what is "strato charged"

[kurtty]

i keep on hearing about strato charged engines like in the 441. what defines a strato charged engine?

 

[PES+]

They have 2 sets of ports and a second butterfly that opens progressively from the main carburetor butterfly.

The transfers open after the main transfer ports and allow more complete combustion of the charge after the initial burn event.

Kind of like an air injection pump on a car engine.....adding oxygen after the initial power burn to oxidize/burn off the leftovers.

A very simplified definition because it is more involved than that

 

[icelation8]

In a 2 srtoke motor your in coming air/fuel mix pushes out the exhaust from the combustion chamber and you always loose some air/fuel mix out the exhaust. A stratified charge engine allows a charge of air into the combustion area in front of your air/fuel mix to push out the exhaust and to greatly reduce the amount of unburned fuel that is released through the exhaust. It boils done to emmisions is why this technology is becoming popular.

 

[PES+]

Are you confusing the compression wave with strato charged?

The Strato works a little different in theory and both designs currently do not deal with air density reduction at altitude well.

 

[icelation8]

Stratified charge introduces air in the cylinder to push the exhaust out. Thats the reason for 2 throttle valves in the carb on the 441 one is for air only the other is for fuel/air mix. There is a cutout in the piston that allows air to enter into the transfer points at the same time air/fuel is entering into the crankcase and the air enters the combustion chamber first to push the exhaust out. The result is less fuel exiting the exhaust which equals less hydrocarbons which equals less emmisions.

 

[Lakeside53]

I see nothing wrong with ices explanation of the 441...

 

[kevlar]

In a 2 srtoke motor your in coming air/fuel mix pushes out the exhaust from the combustion chamber and you always loose some air/fuel mix out the exhaust. A stratified charge engine allows a charge of air into the combustion area in front of your air/fuel mix to push out the exhaust and to greatly reduce the amount of unburned fuel that is released through the exhaust. It boils done to emmisions is why this technology is becoming popular.

Yep!

 

[Lakeside53]

No, I didn't write this (Stihl did), but..... it will help quell arguments that will undoubtedly arise.. I'm sure I posted an extract from a tech note a year or two back that detailed the sequence of operation.

 

[Lakeside53]

Here's the old discussion, See post 13 for tech details..


http://www.arboristsite.com/showthread.php?t=38362

 

[PES+]

That Stihl description (text) is describing the compression wave theory not strato charge theory.

The strato in strato charging means stratified....describing what happens within the combustion chamber. The layering of the gas mixtures to obtain a more complete combustion of the "wasted" extra incomplete burned charge inherent in a performance 2 stroke engine

The compression wave does as Stihl states and only arrives at a "cleaner" burn by changing in main port timing which render the engine it uses quite lackluster in performance

It doesn't help that Zenoah described their original design and patent in this way though that was filtered though the marketing department and lost something in translation from Japanese to English
(englisch for you Stihl guys)

 

[Haywire Haywood]

I always assumed that they called it stratified because of the layer of air in front of the layer of fuel air.

Ian

 

[Griffbm3]

I just thought they were talking about guitars and stuff... But thanks for the explanation Ice/Pes+/Lake...

Jason

 

[Zodiac45]

I just thought they were talking about guitars and stuff... But thanks for the explanation Ice/Pes+/Lake...

Jason

You thought they were "casting" strato charges!

 

[PES+]

The semantics are sticky at best........no question

 

[PES+]

Cool..I am going to call my clean 2 stroke "Telecast charged"

 

[icelation8]

compression wave theory do you mean back pressure from the muffler???
Straified means layer in the dictionary. A layer of air in the combustion chamber. It has nothing to do with a compression wave of any kind.

I really don't think we are talking the same thing here.

 

[PES+]

It is hard to find now but

I will search for the patent and white papers on the John Deere compression wave 2 stroke.

Like I said.....semantics and from the porting layouts I have seen with strato charged motors they do not simply use air at atmospheric pressure to close the exhaust.....it is a bit more involved.........however they may have gone back to that point in search of power which would explain a need for a cat with a strato charged design.

The odd part is, if that is what they have done, there are far simpler methods to achieve the same result.

I have not seen a 441 cylinder yet so I do not know how Stihl has laid it out

 

[PES+]

I will see if I can lay my hands on a 441 cylinder and a Husky 575........if that is what they are doing muffler modding will be a big no no as that will throw the whole design out the window

 

[icelation8]

This was posted by lake in a previous thread this is the new technology that STIHL is using and I have just seen material for i think it was echo having a similar design

Here's how the 441 version works...

 

[icelation8]

I will search for the patent and white papers on the John Deere compression wave 2 stroke.

Like I said.....semantics and from the porting layouts I have seen with strato charged motors they do not simply use air at atmospheric pressure to close the exhaust.....it is a bit more involved.........however they may have gone back to that point in search of power which would explain a need for a cat with a strato charged design.

The odd part is, if that is what they have done, there are far simpler methods to achieve the same result.

I have not seen a 441 cylinder yet so I do not know how Stihl has laid it out

The piston still closses the exhaust port its just the volume of air fuel mix that usually goes out the exhaust is replaced by a pure air charge before the air fuel enters the combustion chamber.