Yes and No.

You want the airflow down the pipe as smooth as possible for the maximum CFM's you can get. Gennerally out of the factory the casting is blasted some, but not to perfection like a speed shop will do.

As for the golf ball, the do interupt the flow of air, but in a positive sense in keeping the ball up in the air longer, compared to a perfectly smooth ball. It wasn't til the early 20s (or around there) that someone figured out by putting the little nips in, resulted in longer drives (because the ball will stay aloft longer.)

 

Hi Ken:

If you look at the drag coefficient on a sphere, it remains pretty constant for a long range of air flow until the flow becomes turbulent, and a large wake (higher pressure) builds up behind the ball, reducing the drag coefficient significantly. Remember, drag is caused by high pressure in front, low pressure in rear. If the pressure in the rear increases, the drag goes down a lot.

The job of the dimples is to force the flow into the turbulent regime earlier, hence reducing the drag, making the ball go further. It has to do with drag, not lift.

 

on the intake a rough surface is desireable. I will give you an example. When air contacts a suface, there is a region known as a boundary layer. To give an example of this, drive down the highway at 70 mph in a mild rainstorm. Notice that the raindrops are moving very slowing, slower than walking speed. Notice that even though they are fighting gravity, they shouldn't be so slow. The air outside is blowing at at least 60 mph against these drops, and should easily wisk them away. The reason it doesn't is there is a boundary layer of air that is nearly stationary. The same thing happens in your intake. However in your intake there won't be water droplets, there will be fuel droplets. You want the fuel to mix with an remain in suspension in the air. The solution is to eliminate the boundary layer. A smooth surface will ALWAYS have a boundary layer. In fact, the smoother the surface, the thicker and slower this boundary layer will be. The solution is to create a rough surface that yeilds turbulence. This turbulence actually increases power, fuel economy, and give a broader powerband. Polished intakes ALWAYS suffer a power loss. If a gain is noticed, it is because the polished intake was not the only modification made. Do a polish alone, and you are guaranteed to loose power, sometimes by as much a 7%. Do a roughened port, and you can sometimes gain as much as 12%, depending on the design of the intake. Most ports are not left factory rough to save on time and money, it makes the vehicle run better. The same mods typically done along with a port and polish often work better with a roughened ports.

 

porting is done to increase port size and thus port flow-most effective on high performance high horsepower engines..never enough airflow into engine especially normally aspirated engine...also to smooth the transition from intake manifold to iron head...carbureted intake manifold throats were ported to increase total air flow, match to larger carb base...

polishing was done on carbureted engines to reduce fuel being pulled out of atomized air/fuel mix by rough manifold surface causing uneven mixture and raw fuel pooling in intake runners....hi pro carb intake manifolds usually do not have exhaust heat riser crossover to heat manifold fuel mixture so intake is colder..
most power gains in modern FI factory engines are to be made on the exhaust side if one is willing to evade the enviromental regs and chop off the power robbing cats and chip the PCM with a non cat profile....hydrogen technology will solve this power robbing crazy cat technology.

 

Thank you guys for advising me to do the right thing, my heads have been rebuilt to A- standards by a 300 year old artisan who does the prussian blue thing on each valve after the precision grinding oeration. Thank You again.

ken

 

If rough is better for boundary layer concepts, How come airplane wings are smooth?

ken

 

Because lift depends on having a boundary layer.

 

Dammit, you're right. If the airflow separates because of roughness (ice) lift stops. Why didn't I think of that?

Putting aero together today.

Ken

 

"polishing was done on carbureted engines to reduce fuel being pulled out of atomized air/fuel mix by rough manifold surface" No quite to the contrary, polishing the intake was done to help shadetree mechanics make money. A rough surface ensured that the fuel and air mixed propery and fully atomized. A polished suface will guarantee that they separate. A smooth surface can help improve high end performance under certain conditions, but at the kind of airflow that occurs in an engine revving at 15,000 rpm, the intake is pretty turbulent regardless of how smooth the intake may be. And such vehicles have no bottom end power or torque, and a polished intake is part of the reason. Many racers (not nascar, motocross), have people with rough intakes consistently winning. The only time the polished intake comunities win is when top speed is the decideing factor. If there are a lot of curves the lost acceleration causes them to fall behind.

 

http://www.superstreetonline.com/techarticles/3227/

Honing Your Engine’s Horsepower Skills
Extrude Hone Pumps Up the Power


By Karl Brauer
Photography: Karl Brauer


<TABLE cellPadding=0 border=0><TBODY><TR><TD vAlign=top align=left>What if you could increase your engine's horsepower and gas mileage while simultaneously reducing its emissions? What if you could do all of these things without adding a single piece of hardware to your engine? No moth ***** in the gas tank or propellers in the intake; instead, we're talking about improving what's already under your hood.


The process, called Extrude Hone, has been around for more than 25 years and gaining popularity over the last decade. It recently hit the big time when the folks at Ford's SVT (Specialty Vehicle Team) division decided to make it a standard upgrade on the Contour SVT performance package. Obviously, if it can impress a major automotive manufacturer, it's likely it can help the average enthusiast looking to gain horsepower and increase overall engine performance.

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What Is It?

To understand how it works, you have to understand what the Extrude Hone process does. As we’ve said too many times before, an engine is basically a glorified air pump. To increase performance, you have to find a way to increase its capacity for processing air. This can be accomplished with various upgrades including freer flowing exhaust and intake systems, extensive head work, and "hotter" camshafts, to name just a few. It can also be accomplished by improving airflow in the stock engine components. This would include the engine's head (or heads), exhaust manifolds, intake manifold, throttle body, downpipe, and even a turbo- or supercharger. The general rule is this: If air moves through it, the Extrude Hone process can improve it.

So what is the process? It begins when a part or parts arrive at the Extrude Hone facility. First, the part is thoroughly cleaned in a solvent bath and prepped for media flow.

The media is a combination of semi-solid rubber and silicon carbide abrasive (it looks and feels like a gritty form of gray Play-Doh). A "fixture" is bolted to the part, which will direct the media flow into a specific passage or passages. Once the appropriate fixture is attached, the entire setup is placed into an Extrude Hone machine for processing. The machine basically consists of two vertically opposed cylinders that will extrude the media through the fixture and the engine component's various air passages. As the abrasive material slides through the passage, it removes small imperfections in the metal to create a smoother finish. Through a combination of opening, polishing, and balancing the ports/runners within the engine component, airflow capacity and flow velocity are increased.

Flow-balancing, for instance, occurs when several passages are subjected to abrasive flow at the same time (like all four intake ports in a cylinder head). In this case, the smallest, or most restrictive of the group will generate more backpressure against the media flow. This will, in turn, cause more material to be removed from it until all the passages in the flowpath are brought more closely into balance.

If the component in question is a new one that Extrude Hone has not worked with previously, a step-by-step process involving flow-testing and multiple media flows is performed to determine the correct combination of media flow and Extrude Hone processing. Once established, this combination is recorded for use on all future components of the same type.



How Is It Better Than Standardized Honing Or Head Work?

Standard honing procedures involving rotating stones are an excellent method for removing small imperfections in metal surfaces. Unfortunately, they can only be performed on relatively large and straight passages (like the cylinder bores) within an engine. It is impractical, if not impossible, to "hone" all the turns and passages that make up an intake or exhaust manifold. Similarly, porting can only be done on those surfaces that can be easily reached by conventional porting equipment. You also have to know exactly what you're doing since bigger doesn't always mean better when it comes to airflow. Since Extrude Hone simply improves the airflow routes already established by an engine manufacturer, there's no chance of "screwing up" the design of a head or manifold. Instead, Extrude Hone refines already established air routes by making them smoother and more balanced.



Before & After

So what does the Extrude Hone process mean to the average enthusiast looking for performance gains? Depending on the condition and quality of the original casting, the amount of metal removal ranges from .030 to .060 inch. Measured airflow improvements have been up to 25 percent and higher depending, again, on the original condition of the engine component. With the increased airflow comes improvements in horsepower and gas mileage and a reduction in emissions. Another, more specific gain is to Extrude Hone the larger aftermarket turbos that can replace factory units. Normally, a larger turbo means reduced low-speed air velocity and, thus, increased turbo lag. By smoothing out the internal turbo passages, air velocity is increased and turbo lag is kept to a minimum. This is especially useful when going from dual small-sized turbos to a single larger turbo upgrade (a la Toyota Supra).



Bottom Line

It’s hard to say exactly how much improvement you’ll get by using the Extrude Hone process on your engine’s airways, since it is highly dependent on how well those passageways were designed in the first place. There’s no doubt that the mass production techniques used by large automakers cannot provide the high-quality finish to internal airways that the Extrude Hone process can. For the truly hot setup, you might have Extrude Hone work its magic on your throttle body, intake manifold, head (or heads), exhaust manifold (or manifolds), downpipe, and any forced induction (turbo or supercharger) units in use by your motor. Follow that up with a port and polish job from a knowledgeable head shop, and you should have one hell of a flow monster under your hood.

also see>
http://www.edelbrock.com/automotive/stories/sf609/intake_overload.html



also NASCAR and most of the pro truck races do not allow any porting or polishing of heads
STOCK HEAD RULE: All cylinder heads must be cast iron only and limited to two valves per cylinder. Must remain stock, untouched and meet the following requirements: Sealing holes will be drilled in the 2nd and 3rd head bolts on the right side head, to accept a wire seal after inspection.

A. Cylinder heads must be a stock cast iron production only, limited to two (2) valves per cylinder. No titanium valves or valve springs are permitted. Only steel valve springs are permitted. No port matching or flow work is permitted. No angle cutting of the head to block mating surface. The head stud or bolt holes cannot be offset or drilled off-center for the purpose of moving the head in any direction.

B. Three (3) angle valve jobs are permitted. When cutting the valve seat angles, no grinding is permitted above the bottom of the valve guide. All cutting in reference to the valve job and bowl area must be centered off the centerline of the valve guide. Upon completion of the valve job, the bowl area under the valve seat down to the bottom of the valve guide must still be the same configuration as far as shape and finish as it was from the manufacturer. Surfaces and/or edges where the cutter or stone has touched must not be polished. No hand grinding or polishing is permitted on any part of the head.

also, you will find intake manifold, head and exhaust manifold polishing at the dragstrip, a 1/4 mile run requires torque for ET along with hp for top end speed.


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So what is a higher max HP? What does that mean? Truth is, it is irrelavant, especially for street use.