The short turn and its many shapes.

[MOPAROFFICIAL]

I was discussing this the other day while picking some parts up.

Every port is different. Ports not designed for all out performance are limited. The ssr is sometimes limited, the roof height or its pre designed shape etc..

The question:
Short turn shape..
Round or ramped,why..and two examples of heads you approach 180 of each other.

 

[pittsburghracer]

Many years ago I bought a head porting cd package from Speedtalk. They interviewed about five well known head porters and asked them various questions about port size, short turn shaping, and asked them how they go about working flow numbers at different lifts. I listened to them only once and treat them like gold but never really applied the techniques as I would have to listen to them over and over to get it to sink in. It may be worth looking into for you but I think I’m at the cement head stage and know what I want to do.

 

[pittsburghracer]

Discussion: "Porting by Numbers" Darin Morgan - Don Terrill’s Speed-Talk

 

[MOPARMAGA]

I'm working on understanding this question.
Trying to figure the common ground between all different heads,
Most iron heads I work on in our performance builds I will roll the short side, I don't remove alot of iron just enough to get a smooth radius. I don't mean smoothe as in polished just smooth transition feeling with my finger.
I am no way saying I'm a pro at porting but I do have a small idea of optimum shaping.
Or at least my boss hasn't complained lol

 

[pittsburghracer]

When I shape a short turn I push it back as far as I can so at the same time I am widening it to gain area slowing the speed at the turn. Then I start flipping the head in different directions and with knowing what part of the chamber the air is heading (center cut or wall) I can shape the turn so the air is headed in the right direction (ex: you wouldn’t want it going towards and into the cylinder wall). That’s why I always say think past the head meaning coming in and out. On stock cast iron stuff this thinking is limited because it’s easier to find water.

 

[MOPARMAGA]

When I shape a short turn I push it back as far as I can so at the same time I am widening it to gain area slowing the speed at the turn. Then I start flipping the head in different directions and with knowing what part of the chamber the air is heading (center cut or wall) I can shape the turn so the air is headed in the right direction (ex: you wouldn’t want it going towards and into the cylinder wall). That’s why I always say think past the head meaning coming in and out. On stock cast iron stuff this thinking is limited because it’s easier to find water.

Good explanation

 

[toolmanmike]

Asking for a friend, do you have to think about how the intake charge will be sucked into the cylinder v/s how the exhaust is pushed past the valve and out the port. Do the ports need to be a different shape? (I would imagine they would)

 

[Hysteric]

.

 

[Rat Bastid]

When I shape a short turn I push it back as far as I can so at the same time I am widening it to gain area slowing the speed at the turn. Then I start flipping the head in different directions and with knowing what part of the chamber the air is heading (center cut or wall) I can shape the turn so the air is headed in the right direction (ex: you wouldn’t want it going towards and into the cylinder wall). That’s why I always say think past the head meaning coming in and out. On stock cast iron stuff this thinking is limited because it’s easier to find water.

I disagree with the cylinder wall part. There isn’t much air there to start with. The air has to be made to go where it doesn’t want to go. Sometimes I take the cylinder wall side of the valve job out to the valve seat to get the air to get around that side of the valve. And yes, the throat is no longer round.

 

[Rat Bastid]

Asking for a friend, do you have to think about how the intake charge will be sucked into the cylinder v/s how the exhaust is pushed past the valve and out the port. Do the ports need to be a different shape? (I would imagine they would)

Yes. Yes.

 

[pittsburghracer]

I disagree with the cylinder wall part. There isn’t much air there to start with. The air has to be made to go where it doesn’t want to go. Sometimes I take the cylinder wall side of the valve job out to the valve seat to get the air to get around that side of the valve. And yes, the throat is no longer round.

There isn’t much air coming down the common wall. Hmmm. Image that.

 

[rumblefish360]

But yet it is highly recommended that the common all be addressed. Like you have shown before correct? Or would this be a porting level move best for an all out approach?

 

[MOPARMAGA]

After reading the article on Don Terrell, I understand .001% of what they're saying. I'll trust my gut on shape & see what a time slip has to say.

 

[pittsburghracer]

After reading the article on Don Terrell, I understand .001% of what they're saying. I'll trust my gut on shape & see what a time slip has to say.

It’s the “glory hole” of any well ported head and the hardest to understand

 

[MOPARMAGA]

It’s the “glory hole” of any well ported head and the hardest to understand

Yeah I think I need to remember that darin Morgan in that thread & most of those guys are head developers and while it pertains to cylinder head porting it is not cost effective to a true low budget racer. But I'm going to do some home electrical work for yellow rose in January and I'm going too pick his brain until it is simplified.

 

[MOPAROFFICIAL]

So how about higher up air down the middle and the floor air on each side...

J head...Say you worked the roof to max, bowl, straight wall n all...then u go round off the ssr near the straight wall ...watch the numbers drop.lol

I don't believe round is mandatory.

 

[MOPARMAGA]

So how about higher up air down the middle and the floor air on each side...

J head...Say you worked the roof to max, bowl, straight wall n all...then u go round off the ssr near the straight wall ...watch the numbers drop.lol

I don't believe round is mandatory.

Maybe more work to the throat would help that out ?

 

[MOPAROFFICIAL]

Maybe more work to the throat would help that out ?

Maybe.
Lipping is a way to manipulate the signal/ air speed...barrow from above.lol

 

[MOPARMAGA]

Maybe.
Lipping is a way to manipulate the signal/ air speed...barrow from above.lol

Lipping, I'm not familiar with the term.
What's that?

 

[rumblefish360]

We used that term when we were kids and it was a “Gross” disgusting term.

 

[MOPAROFFICIAL]

Lipping, I'm not familiar with the term.
What's that?

Where you leave an edge instead of rounding it off.
Anytime something becomes dead,low velocity, you can bring it back from the dead 'if the material is there' with a lip. You're playing with distance, in lamens. Nothings final of course.
Merry Christmas.

 

[MOPARMAGA]

Where you leave an edge instead of rounding it off.
Anytime something becomes dead,low velocity, you can bring it back from the dead 'if the material is there' with a lip. You're playing with distance, in lamens. Nothings final of course.
Merry Christmas.

Gotcha, thank you. Merry Christmas to you !

 

[MOPAROFFICIAL]

There isn’t much air coming down the common wall. Hmmm. Image that.

There's plenty if you dig

 

[MOPAROFFICIAL]

I'm working on understanding this question.
Trying to figure the common ground between all different heads,
Most iron heads I work on in our performance builds I will roll the short side, I don't remove alot of iron just enough to get a smooth radius. I don't mean smoothe as in polished just smooth transition feeling with my finger.
I am no way saying I'm a pro at porting but I do have a small idea of optimum shaping.
Or at least my boss hasn't complained lol

You can round it but if its hanging over/into the bowl..its in the way.
If you want easy low lift, from the 60 angle go 90 degrees leaving about .075-.090 width of 60 degree cut. For stock, 4-5 seat angles work well.

 

[MOPARMAGA]

You can round it but if its hanging over/into the bowl..its in the way.
If you want easy low lift, from the 60 angle go 90 degrees leaving about .075-.090 width of 60 degree cut. For stock, 4-5 seat angles work well.

Sorry to ask this but can you do a rough drawing of what you wrote, lol.
I'm having a hard time visualizing that