cat muffler vs free flowing muffler pros n cons

[67L36Driver]

Cats don't really work on chainsaws & are already phased out. I have gotten over them on cars and trucks. Used to cut em off, but they do work fine in the last 25 years or so.

And, the exhaust system runs much hotter prolonging the life of the muffler and pipes. Our local Midas Muffler shop has closed their doors.

Now where am I going to get free mufflers for 'Old blue'.

 

[1project2many]

Free? Still no fun to replace when you want to drive. Go stainless!

 

[Chris-PA]

A (non-strato) 2 stroke blows raw fuel out the exhaust, and these have carbs that are designed to run rich everywhere but at full load (and maybe idle if they have accelerator pumps). They run so rich that they misfire with only a small increase in rpm from lifting in the cut. Putting a cat on such an engine is like putting band-aid on a severed artery.

 

[67L36Driver]

Free? Still no fun to replace when you want to drive. Go stainless!

Stainless pipes with Midas lifetime guarantee mufflers. Three free pair since the first two I paid for.

 

[sunfish]

A (non-strato) 2 stroke blows raw fuel out the exhaust, and these have carbs that are designed to run rich everywhere but at full load (and maybe idle if they have accelerator pumps). They run so rich that they misfire with only a small increase in rpm from lifting in the cut. Putting a cat on such an engine is like putting band-aid on a severed artery.

Right, the cat just never did work on a chainsaw.

 

[CTYank]

If you're that worried about a little dirty air from the small amount of time you probably run a saw maybe you should stay in the kitchen.

Sent from my SAMSUNG-SGH-I727 using Tapatalk 2

Great country- America. We can have, and deal with, our own concerns, and most certainly have no use for your suggestions to "stay in the kitchen." Isn't that just a little supercilious? Often times, I'll be working in close proximity to multiple two-strokes, and highly appreciate stratos and cat-equipped Tanaka polesaw, regardless of your "guidance". I'm fussy about what I breathe.

If you can't deal with different viewpoints, well Good For You.

 

[CTYank]

Right, the cat just never did work on a chainsaw.

Can you cite references on that? In fact, my little 25 cc Tanaka polesaw has a cat muffler, and once the cat lights off, all the normal noxious 2-stroke schmutz goes bye-bye. Did I mention that I really like that saw? It's a little work-horse.

Any saw I'll buy nowadays will be strato-scavenged. The difference in nearby air quality is impressive to us aerobes. A Good Thing IMHO.

As mentioned earlier, there's a lot of truthiness floating about here.

 

[CTYank]

A (non-strato) 2 stroke blows raw fuel out the exhaust, and these have carbs that are designed to run rich everywhere but at full load (and maybe idle if they have accelerator pumps). They run so rich that they misfire with only a small increase in rpm from lifting in the cut. Putting a cat on such an engine is like putting band-aid on a severed artery.

Chris, youi have two big problems to dance around, regardless of the AFR.
1. If a cat does nothing, then where's the exothermal reaction that's liberating the substantial amount of heat? Could it be the catalytically-encouraged oxidation of the unburnt poo coming out of the port? Sure looks like it.
2. If a cat does nothing, do you not think that CARB and EPA would have picked up on that real quick?

Trying to get past the truthiness thing here, even when you're pizz-revving an engine in the garage, and it's misfiring noticeably, what's to stop the cat from getting the unused air and hydrocarbons to react, even if in part, which would reduce nasty-crap POM emissions?

When you're running closer to 12.5/1 AFR a cat should make major inroads into the poo-effluent.

Some mfgs (e.g. Tanaka in their 260pf saw) take further measures to reduce the amount of unburnt hydrocarbons that would have to be dealt with by the cat, partly to keep its temp lower and avoid damaging it. (Again, problem 1, above.)

IOW, I hope you see why I'm not buying it, and why "Abandon hope all ye who enter here" does not apply.

 

[Chris-PA]

Chris, youi have two big problems to dance around, regardless of the AFR.
1. If a cat does nothing, then where's the exothermal reaction that's liberating the substantial amount of heat? Could it be the catalytically-encouraged oxidation of the unburnt poo coming out of the port? Sure looks like it.
2. If a cat does nothing, do you not think that CARB and EPA would have picked up on that real quick?

Trying to get past the truthiness thing here, even when you're pizz-revving an engine in the garage, and it's misfiring noticeably, what's to stop the cat from getting the unused air and hydrocarbons to react, even if in part, which would reduce nasty-crap POM emissions?

When you're running closer to 12.5/1 AFR a cat should make major inroads into the poo-effluent.

Some mfgs (e.g. Tanaka in their 260pf saw) take further measures to reduce the amount of unburnt hydrocarbons that would have to be dealt with by the cat, partly to keep its temp lower and avoid damaging it. (Again, problem 1, above.)

IOW, I hope you see why I'm not buying it, and why "Abandon hope all ye who enter here" does not apply.

I didn't say it did nothing. Rather I listed the two major sources of raw fuel exiting the exhaust port, and noted that a cat is an inadequate solution to these problems.

• You can modify port timing and use quad transfers to help minimize scavenging losses, but this entails power/performance compromises.
  
• While the porting mods may reduce unburned fuel going out the exhaust port somewhat, the carbs are just the same. You can try to set them lean, but they still have a very non-linear fuel mixture output with increased air velocity and get massively rich. And since these carbs are so crude and inaccurate one risks engine damage with a lean mixture.
  
• The cat doesn't prevent the fuel from being lost out the port, it tries to react with it after the fact. The fuel is still lost. I do not believe a cat has that great a range of fuel mixture at which it can be effective, so unburned fuel is still getting out - though presumably good enough to meet the tests. And of course it gets very hot while trying to react with all that fuel.
  
• The cat may reduce directly toxic emissions, which is helpful for the operator, but it does nothing to reduce CO2 emissions or reduce fuel use.

This is why I say a cat has no place on a chainsaw engine with inherently high fuel loss and equipped with a fuel system that is designed to run rich enough to misfire with minor increases in rpm.

Now the fuel system situation may be a little different on a string trimmer with a small engine or a blower - same problem with the carb and fuel mixture, but the spinning string/fan probably represents a non-linear load that will limit rpm increase. Essentially, you can't "lift in the cut" and have the rpm take off and the mixture get fat the same way.

 

[svk]

I didn't say it did nothing. Rather I listed the two major sources of raw fuel exiting the exhaust port, and noted that a cat is an inadequate solution to these problems.

• You can modify port timing and use quad transfers to help minimize scavenging losses, but this entails power/performance compromises.
  
• While the porting mods may reduce unburned fuel going out the exhaust port somewhat, the carbs are just the same. You can try to set them lean, but they still have a very non-linear fuel mixture output with increased air velocity and get massively rich. And since these carbs are so crude and inaccurate one risks engine damage with a lean mixture.
  
• The cat doesn't prevent the fuel from being lost out the port, it tries to react with it after the fact. The fuel is still lost. I do not believe a cat has that great a range of fuel mixture at which it can be effective, so unburned fuel is still getting out - though presumably good enough to meet the tests. And of course it gets very hot while trying to react with all that fuel.
  
• The cat may reduce directly toxic emissions, which is helpful for the operator, but it does nothing to reduce CO2 emissions or reduce fuel use.

This is why I say a cat has no place on an engine with inherently high fuel loss and equipped with a fuel system that is designed to run rich enough to misfire with minor increases in rpm.

Now the fuel system situation may be a little different on a string trimmer with a small engine or a blower - same problem with the carb and fuel mixture, but the spinning string/fan probably represents a non-linear load that will limit rpm increase. Essentially, you can't "lift in the cut" and have the rpm take off.

Don't argue with him Chris, he knows everything....plus he has all of the best equipment....

 

[Chris-PA]

Don't argue with him Chris, he know everything....plus he has all of the best equipment....

Now I'm not going there - I know you guys don't get along but I'd like to think I can talk to both of you.

 

[svk]

Now I'm not going there - I know you guys don't get along but I'd like to think I can talk to both of you.

You can always talk to me, even if we don't agree. Although sometimes I side with your nemesis the spider

 

[TreeTangler]

Yeah, a lot of guys did that but I never could figure out how drawing hot air from the engine compartment helped! I kept the snorkel hooked up to cool air and made sure the door worked.

It didn't work. We were young and dumb and sounded good with dual tail pipes with no muffler! The girls back then used to like them loud, and I liked them girls!

 

[greenskeeper]

Wat would be the pros n cons o this subject and would ther be a noticable diff in power or zip from the saw any advice would help

Any engine will benefit from a less restrictive exhaust and intake. An engine is basically an air pump. However, the amount of difference maybe too small to notice.

 

[Idahonative]

Great country- America. We can have, and deal with, our own concerns, and most certainly have no use for your suggestions to "stay in the kitchen." Isn't that just a little supercilious? Often times, I'll be working in close proximity to multiple two-strokes, and highly appreciate stratos and cat-equipped Tanaka polesaw, regardless of your "guidance". I'm fussy about what I breathe.

If you can't deal with different viewpoints, well Good For You.

I like clean air as much as the next guy but seriously, if some chainsaw exhaust gets you worked up you have much bigger problems to worry about. If a non-cat chainsaw will ruin your day, just about anything will ruin your day. Besides, there are many new chainsaws on the market that don't have cats or strato technology and meet EPA regs.

 

[svk]

I like clean air as much as the next guy but seriously, if some chainsaw exhaust gets you worked up you have much bigger problems to worry about. If a non-cat chainsaw will ruin your day, just about anything will ruin your day.

Amen!!!

 

[CTYank]

I like clean air as much as the next guy but seriously, if some chainsaw exhaust gets you worked up you have much bigger problems to worry about. If a non-cat chainsaw will ruin your day, just about anything will ruin your day. Besides, there are many new chainsaws on the market that don't have cats or strato technology and meet EPA regs.

I'm guessing that you have no understanding of just how filthy 2-stroke exhaust can be. People have studied this, you know, and not just pulled some "truthy" thing out of their posteriors. In his book "Two Stroke Engine Repair & Maintenance" author aul Dempley quotes CARB: "An hour of weed whacking is the emissions equivalent of driving 834 miles in a modern automobile."

When you consider that most weed whackers are tiny ~20 cc things, you might conclude that most chainsaws may well be an order of magnitude beyond that. That presumes conscious thought, though, and intellectual honesty.

Your presumption to manage anyone's life in any way, based on some silly assumptions, can only be called what it is: B.S. Need I tell you what you can do with it? Have a nice day.

 

[CTYank]

Now I'm not going there - I know you guys don't get along but I'd like to think I can talk to both of you.

Anyone who's proven himself a neo-nazi poser, simply gets ignored. One of only three such. So I get along fine with Steve- I just pretend that such people don't exist. Life is too short to do otherwise. Yank me, sycophant.

 

[svk]

Anyone who's proven himself a neo-nazi poser, simply gets ignored. One of only three such. So I get along fine with Steve- I just pretend that such people don't exist. Life is too short to do otherwise. Yank me, sycophant.

Neo-nazi? You are really grasping now. Keep smoking those strato fumes.

 

[Idahonative]

I'm guessing that you have no understanding of just how filthy 2-stroke exhaust can be. People have studied this, you know, and not just pulled some "truthy" thing out of their posteriors. In his book "Two Stroke Engine Repair & Maintenance" author aul Dempley quotes CARB: "An hour of weed whacking is the emissions equivalent of driving 834 miles in a modern automobile."

When you consider that most weed whackers are tiny ~20 cc things, you might conclude that most chainsaws may well be an order of magnitude beyond that. That presumes conscious thought, though, and intellectual honesty.

Your presumption to manage anyone's life in any way, based on some silly assumptions, can only be called what it is: B.S. Need I tell you what you can do with it? Have a nice day.

Hahahaha. Let me lay a little "intellectual honesty" on you Bro: If you believe "an hour of weed whacking is the emissions equivalent of driving 834 miles in a modern automobile," then I have some real beautiful ocean front property to sell you in Idaho. Just because you read it doesn't mean it's true.

But then again you may be right...maybe I don't have an understanding of just how filthy 2-stroke exhaust can be. I mostly just say half truths and lies to make myself look tough on the internet and to pick on weak minded people.

I said it to someone else on AS recently who had all the answers on God's green earth: I guess you got it all figured out. Maybe I can polish up my conscious thought and intellectual honesty by reading some of that crap you've got your mind wrapped around.