Author Topic: The sound of 4 strokes. (Read 7320 times)

Dennis Toth · « **on:** July 17, 2017, 08:34:57 PM »

Guys,
Several years ago I flew small and medium size 4 Strokes. I kinda liked the engine run and won several contests with them. One thing that always bugged me was the sound note of the 4 Strokes. They always sounded flat. Has anyone worked with mufflers designs to get a different sound from them?

Best, Dennis

Dennis Toth · « **Reply #1 on:** July 26, 2017, 05:39:01 PM »

So everyone is happy with the sound? I've heard it described as a Pig farting into a barrel. I did see some information on changing the exhaust note by using a disc type diffuser, this might be a lot of work but maybe some creative muffler internals would work.

Best, DennisT

Chris Wilson · « **Reply #2 on:** July 26, 2017, 05:43:12 PM »

Bolt another cylinder on at 45 degrees for that American sound!

Dane Martin · « **Reply #3 on:** July 26, 2017, 06:48:16 PM »

Quote from: Dennis Toth on July 26, 2017, 05:39:01 PM

So everyone is happy with the sound? I've heard it described as a Pig farting into a barrel. I did see some information on changing the exhaust note by using a disc type diffuser, this might be a lot of work but maybe some creative muffler internals would work.

Best, DennisT

I grew up on a feed lot in bakersfield. I like pigs. Lol

Chris Wilson · « **Reply #4 on:** July 27, 2017, 07:39:09 PM »

Seriously here, what is with an engine that has the exhaust length about the same as the intake?
Run a decent length pipe and put a muffler at least 6X the engine capacity on it and see how that goes.
And try and pick up the bass notes with an absorption type muffler.

Dennis Toth · « **Reply #5 on:** July 28, 2017, 04:51:53 PM »

Chris,
Interesting idea, so are you suggesting that we us a longer exhaust pipe and something like a glass pack muffler?

Best, DennisT

Chris Wilson · « **Reply #6 on:** July 28, 2017, 05:35:51 PM »

Quote from: Dennis Toth on July 28, 2017, 04:51:53 PM

Chris,
Interesting idea, so are you suggesting that we us a longer exhaust pipe and something like a glass pack muffler?

Best, DennisT

Yes to all except the glass pack as it will get oil soaked eventually.
An interesting idea is to use perforated pipe, glass wrap that section and jam open ended tubing over that.
That way you can simply slide the tubing off to replace the glass packing.
Hope that makes sense.

P.S. thinking about this again, perhaps a simple perforated tube wrapped with glass tape exhaust wrap just wired on may work well enough. All you need would offcuts of alloy pipe and a few inches of tape to test it out.

Dennis Toth · « **Reply #7 on:** July 30, 2017, 07:29:01 PM »

Ok, do you think we could use a tube within a tube (a small one inside a larger one) that would allow a sliding length to tune the note? I'm wondering if the inner tube can be perforated with the end closed then slide the length to get the desired note?

Best, DennisT

Chris Wilson · « **Reply #8 on:** July 30, 2017, 09:37:44 PM »

Quote from: Dennis Toth on July 30, 2017, 07:29:01 PM

Ok, do you think we could use a tube within a tube (a small one inside a larger one) that would allow a sliding length to tune the note? I'm wondering if the inner tube can be perforated with the end closed then slide the length to get the desired note?

Best, DennisT

Like a trombone?
Give it a go!

Jim Carter · « **Reply #9 on:** July 31, 2017, 10:18:29 AM »

Quote from: Dane Martin on July 26, 2017, 06:48:16 PM

I grew up on a feed lot in bakersfield. I like pigs. Lol

I like'm too .... boiled, fried, baked, roasted ......

Steve Helmick · « **Reply #10 on:** August 11, 2017, 10:29:53 PM »

"Pig farting in a barrel" is a perfect description. Try a megaphone and see how that sounds? I've read of folks running without the muffler, only using the tube between the pig and barrel. They said it didn't sound much louder, but then there's no muffler pressure to the tank, which some said was important.

Steve

Steve Helmick · « **Reply #11 on:** August 11, 2017, 10:33:54 PM »

Quote from: Jim Carter on July 31, 2017, 10:18:29 AM

I like'm too .... boiled, fried, baked, roasted ......

SMOKED!!!

Steve

Dennis Toth · « **Reply #12 on:** January 26, 2020, 07:15:03 PM »

I wonder if changing the fuel mix say add a bit of gasoline will give a different exhaust note?

Best, DennisT

Robert Zambelli · « **Reply #13 on:** January 27, 2020, 01:34:21 PM »

Hi, Dennis - don't know for sure but the next time I run a 4S, I'll try a bit of gasoline.

Bob Z.

Dennis Toth · « **Reply #14 on:** January 27, 2020, 06:00:15 PM »

Bob,
I know that the ignition engines running gasoline are louder then when they run them on glow fuel. Maybe a few % gasoline will give them a bit sharper growl.

Best, DennisT

Robert Zambelli · « **Reply #15 on:** January 30, 2020, 02:22:00 PM »

Allow me to quote the mantra of R&D (and test engineering)

"One test is worth a thousand EXPERT OPINIONS".

Bob Z.

Joe Gilbert · « **Reply #16 on:** May 11, 2020, 05:12:03 PM »

I have been very successful with a saito 40. I like the sound it makes if it is winning it is really sounding good to me if you want noise get a Anderson Spitfire and have fun.

Dennis Toth · « **Reply #17 on:** May 11, 2020, 05:20:45 PM »

Joe,
What model Saito 40 do you have, do you use the carb or have you changed it to a straight venturi? What %Nitro do you run? What ship do you have it in, weight and prop? Just interested in what has worked.

Looking at the engine reviews the Saito 40 FA Golden Knight is listed at 10.75oz, about 3oz lighter than the OS FS40. WOW, that is really lots of power for the weight, easily matches any of the modern two stroke 40's if you add the fuel load for each.

Best, DennisT

Dennis Saydak · « **Reply #18 on:** August 04, 2020, 04:54:52 PM »

You need to buy yourself a set of Bagpipes. An adapter is all the extras you would need.

proparc · « **Reply #19 on:** August 05, 2020, 05:29:31 AM »

Quote from: Dennis Toth on July 26, 2017, 05:39:01 PM

So everyone is happy with the sound? I've heard it described as a Pig farting into a barrel.

Best, DennisT

Saito 72. A REALLY big angry pig farting into a VERY large steel reinforced barrel.