Lowering exhaust noise on K-Series

Post your custom tools or how to information here (caption your photo's) and we'll move any that are good to archive, into the How To section of the manuals.
Forum rules
This section is reserved for semi detailed posts describing how you made a custom tool, or a detailed procedure for repairing a certain assembly of a tractor. Pictures are pretty much required
Posts in this section now have to be approved before they become visible.
If your looking for help repairing something please post in the shooting the breeze or the forum that pertains to your question.
Post Reply
PTWannaHave
Posts: 295
Joined: Wed Apr 11, 2012 12:39 pm
First and Last Name: Ben Michaud
Location: Richmond, Ontario

Lowering exhaust noise on K-Series

Post by PTWannaHave »

Hello all,

My recently refurbished 125 is probably not that much louder than when it was new, but significantly louder than a more modern unit such as my 2185. (I know, it's not a fair comparison...!!) Nonetheless, I would like to significantly reduce the exhaust noise (even though it may only represent 1/2 of the 'total noise') without reducing power if possible.

The best ideas I have found so far are:

- SuperTrap brand (short stack) muffler
- Using a motorcycle stock muffler (new take-off) that has been replaced by a new owner with a performance muffler. (Quite common, I think. This may be the less expensive option of the two...)

Thank-you in advance,
PTWannaHave

User avatar
Farmallgray
Moderator
Posts: 1021
Joined: Mon Sep 06, 2010 7:39 am
First and Last Name: Todd Markle
Location: Spring Mills, Pa

Re: Lowering exhaust noise on K-Series

Post by Farmallgray »

Maybe try what David Kirk did on his QL;
http://www.kirkengines.com/downloads/Ki ... PartII.pdf
It is about 1/3 down the page.

On the newer tractors the deck is a lot louder which may make the engine seem quieter.
See my IH, Cub Cadet and tractor pulling youtube videos;
http://www.youtube.com/user/farmallgray

PTWannaHave
Posts: 295
Joined: Wed Apr 11, 2012 12:39 pm
First and Last Name: Ben Michaud
Location: Richmond, Ontario

Re: Lowering exhaust noise on K-Series

Post by PTWannaHave »

Thanks Farmallgray.

I am still looking for a bolt-on solution, but may go go the Kirk route if I get desperate...

I added some cushioning to the hood recently to protect the new paint from rubbing off. Welcomed side-effect: noticeable reduced operating noise! :shock:

Cheers,
PTWannaHave

DaveKamp
Posts: 418
Joined: Mon Sep 06, 2010 10:19 am
First and Last Name: Dave Kamp
Location: LeClaire, Ia

Re: Lowering exhaust noise on K-Series

Post by DaveKamp »

If you look at the changes between the WF and QL series, you'll notice that a bulk of the QL changes all come back to preventing things from rattling and banging.

The next, is putting shrouding over as much as possible, making the shrouding fit down tight against some sort of snubbing surface (so no rattles) and this also contains most of the noise INSIDE the compartments, so it doesn't come out.

After that, is muffler noise.

Realize that many people seem to think the QL mower decks and implements are louder than the older style... most of the time, this is simply because the running noise of the machine is so much lower, that the deck and implements are much more noticeable. :mrgreen:

The K-series engine, being a big single, creates some pretty substantial primary and secondary vibration. In a rigid frame, this turns every other structural member into a mechanical linkage, and every flat surface into a speaker. Mounting it on a soft cradle helps substantially... however, if you've got a mean, strong K-single, it'll make pretty quick work of the iso-mounts... (don't ask me how I know)... having said cradle inside a flexible frame chews 'em apart even quicker, as the working machine gets pretty flexible when traversing the ground with a deeply-engaged implement... so if you do a mod on your machine, keep this all in-mind, and have some sort of secondary restraint in-place so that the motor can't take a long walk in case an iso-mount goes bad.

Keeping flat surfaces from becoming speakers is a DIFFICULT job. One of the techniques used in the NVH abatement field, is to apply heavy material to the backside of a flat surface. By adding mass, it lowers the surface's rattling frequency, and increases substantially the amount of energy required to make it shake. Not much room on most Cub Cadets to do things like that, but something to consider. I haven't done it on a Cub, but I HAVE employed spray-on undercoating to do just this sort of thing... and I've also used spray-on bedliner (the rattle-can variety) to help dampen and contain noise in things like boat engine covers... and it does work. Softer dampening materials are much better than hard-surface, as harder-surfaces reflect high-frequency noise.

Now, if you've got a really strong motor, you'll probably find that typical aftermarket mufflers of today simply don't last too long... Few that I've found were anywhere near the durability of OEM units. Making them control the noise is even more difficult, but I frequenly silence stationary engines considerably by using two mufflers, spread out with a few feet of pipe between 'em. Not something that's readily attainable within the confines of a typical working IH Cub Cadet, but it all depends on the constraints of your needs and the project.

:ugeek:
Yes, I'm a Mad Scientist... but I'm usually happy, even when things ain't goin right.

PTWannaHave
Posts: 295
Joined: Wed Apr 11, 2012 12:39 pm
First and Last Name: Ben Michaud
Location: Richmond, Ontario

Re: Lowering exhaust noise on K-Series

Post by PTWannaHave »

Thanks Dave; all useful comments/info!

I plan to rebuild a 14hp 'properly'. It may turn out to have a bit more Ooomph! than original, but nothing extravagant.

I am also thinking that a balanced rotating assembly (if that can be found for a K-series engine) may also be of great help by reducing the main source/cause of the vibrations...

I keep hearing that ISO engine mounts have a somewhat short lifespan, so I am not currently planning to use them. Then again, with a balanced rotating assembly, perhaps they would last...?!

Bye for now,
PTWannaHave

User avatar
BigMike
Posts: 1296
Joined: Mon Sep 06, 2010 8:45 pm
First and Last Name: Mike Andrews
Location: Niles,Michigan

Re: Lowering exhaust noise on K-Series

Post by BigMike »

Ben,K series Kohlers CAN be precision balanced.The flywheel is easy,spin it and drill where needed.The crank is another story.The majority of our K series cranks do not have matched counter weights.....one is usually thicker than the other.To do a proper balance job the crank needs to have the cheek machined flat and additional weight added then it can be spun and drilled as needed.I had a flywheel done and may have a crank done before the engine goes together.

ISO mounts have a short life span when in a machine that is neglected and abused.Most of us don't use our Cubs daily and even when we do we know them well and take care of them as needed.I believe with good ISO mounts and a front and rear cradle up grade the ISO will last a long time.
I know there are two camps on Quiet Lines.......I firmly stand in the one that likes em :mrgreen:

Post Reply