Mastermind Meets The MS661 Again

[MustangMike]

Keith, as I have previously stated, the objective is to have a uniform mix of air/fuel throughout the entire combustion chamber (no lean or rich areas). This simple concept was the key to the dramatic improvements in the performance of GM's traditional style engines. W/O turbulence, your mix will not be uniform.

 

[old-cat]

A tight squish gap gives extreme turbulence in the combustion chamber. GM used swirl shape right under the intake valve to create turbulence.
I have studied the GM engineer tech papers on their fast burn, swirl port engines.

 

[les-or-more]

Keith, as I have previously stated, the objective is to have a uniform mix of air/fuel throughout the entire combustion chamber (no lean or rich areas). This simple concept was the key to the dramatic improvements in the performance of GM's traditional style engines. W/O turbulence, your mix will not be uniform.

You are comparing apples to oranges, the 2 stroke needs to push the spent charge out with the fresh charge, mixing is not desirable, and there aren't any valves or extra strokes to achieve, what is done in the car engines.

 

[KG441c]

Well fellers GM dont make chainsaws!! Lol! I was interested in mamimum efficiency of the shape of the entrance to the exit of the transfers. Take more material out or leave more in, squared corners vs tapered exits on the upper transfers, flat ceiling vs progressive ceilings on the upper transfers?

 

[Mastermind]

Well, in my weak brain......and after typing this dozens of times.....

Everything you remove from the bottom end will lower case compression.

 

[les-or-more]

Well fellers GM dont make chainsaws!! Lol! I was interested in mamimum efficiency of the shape of the entrance to the exit of the transfers. Take more material out or leave more in, squared corners vs tapered exits on the upper transfers, flat ceiling vs progressive ceilings on the upper transfers?

That is where the incredibly simple two stroke gets incredibly complex.

 

[les-or-more]

Well, in my weak brain......and after typing this dozens of times.....

Everything you remove from the bottom end will lower case compression.

If only !
Everything is always a trade off.

 

[Mastermind]

So.......if you wanna grind all up in the lowers........you best be building a super high rpm race saw.......

 

[KG441c]

Well, in my weak brain......and after typing this dozens of times.....

Everything you remove from the bottom end will lower case compression.

That would include fingers and bridges wouldnt it Randy?

 

[KG441c]

So blend the bottom lip at the lower , smooth out any edges/imperfections in the passage, but the upper shape floor and ceiling and both side corners are where I know u have a nice recipe u like Randy?

 

[Mastermind]

It would include bridges and fingers. You might have noticed that I try just bridges, or just fingers, and sometimes both. I'm still learning you know....

Also think about the size of those bridges and fingers. They likely (I have no way to be certain) flow at a high velocity because they are small......right?

That's why I think (again, I have no way to be certain) they will be better in a work saw than enlarging the existing transfer passages.

All this is just ideas......thoughts.....some observations. What do you think?

 

[old-cat]

I say let's put a blower on the carb

 

[Mastermind]

I just barely knock the lip off the bottom in two port Stihls. I like to think that it keeps fuel from pooling there. It has nothing to do with flow.

Notice that the crank bells are as high or higher than that lip?

 

[Mastermind]

I say let's put a blower on the carb

That would work........if we had valves. lol

 

[KG441c]

It would include bridges and fingers. You might have noticed that I try just bridges, or just fingers, and sometimes both. I'm still learning you know....

Also think about the size of those bridges and fingers. They likely (I have no way to be certain) flow at a high velocity because they are small......right?

That's why I think (again, I have no way to be certain) they will be better in a work saw than enlarging the existing transfer passages.

All this is just ideas......thoughts.....some observations. What do you think?

I agree. Just like a waterhose with a broad or smaller exit tip creating more velocity and turbulance!! I never thought about it and guess thats why I called you in!!! Lol

 

[Mastermind]

These threads get good when we can kick ideas around.

I sure ain't got all the answers though.

Lynn, I'm thinking you may have a lot of good things to input here.

 

[les-or-more]

I say let's put a blower on the carb

How much do ya think ya push a 661 if you force fed it with a br600 Randy?

 

[old-cat]

Stuff I've learned about engines and flow, I don't have words for.

 

[KG441c]

Stuff I've learned about engines and flow, I don't have words for.

Cough that hairball up Oldcat and lets hear it!! Im trying to learn

 

[KG441c]

These threads get good when we can kick ideas around.

I sure ain't got all the answers though.

Lynn, I'm thinking you may have a lot of good things to input here.

Randy you have a slew of saws out there and 3 certified dyno saws that I know of that exceeded any expectations! Fire away if you are willing . Im all ears