Advanced Engineering Tech - Heads... Intake and Exhaust Port Surface Texture

Well after reading the sticky in this forum, it got me thinking about the surface texture of heads in the intake and exhaust ports. I am interested in this because I am going to be buying some heads soon for my 427 project. I am looking at the AFR 225's, Patriot Stage III LS6, or the LS7 heads. I have seen pics of all of these and the surface texture varies. The Patriots have a very ridgy texture, while the AFR's are really smooth. There are some pics below of the pics I found. The pics of PRC's are supposed to be hand finished, but look like crap IMO. I can only assume that the smoother the better, right? So why do some heads come with a ridgy texture? Cost efficient? Do the ridges provide some sort of aerodynamic benefit, like swirling the air before it enters the cylinder? I am thinking that pretty much any head I get, except for AFR, I am going to want to go through with the sand paper to smooth and polish the intake and exhaust ports, then polish them up a little bit.

Right now I am leaning towards the LS7 heads. They only cost a little more bare than the Patriots do bare. Plus they are supposed to flow crazy numbers.

Any thoughts/ideas/expiriences are welcome. I would like to learn more about head design.

LS7 Heads:
http://12.203.3.3:6580/LS7Stuff/IMG_3701.JPG

PRC Heads:
http://members.cox.net/ss20493/videos/prcheads.jpg
http://members.cox.net/ss20493/videos/prcheads4.jpg

Patriot Heads:
http://i3.photobucket.com/albums/y98/99camaro/100_0739.jpg
http://i3.photobucket.com/albums/y98/99camaro/100_0757.jpg
http://ourworld.cs.com/ls1info/Patriot+Heads/DSC00034.JPG
http://ourworld.cs.com/ls1info/Patriot+Heads/DSC00027.JPG
http://ourworld.cs.com/ls1info/Patriot+Heads/DSC00026.JPG

Unknown Heads:
http://img.photobucket.com/albums/v252/lostpatrolman/100_2115.jpg

It is pretty much a cost issue, but can be the discretion of whoever is doing the programming. CNC tool paths are made up of "steps". Ideally, you would have a rough cut and then multiple finish operations with a CNC mill. On a production basis time is everything so many vendors are doing the entire operation in just one pass. That leads to tool chattering from removing a lot of material at one time. The depth steps (the lines you see in the ports) indicates how many and the spacing of the pecks. A step of what seems to be around .1" is a lot courser that steps of .005", but is 20 times faster to do. A super glass smooth CNC porting job is going to take all day, and cost a whole lot more money. The hand finishing option is still very much alive and well but most shops that offer "port polishing" really is an 80 or 100 grit finish and they all say it is not beneficial. But then...... I don't understand the concept of "Rat Rods" either. I understand the atomization and fuel pooling issue with carburated engines as far as ports being too smooth but on the LS1 the injector fires at the back side of the intake valve so I fail to see the benefit of "rough" ports leading to the bowl. Production porting is one thing, custom porting is another.

Worked every day for two months on these. Shop who set them up said they are pretty but to rough them up. I stuck with pretty.........
http://www.thelasershop.net/Corvette/Head2.jpg

Excellent thread Ferocity02 - I have been wondering the same as I try to decide whether or not I want to upgrade my heads. I would imagine a rougher texture would aid in the "mixing", but I'm no head expert either.

:lurk:

This is a good question to discuss :) Its based on Fluid Dynamics.

The effect of surface texture on flow is derived from two-dimensional anaylsis of fluid flows across a surface. What we desire to do is reduce the height of the boundary layer of flow across the surface, in order to maximize a laminar flow quality. There are two types of flow to consider, laminar (smooth) and turbulent. We also need to consider two different flow velocities when speaking about engines, subsonic and supersonic.

Intake flow velocity is subsonic, which is slower than supersonic of course. It has been proven by testing and mathematics that subsonic flows generally form a smoother (less height displacement) boundary layer on a slightly textured surface, compared to a smooth surface.

For example, take a golf ball. What are those dimples on the surface for? They are on the ball to help the flow "hug" the surface of the ball, which greatly reduces the boundary layer of flow across the surface. This creates less turbulence across the surface. Without the dimples, the golf ball would only fly about 2/3 of the distance it normally does. Thats why you never see smooth golf balls!

Intake ports benefit from a slightly textured surface. Polishing them to a mirror finish has shown no benefit. Some head porters glass bead the surface, some of them leave the sanding marks, some of them leave the CNC tool path marks. Even a nice smooth cast finish will work.

Exhaust flow is supersonic, and relies less on the surface texture. With supersonic speeds, there are slightly better gains shown with a high polished flow surface. Supersonic flow is less dependent on boundary layer flow, its more dependent on moving more quantity out, at high speeds. A smoother surface will help reduce restrictions at this higher flow velocity.

If you are interested in the math behind Boundary Layers and Laminar/Turbulent flows, here are some links I found:
http://wings.avkids.com/Book/Flight/advanced/move-01.html
http://www.allstar.fiu.edu/aero/Wing34.htm
http://www.see.ed.ac.uk/~johnc/teaching/fluidmechanics4/2003-04/fluids14/separation.html

didn't have to lurk long. thanks for the info Tony

http://www.thelasershop.net/Corvette/Head2.jpg
omg!! :eek: those things look amazing!!

http://www.thelasershop.net/Corvette/Head2.jpg

Polished combustion chambers are typically a good idea, since they provide less chance of pre-ignition from happening. On a smooth combustion chamber like those, there are less hot spots likely to form, which cause pre-ignition. The exhaust ports on that head would be great, but I'd rough up the intake ports slightly.

This is a good question to discuss :) Its based on Fluid Dynamics.
Intake ports benefit from a slightly textured surface.

I hear what your saying, heard it all before, but WHY do they benefit? Specifically fuel injection where it is just "air" traveling through the ports. Haven't seen too many bullets or planes with dimples all over. Not just trying to argue..... really would like to know.

Re read your post
"Intake flow velocity is subsonic, which is slower than supersonic of course. It has been proven by testing and mathematics that subsonic flows generally form a smoother (less height displacement) boundary layer on a slightly textured surface, compared to a smooth surface."
Pretty much does explain it. Going to research this.
Thanks, RonO

Bullets travel supersonic. Smooth surfaces are better in that case.

Airplanes use the shape of their wings to create lift, they aren't as concerned with surface texture. They are also streamlined by design, and do not create much drag. Same with cars, who would buy a dimpled body car? Some item designs are driven by aesthetics, some by function over form.

Do some research on head porters, maybe call a few of them and ask about surface texture. I can pretty much guarantee none of them will have mirror polished intake ports. Some of them might not know why its bad (haha), but I'll bet they tell you to leave the intakes slightly textured.

Its just about laminar flow across the surface. Slightly textured surface causes the first layer of flow (boundary layer) to hug the surface. This reduces flow friction at subsonic speeds, and allows the flow layers above the boundary layer to 'slip' more easily and reduce turbulence. Turbulence at subsonic speeds causes flow velocity to suffer.

Tony

I found a good link, that describes exactly what you just asked:
http://www.aerospaceweb.org/question/aerodynamics/q0215.shtml

:)

Bullets travel supersonic. Smooth surfaces are better in that case.

Airplanes use the shape of their wings to create lift, they aren't as concerned with surface texture. Same with cars, who would buy a dimpled body car? Some item designs are driven by aesthetics, some by function over form.

Do some research on head porters, maybe call a few of them and ask about surface texture. I can pretty much guarantee none of them will have mirror polished intake ports. Some of them might not know why its bad (haha), but I'll bet they tell you to leave the intakes slightly textured.

Its just about laminar flow across the surface. Slightly textured surface causes the first layer of flow (boundary layer) to hug the surface. This reduces flow friction at subsonic speeds, and allows the flow layers above the boundary layer to 'slip' more easily and reduce turbulence. Turbulence at subsonic speeds causes flow velocity to suffer.

Tony


Had chinese food the other day. My fortune cookie read "A wise man will learn more from a fool than a fool will learn from a wise man". Not sure where I fit in there. You are right about many porters. They do but dont know why and I have a bad habit of dismissing some old school statements without the facts. As far as the thread goes, would you agree that the quality and smoothness of available ports can be dependent on cost or just plain sloppy work?

I found a good link, that describes exactly what you just asked:
http://www.aerospaceweb.org/question/aerodynamics/q0215.shtml

:)
:confused: thats quite a bit to take in at once :jest: maybe i need to stay in the internal forum for now :judge:

I found a good link, that describes exactly what you just asked:
http://www.aerospaceweb.org/question/aerodynamics/q0215.shtml

:)

You should not have replied with that link. Now I have a new question. I read it and it concerns it flowing around objects. Specifically a sphere. Ports are a volume of air traveling within, and not around except for the guide boss. That seems completely different even as far as the being the opposite to me.

No, because I've seen some excellent head porters take a perfectly nice looking and polished port and then hit them with the glass bead blaster to texture the intake ports. I've also seen some use Scotchbrite pad looking drill bits, and some just use a med grade sanding roll. I've also seen their flow bench tests before/after, and the slightly textured ones put out better flow numbers. Its just basic fluid dynamics, backed up by calculations.

Now, some head porters just do sloppy work, period. :)

I'm an Engineer, so just like yourself, I asked alot of questions too! I also enjoy finding proof and calculations of why things work like they do.

I hear what your saying, heard it all before, but WHY do they benefit? Specifically fuel injection where it is just "air" traveling through the ports. Haven't seen too many bullets or planes with dimples all over. Not just trying to argue..... really would like to know.

Ahh but thats where your a little off base here, the intake port on any efi motor is still wet flowing. The manifold may be dry for 99% of it (up to the injector port) but irregardless of where the injector points it will still be an atomized fuel/air mixture (that is the idea right). The injector isn't spraying a stream right into the intake valve, it's a misting spray that fills the intake port, thus wet flow. You would benefit from roughing up those intake ports as stated. They sure are purrdy tho.

You should not have replied with that link. Now I have a new question. I read it and it concerns it flowing around objects. Specifically a sphere. Ports are a volume of air traveling within, and not around except for the guide boss. That seems completely different even as far as the being the opposite to me.

Yes, it can be confusing. You have to imagine just a portion of the surface of that golf ball. Its all about fluid flow over a surface (not an object). Fluid flow over a surface follows the same rules no matter what, whether that is over a golf ball or inside of a pipe. The goals are the same, to reduce the boundary layer along the surface, and to reduce turbulence.

Fun, isn't it? :jest:

I know what a pain in the ass I can be in a debate.... but I am learning from from you ( Mr. 9 ball) and appreciate your patience.

Here is some good reading about how flow goes thru a pipe/intake. They mention boundary layer, and how velocity is highest at the center of the pipe. Boundary layer causes flow friction, and textured surfaces reduce the size of the boundary layer, which increases the velocity at the center of the pipe. Another thing mentioned is smooth curves and piping for intakes and exhaust. Thats another principle, I'm sure most people know that more bends means more restriction due to changes in flow path causing turbulence. Thats why we use mandrel bends and slight angles in those bends, if possible. But, I suppose we are discussing surface texture within those intake tracts, so I'll keep on the subject.

http://www.bankspower.com/tech_howairflows.cfm

My wife suggested that she was a little frisky......... but I told her I was going to read an article on how air is a fluid. A fluid defined as having particles that easily move and change their relative position without a separation of the mass and that easily yield to pressure: ......... and now was not a good time.......
The Vette' needs my attention right now.

...For example, take a golf ball. What are those dimples on the surface for? They are on the ball to help the flow "hug" the surface of the ball, which greatly reduces the boundary layer of flow across the surface. This creates less turbulence across the surface. Without the dimples, the golf ball would only fly about 2/3 of the distance it normally does. Thats why you never see smooth golf balls!...

I'm going to have to disagree with this. The dimples on a golf ball are there to make it fly further, due to lift. The spining of the golf ball, created by the impact with the club spins the top of the ball backwards, which accelerates the air over the top and lowers the air pressure above the ball. The ball spinning forward on the bottom will increase the pressure of the air and give the ball lift.

...Airplanes use the shape of their wings to create lift, they aren't as concerned with surface texture. They are also streamlined by design, and do not create much drag. Same with cars, who would buy a dimpled body car? Some item designs are driven by aesthetics, some by function over form...

Airplanes are in fact concerned with surface texture. Airplanes manufactured with flush rivets will gain speed in cruise, due to the reduced drag on the airframe. e.g. they have flush, laminar flow surfaces, unlike panels manufactured with regular rivets.

You'd be surprised how much drag an airplane can create. :)

WOW! many Q&As, I seen an article in a magazine about ports for Formula 1 heads, they flowed a medium thru the port and micro cameras recorded how flow went , then use of CNC left the grooves, about .060 wide, so as to follow the flow lines thru the whole port, looked kind of weird, but then again they may not know much about engines.---- 900hp 180cu.in. N/A no power adders. just a thought and I prefer 9-Balls theorys

I'm going to have to disagree with this. The dimples on a golf ball are there to make it fly further, due to lift. The spining of the golf ball, created by the impact with the club spins the top of the ball backwards, which accelerates the air over the top and lowers the air pressure above the ball. The ball spinning forward on the bottom will increase the pressure of the air and give the ball lift.


You can disagree with it, but you'd be partially wrong. The dimples are not there to create lift, its the spinning motion of the ball that creates lift. The dimples are there to reduce drag. A golf ball has no lift if it isn't spinning. Golfers learn to strike the ball and create spin, to control the hook, slice, and lift. The ball itself does not create lift, it is forced to create lift. Here is a summarizing statement from that link I posted above:

The purpose of the dimples is to do just that--to create a rough surface that promotes an early transition to a turbulent boundary layer. This turbulence helps the flow remain attached to the surface of the ball and reduces the size of the separated wake so as to reduce the drag it generates in flight. When the drag is reduced, the ball flies farther.

Taken from:
http://www.aerospaceweb.org/question/aerodynamics/q0215.shtml

The golfball example is not applicable to this situation, it only applies to a sphere moving through a fluid. All the dimples do is allow the air to "stick" to the ball.

Main selling point of most light aircraft are their crusing speeds, if any of this were true, why is there not a single production aircraft that uses this dimple magic?

The golfball example is not applicable to this situation, it only applies to a sphere moving through a fluid. And you guys have it wrong anyways. All the dimples do is prevent the air from "sticking" to the ball. Very simple concept, and only works with spheres.

Main selling point of most light aircraft are their crusing speeds, if any of this were true, why is there not a single production aircraft that uses this dimple magic?


What do you have to back up your theories?

Good visual refernce.

http://wings.avkids.com/Book/Sports/instructor/golf-01.html

I'm a dumbass, ports aren't straight. :jest: Now that I think more about it, the dimples would provide an advantage at sharp turns, allowing the boudry layer to stick, but on straight portions it just adds drag maybe?

surface texture always affects the thickness of the boundary layer, no matter what shape the surface is. In school, we did our rough calculations using a simple 2D tile with varying surface textures. The idea is to apply the calculations derived from the 2D flow across that surface and apply it across an entire 3D body made up of small tiles. Look up the details on subsonic airflow inside of a pipe, its a more accurate representation of an intake port flow.

The golfball example is not applicable to this situation, it only applies to a sphere moving through a fluid. And you guys have it wrong anyways. All the dimples do is prevent the air from "sticking" to the ball. Very simple concept, and only works with spheres.

Main selling point of most light aircraft are their crusing speeds, if any of this were true, why is there not a single production aircraft that uses this dimple magic?

You have it backwards, the dimples makes the flow "STICK" to the ball and does NOT allow it to Separate(actually just reduces separation)!!!!! The separation creates drag, which is bad.



Why dont you see it on a wing? i'll tell you why! The flow separation at the trailing edge of a wing is nearly non exsistant... unless it is induced and wanted by the pilot because of the streamlined design of the wing. On a poorly designed wing... yes.. the dimples would help

Essentually what Nine Ball is trying to get you to understand is fluid friction. The dimples are a necessary evil of you will. If you look at the diagram of the golf balls you'll notice that the wake behind the golf ball with the dimples is less than the ball without. In the wake the air is also stagnant and creates a high pressure volume. The pressure differential between the back of the ball and the front of the ball slows it down. The dimples actually create friction and that friction helps the air "wrap" around the ball and reduce the wake, as the diagram shows. As a result, the pressure differential is reduced.

Depending on the situation, the negative can be used as a positive. In head flow the friction helps the air "wrap" around the ports allowing a greater volume of air to be moved through the port that otherwise would not have been able to.

So...... you have a layer of air (liquid, in the past I did some study on the Tesla Turbine for my nitro RC cars) that sticks to the port walls if they are prepared with a controlled scratching, and that enables the whole environment to be more "slippery" for a volume of air to pass through with greater velocity. Is that right? Does it basically "wet" the walls?

You can disagree with it, but you'd be partially wrong. The dimples are not there to create lift, its the spinning motion of the ball that creates lift. The dimples are there to reduce drag. A golf ball has no lift if it isn't spinning. Golfers learn to strike the ball and create spin, to control the hook, slice, and lift. The ball itself does not create lift, it is forced to create lift. Here is a summarizing statement from that link I posted above:

The purpose of the dimples is to do just that--to create a rough surface that promotes an early transition to a turbulent boundary layer. This turbulence helps the flow remain attached to the surface of the ball and reduces the size of the separated wake so as to reduce the drag it generates in flight. When the drag is reduced, the ball flies farther.

Taken from:
http://www.aerospaceweb.org/question/aerodynamics/q0215.shtml


I think with your original post, my first and your reply we covered the idea correctly. I could have worded it better. spinning + dimples = fly further.

Have you seen the golf ball that was baned from the PGA? It had a set of larger dimples on one plane of the ball, to make it always fly straight.


Partially worong means partially right too. :)

The same idea can bee seen in Mitsu lancers which have vortex generators at the rear of the roof, which essentially grab the air flowing over the roof and pull it down over the rear window to better act on the rear wing.

The air always adheres to the walls, no matter how smooth it is. Thats a given, especially in low speed subsonic environments. There is nothing that is more "slippery", the increased friction is being used in a positive manner.

The higher the friction, read: rougher walls, the more the fluid adheres to the walls. This friction helps "pull" the air around the corners. Essentially what you're doing is shaping the flow so you can move it faster around corners. It has a lot to do with the shearing involved with the air.

There is a lot more to head flow. This is just one of MANY considerations and processes going on.

Guys - Let's keep this on topic. I pasted some links for golf and airplane forums. Sorry, couldn't resist. :jest:

http://www.golflinks.com/Default.aspx?AffiliateId=3

http://www.simviation.com/cgi-bin/yabb/YaBB.cgi

The same idea can bee seen in Mitsu lancers which have vortex generators at the rear of the roof, which essentially grab the air flowing over the roof and pull it down over the rear window to better act on the rear wing.
I was reading over a discussion of that a couple of days go.
The way a vortex generator works is to create turbulence along the trailing edge of an object in order to eliminate the laminar flow of air coming from the object. I'm trying to come up with a good example, but the only one I can come up with is inappropriate. Ever have a wet object you're trying to remove from another object and you have hydro suction? Air can do the same thing. If you have laminar flow over/around some objects, a suction is created at the trailing edge that adds a significant amount of drag. When you create a vortex, the turbulence "releases" the suction and eliminates the drag. That's the reason they're used on specific places on an aircraft. If it helps anyone, I'll go out and talk with one of our mechanics about the vortex generators on our aircraft and get a good technical description... well and to double check my information.
Here is a good read that was posted in the thread
http://www.aerospaceweb.org/question/aerodynamics/q0009.shtml
On a car im thinking they make the air thats comming over the roof stick to th surface of the the body panels to 1)reduce drag, and 2)with the air sticking to the body of the car, I dont know how I really want to word this, but basicly puts the spoiler into better non turbulent air. With non turbulent air, im thinking the spoiler can make more down force with the same if not less drag.

If any of this is not correct, please excuse, im still a newb to this.

Not sure how a vortex generator applies inside a port. Have a question. Assuming the data as far as smooth verses rough port walls is conclusive that rougher walls produce better flow numbers, which would be more ideal. A linear, crosshatch or a radial pattern?
Or would that make a difference at all? Also, what data is available as far as the finish grit? Even mirror polished (like mine) is full of craters on a magnified level.

What about the swirl hump/bump thing that comes in stock LSx heads, as far as adding energy to the airstream and making the flow stick better?


I was reading over a discussion of that a couple of days go.

Here is a good read that was posted in the thread
http://www.aerospaceweb.org/question/aerodynamics/q0009.shtml
On a car im thinking they make the air thats comming over the roof stick to th surface of the the body panels to 1)reduce drag, and 2)with the air sticking to the body of the car, I dont know how I really want to word this, but basicly puts the spoiler into better non turbulent air. With non turbulent air, im thinking the spoiler can make more down force with the same if not less drag.

If any of this is not correct, please excuse, im still a newb to this.

Thats how it was explained to me. The "wing" sees smooth air, which allows it to create better downforce.

On an LS1 we have the injector aimed at the intake valve. With the rough port wall, fuel mixture theory then wouldn't there only be benefit to rough port beyond the injector's line of site? What if you had smooth mirror finish from the entry of the intake port up to where the the injector sprays fuel, and then a rough wall from there to the intake valve? Would that create the best of both worlds? Or would it create all kinds of tumble/swirl problems with a portion (floor) of the port having faster smooth flow and then past the injector slower flow from the rough wall?

Question: What would be the better option for the throttle body surface? Mine is polished at the moment, would it be better if it were textured?

Question: What would be the better option for the throttle body surface? Mine is polished at the moment, would it be better if it were textured?
No. The throttle body should be as smooth as possible I'd think since it is only moving air. You do not need to keep fuel suspended in the air stream so there is no need for a textured surface. :)

No. The throttle body should be as smooth as possible I'd think since it is only moving air. You do not need to keep fuel suspended in the air stream so there is no need for a textured surface. :)

Ah, that's what I thought. I guess the same goes for the exhaust port and intake tract up to the injector intersections. Lol, cliffnotes of the thread.

Ah, that's what I thought. I guess the same goes for the exhaust port and intake tract up to the injector intersections. Lol, cliffnotes of the thread.

I've also heard that the exhaust port should be polished so that carbon buildup in the little nooks and crannies is prevented.

I've also heard that the exhaust port should be polished so that carbon buildup in the little nooks and crannies is prevented.
:werd:

Some of you are confusing port design, turns and angles with something else. Vortex generators change the direction the air goes, in simple terms. Do not confuse shape, turns etc. with a finish. To me a golf ball moving in the air with drag is different than air and fuel being vaccumed. Aerodynamics plays a role in the golf ball and has a small effect in the vaccumed sitiuation. Not saying you can not use some of the ideas but there is a difference. Air moves faster than fuel, therefore there is a separation between the two in the port at some point. The term is best descrbe as Limiting Port Velocity. IMHO I think there is nothing to be found in the texture of the intake ports. I have seen ports that are rough on one side and smooth as glass on the other side with puddy. Who cares how pretty it is when installed on the motor as long as it makes power. There are show cars and there are race cars.

I got to thinking about this thread right after I got done porting my Fast90...

Within a cylinder head, a rough (non-polished) finish in the intake runner will increase flow.

Does the same hold true in the intake manifold? Based on head flows, I would think there is some to be gained by texturing the intake runners in the manifold.

And, would this follow true for a T.B. also? If the air is being directed like a cone, would there be less need for the increase in laminar flow? It is being directed unlike the golf ball.

Next we all will be sanding down the body..... 80 grit... maybe the side windows.

I think the throttle body and intake manifold need as smooth a surface as possible since they do not have fuel in them. The slightly rough surface in the intake port is to cause a small amount of turbulence to keep the fuel suspended in the air stream.

I have always been under the impression that the air that hits the "ripples " in
the port tumbles, cousing a increase in velocity for the air flowing over it.

Kind of like a roler bearing affect.

This also aids in fuel atomization. Without texture in the port you would
have puddles of fuel running down the walls, not suspended in flow.

Have you guy's read most of this thread? The Ripple as rough area's are meant to increase the flow of Laminar air.

I'm A Tech Inspector For Two Racing Associations. Heres The Scenario. End Of Season, Big Money Race, Using Spec Engines. One Car Is Obviousy Faster Than Everyone Else, While All Year He Was Slow. Upon Inspection It Is Revealed That The Entire Floor And Walls Of The Intake Are Dimpled, Much Like A Golfball. We Confiscated The Intake, Ran Back To Back Tests On Two Different Engines On Superflow Dyno Swapping Intakes Between Tests. Exact Same Intake, One Dimpled, One Not. Both Intakes Port Matched To The Heads. On These Two Engines The Dimpled Intake Made 23.9 And 23.2 Hp More. All Else Being Equal. Take It For What Its Worth. This Was Performed On Engines In The 650 Hp Range.

AH! the heck with it, just pump 20 boost into the ports and you will forget about what they look like, try it you will believe it. I have been watching this port shape business for 50 yrs , all the cams, all the pistons, rods, cranks , heads, carbs, injectors,ignitions,exhausts, nothing feels more better, he-he, than pressure in the intake. RON

Matty169, if the intake was not supose to be modified in any way. Maybe it was ported and the acid dipped (looks stock). Does the two intakes hold the same volume. Next it would be interesting to know what the flowed.

Unknown Heads:
http://img.photobucket.com/albums/v252/lostpatrolman/100_2115.jpg
i ported those. they are a carbide finish...we do that on purpose on a lot of our intake ports. the exhaust side gets a full polish, but nothing like a mirror, more like the intake ports that most people do.
also to note that runner is NOT a full race port, it is from a budget head, very close to what most would call a 'stage 2.'

HOW about direct chamber injection, would that change a lot of ideas on ports, but back to the old fashioned way , cnc grooves linear down the length of the inlet port then in the bowl the lines would start a swirl just below the seat so as to spin the air out of the valve area. that would also help swirl in the chamber. thats my thinking RON

A golf ball uses the dimpled texture to increase air flow around it to make it go farther when its in the air. Makes you think that the smooth surface may not be the best for direct5ional airflow. Most heads only take into account airflow disruption from an obsticle.

Have you guy's read most of this thread? The Ripple as rough area's are meant to increase the flow of Laminar air.

:stupid:

No. The throttle body should be as smooth as possible I'd think since it is only moving air. You do not need to keep fuel suspended in the air stream so there is no need for a textured surface. :)

The argument for a textured surface has so far not involved suspending fuel... We're mainly talking about 'pulling' the air around corners.

Fluids (dry air, before fuel is introduced, is considered a fluid in the engineering world because it has the same flow properties as a fluid) want to flow straight, and fight towards tangents in a corner. Using the rough surface as a drag it helps pull the air around the corner quicker (like using the rear independent brakes on a tractor to help turn sharper). Who wants to borrow my old Fluid Dynamics textbook? :lol:

off topic - I like the new 'Practical Engineering' forum, NineBall! :D

The argument for a textured surface has so far not involved suspending fuel... We're mainly talking about 'pulling' the air around corners.

Fluids (dry air, before fuel is introduced, is considered a fluid in the engineering world because it has the same flow properties as a fluid) want to flow straight, and fight towards tangents in a corner. Using the rough surface as a drag it helps pull the air around the corner quicker (like using the rear independent brakes on a tractor to help turn sharper). Who wants to borrow my old Fluid Dynamics textbook? :lol:

off topic - I like the new 'Practical Engineering' forum, NineBall! :D

I see. I see. So with the throttle body do we need a rough textured surface since there is no corner to turn? It is just straight into the intake manifold.
And the LS1 has a pretty straight intake port in the heads, so would it be of benefit to only have the textured surfafce at the short side radius, and smooth through the straight port?

no it was not acid dipped, this pattern was very obvious and looked like it was done with a 5/16 or so drill bit. Someone had alot of time involved. Engine builder tried to tell us that the intake was insalled by accident and he wanted us to sell it back to him. That didnt happen and they were fined. Inside of intake ports all micrometered the same and passed other tests. Casting marks inside intake were still visible and nearly identical.

Who wants to borrow my old Fluid Dynamics textbook?

I'll take it