Author Topic: Se cnc heads ?  (Read 579 times)

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Offline Clayton24

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Se cnc heads ?
« on: February 04, 2018, 09:48:01 PM »
Anyone ever notice the hump at the begining of the intake port of the se cnc factory heads ? Just curious and if so whats the purpose torque ? Port velocity?  Thanks just wanted sum opinions !

Offline Timinator

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Re: Se cnc heads ?
« Reply #1 on: February 05, 2018, 06:05:14 AM »
The hump is there to provide a larger, gentler radius on the short side of the intake port. The idea is to keep the flow attached there to try and equalize the flow around of the valve for greater flow. If the short side radius is too abrupt, then the flow gets turbulent, detaches from the port bottom, and is turbulent across the valves backside and amount of total flow suffers.
To increase torque, you can D-port the intake manifold and leading edge of the ramp by filling it somewhat and thereby making the leading edge of the ramp more gentle, or the MOCO could raise the intake port entry by a half inch and D port the entire thing, but they were too busy with the Milwaukee 8 deal. Those things have huge low velocity ports, and tiny cams to try to keep the torque up. Result, you have re-invented a V-Rod, no bottom end torque.
My shop foreman has just installed the SE V-Rod cams, and on our first ride, he killed it several times leaving the stop lites. I can still smoke him with my Breakout. He is still pissed.   TIMINATOR
MODESTY IS A CRUTCH FOR THE INCOMPETENT!!!

Offline BVHOG

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Re: Se cnc heads ?
« Reply #2 on: February 05, 2018, 06:32:51 AM »
I think he is referring to the little hump in the center floor of the port.  Didn't see this on the early versions. I would assume it is to help get the air around the guide.
If you don't have a sense of humor you probably have no sense at all.

Offline kd

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Re: Se cnc heads ?
« Reply #3 on: February 05, 2018, 06:42:49 AM »
Just a guess here and only from the description because I haven't looked at one but any humps are usually meant to increase velocity and cause a low pressure area behind the hump (which then pulls air into that void). Like BVBob says, it will pull or direct flow to an area that is not doing it's share of the work and help with a more efficient cylinder fill rate. The short side that Timinator describes is a good example.
KD

Offline Clayton24

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Re: Se cnc heads ?
« Reply #4 on: February 05, 2018, 06:48:58 AM »
Ok guys thanks ! Yes the little hump is the one i was wondering about . I see what u mean about helping air around the guide ! Thanks for everyones time
« Last Edit: February 05, 2018, 07:06:31 AM by Clayton24 »

Offline TorQuePimp

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Re: Se cnc heads ?
« Reply #5 on: February 05, 2018, 07:57:38 AM »
Has nothing to do with the guide

The hump keeps the air attached to the floor

Grind down the hump and blend it in the cfm goes down as does velocity

The seat,port,port opening,throat are all too large for the valve and yet it still works

The D port I've seen tried worked ok for 95 inch builds but DOA on 103 builds

Offline HD Street Performance

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Re: Se cnc heads ?
« Reply #6 on: February 11, 2018, 07:01:09 AM »
I tested the earlier versions and they had wrong geometry, flat lined and reversed at high lift.
http://harleytechtalk.com/index.php?topic=102052.0

Offline Clayton24

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Re: Se cnc heads ?
« Reply #7 on: February 11, 2018, 09:06:35 AM »
 So does a competition valve job help the flow quite a bit ? I was wondering about that i think now is a 3 angle ?

Offline BVHOG

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Re: Se cnc heads ?
« Reply #8 on: February 11, 2018, 09:28:47 AM »
Has nothing to do with the guide

The hump keeps the air attached to the floor

Grind down the hump and blend it in the cfm goes down as does velocity

The seat,port,port opening,throat are all too large for the valve and yet it still works

The D port I've seen tried worked ok for 95 inch builds but DOA on 103 builds
Interesting, what I was told at S&S years ago regarding the hump in the SS heads it was to have two fast columns of air going around the guide instead of one slow turbulent one.
If you don't have a sense of humor you probably have no sense at all.

Offline kd

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Re: Se cnc heads ?
« Reply #9 on: February 11, 2018, 11:55:37 AM »
Bob, as you know, it may force more flow around the hump as a natural effect, but generally a build up on the short side causes a low pressure zone on the backside that pulls air down to increase the fill and keep the throat pressure more equal around the circumference. As I understand it, one or the other becomes an unintended consequence of the other and need to be balanced to prevent turbulence. I think a better example of what you describe is the "fin" that some weld into the port at the bottom entry to the head. I think DVR is one person that uses that technique but I believe it is a significantly different device than the hump in the SE heads.   
KD

Offline HD Street Performance

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Re: Se cnc heads ?
« Reply #10 on: February 11, 2018, 11:57:24 AM »
There are other ways to accomplish the same thing

Offline TorQuePimp

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Re: Se cnc heads ?
« Reply #11 on: February 11, 2018, 05:50:31 PM »
Has nothing to do with the guide

The hump keeps the air attached to the floor

Grind down the hump and blend it in the cfm goes down as does velocity

The seat,port,port opening,throat are all too large for the valve and yet it still works

The D port I've seen tried worked ok for 95 inch builds but DOA on 103 builds
Interesting, what I was told at S&S years ago regarding the hump in the SS heads it was to have two fast columns of air going around the guide instead of one slow turbulent one.

Seems to work fine for 95-111 inchers but becomes a bit of a restriction on 117-124+

S&S has a void to fill there.....and they seem to be killing off products instead of developing new