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Old 07-05-2015, 05:28 PM   #1
Skoolie
 
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Join Date: Feb 2015
Location: South Dakota
Posts: 196
Year: 2002
Coachwork: Thomas
Chassis: Freightliner HDX
Engine: CAT 3126B250
Rated Cap: 84
Custom exhaust for rear engine buses

2002 Thomas HDX, 84 passenger
Rear engine, Cat 3126B

So, to compliment the design I want, I am trying to figure out a way to create an impressive-looking intake and exhaust system.



INTAKE:
The intake comes through the vents in the side and into the air cleaner. I could just cut those louvers out and put something a little more noticeable, or even just a heavy screen with a riveted/bolted metal border to give it a more industrial look. My concerns are:
- if the intake points towards the rear, like using a rear-facing hood scoop, will that create a suction effect, reducing air available to the motor?
- if the intake points towards the front, like using a forward-facing hood scoop, will I risk sucking in too much water since the rear tires are very close?
- if the intake becomes a flat screened panel with a border that is 1/4" further out than the screen, will a sucking effect be produced, sufficient to reduce avalable air to the engine?

EXHAUST:
Right now the exhaust comes from the driver's side of the engine, wraps around the entire motor, turning to exit on the passenger side in the manner show in the photo, projecting the exhaust towards the ground. Of course, I fantasize about huge dual crome stacks like those on the big rigs, but I really don't think that is possible, since I would have to cut through the body to make room for the pipe, not to mention sealing them properly, and not torching the bedroom as I go down the road. Running vertical exhaust on the outside of the bus, whether at the rear or sides, would violate the DOT width or length restrictions for this vehicle as far as I understand. So what can I do? I was thinking that perhaps I could have it just dump out the side through the bottom grate and make some sort of decorative element there, but I would be shortening the length of the exhaust pipe. Is a shorter exhaust a bad idea for diesels?

Thanks in advance for any help and inspiration you provide.
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Old 07-05-2015, 06:57 PM   #2
Bus Crazy
 
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Quote:
Originally Posted by RHOMBUS View Post
2002 Thomas HDX, 84 passenger
Rear engine, Cat 3126B

So, to compliment the design I want, I am trying to figure out a way to create an impressive-looking intake and exhaust system.


INTAKE:
The intake comes through the vents in the side and into the air cleaner. I could just cut those louvers out and put something a little more noticeable, or even just a heavy screen with a riveted/bolted metal border to give it a more industrial look. My concerns are:
- if the intake points towards the rear, like using a rear-facing hood scoop, will that create a suction effect, reducing air available to the motor?
- if the intake points towards the front, like using a forward-facing hood scoop, will I risk sucking in too much water since the rear tires are very close?
- if the intake becomes a flat screened panel with a border that is 1/4" further out than the screen, will a sucking effect be produced, sufficient to reduce avalable air to the engine?
I would think the designers figured out that is the best design, so I'd leave it. Everything you mentioned is a possibility.


Quote:
EXHAUST:
Right now the exhaust comes from the driver's side of the engine, wraps around the entire motor, turning to exit on the passenger side in the manner show in the photo, projecting the exhaust towards the ground. Of course, I fantasize about huge dual crome stacks like those on the big rigs, but I really don't think that is possible, since I would have to cut through the body to make room for the pipe, not to mention sealing them properly, and not torching the bedroom as I go down the road. Running vertical exhaust on the outside of the bus, whether at the rear or sides, would violate the DOT width or length restrictions for this vehicle as far as I understand. So what can I do? I was thinking that perhaps I could have it just dump out the side through the bottom grate and make some sort of decorative element there, but I would be shortening the length of the exhaust pipe. Is a shorter exhaust a bad idea for diesels?

Thanks in advance for any help and inspiration you provide.
Length wont be an issue. You could do this:

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Old 07-05-2015, 09:00 PM   #3
Bus Nut
 
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Join Date: Jan 2015
Location: Gonvick MN
Posts: 255
Year: 1975
Chassis: Gillig
Engine: Cat 3208t/10 speed transmission
I did pretty much what you have shown in your picture with a five inch Magnaflow muffler.
Works quite well. Very free flowing, sounds good to. Shorter exhaust system won't hurt you.
You are most likely stuck with your air intake location. Problem is it is the dirtiest spot on your bus.
Take a spin on a wet gravel road and see.
Be creative. Chrome is always good.
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Old 07-05-2015, 09:12 PM   #4
Bus Crazy
 
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Location: Vacaville, Ca
Posts: 1,521
Year: 1988
Coachwork: Crown / Pusher
Engine: 8.3 Cummins
This is what I did, 4in exhaust inside of 5in pipe that goes out top of roof, air scoop puts cooling air between exhuast pipe & outer pipe, if it doesn't work I'lll always think it shoulda. right side is intake

Oh & doing so removed about 8 ft of pipe and a muffler that was a good 4ft long now I come straight off the turbo & up the stack
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