No more Muffler

skywarn · **Posted:** Tue May 01, 2007 5:57 pm

hyedipin wrote:

But I am running gas, not CRD. I always thought my KJ rolled pretty free when coasting without need of extra acceleration. Of course I wouldn't mind getting extra few hundred feet coasting. :lol:

for gas go with Flowmaster 40 cant beat em

o8k · **Posted:** Tue May 01, 2007 11:45 pm

would there be problems from the state inspection for not having a muffler on the vehicle?
my hack saw is poised and ready to remove this Giant POS slowing my jeep down and would love to squeek out a few more mpg if it can be done...

On another note:

if back pressure from muffler was really causing the vehicle to slow down when let off the throttle, then if i put vehicle in neutral, muffler or no muffler i should be able to measure a difference in slow down and the engine is no longer connected to the dirive-train right? By this deduction, i measured my slowdown from 50 to 30 on a flat road to be 20sec, w/ in drive and in neutral, absolutly no difference! I would like to believe whacking my muffler off would help, but i cant think this to be the case due to said logic above. Am i missing somthing here?

durangotang · **Posted:** Wed May 02, 2007 1:40 am

You are certainly correct in your logic. The tinkg that you can't take into account with that test is the time that it takes for the turbo to slow down with the decrease in backpressure. The load on the engine is not going to have any effect on this aspect. With less backpressure the turbo has less pressure to overcome in order to slow down... the sustained pressure there is still feeding air into the engine. Make sense? It's late and my logic is rather fuzzy

skywarn · **Posted:** Wed May 02, 2007 10:02 am

o8k wrote:

would there be problems from the state inspection for not having a muffler on the vehicle?
my hack saw is poised and ready to remove this Giant POS slowing my jeep down and would love to squeek out a few more mpg if it can be done...

On another note:

if back pressure from muffler was really causing the vehicle to slow down when let off the throttle, then if i put vehicle in neutral, muffler or no muffler i should be able to measure a difference in slow down and the engine is no longer connected to the dirive-train right? By this deduction, i measured my slowdown from 50 to 30 on a flat road to be 20sec, w/ in drive and in neutral, absolutly no difference! I would like to believe whacking my muffler off would help, but i cant think this to be the case due to said logic above. Am i missing somthing here?

the best answer i can give you is to go buy the place you would get your jeep inspc. at and just ask them. Advise them that a turbo, can and does act like a muffler... :lol:

and if they still say no then just go with a Glasspack or Cherrybomb, both are less than $25 at your local mega mart parts store.

As for the response to your thinking... what the last post said.. less backpress on the "exit" side of the turbo, the faster it can spool down, thus the less "engine braking" we have.

o8k · **Posted:** Wed May 02, 2007 7:19 pm

where i agree less back pressure, lest engine break makes sense. So i assume as you all do the following relationship:

Time@50-30mph deceleration
====================================
(w/ muffler in drive) = Time A (engine load full)
(w/o muffler in drive) = Time B (engine load reduced)
(w/ muffler in neutral) = Time C (engine load illiminated completely)
Assumption: (Time A > Time B > Time C)
====================================
HOWEVER! when i actualy measure this is what i get:
====================================
Time@50-30mph deceleration
(w/ muffler in drive) = Time A = 20sec (+/-)1sec
(w/o muffler in drive) = Time B = ?? could not test
(w/ muffler in neutral) = Time C = 20sec (+/-)1sec
Thus:
Time A == Time C == 20sec (+/-)1sec or 5% ish
=====================================
Conclusion: whacking muffler off has little effect on decelleration of vehicle from 50-30mph or at the most is about 5% better than w/ muffler.
Final however, test case for Test B not acutaly measured, assumption on ( TimeA > TimeB > TimeC ) may be incorrect.

I will probably remove the darn thing anyways b/c for some reason it annoys me now =) its huge and not even doing anything usefull.... could only help things, spools up turbo faster, better mpg ect ect bla bla.... but still the above logic doesnt match and its kinda sitting funky in my head

DocB · **Posted:** Wed May 02, 2007 8:38 pm

Anybody hit a bump yet and the Cat fell off?

Hero · **Joined:** Sun Apr 16, 2006 5:32 pm **Posts:** 122

Durango, if I were smart I would have done what you have done... instead I took off everything cat-back and ran a side pipe. I chopped up the old pipe and threw most of it away, me soo stupid!

CATCRD · **Posted:** Fri May 04, 2007 12:38 am

CRDburnouts wrote:

Aero Turbine is the only way to go, it actually creates a vaccum out of the exhaust! $300 is significantly more though...

This is a marketing gimmick. No passive device can create a suction out your tailpipe - there would have to be a net input of energy, which there is not. The aeroturbine is just a hunk of metal.

It may sound great - I wouldn't know, but that's all your $300 would be going towards.

DarbyWalters · **Posted:** Fri May 04, 2007 9:18 am

Well that is not quite true. Expansion chambers can aid in evacuation of gases...the active input is the heat, pressure and property of gases that already exists. I don't think "suction" is the correct label for this effect but the rate of "evacuation" can increase with the correct setup. Someone needs to get a "turbo blanket" and then Ceramic Coat the downpipe...

skywarn · **Posted:** Fri May 04, 2007 9:25 am

CATCRD wrote:

CRDburnouts wrote:

Aero Turbine is the only way to go, it actually creates a vaccum out of the exhaust! $300 is significantly more though...

This is a marketing gimmick. No passive device can create a suction out your tailpipe - there would have to be a net input of energy, which there is not. The aeroturbine is just a hunk of metal.

It may sound great - I wouldn't know, but that's all your $300 would be going towards.

you bring up a good point, you would need a side hose or a fan to "create" anything... is the Aero Turbine a straight through design?

I'll stick with my $150 magnaflow and i'm using the other $150 i saved to get the provent

skywarn · **Posted:** Fri May 04, 2007 9:35 am

DarbyWalters wrote:

Well that is not quite true. Expansion chambers can aid in evacuation of gases...the active input is the heat, pressure and property of gases that already exists. I don't think "suction" is the correct label for this effect but the rate of "evacuation" can increase with the correct setup. Someone needs to get a "turbo blanket" and then Ceramic Coat the downpipe...

That makes sense... however, have any kind of chambers, would defeat the purpose of having an aftermarket muffler anyway... that's why any Flowmaster just makes it sound good... but doesn't help in getting the gasses out fast enough.. Diesels need and want a straight pipe with nothing to slow it down. And because the Flowmasters are chambered they also increase the undercarriage temp as the hot gasses slow down and heat the muffler up. So for the same reason if the Aero is doing the same thing... But even if it really worked it couldn't "suck" any more gas out faster than they are being pushed out.

DarbyWalters · **Posted:** Fri May 04, 2007 10:17 am

I think you are confusing what an "expansion chamber" is verses a "baffled chamber". An expansion chamber does not redirect the flow of exhaust gases by turning or deflection. Instead, it opens up into a larger space. I know that on two strokes and Rotaries it helps with evacuation of exhaust gases but it also there to reintroduce intake air/fuel that gets puched out during the overlap of intake/exhaust stoke of a two stroke. What I mean is that the chamber actually sends a "shock wave" back toward the cylinder and pushes the raw fuel/air back into the cylinder to burn. 2 stroke and Rotary exhaust gases are easily "slowed down". The Aero and Borla (which I am very familiar with) open up to a larger chamber. The Borla has straight tubes in this chamber but they do not change the direction the gases travel.

Baffled Chambers like in a FlowMaster work better IMHO on larger displacement engines that want some back pressure for other reasons.

It would be very easy to make an expansion chamber for the CRD. Basically you could taper in a section of 4"-5" pipe maybe 18" long and then finish with a 2.5"-3" exit pipe. Would be very cheap to do :idea:

The only problem with this approach on a 4 stroke engine is that it might not do much. With a 2 stroke or rotary, the exhaust and intake stroke overlap. That is why the expansion chamber works so well on a 2 stroke. Now on a Diesel, it would be an intersting experiment

Now, since the "expansion chamber" in our case would be far down the line, it would not be pushing back...just opening up.

Sorry, I am at work and I am sure that this explaination is "All Over the Place" :oops:

Jeger · **Posted:** Fri May 04, 2007 10:40 am

We have all kinds of scrap stainless tubing laying around here at work, and sizers, and welders, heck I even use ceramic insulation here in the foundry.....I think I might have to make myself a mufflers or an expansion chamber. Any other thoughts on what might be ideal?

DarbyWalters · **Posted:** Fri May 04, 2007 10:46 am

If you are going to give it a try here is my take:

Put the "chamber" near the front, probably just after the joint where the CAT and Muffler tie in. Make the chamber 18"-22" depending on diameter of the pipe.If you can make the Expansion Chamber with some type of Cone shape at each end for smooth flow, it would look and work better. The use the stock exhaust from that point on to keep it simple.

Take a look at the shapes of the AeroTurbine:

http://www.blackclouddiesel.com/Aerotur ... fflers.htm

skywarn · **Posted:** Fri May 04, 2007 10:55 am

DarbyWalters wrote:

I think you are confusing what an "expansion chamber" is verses a "baffled chamber". An expansion chamber does not redirect the flow of exhaust gases by turning or deflection. Instead, it opens up into a larger space. I know that on two strokes and Rotaries it helps with evacuation of exhaust gases but it also there to reintroduce intake air/fuel that gets puched out during the overlap of intake/exhaust stoke of a two stroke. What I mean is that the chamber actually sends a "shock wave" back toward the cylinder and pushes the raw fuel/air back into the cylinder to burn. 2 stroke and Rotary exhaust gases are easily "slowed down". The Aero and Borla (which I am very familiar with) open up to a larger chamber. The Borla has straight tubes in this chamber but they do not change the direction the gases travel.

Baffled Chambers like in a FlowMaster work better IMHO on larger displacement engines that want some back pressure for other reasons.

It would be very easy to make an expansion chamber for the CRD. Basically you could taper in a section of 4"-5" pipe maybe 18" long and then finish with a 2.5"-3" exit pipe. Would be very cheap to do :idea:

The only problem with this approach on a 4 stroke engine is that it might not do much. With a 2 stroke or rotary, the exhaust and intake stroke overlap. That is why the expansion chamber works so well on a 2 stroke. Now on a Diesel, it would be an intersting experiment

Now, since the "expansion chamber" in our case would be far down the line, it would not be pushing back...just opening up.

Sorry, I am at work and I am sure that this explaination is "All Over the Place" :oops:

your right! I got the two mixed up... this is how bikes get some sounds by running 2 into 1 pipes... and it is a better flow

o8k · **Posted:** Sun May 06, 2007 5:19 pm

Chopped it off yesterday (muffler). I totaly cant believe how well it coasts arround, its night and day, its like being in neutral. Not sure why my calculations came out contrary to this but for what its worth, it works great not having muffler, havent quantified MPG change yet.

As far as the sound is going, it has a low end drone when the turbo is kicking in at about 2k rpm. Reminds me too much of those Japanese vehicle gassers from fast and furious, so i put on a magnaflow muffler on it P/N 11225. And the drone is virualy gone. Many happy days to come w/ out my stock muffler slowing me down everywhere i go.

CRDburnouts · **Posted:** Mon May 07, 2007 12:01 am

skywarn wrote:

CATCRD wrote:

CRDburnouts wrote:

Aero Turbine is the only way to go, it actually creates a vaccum out of the exhaust! $300 is significantly more though...

This is a marketing gimmick. No passive device can create a suction out your tailpipe - there would have to be a net input of energy, which there is not. The aeroturbine is just a hunk of metal.

It may sound great - I wouldn't know, but that's all your $300 would be going towards.

you bring up a good point, you would need a side hose or a fan to "create" anything... is the Aero Turbine a straight through design?

I'll stick with my $150 magnaflow and i'm using the other $150 i saved to get the provent

It has an airfoil which creates a vortex moving slower around the outer part and much faster through the center. It is no joke, I can hear the hissing sound of the exhuast rushing out of my tail pipe, never heard that before the aero turbine. Don't knock it till you try it :wink:

CATCRD · **Posted:** Mon May 07, 2007 12:08 am

DarbyWalters wrote:

I think you are confusing what an "expansion chamber" is verses a "baffled chamber". An expansion chamber does not redirect the flow of exhaust gases by turning or deflection. Instead, it opens up into a larger space. I know that on two strokes and Rotaries it helps with evacuation of exhaust gases but it also there to reintroduce intake air/fuel that gets puched out during the overlap of intake/exhaust stoke of a two stroke. What I mean is that the chamber actually sends a "shock wave" back toward the cylinder and pushes the raw fuel/air back into the cylinder to burn. 2 stroke and Rotary exhaust gases are easily "slowed down". The Aero and Borla (which I am very familiar with) open up to a larger chamber. The Borla has straight tubes in this chamber but they do not change the direction the gases travel.

Expansion chambers work great on 2 strokes, no doubt about that. The reverse pressure waves make it back to the exhaust port and actually draw spent gases out of the cylinder, letting more fresh air in for the next stroke. It's a tricky science though, involving a lot of variables like tube length, diameter, desired rpm, etc.

But really it wouldn't do anything for our engines, because the pressure waves wouldn't be able to make it back through the cat and turbo.

CATCRD · **Posted:** Mon May 07, 2007 12:18 am

CRDburnouts wrote:

It has an airfoil which creates a vortex moving slower around the outer part and much faster through the center. It is no joke, I can hear the hissing sound of the exhuast rushing out of my tail pipe, never heard that before the aero turbine. Don't knock it till you try it :wink:

Sure it has an effect on sound. That's all you described though.

The claims about creating a vacuum or whatever that increases exhaust flow are not possible.

Let me put it this way - any passive structure you put in the path of a flowing gas can only be an impedance. I've seen the diagram of what's inside an aero turbine. There is no turbine. There's a cool looking structure that probably changes the way your exhaust sounds, but that's it.

The lowest restriction exhaust is a short, straight, large diameter pipe with a smooth interior. Since not all of us can deal with the sound levels though, devices are invented that make it seem like a good idea to drop 2 or 3 hundred dollars on.

Sir Sam · **Posted:** Mon May 07, 2007 12:26 am

CATCRD wrote:

CRDburnouts wrote:

It has an airfoil which creates a vortex moving slower around the outer part and much faster through the center. It is no joke, I can hear the hissing sound of the exhuast rushing out of my tail pipe, never heard that before the aero turbine. Don't knock it till you try it :wink:

Sure it has an effect on sound. That's all you described though.

The claims about creating a vacuum or whatever that increases exhaust flow are not possible.

Let me put it this way - any passive structure you put in the path of a flowing gas can only be an impedance. I've seen the diagram of what's inside an aero turbine. There is no turbine. There's a cool looking structure that probably changes the way your exhaust sounds, but that's it.

The lowest restriction exhaust is a short, straight, large diameter pipe with a smooth interior. Since not all of us can deal with the sound levels though, devices are invented that make it seem like a good idea to drop 2 or 3 hundred dollars on.

ya its not possible to create a muffler that "pulls" air of of an engine, thats not a machine, its a fish-oil perpertual motion machine.

I dont know about you, but I in this house we obey the laws of thermodynamics.

No more Muffler

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