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Discussion Starter · #1 ·
Wondering what guys do to tuck pipes back inside the frame rails when running full length headers that exit outside the frame rails behind the wheel wells?
 

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Discussion Starter · #3 · (Edited)
guna have move to the tranny section.... :)

no for real, what truck? engine? headers? For example, 1st gen, sbc, 1 3/4 headmans..
94 Sonoma ext cab 398 stroker, Brodix C series heads 18*, 2" primary Hedman Hustlers wheel well exit, Looking to see what other people do to get the exhaust pipes back inside the frame rails(cut approx 5" dia hole and weld in thick wall tube) or do people just leave the pipes and mufflers on the outside?
 

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94 Sonoma 398 , 2" primary
so a sbc or possibly a bbc with 2 inch primaries. if it were mine, id have headers built that do what you're asking. Instead of some sort of fender well exit headers, and attempt to modify them to go back under the truck, which no one can really help you with that, because you could be lower or lifted, so without all the info, it's pure guestimates.

I've seen big primary headers split with two tube over the rail, under the rail and then meet up at the collector between he trans and the frame rail under the truck.
 

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Discussion Starter · #5 ·
so a sbc or possibly a bbc with 2 inch primaries. if it were mine, id have headers built that do what you're asking. Instead of some sort of fender well exit headers, and attempt to modify them to go back under the truck, which no one can really help you with that, because you could be lower or lifted, so without all the info, it's pure guestimates.

I've seen big primary headers split with two tube over the rail, under the rail and then meet up at the collector between he trans and the frame rail under the truck.
It's a Dart small M, the Brodix heads are small block with 266 intake runners(BBC Brodix Track 1 are 270 intake runners) with BB valves. I'm leery of the over and under tubes due to the fact this is going to be a daily driver, As these hedders were bought 2 years ago and at over 900.00 i'm way to cheap to toss them in the corner so i'll be using them, i'm really leaning towards cutting out the largest diameter round hole i can and then welding in a tube with 1/2" wall that way i can keep the tube from hitting anywhere and still maintain full frame strength.
 

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2003 GMC Sonoma SLS extended cab 4.3L auto 4x4
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If I understand your idea, you are talking about going through a frame rail with a welded in pipe sleeve, through which the tube can pass. I'm not a licensed structural engineer, but I would be extremely doubtful that cutting a good sized hole through a frame rail (regardless of the wall thickness of the proposed tube 'sleeve') is a viable solution. The load flow (stress) of any load in a horizontal member is directed around an opening (hole), and through whatever material remains above and below the opening. This principal is valid for any material. For example, if a frame rail has a vertical height of 6", and you cut a 4" hole (for say, a 4" tube with a 1/2" wall thickness, leaving a net inside diameter of 3" for the tube) you have only 1" remaining above and below the opening (i.e. 2" total, instead of the original 6", or 1/3 of the unaltered rail) It is the vertical portion of a beam (frame rail) that provides its primary load carrying capacity, and effectively removing a substantial amount of it may result in the concentration of the loads into the remaining material, which could greatly exceed the yield stress of the material; read: failure of the carrying member. And, this doesn't even address the additional difficulty of properly/ safely welding two greatly dissimilar metal thicknesses together. IMHO, a really really bad idea.
 

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Discussion Starter · #7 ·
If I understand your idea, you are talking about going through a frame rail with a welded in pipe sleeve, through which the tube can pass. I'm not a licensed structural engineer, but I would be extremely doubtful that cutting a good sized hole through a frame rail (regardless of the wall thickness of the proposed tube 'sleeve') is a viable solution. The load flow (stress) of any load in a horizontal member is directed around an opening (hole), and through whatever material remains above and below the opening. This principal is valid for any material. For example, if a frame rail has a vertical height of 6", and you cut a 4" hole (for say, a 4" tube with a 1/2" wall thickness, leaving a net inside diameter of 3" for the tube) you have only 1" remaining above and below the opening (i.e. 2" total, instead of the original 6", or 1/3 of the unaltered rail) It is the vertical portion of a beam (frame rail) that provides its primary load carrying capacity, and effectively removing a substantial amount of it may result in the concentration of the loads into the remaining material, which could greatly exceed the yield stress of the material; read: failure of the carrying member. And, this doesn't even address the additional difficulty of properly/ safely welding two greatly dissimilar metal thicknesses together. IMHO, a really really bad idea.
While i appreciate your comment and opinion on the matter i am going to pursue other information avenues and see what i come up for a final answer.....definitely a valid point for consideration.
 

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You are certainly entitled to decide your own course of action(s) and the results thereof. Best wishes on however you decide to proceed.
 

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I don't much about this subject, but it seems that if you can do a frame notch for the rear axel, this should work. I don't mean the huge rectangular tubing, just the half round tubing that gets welded in the frame.
 

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Is there room to go with oval pipe? It tucks nicely.

Sounds like a horsey smallblock, should be a handful on the street, good luck with it!
 

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Discussion Starter · #12 ·
Is there room to go with oval pipe? It tucks nicely.

Sounds like a horsey smallblock, should be a handful on the street, good luck with it!
I will look into the oval pipe, at the end of the day i just never want to hear the exhaust rubbing on anything. It put up 641 hp. @6400 and 560 ft. lbs. at 5700.
 

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This is an addendum to my previous post (#6). Out of curiosity I contacted a structural engineer that I have worked with over the years on numerous projects, regarding the situation you are contemplating. Long story short - a 4" hole in the frame rail (6-7" tall stepped box beam, transitioning to a channel section) is a very bad idea, both on a conceptual level and at a technical level as well. There are multitudes of technical factors as to why NOT to do it, and just because something can be done, doesn't mean that it should be done.. An opening of this magnitude would require a careful and in depth review of the imposed loads (longitudinal, vertical, and torsional - both static & dynamic), along with calculations of the resultant stress/ strain and shear forces at work in the beam. And, for further information, there are multiple websites for companies that perform DOT truck frame modifications that can be referenced, and possibly consulted about this as well. Although most of them deal with larger trucks, the structural principal/ factors/ implications remain the same. This MIGHT be possible, IF a structural engineer could devise a plan to compensate the frame for the introduction of an opening that would be >50% of the depth (height) of the 'web' of the frame rail. Also, the location of the hole (relative to the unsupported length of the frame/ beam) is critical as well. The necessary engineering analysis and cost to properly and safely reconfigure the frame rail would likely be excessively expensive. Bottom line: high potential and probability for creating significantly more problems, headaches, & $ to modify the frame safely rather than routing the exhaust around it. 'Nuf said.
 

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Discussion Starter · #14 ·
Well it looks like i'm going in a different direction, ran across some pics of the way guys are dumping their exhaust thru the lower half of the bedside and i like it, might be a little annoying for some at a stop light but i'm willing to make that sacrifice lol.
 

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Discussion Starter · #16 · (Edited)
Single hole or are you going to re-split 'em and have 4 fender holes?
Haven't really looked into what's available, truck came with all new 2 1/2" pipes ,mufflers and electric cutouts but they'll be set to the side after i watched a test on Master Engine Builders last night where they compared 2 1/2" to 3" in the 600 hp range with the same series Flowmasters and the 2.5" lost over 20 hp. and over 30 ft lbs. torque to the 3". The 3" system lost virtually no power or torque. Tried to convince myself i could live with the 2.5" but i just can't get there. Remind me again how much it cost to pick up 20+ hp. and 30+ ft. lbs of torque. The test they did went right out to the rear bumper, i wonder if the loss is different on a shorter exhaust system?
 

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That's a lot of motor for a street engine. Are you hard mounting the engine? Do you have any intensions of drag racing? I would personally look into different headers to suit your needs. You can sell off what you have and hopefully find something that better fits your game plan.
 

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I haven't found any with 2" primaries that fit inside the frame rails. Custom would be an option but they're high as giraffe nooky.
 

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Discussion Starter · #19 ·
That's a lot of motor for a street engine. Are you hard mounting the engine? Do you have any intensions of drag racing? I would personally look into different headers to suit your needs. You can sell off what you have and hopefully find something that better fits your game plan.
Have new Energy polyurethane ones now but have been thinking of going solid mount, this will be a daily driver in good months weather May- October, as far as header options i think it's these or build my own because of the spread ports.
 

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Discussion Starter · #20 ·
I haven't found any with 2" primaries that fit inside the frame rails. Custom would be an option but they're high as giraffe nooky.
Because of the spread ports i think i'm locked into working with what i've got or building my own, already have the half inch flanges if i go that route.
 
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