RE: Backpressure: The Myth and Why It's Wrong.

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RE: Backpressure: The Myth and Why It's Wrong.

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Honda Civic Forum >> Your Ride >> Header, Intake, & Exhaust >> RE: Backpressure: The Myth and Why It's Wrong.

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RE: Backpressure: The Myth and Why It's Wrong. - 2/11/2007 11:24:20 AM

johnny

Posts: 1906
Joined: 10/30/2006
Status: offline

That was a wicked right up... I totally didn't understand abckpressure before. Im still a little rough on it.. But it will be awhile till i can read again.

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RE: Backpressure: The Myth and Why It's Wrong. - 3/3/2007 2:30:53 PM

project5k

Posts: 118
Joined: 2/18/2007
Status: offline

on the whole 4-1 vs 4-2-1 thing, it has to do with the scavenging effeciency.. meaning having the #1 cyl's exaust pulse help pull the #3's exaust out of the cyl... its kinds like a carb, where the venturi creats a low pressure and sucks the gas into the airstream.. the previous exaust helps the next bunch get moved along.. and where at lower rpm's for a given pipe size the velocity is lower than higher rpm's same pipe size cause your moving more exaust through there... in the 4-1 each exaust pulse dosent really help the next come out much, but with the 4-2-1 there is more helping going on...
just incase your still confused on what a 4-1 vs a 4-2-1 looks like, look at some big v8 headers.. most of thoes are 4-1.. all 4 tubes all come together at the same place, the collector.. now on a 4-2-1, the 4 tubes are broken into 2 pairs of 2, and joined.. now these new resulting larger tubes are joined down the line to form one... so it goes from 4 ports or tubes, to 2 tubes, to one tube.. the stock civic cast manifold is really more of a 4-1 configuration...

as for turbo runaway, i would love to read more about that one... so off to search i go....

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Post #: 62

RE: Backpressure: The Myth and Why It's Wrong. - 3/15/2007 5:33:44 PM

stefo

Posts: 133
Joined: 10/12/2006
Status: offline

wait if i get just some fart can and get it welded onto my civic will i lose power?? or will the muffler not even affect it... like if i get this muffer ...

http://cgi.ebay.com/ebaymotors/UNIVERSAL-4-5-N1-MUFFLER-Integra-RSX-Civic-CRX-Preulde_W0QQcmdZViewItemQQcategoryZ33636QQitemZ110102414438QQrdZ1

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RE: Backpressure: The Myth and Why It's Wrong. - 3/15/2007 5:38:57 PM

Remmy

Posts: 11161
Joined: 1/11/2005
From: Charleston
Status: offline

It looks like the tip is 4.5. the actualy diameter of the pipe is a different story.

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Post #: 64

RE: Backpressure: The Myth and Why It's Wrong. - 4/29/2007 6:14:56 AM

Hola

Posts: 80
Joined: 3/11/2007
Status: offline

Wow, thanks

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Post #: 65

RE: Backpressure: The Myth and Why It's Wrong. - 7/27/2007 9:17:46 AM

sevpva12

Posts: 3
Joined: 7/15/2007
Status: offline

Hey buddy I read what you wrote about backpressure and I am that guy who thought putting a 3inch pipe would really impove my prefromance and what do you know I did loose power. thanks for the article

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Post #: 66

RE: Backpressure: The Myth and Why It's Wrong. - 10/28/2007 12:32:21 PM

EF3 TEAM EOS

Posts: 26
Joined: 10/27/2007
Status: offline

k i still dont get the first post about back pressure.if you think a about it you dont need it at all it will just perform better with the right amout.dosent it depend on your set up if your car is for top end you want bigger piping with higher hp and if your more for bottom end you want 2in, or if you have turbo you want the best flow..if you have all motor non vtec like a ls witch you want the torque you keep the piping smaller but bigger than stock and if you got a fully built vtec for 9k rpm revs you want big pipeing but not as big as turbo cars?

< Message edited by EF3 TEAM EOS -- 10/28/2007 12:33:43 PM >

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Post #: 67

RE: Backpressure: The Myth and Why It's Wrong. - 11/27/2007 10:34:38 AM

rmnz116

Posts: 4
Joined: 11/26/2007
Status: offline

Backpressure also creates a vaccum in your engine(which is not needed with forced induction) which helps to suck the exhaust gases out of the cylinder. You don't need alot of backpressure, but maintaining a small amount of backpressure is necessary...unless you have forced induction.

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RE: Backpressure: The Myth and Why It's Wrong. - 12/1/2007 7:13:22 PM

honda316

Posts: 2
Joined: 12/1/2007
Status: offline

check out the second result, "reducing backpressure", in forumdig: honda civic backpressure

< Message edited by honda316 -- 12/1/2007 7:17:20 PM >

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Post #: 69

RE: Backpressure: The Myth and Why It's Wrong. - 1/22/2008 11:14:02 PM

rit14623

Posts: 247
Joined: 2/25/2006
Status: offline

I don't know if anyone can answer this question, how are OEM mufflers packed? I had a Borla free-flow exhaust on a VW I owned in the past, and you could see through the tail pipe and through the muffler and light coming in from on the other side (when not mounted). If you have narrow pipes like on an OEM exhaust, how much is the muffler packing slowing the exhaust flow? I think (and I might be wrong) that the OEM mufflers don't provide a direct path from the inlet to the tail pipe. So, there seems to be a "back-pressure creating" zone in the muffler.

This might sound like a nutty hypothesis (but I'll accept the Nobel Peace prize and the one mil in cash), but you could increase flow on a wide-diameter cat-back exhaust system by cutting out the 4" tail pipe and welding on a pipe reducer that ends at 2.5" diameter.

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Post #: 70