Need. More. loud!!!!!!

[SHADOW 1100T]

Save a bunch of money, go to a exhaust shop and get some pipes that will over your pipes, you'll have a lot more noise and once you have pissed off your neighbors, friends, fellow riders and lost half of your hearing you can go back to stock and it woulden't have cost a arm and a leg

[slowc10]

litnin is right just remove the baffles, mine have been out for sometime and no problems

[balactm]

Originally Posted by litnin

...and? That doesn't make it correct.

Again, there is no such thing as "back pressure."

I'm quite familiar with exhaust systems and how they work.

Exhaust systems work on pulse pressure and flow velocity, NOT back pressure.
You cannot, under any correctly functioning exhaust system read a steady pressure.
You CAN however, read Pressure PULSES as they travel through the exhaust system.

Exhaust pulses travel in two phases, high and low.
The leading edge of the pulse is the high side and the trailing edge is the low side.
As one pulse travels through the system, the low side of one helps pull the high side of the one behind it.(Natural physics).
High pressure always moves to low pressure. That doesn't mean it backs up and creates "back pressure".

As I said, people throw it around as a buzz word because they don't know
or understand how an exhaust system really works.

i don't doubt that those things exist. I would however, like to gently disagree with you. your argument has it's ups and downs. first of all, yes, a lot of performance has to do with exhaust velocities. second of all, i agree there are pulses. however, there is such a thing as backpressure. in a car with a turbo, the turbo creates a backpressure because there is an impedence of the exhaust flow. This, creates a deadening effect on the exhaust note. however, as the size of the pipes increase, the amount of air per linear inch increases thus increasing the sound because the exhaust pipes will contain more air.

you have a good understanding of exhaust systems however, you're logic is a little flawed, and you're generalizing about a very broad subject. you only covered naturally aspirated engines without catalytic converters, resonators, or mufflers. like a turbo, once you add a cat, resonator or muffler, you add something into the exahust system which causes a tiny, miniscule block in the system, which is known as back pressure.

[jonkun227]

Originally Posted by balactm

i don't doubt that those things exist. I would however, like to gently disagree with you. your argument has it's ups and downs.

balactm, you get a special response for this one. The entire article you linked to is about identifying and resolving exhaust system back pressure. IN OTHER WORDS YOU DON'T WANT BACK PRESSURE. They phrased it that way, but a simpler explanation would be: "Make sure you don't have anything blocking the engine exhaust."

I suppose Litnin' could have phrased his response a little better as well. He said, "Again, there is no such thing as 'back pressure.'" Perhaps what he should have said was, "You're not supposed to have back pressure." In other words, if taking out the baffles in your exhaust reduced back pressure THAT WOULD BE A GOOD THING.

But again, I'm not a fan of louder pipes. I'm not encouraging this behavior. I'm just pointing out that Litnin' does, in fact, know what he's talking about here.

Personally, I think a bike that performs like my 85 Shadow but is as quiet as a full electric would be perfect!


- Jon

[litnin]

Originally Posted by balactm

i don't doubt that those things exist. I would however, like to gently disagree with you. your argument has it's ups and downs. first of all, yes, a lot of performance has to do with exhaust velocities. second of all, i agree there are pulses. however, there is such a thing as backpressure. in a car with a turbo, the turbo creates a backpressure because there is an impedence of the exhaust flow. This, creates a deadening effect on the exhaust note. however, as the size of the pipes increase, the amount of air per linear inch increases thus increasing the sound because the exhaust pipes will contain more air.

Well, you can disagree if you wish, but that doesn't change the facts.
Are you an automotive engineer? Have you ever built an exhaust system?
No, sorry, there is no such thing as back pressure.
No, sorry, a turbo does NOT create back pressure.
A turbo works off heat energy by getting expanding gases in to a
decreasing size impeller housing.
The gases go in to smaller housing and then in to an expansion chamber.
The pressure differential of heat energy expanding in to the larger expansion chamber is what causes the impeller to spin.
Contrary to what many people believe, a turbo does not work on exhaust
pressure, it works off heat energy.
On the other end is a compressor wheel which compresses intake air.
The deadening effect of the exhaust note is due to the baffling effect
that the turbo has as the sound waves pass through it, just like a muffler.
Velocity increases, and exhaust pulse pressure rises and falls, but there
still is no back pressure.
If back pressure existed, the exhaust could not, by the laws of physics,
get out of the pipes.

Originally Posted by balactm

you have a good understanding of exhaust systems however, you're logic is a little flawed, and you're generalizing about a very broad subject. you only covered naturally aspirated engines without catalytic converters, resonators, or mufflers. like a turbo, once you add a cat, resonator or muffler, you add something into the exahust system which causes a tiny, miniscule block in the system, which is known as back pressure.

Yes, I do have a good understanding of exhaust systems.
And no, my logic is now flawed. Your understanding of how exhaust
systems work and your "back pressure" buzz word that is so commonly
misused is what is flawed.

[litnin]

Originally Posted by jonkun227

I suppose Litnin' could have phrased his response a little better as well. He said, "Again, there is no such thing as 'back pressure.'" Perhaps what he should have said was, "You're not supposed to have back pressure."

Well, when you're right, your right.
You are not supposed to have back pressure.
Yeah, I can make back pressure if I stuck a potato in the tail pipe
and blocked it off. In that case, yes, you have back pressure, which
is not good.
When a cat goes back and breaks apart, it causes back pressure.
Again, not good.
However, let me say this... I do believe in one of my previous posts,
I did specific that there is no such thing as back pressure in a "properly functioning exhaust system."

Originally Posted by jonkun227

In other words, if taking out the baffles in your exhaust reduced back pressure THAT WOULD BE A GOOD THING.

Yes, taking out the baffles for performance is a good thing, but again,
it doesn't reduce back pressure. It changes the exhaust pulse, not the pressure. But I get the idea you were trying to make.

[gelsbern]

Just to put a quick 2 cents in on the back pressure and the fact it does exist.

You do want some back pressure.

There are 3 things in effect when it comes to the valves in a 4 stroke engine, there is lift, duration, and overlap.

When your exhaust valves open, there is a minute amount of time where the intake valves are open as well (overlap). If you don't have enough back pressure, you can suck the fresh fuel/air mixture out through the exhaust valves. Not enough back pressure can cause a lean condition, and poor fuel mileage due to dumping unburned fuel into the exhaust system. Too much back pressure can cause rich conditions and poor fuel mileage due to not having an optimal fuel/air mixture in the cylinder for complete combustion. It is a delicate balancing act.

[litnin]

Originally Posted by gelsbern

Just to put a quick 2 cents in on the back pressure and the fact it does exist.

You do want some back pressure.

There are 3 things in effect when it comes to the valves in a 4 stroke engine, there is lift, duration, and overlap.

When your exhaust valves open, there is a minute amount of time where the intake valves are open as well (overlap). If you don't have enough back pressure, you can suck the fresh fuel/air mixture out through the exhaust valves. Not enough back pressure can cause a lean condition, and poor fuel mileage due to dumping unburned fuel into the exhaust system. Too much back pressure can cause rich conditions and poor fuel mileage due to not having an optimal fuel/air mixture in the cylinder for complete combustion. It is a delicate balancing act.

Sorry, but that's not correct.
You are talking about cylinder scavaging and it has nothing to do with "back pressure".
The exhaust pulse is what determines cylinder savaging.
Not enough back pressure can cause a lean condition huh?
Again, tell that to every top fuel race car in the world that run 2 ft open
headers. It has nothing to do with being a lean condition.
A lean condition exists when your fuel system is not correct for the
amount and velocity of air FLOW IN and the exhaust FLOW OUT. NOT back pressure.
Oh, and all engines don't have overlapping intake and exhaust valve timing. In fact, most do not... Valve overlap is for high revving performance engines, not low power street engines.

[gelsbern]

I put in my 2 cents, if you don't believe back pressure exists, that's your perogative.

However engine exhaust is a gas and follows the laws of physics and fluid dynamics, and every curve and bend, and obstacle in the way of a gas or fluid going through a confined space causes back pressure.

EDIT: Oh, yeah one more thing. The average NASCAR Winston cup car gets about 4.5 mpg. They make up for the lean condition by dumping fuel into the system .

[litnin]

Originally Posted by gelsbern

I put in my 2 cents, if you don't believe back pressure exists, that's your perogative.

However engine exhaust is a gas and follows the laws of physics and fluid dynamics, and every curve and bend, and obstacle in the way of a gas or fluid going through a confined space causes back pressure.

EDIT: Oh, yeah one more thing. The average NASCAR Winston cup car gets about 4.5 mpg. They make up for the lean condition by dumping fuel into the system .

No, it's not my prerogative, it's a fact.

No, every curve, bend, and obstacle does not increase back pressure.
It decreases exhaust pulse speed and slows down the rate of the
exhaust exiting the system.
If you had true back pressure, pressure INCREASES velocity, it doesn't decrease it.
Add a muffler to an exhaust system and you SLOW the velocity, NOT increase it.

And... on the NASCAR Winston cup car... who cares what the mileage is?
Yeah, they feed the motor a lot of fuel. That's not making up for a lean
condition. That's doing exactly what I said and keeping the fuel mixture
correct for the volume and velocity of incoming air and out going exhaust.

You know what we run in nitro motors? We put 18 gallons of fuel through
the motor in 1/4 mile. That's 72 gallons of fuel in less than 20 seconds in 1 mile.
Ya know what? We aren't compensating for a lean condition.
That's how much fuel it takes to keep the mixture correct for
the volume and velocity of air we push the the motor.

A street car runs less volume and lower velocity in and out and therefore
needs less fuel to keep the mixture correct.
Back pressure has NOTHING to do with it.