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headers v free flow |
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hacksaw1971
Supporter of TheAMCForum Joined: Feb/11/2020 Location: hopewell Status: Offline Points: 1364 |
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Posted: May/24/2022 at 11:30am |
ok .. i have spent alot of time and money gathering all the smog stuff for my S/C. i know the free flow ain't stock for the pass side but its better than the log and i can still do the smog look.
but now im starting to wonder if i want headers. so im want to know just how much she will pick up with headers v the free flow. i know a good set ain't cheap and i will have to sell all the smog stuff to help pay for a set. so .. is it worth it? if 60 foot pounds and a 75 hp gain can happen i mite do it. anyone have data on this?? and what are a good set that will fit best and not be leaking all the time?
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its the little things that make the biggest difference
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Trader
AMC Addicted Joined: May/15/2018 Location: Ontario Status: Offline Points: 6754 |
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This was done back in 2012, and the more RPM you add the better long tube headers will perform. Believe you should cut your expectations in half unless well built for racing and seeing 6000+ RPM a lot:
We ran a series of dyno test on my 401 yesterday. Here are the results of the free flow (massaged) manifolds, Edelbrock shortys, and long tube headers.
Manifolds - 366.2 hp and 401 torque @ 5050 rpm Edelbrock shortys - 368.7 hp and 412 torque @ 5250 Long tube headers - 382 hp and 430 torque @ 5050 The test was conducted by SC397. Needless to say we are leaving alot of hp and torque untapped by the use of the manifolds but there is not enough gain by using the shortys. Also the long tubes will not work on my car due to how low the car sets. |
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hacksaw1971
Supporter of TheAMCForum Joined: Feb/11/2020 Location: hopewell Status: Offline Points: 1364 |
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ya kinda what i thunk ... not worth the BS that gose with the headers .... thanks
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its the little things that make the biggest difference
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Sonic Silver
Supporter of TheAMCForum Joined: Nov/23/2011 Location: East Tennessee Status: Offline Points: 7901 |
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My modified 360 made 411 hp and 426 torque with free flows, and 433 hp and 458 ft/lbs torque with full length headers. basically 20 hp and 30 torque difference. This is an engine with a lot of head work too. A near stock engine should be less of a difference.
Edited by Sonic Silver - May/24/2022 at 12:58pm |
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1982AMCConcord
AMC Addicted Joined: Jul/13/2012 Location: Kenosha, WI Status: Offline Points: 1286 |
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Here is the test Rick did on IFSJA... I think it's important to make clear that he ported the OEM free flow exhaust manifolds... So those numbers were not made with stock from the factory castings... |
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BU1
AMC Addicted Joined: Aug/11/2016 Location: MN Status: Online Points: 1971 |
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I don't understand the appeal of headers on most street driven cars. They hang low, leak, make changing starters an Olympic event,................. How much driving do you do at 5k rpm? Help me understand.
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AMO #2726
#1 1968 AMX Rally Green 343 Z code 4spd since 1975 #02642 #2 1968 AMX Rally Green 290 N code 4spd since 2019 #02959 |
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BBO UK
AMC Nut Joined: Feb/17/2020 Location: UK Status: Offline Points: 287 |
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It sounds better and gives you a warm feeling inside....because your feet are burning I just turned down a `70 AMX because it won`t get over "road humps" with it`s headers, goes well though ! |
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Sonic Silver
Supporter of TheAMCForum Joined: Nov/23/2011 Location: East Tennessee Status: Offline Points: 7901 |
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ericdowneast
AMC Apprentice Joined: May/08/2021 Location: Maine Status: Offline Points: 68 |
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I always kinda liked the more stock look but my first '74 Javeling had headers. Aside from hitting speed bumps and replacing starters a lot and exhaust leaks headers were OK I guess..... Honestly, if you are 5800 rpm or less it probably won't be worth it. You might gain a little but the PITA factor doesn't =the return IMO.
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ccowx
AMC Addicted Joined: Nov/03/2010 Location: Yukon Status: Offline Points: 3510 |
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Another consideration with long tube headers is that they do a better job of scavenging in the mid range and can fatten up the power curve there, which is nice in a driver. However, having run long tube headers as much for the look as anything else for years, I also agree that for most people they are not worth the hassle. Even less so if you are not using top quality headers made of thick metal.
Chris
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