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How to run exhaust pipes outside the frame rails?

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by BadDog, May 21, 2002.

  1. BadDog

    BadDog SOL Staff Member Super Moderator Author

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    Is there a factory exhaust manifold for the passenger side of my 350 that drops down in front of the starter but behind the mounts? I thought I remembered a post on this a while back but can't find it.

    BTW, the reason for my interest is that I want to get my exhaust on the outside of the frame rails, like the Jeep guys run. Any suggestions? I really don't even want to run duals but, the cross under pipe is gonna be a PIA. Probably wind up with a pair of small diameter pipes through glass packs. Running duals with the 205 and the gas tank setup I'm planning are also going to be a PIA going down the inside. Best thing I can come up with so far is dropping down and crossing outboard in front of the shackle on the front springs. With my lift there is lots of room in there and it would never hit anything. I think the biggest clearance problem would be the back of the 42s when turned. I'm just starting to mull this over in my head. Anyone ever looked at this or done it?

    Edit : Changed subject line...
     
  2. Twiz

    Twiz 1/2 ton status

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    Re: Exhaust Manifold - Passenger side, center drop???

    What about headers? Swipe some from a early Nova, and go over the frame and back. (probably hit 'em with the tires tho.)

    Shoty headers or intermidiates would probably fit the bill too, check out headers for the IFS trucks, they look like they would be a clean tight fit to the fire-wall and allow you to cross out under the frame, maybe even over the frame if you trim the fire-wall a bit. (I think that Stephan used IFS headers on the ORD blazer, intermidiates, maybe ?!!?!?)

    If your want cast-manifolds, look at some corvettes - I think they exit around the center.
    The guys to ask would be the "Hot-rodder" group, they know whats what as-far as manifolds go. I think SoloWhookie (Jeff) is in the middle a a "hot-rod" build up, he might know a good web-site to check.
     
  3. m j

    m j 1/2 ton status

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    Re: Exhaust Manifold - Passenger side, center drop???

    early corvette or ?? cast iron rams horns
    there is a cool tubular stainless version from the 80s or 90s that was available in the chev motorsports catalogue
     
  4. m j

    m j 1/2 ton status

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    Re: Exhaust Manifold - Passenger side, center drop???

    or look for old fenderwell style headers, maybe chevy II styles
     
  5. dyeager535

    dyeager535 1 ton status Premium Member

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    Re: Exhaust Manifold - Passenger side, center drop???

    Even if you can find manifolds that dump like you want, you'd probably end up with a near 90 degree bend trying to get them over the framerails...if thats no concern to you, then no problem, but in my thinking, that would be the first major hassle, the restriction caused by that, and trying to bend a 2-2.5" pipe in a 90* angle.
     
  6. BadDog

    BadDog SOL Staff Member Super Moderator Author

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    Re: Exhaust Manifold - Passenger side, center drop???

    I'm not a big fan of headers. The only headers I've considered are the Thorleys. As for trimming the fire wall (or floor), I've considered that too. Seems like someone said the Vette manifold hits the motor mounts, but not sure...
     
  7. BadDog

    BadDog SOL Staff Member Super Moderator Author

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    Re: Exhaust Manifold - Passenger side, center drop???

    Like I replied to Twiz, seems I remember reading that the Vette and Ram's horns interfere with the motor mounts. Do you know if this is true, or do you know anyone running these?
     
  8. BadDog

    BadDog SOL Staff Member Super Moderator Author

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    Re: Exhaust Manifold - Passenger side, center drop???

    Yeah, I don't think there is enough room to go over, the engine sets way to low for that. One thing I was considering is going under the frame in front of the front spring rear shackle. Or maybe keep the current manifolds and jump over the frame rail under the front seat. On the pickup floor there is a big hump there that the seat sets on. It forms a sort of tunnel going over the frame. With a little heat shielding that might work.

    I'm mostly just fishing for ideas. My main objective is to get the exhaust outside the frame rails to have more room for the stuff I want to put between them. Does anyone know of a GM fullsize with exhaust outside the rails? If so, how did they do it???
     
  9. m j

    m j 1/2 ton status

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    Re: Exhaust Manifold - Passenger side, center drop???

    I have run the rams horns from about 2 weeks of owning my truck.
    the leaky headers a PO had on there had to go
     
  10. wheelnut46

    wheelnut46 1/2 ton status

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    Maybe someone else can confirm or deny this but it looks as though blockhugger style headers would work. They dont seem to interfere with the motor mounts and they exit right below the center of the manifold. You will have to have a 90 degree exit but most streetrods do this without any problems. I am considering this because coated inside and out blockhugger style headers can be bought for about $170 and full length coated headers are at least twice that.
     
  11. HarryH3

    HarryH3 1 ton status Author

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    Re: Exhaust Manifold - Passenger side, center drop???

    I have the stock '87 'vette factory stainless steel mini-headers on my '75 K5. They dump straight down. I just went out and took a look and it seems that you could make an S-curve pipe that would attach to the manifold and then go up and over the frame rail on each side. I had to make about a 1/2-inch notch in the bracket that holds the drivers side motor mount. The motor mount itself wasn't in the way, just the bracket that the motor mount bolts to. You can remove it without yanking the engine. /forums/images/icons/cool.gif
     
  12. BorregoK5

    BorregoK5 1/2 ton status

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    Re: Exhaust Manifold - Passenger side, center drop???

    I'm with you on this one BadDog! I was thinking of running them in front of the spring shackle as well. I'm adding a body lift soon to help clear my new tires and thought of running them up over the frame under the passenger seat as well but even with heat shield, the floor is going to get hot. Are you thinking of exiting the pipes in front of the back wheels?
     
  13. BadDog

    BadDog SOL Staff Member Super Moderator Author

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    Re: Exhaust Manifold - Passenger side, center drop???

    Cool, glad to know it works. I like the rams horn idea. I'll avoid headers if at all possible...
     
  14. BadDog

    BadDog SOL Staff Member Super Moderator Author

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    Re: Exhaust Manifold - Passenger side, center drop???

    Hmm, haven't seen those vette headers but, seems like an "S" pipe would be awfully tight on the starter. I still think coming straight down behind the mount, straight out under the frame, and then swing back following the frame would work the best.
     
  15. m j

    m j 1/2 ton status

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    Re: Exhaust Manifold - Passenger side, center drop???

    if the newer vette ones are stainless I bet they would be cool and trouble free
    my rams horns are the straight down outlet style, havent tried the angled ones
     
  16. BadDog

    BadDog SOL Staff Member Super Moderator Author

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    Re: Exhaust Manifold - Passenger side, center drop???

    I'll probably run them out the back. I'll have an open rig and I don't like smelling the exhaust more than necessary.
     
  17. BadDog

    BadDog SOL Staff Member Super Moderator Author

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    Re: Exhaust Manifold - Passenger side, center drop???

    Cool, trouble free, and $$$$$. /forums/images/icons/laugh.gif The straight down version of the Ram's Horns seem made to order for what I'm thinking of. Also helps keep the pipe clear of the starter...
     
  18. 84_Chevy_K10

    84_Chevy_K10 Banned

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    Re: Exhaust Manifold - Passenger side, center drop???

    That's where mandrel bends come in. A press bent 90 degrees is too tight/restrictive.
     
  19. m j

    m j 1/2 ton status

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    Re: Exhaust Manifold - Passenger side, center drop???

    big bank EH? I never priced them. too bad but if it says vette it usaully is overpriced
     
  20. BorregoK5

    BorregoK5 1/2 ton status

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    Re: Exhaust Manifold - Passenger side, center drop???

    I have mine run straight out the back now and the fumes are worse than ever. Although, I don't have turn downs on them so that may be contributing to the problem. It's easier to tune the carb this way though /forums/images/icons/smile.gif.
     

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