.prostreetonline.com/forums...php?t-1639.htm
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Old 08-27-2012, 08:33 AM   #21
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It's not really backpressure you want as much as the proper exhaust velocity which does in turn create backpressure. But the correct exhaust velocity is the main goal when an exhaust system is designed. Sorta the same idea as a throttle body and plenum. You're looking for the correct size to get ideal velocity
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Old 08-27-2012, 09:02 AM   #22
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Originally Posted by poncho2049
It's not really backpressure you want as much as the proper exhaust velocity which does in turn create backpressure. But the correct exhaust velocity is the main goal when an exhaust system is designed. Sorta the same idea as a throttle body and plenum. You're looking for the correct size to get ideal velocity
+1 Exactly.
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Old 08-27-2012, 09:39 AM   #23
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Re: Open headers!

It may be just my 2 cent but there has to be a reason the 2013 copo camero, 2013 cobra jet, the v10 mopar challenger drag pack car all run open headers.
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Old 08-27-2012, 10:40 AM   #24
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It may be just my 2 cent but there has to be a reason the 2013 copo camero, 2013 cobra jet, the v10 mopar challenger drag pack car all run open headers.
Yeah its what they were designed for just like any top fuel car has open headers. It's the way the engine and valvetrain is designed.
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Old 08-27-2012, 11:01 AM   #25
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Yeah its what they were designed for just like any top fuel car has open headers. It's the way the engine and valvetrain is designed.
Also the tune plays a big role.
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Old 08-27-2012, 12:23 PM   #26
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Also the tune plays a big role.
+1
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