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Fumes and open headers

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by 1979Jimmy, Jan 15, 2002.

  1. 1979Jimmy

    1979Jimmy 1/2 ton status

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    I was thinking about running open headers. The thing is though that before i had a set of pipes fabed up I wanna see how it sounds. How bad would it smell and how many fumes would be coming in if i took off the pipes right where the headers end. I know that at a stnadstill it might be an issue but when i an moving would i be ok? Thanks for the help. Rember this would most likely be only temporary.

    79 Jimmy, 5" lift 35 M/T with a 383 puttin out 400hp and 450lb/ft. 4.11s Locked front and back.
     
  2. xnoahx

    xnoahx 1/2 ton status

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    I would say dont even bother with open headers. Its way to loud and its not a healthy loud. It does not sound good when you are driving. Keep some pipes on it and some sort or muffler. if you want it loud, put some glasspacks on it

    My 73 K5 <a target="_blank" href=http://www.geocities.com/xk5blazerx/73k5.htm>http://www.geocities.com/xk5blazerx/73k5.htm</a> 350/TH350/NP203, Q-jet, Edelbrock intake, Vortec heads, 4" lift, and 36" TSL's
     
  3. tRustyK5

    tRustyK5 Big meanie Staff Member Super Moderator GMOTM Winner Author

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    I ran open headers...to the exhaust shop. What a gawd-awful racket. It was mind numbing loud and definitely not a 'cool' sounding loud either. Fumes was the least of my worries...

    Rene

    <font color=green>Dyslexics of the world...UNTIE!</font color=green>
    <a target="_blank" href=http://coloradok5.com/gallery/project_T2> tRusty pics...</a>
     
  4. Slayer

    Slayer 1/2 ton status

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    Two problems with running open headers.

    The first problem, and this can be very costly, is to run open headers when the ambient temperature is under 50 degrees. The cold air can be sucked back into the engine warping the valves.

    Second problem is the lack of backpressure, which will cost you in low-end power. Open pipes are for drag racing (that's why straight open motorcycle pipes are called drag pipes) and they only work at high-end rpm ranges. If you're running a mud drag racer, then fine, but on the street you would lose road rage manuevering power.



    <font color=blue>I don't know everything, I just think I do.............</font color=blue>[​IMG]
     
  5. dyeager535

    dyeager535 1 ton status Premium Member

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    I've been told by a machinist with an internal combustion degree (I guess there is such a thing) that the cold air "theory" isn't true.

    personally, I've run for miles with either just manifolds, or no exhaust whatsoever (like running to exhaust shop, testing, etc) and never had any problems. I rarely watch drag racing, but for the most part they are running with open exhaust or headers right? (and punishing them extremely hard, even if they do go for only one race or something)

    I typically don't trust anyone anymore, someone got any links to online articles discussing this?


    Dorian
    My tech/links page: <a target="_blank" href=http://www.dorianyeager.com/index2.html>www.dorianyeager.com/index2.html</a>
    Why insist on counting when the ring gear has the tooth counts stamped in?
     
  6. Rob 85K5

    Rob 85K5 1/2 ton status GMOTM Winner

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    The sound is deafening and your friends will never follow you anywhere. Heat build up in the floor(HOT FEET) and your tranny will be a problem too.

    Rob

    <font color=orange>Bleedin' Chevy Orange</font color=orange>
     
  7. Slayer

    Slayer 1/2 ton status

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    Hey, you gotta go with what you know..........................
    <font color=red>
    I've been around the block way too many times, and this is what I've learned, and like a typical stubborn guy, I stand by my information, right or wrong...[​IMG]...[​IMG]...[​IMG]...[​IMG]...[​IMG]...[​IMG]...[​IMG]...[​IMG]...[​IMG]...[​IMG]...
    </font color=red>



    <font color=blue>I don't know everything, I just think I do.............</font color=blue>[​IMG]
     
  8. Slayer

    Slayer 1/2 ton status

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    <font color=blue>My absolute FAVORITE part of the last post was the bit about not trusting anyone anymore, but yet still asking for advice. You gotta love it...............................................
    </font color=blue><font color=red>
    Actually have to admit that the heat could affect the tranny. Good call, didn't even think about that one.
    </font color=red><font color=orange>
    But of course I still stand by my hard-earned bit about the valves being warped. I have seen this happen to Harleys, but never seen it happen to a V-8 motor. And most of my experience is with motorcycles................................
    </font color=orange>



    <font color=blue>I don't know everything, I just think I do.............</font color=blue>[​IMG]
     
  9. dyeager535

    dyeager535 1 ton status Premium Member

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    When you can get 30 answers on how to check rear axle ratio, or people claiming that "010" and "020" on the back of a chevy block means its got more nickel in it, with absolutely no proof whatsoever, my thinking anymore is that I will gather as much data, opinions, and experience as possible, and draw conclusions from that.

    If I asked questions, but didn't listen, I'd be an idiot. I'd also be an idiot if I believed every person, without question, that told me something. No?

    You have to admit, there are a whole LOT of "experts" out here in cyberspace...if they were all right, no one would need to ask questions anymore.

    Dorian
    My tech/links page: <a target="_blank" href=http://www.dorianyeager.com/index2.html>www.dorianyeager.com/index2.html</a>
    Why insist on counting when the ring gear has the tooth counts stamped in?
     
  10. 1979Jimmy

    1979Jimmy 1/2 ton status

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    OK im here in sunny CA so real real cold temperatures are not a real issue. I know some people say its ungodly looud but i would probably only have it off for a little bit. I guess i would call it youthful curiosity. As for heat on the tranny the pipes run by it anyway so how would the exhaust out of the headers really be that much worse. I mean it seems so easy to get them on and off i thought i might just try and check it out.

    79 Jimmy, 5" lift 35 M/T with a 383 puttin out 400hp and 450lb/ft. 4.11s Locked front and back.
     
  11. Rob 85K5

    Rob 85K5 1/2 ton status GMOTM Winner

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    Start the truck and then put your hand near the pipe by the tranny, then put your hand at the tail pipe feel any difference? Imagine the heat with direct flow w/o muffler or Cat or the other 6' of pipe to dissipate heat.
    Friends of mine that race have gone from cheap sneaks to racing shoes in a heartbeat, because the soles of their sneaks melt to the floor, and they run about 12-20" pipe off of the headers. They run manual trannies though

    Rob

    <font color=orange>Bleedin' Chevy Orange</font color=orange><P ID="edit"><FONT class="small">Edited by Rob 85K5 on 01/15/02 09:32 PM.</FONT></P>
     
  12. 84_Chevy_K10

    84_Chevy_K10 Banned

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    It's very loud. I did it for the mud pit at the 4x4 show. It sounded cool for the crowd and was very, very loud.

    Drove all the way home that way. Even past a state trooper. Fixed it the next day. It sounds bad going down the road, but awesome at WOT going through the mud.

    Tim
    '84 Chevy K10, lifted, loud, fast, and 3/4 ton axles
     
  13. 1979Jimmy

    1979Jimmy 1/2 ton status

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    If i got some pipes fabbed up and threw them on would heat still be an issue.

    79 Jimmy, 5" lift 35 M/T with a 383 puttin out 400hp and 450lb/ft. 4.11s Locked front and back.
     
  14. 84_Chevy_K10

    84_Chevy_K10 Banned

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    Nope.

    Tim
    '84 Chevy K10, lifted, loud, fast, and 3/4 ton axles
     
  15. 1979Jimmy

    1979Jimmy 1/2 ton status

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    Im a poor student and some pipes would be 60 bucks. What you gunan do?

    79 Jimmy, 5" lift 35 M/T with a 383 puttin out 400hp and 450lb/ft. 4.11s Locked front and back.
     
  16. txbartman

    txbartman 1/2 ton status

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    I had a 72 with a wild 350 that I used to street drag back in HS. My dad and I tacked the 3-bolt flanges to the header and tacked the other one to the tail pipe. When we would street drag, I would unbolt the flanges, shift the pipes, and rebolt one hole of thye flange. This would keep my pipes from falling but allow me to run open headers.

    Only problems it caused was that it was DEAFENING!!! In addition, the floor board would get REAL HOT. Even with heat shielding under the carpet. At WOT, the unburnt fuel was burning right under my feet.

    If you want to see what the sound would be, try this... Disconnect your current pipes from your headers in your driveway. Then, get in, fire it up, and rev it a few times. Now, imagine listeneing to that sound constantly while driving. Even if for a shirt bit, you will find it to be VERY VERY LOUD.

    As far as valve warpage, my mom and dad both used to drag. They would run open headers or cut-outs. They liked to run when it was cold because of the HP gains. Granted, cold here in TX is a relative term, but often below 50 degrees. In 20 years of racing between the two of them, NEVER had a warped valve due to the open headers.

    There are a lot of commonalities between bike motors and truck motors, but there are also a lot of differences. Just because something happens to one, I wouldn't presume it is going to happen to the other. I have also run open headers on a 454 boat motor. Never had a problem there either. Well, beside a little premature deafening!

    If you have never seen something happen, have never heard someone else have it happen, and have no expert knowledge that would qualify you to say it would happen to the same configuration, it should be presented as opinion, not as fact. Too many people here seem to present opinions as facts.

    I do not consider myself an expert, as my experience does not always apply to everyone else's situation. So, I present my experiences and my opinions as just that. Helps to keep from misleading anyone. Let's then draw there own conclusion knowing exactly where I came up with mine.

    Brian
    Check out <a target="_blank" href=http://tx85gmcguy.alloffroad.com>My Jimmy</a> with all her projects!
     
  17. DesertDueler

    DesertDueler 1/2 ton status

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    I dont think you have to worry about warping a valve with headers on. If you had nothing on (no headers or manifolds) then yes it will happen. Look at jet boats, they run open headers with cold water injecting into them. They would be at the most risk, but dont have any problems.

    86Jimmy 4"&35"MTRs,87 burb 4"&33"MT,69Firebird w/525 hp,and 70GTO live in PHX,AZ<a target="_blank" href=http://www.geocities.com/modifierperformance>My vehicles</a>
     
  18. 1979Jimmy

    1979Jimmy 1/2 ton status

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    I bet i would get some aatention at our local street races around here. How would you make those diconects?

    79 Jimmy, 5" lift 35 M/T with a 383 puttin out 400hp and 450lb/ft. 4.11s Locked front and back.
     
  19. 1979Jimmy

    1979Jimmy 1/2 ton status

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    Stupid me i just realized how you did do it, Thats pretty simple. Now how would i seal up the flanges Gaskets?

    79 Jimmy, 5" lift 35 M/T with a 383 puttin out 400hp and 450lb/ft. 4.11s Locked front and back.
     
  20. 1979Jimmy

    1979Jimmy 1/2 ton status

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    ...

    79 Jimmy, 5" lift 35 M/T with a 383 puttin out 400hp and 450lb/ft. 4.11s Locked front and back.
     

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