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  #1  
Old 09-23-2015, 10:26 PM
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CarterKraft CarterKraft is offline
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Through the body exhaust ????S

So I have designed something I don't know how to do. Pretty standard for me actually.

This Bronco project I have been working on has to have the exhaust ran out the side as with no rear tailgate the exhaust is pulled into the cab driving down the road. I was anticipating this but after looking at the exhaust and the real estate available for the steps and exhaust there was going to be a problem.

I found the exhaust could exit the body between the wheel well and the front door. This add's to the over the top attitude of the truck and after getting the turn outs completed sounds awesome I must say with 40 series flowmasters. (what can I say I am a kid of the 90's).

So as it is I have a 2.5" pipe centered in a 3" hole in the body. I am to have stainless "bezels" laser cut to frame the pipe. I actually had no idea of how to interface the two tubes when I made this decision but I think I have it nailed down now and why I am asking this question.

If I was to weld a 3" 304SS pipe to the bezel and leave 1.5" inside the body and a small 3/8" eyebrow outside of the bezel then bolt that to the body.
I was thinking I could then cut the 2.5" pipe to come almost flush to the 3" tube then use a 2.5" to 3" silicone reducer hose to connect the two. This will isolate any metal to metal contact and heat from the body.
The silicone hose I have seen is rated for 500* and I don't think there is any way the exhaust pipe at that point will get that hot.

I think my original plan was to use a piece of high heat rubber with a 2.5" hole cut in it to create a grommet through the body hole.
This system with the reducer seems so much better but the heat on the hose to concern me.

Any arm chair quarterbacks have a better idea?
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  #2  
Old 09-24-2015, 12:58 AM
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Overall I have to say I never would have thought about using the Silicone coupler, I think it is brilliant!
The one thing I can see is that you are in essence bolting the exhaust to the body and I'm thinking that you are going to (possibly) need more motion then you may get with the coupler and Vibration could be an issue.... maybe one of those ball couplers?
I do not think that you need a seal at the point of the coupler and if you simply over lap that joint by a few inches you could get the exhaust out without the coupler... maybe, or I could be completely wrong!

I have no worries about the temperature issue at all.

I do like the idea!!

E
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Old 09-24-2015, 08:52 AM
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You are probably right about not needing a coupler. My concern was keeping the inner tube from contacting the outer tube creating a rattle, vs a vibration with the coupled pipes.
I will probably build the tips the same way and try it with no coupler hose. I just remembered another issue was getting the run to the flnge on the same axis as the tip. That may take another bend mitered on to get the transition on plane.
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Old 09-24-2015, 10:48 PM
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I agree with E, brilliant idea with the coupler. I'd be worried about the heat . Maybe you could put some vents in the 2.5" pipe right before the coupler, create a venturi affect to pull air in to cool the exhaust. (Idea stolen from Ford Motor Co., 08' f-250 diesel)
If you cut the 2.5 back some, the coupler could flex more.
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Old 09-24-2015, 11:28 PM
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Good point on the vents, I had similar thoughts but I am still not sure the heat is an issue.
I will take my temp gun and cruise up the interstate to see what kind of temps are actually there.

When I originally thought about the coupler I thought I would cut the 2.5" all the way back to the edge of the hose, just leaving enough to get a clamp on. I then changed my mind and thought I would run it out almost flush to the tip edge so the exhaust gas would not actually come in contact with the silicone hose. I think I will start leaving it long and then adjsut it back from there.

The hoses are about $6 ea. so as long as they don't catch on fire and burn the truck to the ground it won't matter much.
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Old 09-25-2015, 03:33 PM
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Quote:
Originally Posted by CarterKraft View Post
I will take my temp gun and cruise up the interstate to see what kind of temps are actually there.
You'll want to measure the EGT at that point, not just the surface of the tube. once you insulate the tube with the silcon coupler, the tube under it will get closer to the EGT since it is insulated by the coupler. I suspect heat conduction through the tube will still cool it significantly, but I wouldn't want to run it if the EGT is more than the silicon temp.
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Old 09-25-2015, 05:19 PM
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I will do my best at getting some measurements.

I think as long as the inner tube is slid into the outer tube enough the silicone won't get much over the tube temp. Of course without knowing these temps this all conjecture.

I guess I am feathering this also from the intended use of the truck.
It is a cruiser only, no off road or high output duty.

Last edited by CarterKraft; 09-25-2015 at 05:26 PM.
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Old 09-25-2015, 08:23 PM
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I've done a couple of side exit exhausts ,actually pretty common over here and I really don't understand why you want to couple up to your body bezel at all,if your system is fixed to engine and inclined to move a lot then you should probably look at isolating it,in my opinion fixing it to your body will result in resonance and vibration through your body,IF it can't be altered then maby it would be better to run your exhaust slightly proud of the body(looks better IMO) and fit your silicone over your exhaust but inside your bezel sleeve without attaching
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Old 09-26-2015, 10:23 AM
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I didn't initially want to couple the exhaust to the bezel but I couldn't decide on a method to locate the pipe reliably in the bezel.

I have ordered the silicone hose and clamps and if I don't need them so be it.

I might just try putting a hanger out there off the body and see if it will stay in position.
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Old 09-26-2015, 01:17 PM
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JaysinSpaceman JaysinSpaceman is offline
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I have done 2 exhausts through the body like this. I will tell you right now you do not want to attach it directly to the body, I think the silicone coupler might even be too much attachment, the noise will resonate through the body. The way that I ended up doing both was to isolate the tail pipe/exhaust tip from the rest of the exhaust with a flex coupling like this...



...and then using several rubber isolator hangers to steady the tip in the hole. That was the only way I could get the noise down to an acceptable level for my customer.

You will have a lot of exhaust movement on a side exit, more then straight out the back, so you will need a considerable amount of flexibility in the exhaust especially on a very short system like you are going to end up with on a Bronco. I have seen several exhaust systems that broke hangers and tubes when the tail pipe/exhaust tip is held rigid and the engine is free to move on the mounts.

If the truck isn't going to be driven much (show car style) then there are a lot of easy ways to do it but if durability is a concern then I would put a lot of thought into how to isolate the tail pipe from the rest of the exhaust.

Jaysin
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Old 09-27-2015, 03:40 PM
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Looking at it today I did allot better job of centering the pipe than I thought. This means I might be just fine with a short tube welded to the bezel and a outboard hanger on the tip.

Thanks to all for the suggestions. I need to get the bezels and the tubes welded up and I can make a decision on how much support is needed and where.
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Last edited by CarterKraft; 09-27-2015 at 03:44 PM.
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Old 09-27-2015, 10:12 PM
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So preliminary temp testing looks like a peak of 200*F and more like 114*F normal temp.

The movement is the major issue to have it slip fit in another pipe.
https://youtu.be/AfY6nnNikck
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  #13  
Old 10-05-2015, 02:33 PM
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Here's how I have it for now. I am not sure if I like the sound though the air sucking through the inner and outer does change the sound.
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Last edited by CarterKraft; 10-05-2015 at 03:58 PM. Reason: added pix
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