The Home Machinist!

https://www.youtube.com/watch?v=qS09QSdr_9k

https://seattle.craigslist.org/see/bpo/ ... 72317.html

I would of thought there is a lot higher health risks, breathing in diesel fumes..The anti pollution gear on diesel seem a lot more than petrol.

Co2 emissions are lower with diesel, but the increased particulates in it are also cancer causing and likely the reason for the extra smog gear on diesel engines.
Unfortunately I don't think any small engine is going to be a realistic deep sounding one for scale hobby train use, and with the winter temperatures occasionally pushing the envelope of where diesel turns to Jelly in my locale I'm going to stay with gas.
The little 2-3 cylinder Kubota, Yanmars, and the like are probably the best bet though. The OP, Glenn, lives out of the range of the Frasier valley northeaster "freeze" and shouldn't have to worry about having issues with diesel due to the cold.

Perhaps a really good, sound deadening exhaust system and enclosure that make the engine quiet....and a really cool electronic sound system to make it sound like a big diesel...????

At TM the Klamath and Western Railroad uses a small industrial diesel in their 1.5 F unit setup. I don't have the particulars here with me at home but I will get that info tomorrow and add it to this thread. Russ

Bill, I am going to be playing with acoustic foams, rock wool, and sound deadening, along with a larger diameter longer exhaust pipe exiting a custom muffler on my locomotive to quiet the engine and deepen the tone of any remaining noise to hopefully make things sound more realistic from my Honda GX390. I'll let everyone know how it sounds and try to get a short video posted when the time comes.

When it comes to mufling thevsound of small engines, a can of some sort, be it tubing or square tube stuffed with screen wire and vented out is hard to beat. It takes the sharp pulse out of the exhaust and softens it to a whoosh cutting the explosive noise way back. the larger problem is getting rid of the heat captured by the can under the hood. It is where some insulation and well placed vents come in handy.

I've got a piece of 8x6x3/8 rectangle tube about 15" long that will be my "fuel tank" muffler. Exhaust will flow into the top, make several passes through some tubes and perforated metal packed with rock wool, then exit into the stack.

I will warn that rock or glass wool is too fine and either breaks up or plugs up. Better off with a screen type of baffle that offers alot of flow without restriction to the exhaust. It will hush things quite a bit. The more open the longer the run must be but keep the back pressure low to not choke the engine. Play with it and see if it makes a difference.

I've built a few mufflers for my racing karts because I felt that the little tiny things that are marketed are a joke, and the perforated metal core rusted out quickly and the cost was nearly $40. The last one I built myself, I used a piece of 2-1/2" exhaust tubing, welded fender washers to each end, and then stuffed it full of rock wool. It lasted about a year and the packing started to go away.
I first one, I made the core by tapping some .060" perforated steel sheet around a piece of 1" bar stock with a rubber mallet, tack welded the ends in many places to keep it together, and then stuffed it into the muffler and welded the ends to the washers inside diameters. The next one I made I wrapped the perforated tube in header wrap, stainless wire wrapped it to stay in place, then inserted it into the core before I welded the other washer on the end. Over three seasons it worked well on my modified 420cc predator and I haven't lost any packing. Because weight isn't a concern here with my train, I may play with a re-packable design of some type that has one end that unbolts so I can service it.

Here are a couple of pages that might help you from the out of print book "Master Railroad Builder" by Steve Booth. It also has an article on building a muffler entitled "Eliminating the Lawn Mower Effect".

Daris

another way to 'eliminate the lawn mower effect' is to put steam through the exhaust