Gee, you really want the noise cops to pay ya a visit, eh?
I'd say, a tuft of cotton in each ear is about the best way to solve that problem. Or, some hunting ear muffs! Holy Cow! You could rig up a water tank, and run the muffler outlets into the tank, to muffle more of the sound! Or fabricate a long stack, to carry the exhaust up, up, and away That would make ya really look good, with the tall stacks a-puffing away as you mow the lawn!
You could rig up some of those little caps that keep the rain out, and flap up and down as the engine runs. You could make folks think you have a drag race tractor. The little kids would be out there, trying to race you! Think of the possible opportunities! RJ

"Gee, you really want the noise cops to pay ya a visit eh?"

Well...I wear earplugs when mowing anyway...my neighbors are pretty far away and...the Mrs. don't hear too good anymore... :--]

I have heard from some that running with open headers may 'burn an exhaust valve'. I would be still running with about 24 inches of pipe without the muffler. Does this sort of open pipes still potentially burn exhaust vlaves?

***"Does this sort of open pipes still potentially burn exhaust valves?"***
This sorta kinda falls into misrepeated folklore/myth.
The risk of burning an exhaust valve is not in itself caused by running "straight pipes".
The risk of WARPING an exhaust valve, which would very likely LEAD to a burned valve/seat occurs when there is NOT ANY EXHAUST PIPE or header/manifold connected to the cylinder head exhaust port.
Here's why: As the exhaust gases are pushed out of the combustion chamber on the exhaust stroke without any pipe/header or manifold connected to the cylinder head, they will follow the "path of least resistance" as they rush out. With no "back pressure" standing in the open port, the gases will tend to favor one portion of the valve stem and face over the other portion. Because there is no back pressure AND there is cool outside air available near the port opening.....the exhaust stream coming out and favoring one side of the port over the other will cause a vortex draft of cool air to ENTER the port and this vortex of cool air tends to keep a region of the valve face cooler than the other area of the face. This will cause uneven heating of the valve stem and face which may cause cause the valve to warp and assume an "off center" fit to the valve seat.
Once the valve has assumed this "tilted" geometry, it may never return completely to its correct shape upon cooling down when the engine is not running.
The changes in shape and fit of the valve to seat will eventually result in erosion ("burning") of the valve face and seat. But even before the burning takes place engine power and performance will be affected because the warping is enough in itself to mess things up a bit.
There are probably quite a few formulas that engineers might use to determine the minimum required length of a certain diameter of pipe/tube needed to rule out warping of exhaust valves in "open pipes" exhaust systems.
I would believe that 24" of 3/4" or 1" pipe (especially with some bends) would be adequate.......but I ain't no engineer.

Thanks Mownie...you always seem to have a well thought out answer....

And I don't believe for a moment what you wrote:

".......but I ain't no engineer"

I would think that the engineers who designed that exhaust system knew what was needed to muffle the noise, and to remove the hot gasses that will harm the engine otherwise!
Also--just why do you think that a hot muffler, stuck down in the frame area, is going to harm your engine?
They have been that way for years, and i've never heard of any problems with the location. Everything there is steel, and the temps of the muffler are not going to affect the steel in that area. The cooling fan on top of the engine blows cooling air right down into that area, and carries some heat down under the machine.
Should you manage to change the path of the hot exhaust gasses, you could ostensibly burn the tires when running! BT/DT, inadvertently, myself, when i changed an engine, and had to install a different muffler system.
But--it is your machine, so, design a different exhaust system.. i'm quite sure it will be much better than that "stupid design" that is on it, now! RJ

Rustyj14 wrote:

"I would think that the engineers who designed that exhaust system knew what was needed to muffle the noise, and to remove the hot gasses that will harm the engine otherwise!
Also--just why do you think that a hot muffler, stuck down in the frame area, is going to harm your engine?
They have been that way for years, and i've never heard of any problems with the location."

This mower, with the Briggs 26hp Intek engine (on a GT5000), is noted for having heat related problems. One problem that I know of, personally, is the infamous 'ejected exhaust valve guides'. Clearly it is caused by temperatures too high for that area of the engine. Is the cause the engine design? Is it caused by dumping exhaust heat into the chassis, which easily gets conducted right back into the base of the engine? The cause really does not matter to me. I am taking all possible precautions (like frequent cooling fin cleaning) to minimize higher temperatures. My desire to remove the muffler completely and 'send' most of the exhaust heat directly into the atmosphere is to aid in reducing operating temperatures in the engine.

Concerning..."I would think that the engineers who designed that exhaust system knew ....", you may be assuming way too much. Remember that the engine was designed and built by Briggs as a general purpose vertical shaft engine. AYP designed and builds the mower and chassis. The two designs 'meet' at the header/muffler interface. To assume that the two sets of engineers even talked about the header muffler interface is a leap of faith.

If you look at any automobile design you will never see any part of the headers or exhaust system directly bolted to the chassis. There is always an insulator that prevents heat from conducting to the chassis. At the very least, AYP should have bolted the muffler to the chassis through a heat insulating connection.

"Thanks Mownie...you always seem to have a well thought out answer....
And I don't believe for a moment what you wrote:"

Hey Mownie, so much for your long thought out reply, makes it all seem worth while huh? (grin)

Walt Conner

Well Walt, I was hoping BGM was only referring to the part where I said "but I ain't no engineer".
:^)

"Well Walt, I was hoping BGM was only referring to the part where I said "but I ain't no engineer".
:^)

....For Sure!

BGM