Muffler restriction vs. cylinder temp.

[Fruecrue]

been doing some thinkin’

If an EGR valve was designed and implemented to reduce peak combustion temps in vehicle engines in order to drop emissions of noxious gases, would a stuffed up muffler on a two stroke do the same?

If so, the theory of reduced combustion temperature should lead to lower cylinder and combustion chamber temperature (at least that is what is stated in the explanation of EGR function).

Here’s where I’m going with this...
I have been working under he assumption that opening a muffler reduces restriction and promotes flow to make a two stroke run cooler.

This defies the logic of EGR design and combustion temperature. Does increased combustion efficiency actually raise operating temperature.

Has anyone ever tested this?
Are we all just operating on assumption?
Are there more factors at play here?

@Redbull661 - what say you? Are tests required?

 

[Chainsaw Jim]

Exhaust Gas Recirculation feeds exhaust gasses back through the intake to cool the temperature.

 

[XP_Slinger]

The way I’ve always understood EGR is the temp is lowered in the cylinder because the recycled exhaust acts as an almost inert gas that mixes with the fresh charge preventing a hotter, clean burn. This process also reduces the efficiency of combustion and engine performance as you know.

Though I don’t have empirical proof as you stated, I believe opening up the muffler does help reduce overall cylinder temp simply because the muffler isn’t holding onto exhaust as long. Would be a pretty easy experiment with a pyrometer or one of @Redbull661 s thermocouples.

Interesting topic

 

[Fruecrue]

Exhaust Gas Recirculation feeds exhaust gasses back through the intake to cool the temperature.

Would you agree that the end result would be similar? inert gases mixed with air / fuel before combustion.

 

[Chainsaw Jim]

The way I’ve always understood EGR is the temp is lowered in the cylinder because the recycled exhaust acts as an almost inert gas that mixes with the fresh charge preventing a hotter, clean burn. This process also reduces the efficiency of combustion and engine performance as you know.

Though I don’t have empirical proof as you stated, I believe opening up the muffler does help reduce overall cylinder temp simply because the muffler isn’t holding onto exhaust as long. Would be a pretty easy experiment with a pyrometer or one of @Redbull661 s thermocouples.

Interesting topic

There's over 1 billion automobiles in use around the world every day. I imagine if there were as many chainsaws in use there would be a major difference in the emission technology.
I'm wondering if a two stroke motor is able to run with one.

 

[Chainsaw Jim]

Would you agree that the end result would be similar? inert gases mixed with air / fuel before combustion.

With the sole focus on temperature...I'm assuming so. I'm wondering if their target was restricting emissions and the cooler temp was just a by-product.

 

[Stump Shot]

There are plenty of examples of stopped up 2 stroke mufflers in the home owner grade of equipment for examples to look to. From what I see, it's a stop gap measure to reduce emissions at the expense of the longevity of the equipment. Stuff today is just flat out designed to fail at this level and on purpose. I see lots of ring collapses from caramelization of the excess carbon deposits. Repairing this equipment includes a repair to the muffler as well for it to last and last well past it's design parameters.
I don't think I would want exhaust in the crankcase with the bearings and such, would be the next design failure in my opinion. The gubberment would probably think it a good idea though, surely.

 

[XP_Slinger]

A tuner pipe would be about all the EGR I would want on a saw

 

[RI Chevy]

I think EGR in cars also reburns any excess fuels that were not burned in the original intake/exhaust process to further reduce emissions. At least in theory. LOL

 

[blsnelling]

No. Preventing hot exhaust gasses from exiting a saw will never make it run cooler.

 

[Al Smith]

--just the opposite---if anything it will toast the exhaust side of the piston .

 

[RI Chevy]

What about these things? Copper plates that go on exhaust. They work?

 

[nohoff]

Car engines have 2 types of EGRs.
Internal EGR which uses only intake/exhaust valves.
Or external EGRs with cooling.

 

[Wilhelm]

What about these things? Copper plates that go on exhaust. They work?

That thing looks as if it would only help restrict air flow around the cylinder fins.

Copper heat sinks are great compared to aluminum, but the design is crucial.

Back in the days of overclocking my desktop PC I reduced idle CPU temps by 10°C by replacing Intel's stock aluminum heat sink with a full copper Zalman.

 

[Outback]

I think high cylinder peak pressure/temp is responsible for nitrogen oxides, the purpose of egr I believe is to reduce peak combustion temperatures and reduce NOx emissions specifically. That's why they want egr on all the diesels so bad, because of the higher cylinder operating pressures resulting in NOx. I've heard of new f350's getting 25mpg with the egr and other emissions equipment removed so I would argue egr is a performance hindrance. The cat cleans up the dirty excess hydrocarbons, the egr reduced NOx at the combustion point. Or I'm dumb, who knows.

 

[nohoff]

I did a egr remove on my VW Diesel and it gave me additional 7 mpg. (63 mpg )

Who likes to smell his own farts all day?

 

[RIDE-RED 350r]

EGR=*s-word

 

[XP_Slinger]

My 5.9 non-emissions Cummins gets over 20mpg, my friends smogger 6.7 barely gets 16mpg. Diesels HATE breathing their own farts

 

[Al Smith]

Most if not all modern mandates for small engines,like chainsaws etc serve very little purpose in the broad spectrum of things .It only appeals to the anal retentive types concerning noise ,pollution etc .They are so small compared to the zillions of motor vehicles its almost an exercise in futility .Everybody has an opinion and that's mine .

 

[blsnelling]

What about these things? Copper plates that go on exhaust. They work?

They work very well.....at restricting air flow.