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  1. #136
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    Quote Originally Posted by dwilfong View Post
    It only is a effect on a stream in reference to a curved surface.
    Don't read to much into it. look at the basic form.
    A jet of air will fallow a curved surface.
    That is why a inside radius is important in flow scenario in a eng
    Just one more thing to see with your 3rd eye when looking at flow in a block.
    I got some **** in my eye so it is hard to explain it.
    thats what I mean, it follows a curved surface if its open on the other side to apply the force from ambient
    Anyone that has worked on plumbing with high flows knows it detaches from the inside curve and creates cavitation that will erode holes in that inside curve
    Does it work better with a gas than a liquid?
    Where does that leave it when you have fuel in air mix?
    Head porters do wet flow testing for a reason
    Last edited by powerabout; 01-09-2018 at 08:49 PM.

  2. #137
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    The flow in a vee 2 stroke is very convaluted.
    From laminar to turbulent and back several times
    Not to mention stopping and starting and being hit with pressure waves

  3. #138
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    Quote Originally Posted by dwilfong View Post
    I just go off the premise that it's difficult to bend a column of air and keep it uniform at the same time ...

    https://en.wikipedia.org/wiki/Coand%C4%83_effect

    Thy this on for size and tell me if it fits.
    In the context I was using it . Number 5 illustration comes closest . While the media passing thru the rod slot is at less than ambient , if follows the path resembling that of going from a hallway into a large room . Resulting in the vortex seen at the bottom . Except for it is tumbling on both sides of the slot .

    Not sure your point , but you'll be happy to know ... when I deliver the next batch of "Championship winning" Porsche heads that I weld the floors up and add valve guide vanes . I'll be sure to tell the "wind doctor" dat Fong say "day better have day canoda effect bangin" ...

    When he ask's ...... Who ?

    Do you think he'll mean H. Canoda ... or you ?










  4. #139
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    Is it better to chamfer the lip or leave a lip on the rod slot?

    Click image for larger version. 

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    I CAN ALWAYS MAKE ANOTHER DOLLAR, BUT I CANNOT MAKE ANOTHER DAY

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  6. #140
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    Some of those ports will work better if there is a blended path from slot to them i would say.
    Boost and one finger?
    Imagine if the rod slot lined up with boost but because of the twisted layout of a outboard, they dont.
    Saying that inline engines dont make more power than a vee so i wonder how big an issue the rod slot is?.
    2hp/ci doable with both
    Last edited by powerabout; 01-10-2018 at 02:36 AM.

  7. #141
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    Chaz are you saying if you check for the coanda effect in a cannoli you get a "canoda"?

  8. #142
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    Doesnt hogging out the rod slot kill the bottom end?

  9. #143
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    Haven't noticed any loss by cutting just the end leading to the booster ports to straighten out the path to improve the straight through flow from intake through crankcase to cylinder in last half of port duration. Any other areas of it and I would expect it would, but haven't tried because feel it's a bad idea.

  10. #144
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    Quote Originally Posted by dwilfong View Post
    Mister Spaz I don't think he need a lesson .
    Looks like he knows about it already.......
    So your answer to the question is : Fungus Who

    Now do I believe you plucked a 6.0 out of a 05 to 14 Corvette or GTO , to drop in some rust bucket ... Nope .
    4.8 or 5.3 with early cathedrals ... dime a dozen .
    But without proof , I can't argue .

    Speakin of car motor's .. I still have a 706 ci 14* Big Chief that made 1350 on mule , plus 300 in the first gun and 250 in the second . I was thinking about slippin that in my Corvette ....



    B
    ut the 406 that's in it now is more than enough to get me in trouble ...


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  12. #145
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    Quote Originally Posted by AZMIDLYF View Post
    Is it better to chamfer the lip or leave a lip on the rod slot?

    Click image for larger version. 

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    As the piston ascends from BDC it closes off the transfers completely within the first 60* of movement . After that , there is no magic bullet theory that will have air making a sharp turn out , packing the transfer by turning back upward and filling a closed hole .. aint happening . However air will take the path of least resistance and follow the source up the bore .
    I've had a couple blocks here that had stuffers bolted to the floor that actually blocked the magic bullet . From what I hear , those motors are brutally fast and only have the pumping action to move media from one area to the next .

    I did get a good laugh at the whole 2.0 idea of as a way to make power .
    Going the other way , the big bore stuff lets you open the rod slot area more that a quarter inch after most of the old sleeve shelf is removed . The port width's also grow quite large , even sticking with the mild factory port / bore ratio .
    All you have to be able to do is blend the floor into the ports long wall and grind an effective transfer from the abundance of "extra" material that is now available .
    On the next set ( 3.6 L ) I think I want to weld a dam around the rod slot . It will slow reversion and if ground properly , will make a nice ski slope to roll the charge ..


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  14. #146
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    A little thinking out loud on the subject of rod slot mods and crankcase volume. I know there are two thoughts on the rod slot mods, one for and one against. The side against them claims the floor acts like a wall and reflects the charge into the boosters and side for them says the mod helps give a direct shot from the crankcase into the boosters ( Ive always run the mod, and feel it helps, and there was a reason merc done the mods on the hi-po motors . But when I do the mod, I fill in the crankcase elsewhere to make up for the increased volume)

    It seems to me for the mod to hurt would mean that the charge would be relying on a push from positive crankcase pressure the entire duration of the boosters to need the reflecting from the floor. But what if for the first half of the booster duration this is true as the piston is moving downward causing more than atmospheric pressure on crankcase, but as the piston changes direction and starts up the pressure now drops below atmospheric pressure causing reeds to open. Now you have a cooler fresh charge now flowing from intake through crankcase through rod slots and booster ports to cylinder on the second half of the duration of the boosters? In this case the slot mod would be beneficial.

    It seems to me if you are under pressure the whole time of booster duration and wait until after they close to drop crankcase pressure below atmospheric pressure to open reeds to fill crankcase , you would only get sufficient charging of crankcase in a small window of rpm. But if you start the flow at bdc, the slot mod works and once the piston closes the ports the air flow momentum is aready there to fill crankcase for the next go around and won't be as critical on the switching point from pressure change in crankcase causing a much wider power band range. Also the piston speed is much slower at bdc than it is as it travels up the bore giving a little leeway time to make the switch. Just my thoughts on the matter, now let the fun and criticism begin
    Last edited by FORBESAUTO; 01-12-2018 at 05:15 PM. Reason: Stupid auto correct on spelling

  15. #147
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    That's some funny stuff rite dere!

  16. #148
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    Quote Originally Posted by FORBESAUTO View Post
    A little thinking out loud on the subject of rod slot mods and crankcase volume. I know there are two thoughts on the rod slot mods, one for and one against. The side against them claims the floor acts like a wall and reflects the charge into the boosters and side for them says the mod helps give a direct shot from the crankcase into the boosters ( Ive always run the mod, and feel it helps, and there was a reason merc done the mods on the hi-po motors . But when I do the mod, I fill in the crankcase elsewhere to make up for the increased volume)

    It seems to me for the mod to hurt would mean that the charge would be relying on a push from positive crankcase pressure the entire duration of the boosters to need the reflecting from the floor. But what if for the first half of the booster duration this is true as the piston is moving downward causing more than atmospheric pressure on crankcase, but as the piston changes direction and starts up the pressure now drops below atmospheric pressure causing reeds to open. Now you have a cooler fresh charge now flowing from intake through crankcase through rod slots and booster ports to cylinder on the second half of the duration of the boosters? In this case the slot mod would be beneficial.

    It seems to me if you are under pressure the whole time of booster duration and wait until after they close to drop crankcase pressure below atmospheric pressure to open reeds to fill crankcase , you would only get sufficient charging of crankcase in a small window of rpm. But if you start the flow at bdc, the slot mod works and once the piston closes the ports the air flow momentum is aready there to fill crankcase for the next go around and won't be as critical on the switching point from pressure change in crankcase causing a much wider power band range. Also the piston speed is much slower at bdc than it is as it travels up the bore giving a little leeway time to make the switch. Just my thoughts on the matter, now let the fun and criticism begin
    First , great job on filling the front half on each side of the rod bolt "trench" with splash zone. I use it too , but I can never get it to lay down as nice as yours looks .


    And no criticism meant . Just can't break the laws of physics , as much as any of us might like to . Or somehow think we are exempt .
    I also agree with the statement about a column of air ( or any mass) in motion will continue to move in the same direction until it either loses momentum or hits the wall and stalls out .
    Lots of crankcase compression and angle on the transfer roofs are good if you have an expansion chamber to shove the lost charge back in . Without it , not so much .
    The 300 drag motors I was referring to , have floor stuffers that fill the piston's pretty good @ BDC . Everywhere else along the trip , they are in the way of "line of sight " transfer filling .
    Everybody , myself included .. put too much effort into the "boost port window area" because like I said earlier , once the port closes , that is no longer the path of least resistance . And as much as we would like it to , air will not "pre-pack" a closed ended hole under low pressure conditions ...

  17. #149
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    A person has to be seriously suffering from a severe case of Fungolosis to search out and mark a dog pooping on the wall as one of their favorite youtube video's ..

    I can understand the welder guy . It's a fake .. just like your video ..

    But I must admit , I am inspired by your series of educational videos ...

    So much so , that I think I will make one of my own .

    Topics to cover :

    How to video with a cell phone .

    Dragging pistons thru grindings on the table .

    Piston bowling with the block and front half .

    Dremel porting for $39.95 total investment.

    Engine assembly in the grinding room .

    And many - many more to follow ...

    PS ... nice soccer mom four door mini van ...


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  19. #150
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    So if it was covered already sorry. My question is at what point could the incoming charge over power the exhaust wave. By stuffing the crankcase. It seams like the returning exhaust wave could over power the incoming charge if you were to lower you crankcase volume to much. I would venture a guess that the engineer's at mercury would have calculated this in to the design of the 260's and 280's. Making stuffing only necessary to return the balance after working the rod slots and ports. Well just wondering if I'm to off based here or not?

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