1st Generation Specific (1979-1985) 1979-1985 Discussion including performance modifications and technical support sections

Open RB Headers, gain or loss hp?

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Old Jan 14, 2009 | 06:55 PM
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Open RB Headers, gain or loss hp?

Hey Guys,

I have a 12a engine and I was wondering how it will run harder, with open and short headers or with going a few inches long and then collecting them 2 into 1 ?

I have RB Headers.

Thanks.
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Old Jan 14, 2009 | 07:17 PM
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Well first, let me say you better have ear protection, and I would advise it for anyone else that comes with in 50 feet of the car.
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Old Jan 14, 2009 | 07:28 PM
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Originally Posted by MattG
Well first, let me say you better have ear protection, and I would advise it for anyone else that comes with in 50 feet of the car.
lol I think I will have to run them a few inches to the back then
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Old Jan 14, 2009 | 07:29 PM
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straight pipes back to a muffler isn't too bad
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Old Jan 14, 2009 | 08:06 PM
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Best of both worlds http://s222.photobucket.com/albums/d...ortexhaust.flv
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Old Jan 14, 2009 | 08:54 PM
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I ran a bridgeport with no header to get it running. It was loud, but not bad.
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Old Jan 14, 2009 | 09:12 PM
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It's better scavenging for the motor to run it longer as dual pipes then collect them towards the end. Low end torque will suffer from running straight pipe but you should see a little more hp on the top end. I ran open RB header on my FB a couple years ago and it had no torque at all. I'm not sure if it had more top end power or not as it was far too painful to attempt greater than 4k RPMs
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Old Jan 14, 2009 | 09:43 PM
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Originally Posted by FirebirdSlayer666
It's better scavenging for the motor to run it longer as dual pipes then collect them towards the end. Low end torque will suffer from running straight pipe but you should see a little more hp on the top end. I ran open RB header on my FB a couple years ago and it had no torque at all. I'm not sure if it had more top end power or not as it was far too painful to attempt greater than 4k RPMs
so whats the best way to get some torque ?
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Old Jan 14, 2009 | 09:49 PM
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Pretty much something like the RB street port exhaust system. Search "Long Primary exhaust"
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Old Jan 14, 2009 | 09:49 PM
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I ran an open factory header for just after I changed my clutch, just to make sure everything was working. It certainly felt like there were some power and torque gains, and it was definitely more responsive. But the factory header is more restrictive, so I don't know.
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Old Jan 14, 2009 | 10:16 PM
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I like that stealth 2 way system have read about that before. Stick to high flow components instead of just open.
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Old Jan 14, 2009 | 10:34 PM
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I have run multiple combinations of most of these on the same car searching for power and speed on the strip, what I found was with the RB complete system, single presilencer I was good (my numbers won't tell you squat cause the engine is supercharged) I switched a dual presilencer setup and it got better no low end loss consistant .3-.4 loss in ET Dropping the exhaust back of the header I had no gain from the dual presilencer setup, however the *** DYNO said the launch was flatter but the time slip said the trap speed was higher. Trying to be cute I put the dual presilencers back in didn't tighten the header all the way down so I still had a pretty good exhaust leak and repeated the test the launch came back to me but the trap speed stayed a the higher mark and I gained anothe .1-.2 cosistantly. The end result for me was I dumped the first gen setup which was mostly 2in stuff and stepped up the 2.5inch stuff, all of the previous gains stayed. How does this help your question, well the inference from the track testing told me that with open headers I was losing considerable low end toruque but gaining HP at the top End is the trade-off worth it? NO because on the track your launch and 60foot is where many races are won.
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Old Jan 15, 2009 | 06:59 AM
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Originally Posted by rotarydude
I have run multiple combinations of most of these on the same car searching for power and speed on the strip, what I found was with the RB complete system, single presilencer I was good (my numbers won't tell you squat cause the engine is supercharged) I switched a dual presilencer setup and it got better no low end loss consistant .3-.4 loss in ET Dropping the exhaust back of the header I had no gain from the dual presilencer setup, however the *** DYNO said the launch was flatter but the time slip said the trap speed was higher. Trying to be cute I put the dual presilencers back in didn't tighten the header all the way down so I still had a pretty good exhaust leak and repeated the test the launch came back to me but the trap speed stayed a the higher mark and I gained anothe .1-.2 cosistantly. The end result for me was I dumped the first gen setup which was mostly 2in stuff and stepped up the 2.5inch stuff, all of the previous gains stayed. How does this help your question, well the inference from the track testing told me that with open headers I was losing considerable low end toruque but gaining HP at the top End is the trade-off worth it? NO because on the track your launch and 60foot is where many races are won.
Thank you for your input, I also agree with you on the torque theory
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Old Jan 15, 2009 | 12:48 PM
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Read the book, "How To Modify Your RX7", it's on SgtFoxes website.
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Old Jan 15, 2009 | 12:58 PM
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Originally Posted by trochoid
Read the book, "How To Modify Your RX7", it's on SgtFoxes website.
Can you please provide me with a link of which section of the site I should look in ?

THanks.
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