Mastermind Meets The MS500i

[Farmchuck]

So.....color me confused.

There's no way at this point that I can pretend to really know that any of this is based in fact. As soon as I start to think I'm gonna kick a field goal, they will move the goal post.

There are a lot of areas in my life I feel this way about Randy.

 

[MG porting]

I think the blowdown time on this engine has more to do with emissions than performance.

There is that to good point.

 

[CR888]

Is it possible Stihl employed the staggered transfer port opening to better control the transfer charge bursting into the cylinder all at once?

 

[Mastermind]

Is it possible Stihl employed the staggered transfer port opening to better control the transfer charge bursting into the cylinder all at once?

Keep in mind that they open on the exhaust side first. Is that to help control the pattern of entrance, or is it to better allow exhaust gasses to enter?

 

[Stump Shot]

I don’t know one way or the other, but if blowdown allows time for the combustion gases to escape via their own pressure differential to atmosphere, couldn’t there be a problem with mixed fresh and spent gases that is causing the benefit of added blowdown, not simply a transfer duration or feeding the top end problem?
Run on sentence.....
Surrry.

I'm just looking at it from the angle that we added more intake and exhaust time, therefor why not a little more transfer time, being it's in the middle between the two?

 

[Stump Shot]

So.....color me confused.

There's no way at this point that I can pretend to really know that any of this is based in fact. As soon as I start to think I'm gonna kick a field goal, they will move the goal post.

Better than moving the ball at a critical moment.

 

[Stump Shot]

Keep in mind that they open on the exhaust side first. Is that to help control the pattern of entrance, or is it to better allow exhaust gasses to enter?

Put a factory jug under a faucet in the sink and the light will come on in U head.

 

[Agent Smith]

Good discussion! Just soaking up info here trying to learn something

 

[huskihl]

Keep in mind that they open on the exhaust side first. Is that to help control the pattern of entrance, or is it to better allow exhaust gasses to enter?

I think the slanted transfers allow back-stuffing on the exhaust side, which allows the fresh charge to be focused on the intake side of each transfer

 

[Mastermind]

Put a factory jug under a faucet in the sink and the light will come on in U head.

Yeah. I first started doing that on 346 jugs about ten years ago. LOL

It can be "illuminating"

 

[Mastermind]

I think the slanted transfers allow back-stuffing on the exhaust side, which allows the fresh charge to be focused on the intake side of each transfer

In my mind I picture what is going on in the transfer ports looking a lot like what we see when we look at the spitback on a saw running with no air filter or air horn.

 

[Mastermind]

Could widen a lot by ditching the bottom ring. But I'm not doing that on a real working saw.

 

[Mastermind]

Epoxy in all of em. In for a penny....in for a lb.

 

[Mastermind]

This is what 83° looks like.

 

[Mastermind]

Mmmmm metal splinters.

 

[Agent Smith]

Mmmmm metal splinters.

View attachment 218266 View attachment 218267 View attachment 218268 View attachment 218269

Gotta love working with nice new clean mufflers!

 

[TreeLife]

Could widen a lot by ditching the bottom ring. But I'm not doing that on a real working saw.

View attachment 218262 View attachment 218263

Love seeing your work Brother

 

[Mastermind]

Gonna take my lovely wife out here in a couple of hours. Hoping to get these mufflers and jugs done before we go....

 

[Agent Smith]

Well......

They increased the length of the transfer tunnels on the 462, and the 500i by casting part of them into the case. It's my understanding that allows the transfers to be back fed by exhaust gasses without them getting all the way into the crankcase. This then is used to purge the spent gasses from the combustion chamber with the back fed gasses in the transfers.

Yeah?

Nope?

GFY?

So they're using exhaust to purge exhaust? Seems counter productive to me.

 

[Mastermind]

So they're using exhaust to purge exhaust? Seems counter productive to me.

This is a good point to discuss.....

Anybody?