Echo CS-590 Timberwolf Muffler Mod - Flow bench Measurements

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Try removing the black intake....stack for lack of a better word from inside the air filter. It takes 30 seconds. Just pop the air filter apart and the black piece just falls out.


Wow. I had no idea that thing was inside there! Good catch and thanks for the tip!

rps20160821_221750.jpg


Out it goes. And back to the bench I go.



Here's the quick results (corrected flow data).

Carb + air filter, with black insert = 17.2 CFM
Carb + Air Filter, without black insert = 18.4 CFM

The black insert costs you 1.2 CFM!

Carb + air filter + orange filter cover with black insert = 16.8
Carb + air filter + orange filter cover without black insert = 17.6


So installed on the saw you gain back .8 CFM (the cover still has a detrimental effect)

I retested the carb+filter_cover with insert to compare to last night and I am within 0.1 CFM so the tests repeat well.


I am definitely removing that part from inside my air filter! I will likely machine a spacer for the stud to prevent collapsing the air filter when I tighten the cover.
 
Based on what I learned from these measurements, my approach to improving the performance on the Echo-CS590 saw will be:

1. Modify the exhaust deflector as shown to improve airflow
2. remove the air filter black plastic plenum insert
3. re-tune the carb
4. sharp chain! :)
 
Based on what I learned from these measurements, my approach to improving the performance on the Echo-CS590 saw will be:

1. Modify the exhaust deflector as shown to improve airflow
2. remove the air filter black plastic plenum insert
3. re-tune the carb
4. sharp chain! :)


Thanks for taking the time to do this. I appreciate it. So, based on your testing, do you think removing or drilling a few holes into the inner tube will make more improvements ? I know you just modified the deflector. Just wondering how much more one can go, and maintain appropriate back-pressure ?
I would like to do a MM, but don't want it so loud that I irritate my neighbors. We all get along.
 
Thanks for taking the time to do this. I appreciate it. So, based on your testing, do you think removing or drilling a few holes into the inner tube will make more improvements ? I know you just modified the deflector. Just wondering how much more one can go, and maintain appropriate back-pressure ?
I would like to do a MM, but don't want it so loud that I irritate my neighbors. We all get along.


You are welcome.

More holes will improve airflow. But it will make it much louder, and reduce the back pressure. At some point you will surpass what the intake tract is capable of flowing. That would be too much, in my opinion.

Without a dyno, its very tough to quantify. You can over do it.
 
Thanks for taking the time to do this. I appreciate it. So, based on your testing, do you think removing or drilling a few holes into the inner tube will make more improvements ? I know you just modified the deflector. Just wondering how much more one can go, and maintain appropriate back-pressure ?
I would like to do a MM, but don't want it so loud that I irritate my neighbors. We all get along.
My 590 is noticeably louder with just the deflector opened up. These saws get obnoxious fast when you start drilling holes inside the muffler. Maybe @Big Block still has some of his videos of the different muff mods he did on his 590.
 
More holes will improve airflow. But it will make it much louder, and reduce the back pressure. At some point you will surpass what the intake tract is capable of flowing. That would be too much, in my opinion.

Without a dyno, its very tough to quantify. You can over do it.
I don't like really loud, wide open muffler mods either, and usually try to keep the longest path length through the muffler I can while reducing restriction. Without a dyno you can get some guidance from the non-linear fuel delivery characteristics of the carbs.

It's known that just increasing air velocity a small amount by lifting in the cut will cause the mixture to go so lean it missfires (4-strokes), so it follows that anything which increases the air velocity through the venturi will also cause it to get richer. Since increasing air flow (and velocity) through the carb is the goal, then an effective muffler mod will do the same. So if your mild muffler mod is successful then you will likely need to lean out the H slightly, and possibly make the L slightly rich to allow for faster acceleration (yes, I know this is counter to the standard advice about MM tuning).

If you open the muffler up far enough, you begin to pull fresh air back into the cylinder before the exhaust port closes. This is air that has not passed through the carb or picked up fuel, so you will need to enrich the H to compensate. This probably does make more power, but at this point also there is not much of an enclosed can so that any fuel lost out the open exhaust port due to scavenging losses is not recovered and fuel use goes up quickly. And it will be loud as hell.
 
@Chris-PA Iirc 620 is 17.5mm venturi compared to something like 16mm for the 590, I get some time i will dig up carb numbers and verify those measurements.




Very interesting thread :clap::clap:
 
Interesting... The screen makes less difference than I would have guessed.

In winter, under cold/wet/snow conditions you could run a saw without a screen with no worries. But I took the screen out of one of my saws during a hot, dry period in summer, testing to see if I could get more power. I was cutting some dry pine and started a fire in the sawdust. It had the potential to have started a serious forest fire had I walked away from the cutting site without noticing the sawdust fire. With no screen the hot sparks coming out of the muffler are easy to see.
 
@Team FAST

If I sent you a modified 590 muffler would you be willing to test it?

I just got done porting my 590, still fighting some carb issues. But with a hole punched around the tube. Roughly 3/4" area and a new deflector on top, I feel it gained a good bit. Other than being real loud.



I added one of my large deflectors, and opened up most of the area around the tube.
I have 2 mode 590's to port, would be nice to Taylor port timing to flow bench numbers. Similar to selecting an auto camshaft to match head flow.
 
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