What makes a nicely resonant exhaust ?

[mike90045]

I don't want to muffle the 6/1 completely, but is there a method that takes the harshness out of the exhaust, leaving the "poing  poing  poing" sound?  Long pipe, no expansion chamber, large diameter, small diameter ?

[BruceM]

A good sized auto muffler will result in a pleasant chugging.

[veggie]

or......you could buy the "Giant Muffler" from Acme Muffler Co. 

Veggie

[rcavictim]

or......you could buy the "Giant Muffler" from Acme Muffler Co. 

Veggie

I pitty the engine on that if the exhaust valve was left open.  Rain will get into the pipe the way it is set.  A LOT of rain.  Perhaps they should use this to try to refill Lake Meade. 

[rcavictim]

When I was a kid early teens I had a small four stroke lawn mower engine to play with.  I found that placing a 10 foot long'ish piece of rain gutter downpipe over the exhaust outlet made a really cool resonant exhaust sound with the echo in with the pulsations.  Maybe the idea is to use a long section of straight pipe that is much larger cross section than normal but not too big.  Adding an air inlet port to this exhaust pipe at the engine end in such a way that exhaust is used to draw air into the pipe along with the exhaust might help the effect.

[veggie]

When I was a kid early teens I had a small four stroke lawn mower engine to play with.  I found that placing a 10 foot long'ish piece of rain gutter downpipe over the exhaust outlet made a really cool resonant exhaust sound with the echo in with the pulsations.  Maybe the idea is to use a long section of straight pipe that is much larger cross section than normal but not too big.  Adding an air inlet port to this exhaust pipe at the engine end in such a way that exhaust is used to draw air into the pipe along with the exhaust might help the effect.

rcavictim,
They had internal combustion engines when you were a kid?  

Getting back to Mikes question, I used a free flowing automotive muffler and they really make a big difference. Get the kind that reverses the flow twice inside the can (not the straight through style). Perhaps the propane tank modification that some people do removes a lot of the "thud" from the exhaust sound. I have not tried that one.

Please post your results if you find a solution,
Veggie

[BruceM]

Lots of volume in the muffler, or perhaps a resonator to add volume first and then maybe restrict the outlet to 1.5".  Mine is 2" all the way and the woof is more than it needs to be.  A baffled flow as veggie suggests sounds good.

[AdeV]

"Re: What makes a nicely resonant exhaust ? "

Petrol power, 8 cylinders and no silencers [q.v. muffler] 

So, another 7 CS's would be a good start, then you need to synchronise them 

[sorry, back to the sensible answers now]

[mobile_bob]

a 12V149tta detroit running at 2750 with short stacks off the turbo

now that is music to anyones ears,, just before you go deaf

bob g

[rcavictim]

This Lister Blackstone engine for sale in Ontario for $10k ought to make a nice exhaust sound.  600 HP @ 750 RPM.

http://www.scrutonmarine.com/E2034.htm