Homemade exhaust for your old lawnmower

Step 5 Fit and Finish

The final steps are up to you.
The muffler may need extra support, which could be accomplished with cleverly placed bolts, hose clamps or pipe support straps. Use your head and think of where the forces are going to be transferred.

Dress up your exhaust tube and add a margin of safety with an exhaust tip or cover.

Don't be afraid to experiment with the amount of packing material, number, size and placement of holes, etc. This muffler is completely customizable.

I originally designed a much smaller muffler with larger diameter pipe, but when I moved to the black gas pipe, the larger pipe diameters were not available.

Comments

[ELITE-01]

Nice one, I'll try something like this on my go kart

[hifatpeople]

heres an idea, make the muffler look like a machine gun barrel.

[Junkyard Dawg]

Man, that exaust makes the lawn mower look like a hot-rod. If (and when) you re-paint it, can I suggest a hot-rod type flame job? I got to try this for my mower. It's newer, but it will look better with something like that on it. Almost like the NASCAR exaust system.

[cambigfoot]

put a nos system too??? lol :)

[Junkyard Dawg]

I wouldn't take it that far, but I may consider puting a big-block V-8 on it. Immagine the drag-races the thing would win... =)

[Junkyard Dawg]

Accually, no to the big-block V-8. How about a NASA type solid-rocket booster? (man, the lawn would be mowed in 1.2 seccondswith a V-8 alone, never mind the fact it will be done in the blink of an eye with rocket fuel.)

[segcd]

OK, I see some problems here. 1. This idea needs to have the amount of backpressure figured out so you don't burn the valves or cause power loss. 2. I have seen pipe systems like this before and the weight of the pipe usually wears out the threads in the engine because you cannot keep them tight. 3. Spark arresting features of this system probably will not meet US Dept. of Forestry specs. 4. Might be more dangerous if fuel is spilled on the mower. 5. Bigger exhaust system = more possibility of skin burns or setting dried grass on fire. 6. The cost of the pipe and fittings is way more than the $2-3 for an approved muffler.

On the plus side, it looks cool, especially with the chrome cover.! LOL!

[Viqilance]

I want you body....

[Kaptain krunch]

No one cares about safety, seriously, there are many more dangerous things than a funkin lawn mower muffler. Second, with a 4 stroke you dont need backpressure, as long as you have some sort of pipe longer than a few inches you WILL NOT burn out your exhaust valve, and there is no way to lose power by not having back pressure on a 4 stroke. gas evaporates fast enough, that if you spilled a bit on the muffler, by the time it got hot enough to ignite gas, all the gas would be gone.

[maize5]

First things first. You're a killjoy, and if you're so worried about obscure, irrelevant and stupid regulations and rules, then what are you doing on this website? I'm really quite serious. I know I read three articles on bomb-making and two about lockpicking before breakfast. 1. The brilliant thing with projects like this is the overkill. Drill more than enough holes and it won't cause any back pressure. 2. So far as the stripping or cross-threading is concerned, the man even suggests supporting the weight somehow. Also, it's a thirty-year-old law mower, what does it matter if it does strip? He can take the entire muffler off and have a SUPER loud lawnmower just for the heck of it. 3. Who cares? 4. Oh, wow... My lawnmower is on fire. Hold on while I call a few people to come over and watch and maybe bring some thermite so we can do this right. 5. Oops. I burned myself on an exhaust. Again. I'm tattooed up both arms and legs from exhausts from motorcycles and cars and ovens and god-knows what else. Go somewhere else if you're going to live in fear of life. Some of us do things with the full expectation of getting hurt. It's half the fun to have a scar to associate with something really fun or really stupid your did. Most times both. 6. Did he ever mention this was going to be a money-saving endeavor? The whole point of this is that the stock muffler wasn't quiet enough for this man's liking, so he built a bigger one and put a chrome tip on it. Just because he could. Welcome to America, a country founded upon the principal of experimentation, the Rule of Cool, and getting away from killjoys. I, for one, would try to make an exhaust cover like they put on the AC Cobra's side pipes, or maybe built a mini diesel smoke stack just to make it look cooler. I bet with a little welding and some pre-planning, you could give your lawnmower twice-pipes. I'd absolutely love to try this on a gas-powered rotary mower, just for the look. Maybe even vent the exhaust to the side, and put a spark plug in it hooked to a battery. Nothing says "Good mornin'!" like flaming exhaust when you're mowing the lawn. Maybe you could even vent it straight up and brace it, so everyone can enjoy the flames.

[lukeyj15]

Amen.

[Danish M1Garand]

Hell YEAH!

[segcd]

You know something, I really don't care what anybody builds here. All I tried to do is make sure the builder is being careful to make sure he isn't hurt, maimed, or killed. If any of the three happened to the builder, I'm sure it would kill somebody's joy in a hurry. Let's not call people names and criticize why they are here. Every year someone modifies a lawnmower in a way that causes them pain or death. The next thing that happens is that the manufacturer and the dealer get sued. I don't care what anybody builds here but please be careful and when things go wrong, take responsibility for any negligence on your part..

[maize5]

Firstly, nobody called you a name. Calling you a killjoy is no more calling names than saying that someone who runs professionally or competitively is a runner.

Secondly, you are again being incredibly offensive by, effectively, calling the builder a moron incapable of foresight or any knowledge of safety. For all you know, this gentleman is an engineer who designs two-stroke engines for NASA, or some other type of engineering hyper-genius. Both of your posts are insulting and degrading to the gentleman who wrote this article and I am, again, deeply offended by your treatment of someone who took time out of his life to share his experience and ingenuity and bring a smile to people's faces. So, because of your condescending posts, I'll respond in kind.

"You know something, I really don't care what anybody builds here."
"I don't care what anybody builds here..."
- Then why did you bother to comment in the first place?

"All I tried to do is make sure the builder is being careful to make sure he isn't hurt, maimed, or killed."
- Via a text post, after the fact, online, anonymously, with alleged "facts" of things that are so improbable it's insulting? Also, this contradicts your previous statement that you "care what anybody builds here". Has the Nobel committee been made aware of you?

"but please be careful and when things go wrong, take responsibility for any negligence on your part.."
- LOL. What?

"Spark arresting features of this system probably will not meet US Dept. of Forestry specs."
- Please submit a detailed diagram of exact blue-prints of the builder's design and highlight the specific faults you have found. Also, please post the specific and applicable "US Dept. of Forestry specs" along with exactly how they affect this build. Please cite your sources.

"Every year someone modifies a lawnmower in a way that causes them pain or death."
- Please list specific examples of both death and injury each year starting from the invention of the lawn mower by Edwin Beard Budding in 1827. Please cite your sources.

"I have seen pipe systems like this before and the weight of the pipe usually wears out the threads in the engine because you cannot keep them tight."
- Please cite each and every specific instance you have personally had direct experience with. Please note dates, locations, and potential witnesses. Also, please post the exact weight of the exhaust system the builder implemented, along with equations to prove your hypothesis. Please show the exact torque at the fulcrum and detail the exact tolerances of the materials and threads on both the engine block and the exhaust system. Please cite your sources.

"5. Bigger exhaust system = more possibility of skin burns or setting dried grass on fire."
- Please explain how. The chrome tip on the exhaust will actually act as a heat shield as there is minimal contact with the muffler, and the exhaust is not venting openly, but inside the tube of the exhaust tip which would act as a crude flame arrestor along with the fibreglass inside. Plus, the muffler is pointing forward, away from the operator position, which would severely diminish the likelihood of ever coming in direct physical contact with it. Also, note the builder's own writing, "Dress up your exhaust tube and add a margin of safety with an exhaust tip or cover".

"6. The cost of the pipe and fittings is way more than the $2-3 for an approved muffler."
- Please cite examples. Lawnmower mufflers can cost up-wards of $11 or more (http://www.amazon.com/b?ie=UTF8&node=155375011). Please list for us the exact model number of the specific "approved muffler" for this engine, along with a website showing an average price a consumer could expect to pay in USD. Please cite your sources.

"1. This idea needs to have the amount of back-pressure figured out so you don't burn the valves or cause power loss."
- How do you know the builder did not? He, in fact, states quite clearly that, "I drilled 5 3/16 inch holes. I discovered that two holes was not enough and 5 seemed to be OK". Please list the exact exhaust pressure for this specific model of engine, taking into account it's exact current age and operating condition. Please also note what the optimal operating exhaust pressure range should be, taking into account weather and other operating conditions, and an equation showing exactly how to calibrate a custom muffler to operate within these specs. Please also note the exact amount of back-pressure created by the current exhaust system and note whether or not it is operating within acceptable tolerances and, if it is not, how to modify it to bring within the optimal operating specs. Please cite your sources.

Please also list any degrees, certifications, qualifications, and/or training you have that make you qualified to provide criticism on this project, including your practical experience with federal regulations. Please cite your sources, examples, and proof of above.

In the future, you may want to try acting like less of a buzz-kill and just enjoy things. You don't need to be condescending, rude, confrontational, or even just plain mean to get attention or start a conversation. Perhaps a better way of approaching the matter would have been to ask, "Hey, have you had any problems with the back-pressure or it flaring up on you". That would have brought his attention to your concerns, over what you perceive to be a death-trap, in a neutral, non-confrontational, and almost friendly way. Then it leaves the door open for him to say if he has had the problems and, if so, how he resolved them, or to note that he hasn't and won't have the problems because he took things into account.

Something to keep in mind is that most of us who tinker around with these, and more potentially dangerous projects, are most usually pretty darn aware of not only the physics and chemistry of what we're playing with, but the safety precautions as well. This project is about as far from dangerous as one can get without using Play-Do, yarn and blunt-tipped scissors. The engine is so under-powered that even if he had completely plugged the exhaust, nothing more dangerous would likely have happened except the engine dying.

Of exhaustion. *rimshot*

You could have handled this all much better and in a far nicer way. You could have at least approached this in a manner that didn't involve insulting people and coming off as such a condescending, arrogant, and mean person. I'm not saying that you are any of these things, just that you are coming off as such. You could have just been social and human.

Perhaps this can all end here, as I know that I won't bother responding to any further posts here. This is the end of my fun and it's going to just get dumb after this. I really can't believe that you are so oblivious about your behaviour, but perhaps you will keep it all in mind next time you post a comment to a project someone posts and is obviously proud of. Tearing people down is not the way to get positive attention. In the end, however, there's certainly nothing more for you to say as I've really kind of put you in a corner. So let it drop and walk away or you're going to look silly. This isn't a fight, so just be human and social.

Good luck in your future endeavours. I really do mean that.

[Waste Of Space]

        Thanks for the laugh, that was really funny.

[maize5]

I'm actually a little upset that nobody has specifically made a comment on my joke about the engine dying of exhaustion. I really thought that was funny.

[millenniumtree]

Woah, woah, hold it. No one needs to defend me here - I'm not offfended, and in fact I'm quite proud that my little project has created so much healthy debate! Segcd's concerns are real and legitimate. Yes, this thing gets HOT. I mean real hot. I mean crazy hot. Don't touch it! I did and I got burned! That's why I put the loony muffler tip on it. It didn't help a whole lot, but it looks outrageous, so I like it. People get burned all the time when they step out of their $50,000 AC Cobra replicars onto the shiny muffler. Protect yourself, put a heat shield on it, or design yours better. This is by no means a copyrighted design. Use it, improve on it. Or use it, burn yourself, and give up on it. Yes, it will probably start fires if you throw dry grass at it. Don't do that! The project as I envisioned it was never intended to be used as a lawnmower. I wanted actually to put a pulley and V-belt on the bottom and to power a recumbent bicycle project with it. The lawnmower actually has no blade on the bottom. No, it's not much of a spark arrestor. It doesn't even quiet the engine down all that much. Maybe your design will work better than mine did. Yeah, it's heavy and it WILL bugger up your threads if you don't support the weight of the muffler. Black pipe is much MUCH heavier than the stock muffler. I literally rescued this lawnmower from the curb. It's somewhat of a miracle I could get it running actually, considering it had no working throttle or governor system, and I had no previous experience with small engines. The aftermarket mufflers probably work much better than my pipes, and are probably cheaper and easier to deal with in the long run, AND they're approved for all your spark-arresting, lawn-mowing needs. I have another (much newer) lawnmower for that requirement. I basically created this project to see if it could be done, and to contribute something eccentric and creative to Instructables - a site which I love dearly. I consider it a success on both fronts - it DOES work, albeit with the caveats above, and I'm thrilled that the project was actually picked as a feature on Instructables! As with ALL projects on Instructables... Builder BEWARE! Most of all though, have fun! Now go thread a pipe into your 30 year old lawnmower, yank the starter cord, annoy the neighbors, invite some friends, stand around your creation and be proud. Then put it back in the garage, and go buy a purpose-built, USDA-approved muffler. Lastly, "be nice", as the little pink box says.

[bigredlevy]

point of order, Mr speaker, relevance. come on lads, it looks good, that's all that counts. didn't your mother's ever teach you that if you don't have anything nice to say, then don't bother commenting on other blokes instructables.

[millenniumtree]

Yes, I know it's ridiculous. ;) You can buy premade quiet mufflers for these things too, but I wanted to have a bit of fun and see if I could do it.

[socrateez]

Turn that pipe vertical and drill holes in the sides. Would look like a big-rig exhaust or something from a tractor pull! LOL Nice job.