Stihl Chainsaw

[walhondingMF]

562xp. I've been considering doing my own muffler mod but would prefer (for a reasonable price) just try a modified muffler. I have seen that the autotunes are actually good with exhaust changes because you just have to go through the tuning process.

 

[WinterDeere]

Here is a dyno of just muff mod on 261.

Nice! Looks like roughly +28% torque and +32% HP at 12k RPM. When you load it up, and RPM's drop (e.g. 8k) the margins get thinner, but still not bad. Also, RPM's are unlikely to drop as much with the higher torque up high.

Any word on how it affects operating temperature and reliability? Whenever I bring up mod's to my local saw shop, that's always their first response. I'm running some 30 and 40 year old saws every weekend, and one of them was bought off a pro that used it almost daily for most of it's life. These things last a long time in stock configuration.

 

[JeepHead]

Nice! Looks like roughly +28% torque and +32% HP at 12k RPM. When you load it up, and RPM's drop (e.g. 8k) the margins get thinner, but still not bad. Also, RPM's are unlikely to drop as much with the higher torque up high.

Any word on how it affects operating temperature and reliability? Whenever I bring up mod's to my local saw shop, that's always their first response. I'm running some 30 and 40 year old saws every weekend, and one of them was bought off a pro that used it almost daily for most of it's life. These things last a long time in stock configuration.

I have ported mufflers on many of my saws and run some every single day for a couple hours and 6-10 hours on weekend days. Have a few years on some of them with no issues.

 

[5030]

In reality, ANY muffler on ANY chainsaw is ALWAYS a compromise between noise abatement and scavenging. 2 stroke engines rely on exhaust gas scavenging to produce the most power and torque and no muffler will provide that efficiently. If you want to extract the ultimate power of any chainsaw you must remove the muffler entirely and install a tuned expansion chamber (Just like all competition sawyers use).

Of course that is impractical on a saw used for everyday operation so a muffler, which in reality isn't an efficient scavanger of exhaust gas is used.

I don't believe an expansion chamber would be very conducive in everyday application.

It helps to 'open up' a restricted (for noise abatement muffler but again, it's a muffler and not an expansion chamber so it will never be an efficient scavanger of exhaust gases which is paramount for extracting the most power from ANY 2 stroke engine.

Stihl is notorious for restricted mufflers because the succumbed to the 'noise police' years ago. On top of all that, 'approved' mufflers all have the required spark arrestor screen in them that further restricts the exhaust pulse and further lowers the already inefficient muffler.

Mufflers on ANY saw will hamper the engine's ability to rid itself of exhaust gasses.

Like I stated, you want maximum performance, fit an expansion chamber to it. A properly tuned expansion chamber is designed to use the exiting exhaust gas pulse to extract the next pulse and so on.

I modify ALL my saw mufflers to allow them to 'breathe' better, but no muffler will ever provide efficient scavenging of exhaust gas (and the intake of gas/oil mix) like a tuned expansion chamber can because NO muffler is capable of scavenging the exhaust pulse.

Once again, why ALL competition sawyers use expansion chambers and not mufflers.

Why, back in the day, 2 stroke MX bikes all had expansion chambers as well and even the famous Yamaha RD 350 Kenny Roberts street racer had expansion chambers fitted from the factory.

 

[Hay Dude]

I understand. I don't wear hearing protection and it doesn't bother me a bit. it's not obnoxiously loud but that may be different for you. But I thought you wore those fancy Bluetooth ear muffs?

I do wear the “fancy blue tooth earmuffs”.
It’s not me I’m worried about, it’s the customers.

I don’t do loud trucks or tractors or equipment. Turns off customers.
If I could, everything would be deleted, ported, tuned, etc., but it wouldn’t work in my area.

 

[xyz123]

For some reason I didn't think Egan was making one for the 261 yet. I own a couple of his mufflers and really like them. I also like that he dynos the saws and shows you exactly the gains from them. People woul be really surprised if they knew how much power these muffs add to a saw.

I thought it was 500i ask about.

 

[xyz123]

Does anyone make an exhaust like that for huskys?

I can tell ya a guy in OK that does some sweet muffler modding on huskys etc.

He did this 359 I have. I am not one to like pipes over a added deflector or a gill. But his welds is unreal.

Then my stock gasket delete 359 with just a FREE mod with gill.

Both have inner baffle opened up too. His way better then mine.

 

[walhondingMF]

Lots! Which model you looking for?

562xp

 

[xyz123]

I'll admit my saws are all bone-stock. Despite having spent most of my younger years building engines and hot rods, I've just never bothered touching my saws... but I've always been "saw mod-curious".

The thing I used to see so often with cars, would be guys putting a free flowing exhaust onto a stock engine, wrongly thinking they'd gain something from it. The trouble was that their OEM intake, cam, and even carb or ECM were all set up for building low-RPM torque for around-town driving. By making the exhaust mod, these guys would lose the back-pressure required to maintain this low-end torque, with the obvious goal of making up for it at higher rev's, but their intake side of the engine as all too starved to allow the free-flowing exhaust to actually provide any advantage at higher RPM. Guys would spend money on these exhaust systems, and their car would be louder and feel more exciting, but very little actual time and speed was gained at the track... if any.

Maybe saws are different, if the bottleneck is entirely on the exhaust side of the engine? Can a muffler mod alone really make much of a difference, without also making changes on the inlet side of things? I am definitely not looking for "louder" from my saw, just for the sake of noise, they're already too loud to let me hear my audiobooks while cutting.

Just his cover good for around 10%. But they are loud as

 

[xyz123]

I’m not sure if I want louder. I would really like more free flowing, but with that usually comes more noise.

Jason's little pipe puts out more then some of these guys ported 2511 with muffler mod. The 2511 is so choked down that is where most of the gains are.