Okay....exhaust time...have a wierd idea

[Beezil]

I do not have room to run a 2 or 2.25" exhaust all the way back.

gong through the floor is not going to work.

I am pretty much all in the clear except for two places.

these areas are right around the crossmember area, and are only around 16" between one-another....

here's my idea....

in order to squeak by these areas, the way i see it, since i can't fit a 2.25" tube, why not run 3 1.25" tubes????

I could have a nice splitter, run t he three seperate tubular noodles, and re-connect after the obstruction.

should be groovy

[Rev Den]

Why not run a 1.5x4.5 rectanglular tube?? You could always notch around any obstructions. Who says exhaust tubing has to be round?

Now....if you don't have room for this...then the 3 tube idea is not bad, I would have a very large collector at the end to prevent colliding exhaust pulses from hampering performance.

Rev

[MaXJohnson]

I like Rev Den's idea. That's what the NASCAR boys do to get under the frame rail with minimal clearance.

Make sure to chrome it to match up with all that bling bling under there.

[Beezil]

should I account for more volume if I go rectangular tube?
or something close to 3.5" (apprx inside radius *pi )

its not like I'm worried about shaving miliseconds off of my 1/4 mile time....

a touch more backpressure would actually be helpful.

[lesslimited]

I'm no rocket scientist, but my hunch is that a rectangular tube would create more turbulance than round ones? Maybe one of our pipefitter members would know about this? Or maybe this could eliminate your need for a muffler?

[MrShoeBoy]

So why dont you run it through the roll cage?:D


If you cant use round exhaust tubing, what about oval tubing? I remember from somewhere that nascar used ovel shaped tubing because of clearance issues. Have you though about side exit?

AARON

[xj4rocks]

straight pipes through the hood --- :)

i would think that rectangle or oval would work. we're not talking a million HP or anything.

could you get it to exit right in front of the rear tires? and avoid going the whole way back?

[Flowers]

BJ,

It's been over a week since I've been under your machine. But, if I remember correctly, you could run it in the stock location (snaked under the bellhousing, then above the crossmember on the passenger side) all the way to the area where the rear shocks will come through the floor. Cut away more sheet metal (to make Sean happy) and come up through the floor in the "bed" on the passenger side. Realizing you now have the rear links in place, this may not work. Is there room to go above the crossmember?

Flowers

[Rev Den]

Just thinking here....if you used rect. tubing you could weld in baffles the whole way.....kinda combining the pipe and muffler in one. I have no idea what the formula is to figure flow capacity, but I would think that you could figure that out. If it were me...I would just eyeball it and shoot from the hip, hell....its only exhaust.

Rev

[Fergie]

Originally posted by Beezil
should I account for more volume if I go rectangular tube?
or something close to 3.5" (apprx inside radius *pi )

its not like I'm worried about shaving miliseconds off of my 1/4 mile time....

a touch more backpressure would actually be helpful.

Not sure if you want more volume, as I would think you want the cross sectional area to be the same, or slightly larger.

Also, if there is room, run a small H-pipe between the three to even out the gases.

So those are my thoughts, let us know how it goes.

Fergie

[rixXJphx]

Just some thoughts:

1. Surface area of walls = friction = less effective flow.

2. Flat sections of light gage metal = reflection of sound waves = drumming & other (generally) undesirable sounds.

3. More small round sections = much more wall surface = much more friction.

Round = Greatest volume / surface area of walls.

Oval = Best balance of volume-to-surface-to-restricted depth.

Rectangular = Best volume-to-restricted depth; if weight isn't a major factor, heavier walls (3/16 +) will prevent the drumming of light gage.
Sound waves will still be reflected and *possibly* reinforce each other into undesirable tones.
Line the sides with adhered/pinned dense fiberglass board insulation, and call this heavy son-of-a-gun your muffler.

Photos expected, of course. :D

-Rick

[Dirk Funk]

Beezil,
If I remember right, earlier you said you didn't want some super loud exhaust, but more of a quiet one. Well, the way air, exhaust, or anything else performs accoustically in a port or pipe has absolutely nothing to do with volume, but rather cross sectional area and length.

It IS effected by friction from the walls of the exhaust tube; this is what defines what it sounds like. So if you went rectangular, make the cross sectional area about the same, and the length about the same to get the same sound characteristics.

I have no idea how this relates to performance, but rectangular tube should not be more restrictive than round. They both flow the same "numbers."

[Beezil]

dirk, do you know of any exhaust designs that use cellular lupis?

[Dirk Funk]

That technology has not been made available from Tandy as of yet. You can try giving Underboky and Associates a call for more information. Oh, and by the way, the work you are doing on that assault vehicle that looks like a Cherokee is bitchin.

[andyr354]

Run it out the drivers fender like a snorkel and put a stack out there :)

I don't see anything wrong with using rectangular tube.

[Beezil]

I think I've seen all these funny replies on the last thread??????

[Georgia Mike]

Just an FYI: The NASCAR guys run round exhaust to the frame rail,then get converted into an oval for clearance, then converts to rectangle at the outlet. The rectangle sections have these "splitter" sections,kind of like baffles,only they face the direction of the exhaust flow. I'm not sure,but I'd have to bet they are there for flow characteristics and avoiding exhaust pulse cancellations more than anything. Maybe you could do like the above suggested. Build a heavy guage rectangle box with an inlet and outlet,and experiment with different baffle designs until you come up with a combination you like. You could feasably build the "enclosure" and make the bottom panel temporarily removable. That way you could tune it to your liking,then weld the panel in solid when you're happy with the sound. Just a redneck's thought process :anon: so don't laugh at me too hard :D

[BLUTO]

Airflow through a pipe or duct (whether round, oval, or square) is "laminar"....it stays close to the walls. It is nice to use a transition piece when going from round to square; it helps to redirect the airflow and alleviate "eddy currents" or tumbling and distortion in the airflow. Square pipe is fine, you have round AND square ductwork in your home, don't you?
The key is to keep a certain feet/minute velocity in your flow, this is how you attain your effficiency and helps to alleviate resonance.
I can't tell you what that # is, too many variables.

BLUTO :)

[Gojeep]

Beezil, you opened the post saying you were thinking of running three 1.25 pipes instead of one 2.25. I take it you have enough clearance for the 1.25 then? Well the area of a single 2.25 pipe is 7.07" where only two 1.25 pipes would already exceed that at 7.85" which is indentical to one 2.5" pipe! It would seem alot simpler to me going that route. Even two 1" pipes would give you 6.28" the same as a single 2" pipe which would help the torque at low revs but will have slightly more friction than a single pipe of twice the diameter so maybe a couple of 1.1/8" ( 7.07" ) if you need that little bit of extra clearance and still compensate for any extra friction.

[Beezil]

you have round AND square ductwork in your home, don't you?

nope!

I don't have ANY ductwork!

[skog]

Gojeep you are wrong.
the area for 2x1.25 is 2.45 in^2
the area for 3x1.25 is 3.68 in^2
the area for 1x2.25 is 3.97 in^2
the area for 2x1.00 is 1.57 in^2
you found the circumfrances. you used pi*D
the correct formula for area is pi*r^2

so 3@1.25 is still lower in volume then 1@2.25 and has 166% of surface area of the 2.25. that is going to result in alot more friction.

i personally like the stack like a snorkel idea then run it along the roofline with a muffler in there

skog

[4ward]

Our Corvette runs square tubing for most of the system. Must not be that bad. It's the same size as the round on either end.

[XJTripp]

Skog is right. If you assume all other things being equal except pipe size, Mannings equations for flow resolves down to this:

Q = K X (Diameter)^2.67.

That is, flow varies with the diameter to the 2.67 power. Small changes in diameter equal large change in cross sectional area. If you double pipe size, you increase flow area by 400% but you increase the friction causing perimeter by only 100%. It would really take almost 5 of the 1.25-inch diameter tubes to equal a 2.25-inch. Would you feel the difference over a short length of pipe. I doubt it.

The thermo properties of exhaust would mitigate this some. The above derivation is for water which is incompressible. With exhaust, extra cooling of the multiple pipes increases density and would help some. How much I don't know.

[Ed A. Stevens]

You have to love the math ...


Go with round of the size desired for collected flow extraction to the cat (120 ft/sec) and muffler, and then run oval or rectangle to the rear.

Rectangle duct airflow is impacted by the aspect ratio of the rectangle, square being best. Flatter duct, width to height, ratios are more flow restricted. A flatter aspect ratio rectangle must have a higher cross section area to flow the same as a round or square duct.

Fittings in rectangle duct are extremely restrictive, compared to large radius round duct/tube. The killer with rectangle exhaust is fittings and noise (the resulting sound can be ugly).

Run the pipe up the A-pillar ;) and down the side of the roof rack.

[JJ13]

Geez I wish someone in the other exhaust thread would have suggested to build some rectangular rock rails that would also serve as mufflers........oh wait they did... Drill a hole in the framerail ( I KNOW), sleeve it with pipe and then run your exhaust tube through that to a rectangular rock rail converted to a muffler

[Gojeep]

Yep my bad guys:( Should have remember the old 2pieR rule! I must be getting too old for this:rolleyes: Too long out of the work force it seems:eek:

[Gojeep]

See there I go again:mad: I still used the circumference rule.:rolleyes: Sorry skog I should have read your post more carefully. I am really having a bad night. You guys wont believe anything I say again that involves formula's anyway;)

[Flowers]

Originally posted by JJ13
Geez I wish someone in the other exhaust thread would have suggested to build some rectangular rock rails that would also serve as mufflers........oh wait they did... Drill a hole in the framerail ( I KNOW), sleeve it with pipe and then run your exhaust tube through that to a rectangular rock rail converted to a muffler

It won't work. You guys throwing out ideas need to crawl under your XJ on a creeper and just lay on your back and look. Although Beezil's exhaust routing problem is a bit different since everything (suspension, crossmemebr, etc,) is now changed.


Flowers

[Rev Den]

Originally posted by Flowers
It won't work. You guys throwing out ideas need to crawl under your XJ on a creeper and just lay on your back and look. Although Beezil's exhaust routing problem is a bit different since everything (suspension, crossmemebr, etc,) is now changed.


Flowers

Judging by what I have seen in the photos....the only truley workable idea is to run it thru the hood, I do not envy Beezil in his quest. However, brainstorming frequently generates silly, unworkable, far-fetched, half-thought, and totally bizarre ideas. One of these ideas can generate a workable soulution, or a path toward one.

If I where Beezil, I would do one of two things:

1. Run flex pipe the whole way.
2. Take it to an exhaust shop and tell them to call me when its done.

I cannot even imagine trying to run a pipe of any size or dimension thru that jungle he has created, but, I know that he will again amaze us all.

Rev

[Beezil]

there's only one area that's troublesome, and i think i will just cut more floorboard out and "hop over" the obstruction.

flowers is my passenger in moab, so he'll have to deal with the hot asspipe, not me.

[KY Chris]

Originally posted by Beezil
there's only one area that's troublesome, and i think i will just cut more floorboard out and "hop over" the obstruction.

flowers is my passenger in moab, so he'll have to deal with the hot asspipe, not me.

I doubt that the hot asspipe will bother him too much.

[Flowers]

I have never dealt with hot asspipes, but I'm sure it will be fabulous. Can you use water soluble products in it?



Flowers

[Georgia Mike]

Speaking of that! Did anyone catch the "Biker Buildoff" on the Discovery Channel a few weeks ago? Billy Lane routed the exhaust system on one of his bikes under the seat and made the rear fender a chromed fender/drag pipe combo. It looked trick as hell,but while riding it,it actually set his pants on fire! :laugh: Gotta love choppers!!!!

[macgyvr]

whatever you do, make sure ya mama welds a coffee can for a tip on the end of the pipe whether its round/oval/square.....


mac 'low rider' gyvr

[Fullsizexj]

Hey Beezil, here is the answere to all your exhaust problems :) http://tellico.off-road.com/wwwthreads_uploads/1193101-getimage.jpg

[sarvermr]

Originally posted by Dirk Funk

Well, the way air, exhaust, or anything else performs accoustically in a port or pipe has absolutely nothing to do with volume, but rather cross sectional area and length.


that has to be the quote of the day... "not volume but cross sectional area and length."
volume = area x length.
same thing! i'm just messing with you. please don't take it personally. i just thought it was funny when i saw it. wish i had something constructive to add to the debate, but i don't. its pretty much all been said.
matthew

[Beezil]

hey flowers.

the exhaust is done!

the exhaust comes up through the floorboards right near where your browneye will be (when yer seated).....

I put exhaust wrap on da pipe, but if worse comes to worse, and the seat begins to melt, I'm gonna need to remove the seat, so you'll have to thumb wrestle mrs. rose for the passenger seat to the fug-mobile.