Air Flow / CFM's

[Chaz]

Yes thy where all single cyl eng with a tune pipe.

https://youtu.be/CKtKA7Sg0Bs
Here is a little test I did on a bet that it would not work.
24/7 intake on a 2 stroke eng. In other words no intake valve at all. Intake open strait to the case.
Will get back to this after my Vector 2.5 Merc project is done.
24/7 is the holly grail of 2 stroke theory right now.
Stratified intakes on 2 strokes is a thing that has not bin tested except for leaning out the charge at High RPM for emissions on small 2 stroke eng.
There is much more there than that.
The next test eng will be a stratified intake 2 stroke.

Fong ,
I played with model airplanes when I was a kid , and then 30 years later with my son. I also am pretty good friends with Mike Smith , son and instructor at his dad's Top Fuel School . I can tell you that there is not much in common between those two entities , let alone a two stroke outboard motor running on gasoline .
Now all the Einstein theory stuff is fun to read and laugh about , but when you post the slight of hand trick video ... you give proof positive ..

2:37 Left hand ,, now watch no funny business ...



2:38 OK , I'm taking the cover off now ....



2:40 Pay no attention to the man behind the curtain , or where my left hand went ..



2:40 See , no disc valve ....



2:42 Or in the cover which has been gone from sight for aprox five seconds ...



Yippppie ... I won the bet ! Pfffttttttttttt
Everyone deserves a chance to prove their point .... when you get your hydrostream up . Your shoud run it with the cowl off , so we can quantificate the pulsifacation thru the 1/2" holes you drilled thru your block , proving that with the correct stratification there is no need for crankcase pressufacation ...

[Chaz]

Probably not as boring as watching Fast and Loud last night .

And this might belong in the "finger port" thread , but I'll post it here ...

Notice how quick the pulse is diminished as he moves away from the source of vacuum .

Look at the river of fuel and how it runs down some ports while others it's barely noticeable .

Imagine how it looks while subjected to 3 - 4 G's as it leaves the starting line ...

[W2F a V-King]

That's an awesome video. Never thought so much liquid fuel moving around like that. Figured it would head for the port.

Maybe different in an EFI environment? With better atomization of fuel out of the injectors?

Would a two stroke have such the radical pulses? Thought at high rpm it more of a flow than a pulse in the two stroke.

Cool Vid..THX

[powerabout]

That's an awesome video. Never thought so much liquid fuel moving around like that. Figured it would head for the port.

Maybe different in an EFI environment? With better atomization of fuel out of the injectors?

Would a two stroke have such the radical pulses? Thought at high rpm it more of a flow than a pulse in the two stroke.

Cool Vid..THX

hence just about all OEM's are going DFI and outboards were pretty much main stream first but this has only really worked since they generate massive injection pressure to atomise the fuel as there is very little time to mix with the air.
( yeh yeh Mercedes did it in the 50's)

[dwilfong]

Fong ,
I played with model airplanes when I was a kid , and then 30 years later with my son. I also am pretty good friends with Mike Smith , son and instructor at his dad's Top Fuel School . I can tell you that there is not much in common between those two entities , let alone a two stroke outboard motor running on gasoline .
Now all the Einstein theory stuff is fun to read and laugh about , but when you post the slight of hand trick video ... you give proof positive ..

2:37 Left hand ,, now watch no funny business ...



2:38 OK , I'm taking the cover off now ....



2:40 Pay no attention to the man behind the curtain , or where my left hand went ..



2:40 See , no disc valve ....



2:42 Or in the cover which has been gone from sight for aprox five seconds ...



Yippppie ... I won the bet ! Pfffttttttttttt
Everyone deserves a chance to prove their point .... when you get your hydrostream up . Your shoud run it with the cowl off , so we can quantificate the pulsifacation thru the 1/2" holes you drilled thru your block , proving that with the correct stratification there is no need for crankcase pressufacation ...

YA you got me................. what ever Chaz.............no slight of hand sorry.............the disk did not just lift of the crank pin and stick to the back plate. .........LOL
Did more than win a bet got a lot of people thinking and credit for running it like this in a noted publication.
This aint your dads Cox .049......LOL
As far as it not pertaining to a gas outboard.....got the same BS from the toy boat guys when I started messing with them.
A eng is a eng no mater what it is on.
There is no need for a intake valve with the right ex system and resonator on the intake.

[AZMIDLYF]

So that's what a finger port is.

DFI would take care of the fuel equation but tuning those pulses should reap big benefits.

[FMP]

[QUOTE=AZMIDLYF;2929034]So that's what a finger port is.


that's what she said LOL Honestly, she had no idea. Thought we're a bunch of degenerates!

[dwilfong]

Yes the pulses out the intake are what intrigued me the most. This was a no load test run and the pipe was not involved as it would be under load.
Have a feeling the intake pressure wave will diminish when the pipe starts to suck on the finger port........LOL
I will do more testing under load with a constant load dyno I have in the design stages. Hard than you would think to constant load 8+ HP at 30000RPM
Yes that's 8+ HP from 1 CID eng you can hold in your hand..................................
Those Italians take there toys seriously..................
So you see calculating CFM on a 2 stroke is not as strait forward as on a 4 stroke.
That is what this whole tread is about now is it not????????????
You all keep looking at the slow motion animation of a 2 stroke eng as described in the bibles and I will keep pondering on Tesla......................

[FMP]

What's the idle speed on that little motor? No pipe,exports to the wind,I would think
without a Reed the only thing keeping it running is the small amount of ex scavenging
behind the pulse at high RPM dragging fresh charge into the cyl with the help of atmospheric pressure . Think at least one of my chainsaws works the same.

[dwilfong]

What's the idle speed on that little motor? No pipe,exports to the wind,I would think
without a Reed the only thing keeping it running is the small amount of ex scavenging
behind the pulse at high RPM dragging fresh charge into the cyl with the help of atmospheric pressure . Think at least one of my chainsaws works the same.

Under a load in the water it will idle down to about 2000 and still pull up. Thy have a pipe on them. That is where most of the power comes from.
On the no load test it started because the carb is closed to idle and not all the pressure will push out the carb.
Yes the pressure difference is what fills the cylinder. That is where the pipe comes into play.
The scavenging from the ex has a lot to do with how a 2 stroke breathes. The problem is it is a narrow window of power.
As far as a consumer friendly wide power band eng this is all useless.............

[FMP]

So 8hp with or without a valve? Yes ex scavenging has a lot to do with it. That pressure not leaving the closed carb, do you think it's from decreasing cyl volume spilling back into the case prior to port closing or rebound of flowing fresh charge hitting the
closed port, inertia?

[dwilfong]

With a valve. The run in the video was just to prove a point for now. The flow from starting is from the area difference between the carb and the transfer port. Nothing more than just a piston pumping action. Now after it was running the pipe took control of the pressure difference. It creates a lower pressure wave that travels to the case and that was what draws the air in to the carb opening.
The reason this eng would take air and fuel as where others would not is the porting in the case. I call it line of sight porting.
I cut the skirt off the back side of the piston higher than the wrist pin. Then I cut the sleeve to match.
The piston and sleeve gust get in the way............LOL
Bet you never seen a 2 stroke piston cut like this and still run hard and not blow up. Screwed with a few peoples heads.................
The rocking is controlled in this front to back eng set up by the wrist pin and the wide front skirt. Dose not take as much as you think to control the piston. These are all bottom guide rod setups so it takes the rod control off the piston. There are two different ways to look at the replicating mass control and where the friction matters most.
This was the first eng I did in a smaller displacement.

[FMP]

I didn't notice a pipe,just ex ports open facing the camera. The lower pressure wave is simply the low behind the pulse leaving the ex port. As the transfer opens this draws the charge however without valving the down stroke will expell the case out the carb at low RPM. At high RPM such as you described, it could just be pure flow enertia of the fresh charge and the compression of the CC with pumping is overcome until the transfer opens. Is the skirt cut to expose the case at TDC to the ex passage?

[dwilfong]

No sub porting on this eng. Like I said the sub porting did not pan out on this kind of eng.
You have to get the picture of the animation out of your mind for get about the piston.
Think about how much air is moving threw the case. Do you think it is all making that trip like you see in the animated 2 stroke diagrams?
How many time a second is the piston moving up and down in 1 second at lets say 6000 RPM now how many at 10000rpm?
Yet alone 30000rpm!!!!!
Do you think that animation it a true representation of what is going on in the case of this eng ?
You have to look past what you have bin taught. The 2 stroke eng is not a static model it is more of a living entity.
It runs more on harmonics than mechanical function.
I know I am crazy......This is where most stop listening to what I say........LOL
I will leave it there for those that want to ponder over it.......
Haven to get back to sanding this dam Vector before I lose my mind.
Crap what am I saying I already lost that a long time ago.

[dwilfong]

O one last thing to ponder pulse jet............................