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  #81  
Old 01-24-2015, 03:54 PM
Desertduler Desertduler is offline
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After more testing I am happy with the outcome.Next I am going to remove my cylinder and match it to my crankcase just like I have done to this spare piston port cylinder.These engines need the bottom of the cylinder opened up and matched to the crankcase like in these pictures and this is how I do it.One can see the path of the air fuel mixture as it leads out of the crankcase and into the transfer ports,it is very important to have the cylinder and transfer ports match here for maximum flow.The porting needs more hand blending in these photos and this is just the rough matching phase.I like to make changes one at a time and see what the effect is.
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  #82  
Old 01-24-2015, 05:08 PM
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So.....my question is......as you mill this "crankcase" through....is this a parallel track.....or is it out of parallel? ???

And would having it be out of parallel have any possible benefits? ??...(Like compressing air in a certain direction? )

Edit:.....Oh wait....I think I see it now....so....let me alter my question slightly.....it looks like the troughs are symmetrical....have you thought about or done any asymmetrical troughs?
  #83  
Old 01-25-2015, 07:17 AM
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Quote:
Originally Posted by Poboy kartman View Post
So.....my question is......as you mill this "crankcase" through....is this a parallel track.....or is it out of parallel? ???

And would having it be out of parallel have any possible benefits? ??...(Like compressing air in a certain direction? )

Edit:.....Oh wait....I think I see it now....so....let me alter my question slightly.....it looks like the troughs are symmetrical....have you thought about or done any asymmetrical troughs?
Doug,
What I am doing here with the mill is widening the bottom of the cylinder sleeve out to the width of the crankcase passage that leads to the transfer ports because there was quite a restriction in this location and the cylinder sleeve was narrower than the crankcase in this location thus causing an obstruction in the path of the intake track.This cylinder is a spare that I have and I am going to have it bored .050 mm (.020) and I set it up in my mill and did this procedure so that I would have my mill all set up as to do the same thing to my cylinder currently on my kart.I did not do this case matching to my engine before when it was a piston port because I did not what to remove any material out of the crankcase therefore increasing the volume of the crankcase and maybe cause the engine to have less bottom end power that it had at that time but now I am sure that I will have enough and I am going to remove my cylinder off of my kart and do the same thing to it today.As far as these cuts being symmetrical as they are in this state they will be blended by hand with stones and carbide burrs and the edges of the cut liner will contoured to the direction of air flow so they will be somewhat asymmetrical.Performing this procedure with my mill saves me a ton of time than doing it by free hand and one can get the dimension that is needed real fast and accurate compared by free handed work,yes there is some free hand work involved to finish the case matching but I cut over .200 off with all four cuts each and by using a long mill that is the correct size that cut the correct radius saves time.Notice in the picture with the crankcase (which is from a spare engine) that the cylinder sleeve matches the crankcase perfectly.I will post before and after pictures of my reed valved cylinder when I match it up to the crankcase.
  #84  
Old 01-25-2015, 08:31 AM
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Jeeze..Brett....you answered my question....but....I'm not sure anyone else can understand.....

Keep on trucking.......errr....sand flat karting......
  #85  
Old 01-25-2015, 08:55 AM
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hehehe.. I was able to follow, so I'd say a native speaker should be too

But I admit, I had to read it twice

'sid
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  #86  
Old 01-25-2015, 09:12 AM
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I guess I am confusing?I am confused that you guys are confused? Maybe I am just confused?
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Old 01-25-2015, 09:43 AM
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We're not confused......just awed.....and as far as this "two brain cells left" guy goes....struggle a bit.....to figure out what you are doing....exactly .....

It's not you.....it's me....WAIT....that was something else.........nevermind.....no....really....LET'S NOT GO THERE......IT'S OVER! !!!.....

Ummmm....I'm okay now.....really.....well....almost....
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Old 01-25-2015, 10:08 AM
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Quote:
Originally Posted by Poboy kartman View Post
We're not confused......just awed.....and as far as this "two brain cells left" guy goes....struggle a bit.....to figure out what you are doing....exactly .....

It's not you.....it's me....WAIT....that was something else.........nevermind.....no....really....LET'S NOT GO THERE......IT'S OVER! !!!.....

Ummmm....I'm okay now.....really.....well....almost....
Dude, give yourself some credit,both of you guys are smart as ****!
  #89  
Old 01-25-2015, 02:26 PM
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Everything's good Bret,
I had to read it twice since I think I skipped a line on my first try (or wasn't able to 'process the information' correctly)..
I can't tell anymore..

But I think it's pretty clear what you did and why.
at least to me...

In fact I understood Doug's question differently, again that might be 'my' lingual problem...
I thought he'd asked about a more significant asymmetric shape, to IDK...
...compensate airflow differences because of the crank / con rod position or something.
*shrugs*

But I guess "pretty much symmetric, except for differences due to manual fine tuning"
would answer that as well

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  #90  
Old 01-25-2015, 03:27 PM
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Quote:
Originally Posted by itsid View Post
Everything's good Bret,
I had to read it twice since I think I skipped a line on my first try (or wasn't able to 'process the information' correctly)..
I can't tell anymore..

But I think it's pretty clear what you did and why.
at least to me...

In fact I understood Doug's question differently, again that might be 'my' lingual problem...
I thought he'd asked about a more significant asymmetric shape, to IDK...
...compensate airflow differences because of the crank / con rod position or something.
*shrugs*

But I guess "pretty much symmetric, except for differences due to manual fine tuning"
would answer that as well

'sid
Not as much lost in translation as you might think Sid.....yes....what I was alluding to was whether the shape/flow/direction of this mod would vary from what was done on the intake side vs. the exhaust.....

At the end of the day.....this is going to be a very, very, minute difference......but.....this whole crankcase vent thing isn't going to add 1/10 hp most likely......but it's all about the little things that separates the winners from the losers......especially the more restrictive classes.....where everyone is on a "level' playing field......

I see what he is doing.....just wondered if he had gone to the point of considering altering each side differently.......
  #91  
Old 01-25-2015, 06:41 PM
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Ok,here are two side by side photos of the cross section of the cylinder liner in relation to the crankcase cross section and you can see the difference in width on the liners.One thing about two strokes a lot of people think that they are just a simple engine but that is not the case they are very complex. You are right Doug it is about all the little things that add up that make the difference but to feel 1 / 10th of a hp is hard to feel by the seat of the pants one thing about me is I do not sugar coat things and I have indeed spent many hours running engines on a Dyno and they do not lie, a Dyno opens ones eyes to fact and fiction for sure!
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  #92  
Old 01-25-2015, 06:55 PM
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Ohhhhh.....I get it now!!!! You draw arrows so the air knows which way to go!!!!!!

Edit:BTW:......As JJ Evans would say: DYNO.....might!!!!!!lol.....
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Old 01-25-2015, 07:07 PM
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I have a hard time with words sometimes!
So I have to use signs!
  #94  
Old 01-25-2015, 07:10 PM
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These are little things that make BIG booms! DYNO might!!!!
  #95  
Old 01-25-2015, 07:51 PM
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I pretty much sucked in fluid dynamics back in physics class, when it came to variable diffusion or what it's called...

it makes perfect sense to me, that you would not want any obstacle course for the air to tackle,
porting, "polishing" that's all pretty straight forward stuff I'd say.. even the semi smooth (ideally shark skin textures)..
or fitting the cylinder to the crankcase as in this example...

But even thinking about what asymmetry would offer an enhancemend..
purely theoretically... that makes my brain hurt.

And I doubt you could build a transparent crankcase just to visualize the airflow inside the crankcase with a running engine
so experiments would require a good amount of differently modified crank cases , a dyno and an insane amount of time.

I'm sure there's some kind of advanced software to figure that out on a computer, but even that would require an amount of effort, that is beyond me I assume.
(and I guess the software itself wouldn't be too cheap either )

What I do remember from physics class though is,
that a well placed obstacle can in fact IMPROVE the flow rates,
So, long story short...

Have you ever played with the idea of adding some sort of fin to the center of the transfer port?

'sid
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Old 01-25-2015, 09:35 PM
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There is a divider that separates the two transfer ports in the cylinder.
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Old 01-25-2015, 10:37 PM
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yes way up in the port...
but it .. oh dear, how can I explain that....
from what I remember the key point to divide interferring fluidal movement is
slightly in front of the entrance to the bottleneck...
that way, said 'fluids' (air for that matter) will not collide into each other but into a rigid wall, thus preventing most of the interferences... and can move much faster and with less effort through said bottleneck...

whoa, I hope you understand what I mean
Otherwise I'd rather draw a pic than to try again

Anyways, that is solely based on what little I remember, but it stuck to my mind, because at first it seemed counterintuitive for me, that a barrier can actually speed the flow up if it's at the right place...

'sid

[EDIT]
Oh wait.. that's exactly the same principle as for stadium exits...
like this one:

the rails you see just in front of the actual exit, help reducing the "interference"
(masses of people behave just like a fluid.. isn't physics wonderful?)
and thus reducing the time it takes to leave the stadium...
since up until that gate, they come from any direction, but all need to go in the same afterwards...
blablabla... channeling, faster.. because of an obstruction
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Old 01-26-2015, 06:26 PM
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I think that I am just going to do what has worked for me in the past and leave it at that.
No use messing up a good thing and I want to keep it that way.
I am done with all my blending of the liner and I will give the engine a test soon.
  #99  
Old 01-26-2015, 06:51 PM
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Quote:
Originally Posted by itsid View Post
yes way up in the port...
but it .. oh dear, how can I explain that....
from what I remember the key point to divide interferring fluidal movement is
slightly in front of the entrance to the bottleneck...
that way, said 'fluids' (air for that matter) will not collide into each other but into a rigid wall, thus preventing most of the interferences... and can move much faster and with less effort through said bottleneck...

whoa, I hope you understand what I mean
Otherwise I'd rather draw a pic than to try again

Anyways, that is solely based on what little I remember, but it stuck to my mind, because at first it seemed counterintuitive for me, that a barrier can actually speed the flow up if it's at the right place...

'sid

[EDIT]
Oh wait.. that's exactly the same principle as for stadium exits...
like this one:

the rails you see just in front of the actual exit, help reducing the "interference"
(masses of people behave just like a fluid.. isn't physics wonderful?)
and thus reducing the time it takes to leave the stadium...
since up until that gate, they come from any direction, but all need to go in the same afterwards...
blablabla... channeling, faster.. because of an obstruction
Yeah....ummmm.....here in Texas....we just put in a bunch of huge exit doors......but we do have something like that we use on cattle at the slaughter pens......
  #100  
Old 01-26-2015, 06:56 PM
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Quote:
Originally Posted by itsid View Post
yes way up in the port...
but it .. oh dear, how can I explain that....
from what I remember the key point to divide interferring fluidal movement is
slightly in front of the entrance to the bottleneck...
that way, said 'fluids' (air for that matter) will not collide into each other but into a rigid wall, thus preventing most of the interferences... and can move much faster and with less effort through said bottleneck...

whoa, I hope you understand what I mean
Otherwise I'd rather draw a pic than to try again

Anyways, that is solely based on what little I remember, but it stuck to my mind, because at first it seemed counterintuitive for me, that a barrier can actually speed the flow up if it's at the right place...

'sid

[EDIT]
Oh wait.. that's exactly the same principle as for stadium exits...
like this one:

the rails you see just in front of the actual exit, help reducing the "interference"
(masses of people behave just like a fluid.. isn't physics wonderful?)
and thus reducing the time it takes to leave the stadium...
since up until that gate, they come from any direction, but all need to go in the same afterwards...
blablabla... channeling, faster.. because of an obstruction
Rotax has that all figured out Sid,I am just letting more people go to the gate and then shoving there butts through it!
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