valve seat angles and air flow



valve seat angles and air flow

Postby grumpyvette » January 18th, 2013, 8:04 am

valve seat angles and the actual angles cut on the valve edges them selfs and how you have the area under the valve in the port bowl area cut and blended has a marked effect on your engines air flow.
as a general rule air flowing over a change in angle across a surface tends to become noticeable more turbulent, if the change in angle exceeds about 15 degrees,and that tends to reduce flow. so if you look closely you see a tendency to cut the seat on a port in 15 degree steps or less.
when I first started building engines it was rather common for guys to drop heads off at the local machine shop and have the heads rebuilt and a valve job done, this consisted in most case in getting a 3 angle valve seat cut and a two angle cut on the valves and checking the guides and seals for wear and replacing them if it was required.
but after a few years of reading and doing some research I found I got much better results driving over a 120 miles to a PERFORMANCE machine shop that charged about twice as much for a valve job, but they cut three angles on the valves and 5 angles on the seats and cleaned and blended the bowl area under the valves, it was not unusual to see a car run one or two tenths faster in the 1/4 mile once that was done, compared to the stock, as cast factory heads, on a muscle car.
in fact one secret I had was building big block Chevy heads and having that shop upgrade the valves to the larger manley or TRW, valve sizes and cut and blend the seats, a set of BBC heads that came with 2.06 (oval port heads) 0r 2.19 intake valves (rectangular port heads)could usually accept the larger 2.19-or 2.30 intakes after some rather expensive machine work and having new valve seats installed, and 1.88" or even 1.94"exhaust valves VS the stock valves and some porting work.
the change in power was usually noticeable.
keep in mind the valve starts flowing at least some airflow as the valve lifts off the seat but generally not a significant amount until the valves at least .006 off the seat and by .050 lift its generally flowing enough to measure easily, but keep in mind that even at only 1000rpm those valves are going thru repetitive cycles from fully seated to fully open and back to fully seated 8.3 times PER SECOND , and at 7000 rpm its 58 times PER second, so the time a valve remains at any specific lift is very minimal
in fact a simple change like a 30 degree back cut on a set of big block valves is usually worth an additional 10-15 hp, at very minimal cost and double angle back cuts have occasionally shown a bit more, flow especially at lower valve lifts.
Remember the valve is at minimal valve lift twice in each cycle while its only at peak lift once.
the port area under the valve seat must be smoothed and blended into the seat area to maximize air flow , but you generally don,t want the seat throat to exceed about 88%-90% of the valve diameter, or both flow and valve heat transfer to the valve seat is compromised.
we also learned that there were valves with longer valve stems and smaller diameter and lighter weight valves stems that would allow taller spring installed heights and larger springs for improved clearances, if you were willing to use custom length push rods and verify your valve train clearances and geometry, etc.
http://www.alexsparts.com/
http://www.summitracing.com/parts/man-11730-8
http://www.summitracing.com/parts/mil-45135-8
http://www.summitracing.com/parts/mil-45117-1
http://www.summitracing.com/parts/man-11847-8
http://www.youtube.com/watch?v=wzKtaDke22k
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ideally your port cross sectional area doesn,t change suddenly
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valve seat and back face angles ,valve diameter and valve lift and duration effect the flow thru the curtain area
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PROJECTED HP PORT VOL.
MIN - MAX MIN - MAX
350 - 400 140 -160
400 - 450 160 - 180
450 - 500 180 - 200
500 - 550 200 - 220
550 - 600 220 - 230
600 - 700 230 +

This chart gives a good working guideline as to the intake port volumes to target for a small-block Chevy. Remember, a little too small is much better than a little too big. If the port volume of the heads you have seems a little too big, go for all the compression ratio the fuel intended will stand, as this will, to some extent, compensate.
READ THRU THIS LINK
http://www.circletrack.com/enginetech/1 ... ch_engine/


USE THE CALCULATORS to match port size to intended rpm levels... but keep in mind valve lift and port flow limitations[/color]

http://www.wallaceracing.com/runnertorquecalc.php
http://www.wallaceracing.com/ca-calc.php
http://www.wallaceracing.com/area-under-curve.php
http://www.wallaceracing.com/chokepoint.php
http://www.wallaceracing.com/header_length.php
Most of the machinists prefer an intake-seat width of 0.040-0.060 inch. Narrower seats generally improve flow but are also less durable. Narrow seats work best on drag-race applications where the engine is freshened often. Harder seat materials (e.g., induction-hardened seats) allow you to run slightly narrower seat widths than in the past while retaining excellent durability. Since exhaust valves operate at extreme temperatures, they require a wider seat to conduct heat away from the valve through the seat. Most shops specify 0.060- to 0.080-inch seat width for the exhaust side.

http://www.chevyhiperformance.com/techa ... z2bm45kKdb

http://www.stockcarracing.com/techartic ... to_04.html

http://worldtracker.org/media/library/C ... pter23.pdf
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THERES A GREAT DEAL MORE INFO IN THE LINKS AND SUB LINKS AS USUAL


http://zhome.com/ZCMnL/PICS/detonation/detonation.html

http://rlengines.com/Web_Pages/Serid_10 ... chine.html

http://www.superchevy.com/how-to/engine ... w-testing/

http://www.superchevy.com/how-to/engine ... omparison/

http://www.reidsautomotive.com/Cylinder ... vices.html

http://www.strokerengine.com/SBCHeadsFlow.html

viewtopic.php?f=52&t=181

viewtopic.php?f=52&t=462

http://www.chevyhiperformance.com/techa ... ve_angles/

viewtopic.php?f=52&t=333

viewtopic.php?f=52&t=10602

viewtopic.php?f=55&t=58&p=36446#p36446

http://www.popularhotrodding.com/tech/0 ... to_06.html

http://www.enginebuildermag.com/Article ... gines.aspx

http://www.enginebuildermag.com/Article ... pdate.aspx

http://www.aera.org/engine-professional ... echnology/

http://www.precisionenginetech.com/tech ... ns-part-2/

http://www.carcraft.com/techarticles/11 ... lve_angle/

viewtopic.php?f=56&t=495

viewtopic.php?f=52&t=333&p=407#p407

viewtopic.php?f=69&t=8540&p=30192#p30192

http://www.allpar.com/fix/holler/valve-prepping.html

viewtopic.php?f=52&t=2630&p=13144&hilit=probe#p13144

http://www.enginebuildermag.com/Article ... _jobs.aspx

viewtopic.php?f=55&t=624&p=28123&hilit=curtain#p28123

viewtopic.php?f=52&t=2630&p=21649&hilit=curtain#p21649

http://www.chevyhiperformance.com/techa ... ewall.html

viewtopic.php?f=55&t=624&p=28127&hilit=port+cross+section#p28127

http://www.popularhotrodding.com/tech/1 ... ewall.html

http://www.carcraft.com/techarticles/11 ... ewall.html

viewtopic.php?f=52&t=333

http://www.enginebuildermag.com/Article ... _flow.aspx

viewtopic.php?f=52&t=1159&p=2362&hilit=lapping#p2362

viewtopic.php?f=50&t=903&p=1465#p1465

viewtopic.php?f=52&t=389&p=7266#p7266

By Larry Carley


Page 1 of 2

Next Page >>
Larry Carley

No one knows airflow better than the legendary Joe Mondello, who rose to fame back in the 1960s for his race-winning cylinder head work.

“Back in those days, we didn’t have flow benches to test our work. Our test bench was the drag strip. If a modification worked and made the car run faster, that’s what we used. If it didn’t work and the car ran slower, we went back to Plan A or tried something else.”

Today, it’s an entirely different situation. Mondello’s tech center in Crossville, TN, uses state-of-the art equipment to test and verify cylinder head modifications. Mondello says most of the development work he does today involves using a wet flow bench, a machine that mixes an ultraviolet dyed liquid mist with air to simulate what actually happens to the air/fuel mixture as it flows into the combustion chamber.

A dry flow bench measures airflow in cubic feet per minute (cfm), which is useful information for evaluating how changes that are made in the configuration of a port or the angles on a valve seat affect airflow at various valve lifts. But a wet flow bench shows you how those changes affect turbulence in the air/fuel mixture, and where fuel may be separating or puddling in the valve bowl, seat area and combustion chamber.

In other words, a wet flow bench shows you things you can’t see with a dry flow bench. It also allows you to verify the effect any modifications you’ve made are having on the air/fuel mixture that might hurt performance because of turbulence, fuel separation or puddling in the combustion chamber. The basic idea is to make sure the air/fuel mixture stays mixed and disperses evenly as it enters the combustion chamber so it will burn properly and produce maximum power.

“It’s important to remember that the engine is the primary guide for what kind of modifications actually produce more power, not just airflow numbers alone,” says Mondello. “That’s where the wet flow bench has really helped. The results we see on a wet flow bench are confirmed on the dyno and on the track. We can tear down an engine and look at the patterns on the pistons to confirm what the wet flow bench already told us.”

How Seat Angles Affect Airflow
Generally speaking, the more angles there are on the seats, the better the seat flows. A stock valve seat with only a single 45 degree angle cut on it will have a sharp edge just above and below the area where the valve sits on the seat. As the valve starts to open and air begins to flow past the valve, the abrupt change in angles create turbulence that reduces air velocity and flow.

This abrupt angle can also cause the air/fuel mixture to separate. So cutting another angle above the primary seat and a third angle below the seat helps smooth out the airflow. That’s why a traditional 30-45-60 degree three-angle valve job produces more power than a stock valve job. The extra angles help the air turn the corner so-to-speak, which reduces turbulence to improve air velocity and flow. It also lessens air/fuel separation to improve combustion, too.

Mondello says the traditional three-angle valve job is old hat in today’s performance engines. A 30-45-60 degree three angle valve job is still better than a single 45 degree cut on the valve seats, but it can’t come close to what’s possible by optimizing the valve seat profile with additional angles.

“A few weeks ago, we had three engineers from Harley-Davidson Screaming Eagle Division here for a technical session. They just designed a new 103 head and a 110 head and were quite proud of how well it flowed. We took their head, and in three days time we improved the airflow 52 cfm over their initial design. Out of the 53 cfm that we picked up, 25 cfm was due to changes we made in the valve seat angles alone. That shows you how critical valve seat angles are for maximizing airflow and power,” says Mondello.

“Many cylinder head manufacturers are using single point cutters on a CNC machine to cut their valve seats, and they are not spending much time blending the chambers or doing all the things they really should be doing to make the valve job work properly. That’s actually good for our business because we rework a lot of these cylinder heads, especially Harley heads,” Mondello explains.

The most important part of building any performance cylinder head is cutting the angles on the seats, Mondello says. “Over the years, many engine builders have relied on the basic 30-45-60 degree three angle cutter. They think they can use the same three seat angles on every cylinder head they do – but that’s not true. The angles that work best will vary depending on the application.”

Mondel says he prefers to use a fairly steep top angle, because a steeper angle improves airflow. “When the valve first opens, a steeper angle allows better flow into a combustion chamber that has hills and valleys and is not perfectly flat. If you have a 30 degree top angle, the air coming off that seat will be turbulent and you’ll get separation between the air and fuel which hurts power. Increasing the angle allows for a better transition from the seat into the combustion chamber. It’s more efficient, offers less resistance and makes more power.”

Mondello recalls that in his early days of reworking cylinder heads, he discovered that four angles often provided the best airflow, throttle response and power. The four angles he used were 45 degrees for the primary seat, a 33 to 37 degree top cut, a 58 degree undercut below the primary seat, and a 70 degree cut below that made with a hand-driven reamer. Using these angles can often improve airflow 8 to 15 cfm or more.

Finding the angles that work best with a given cylinder head, camshaft and valve combination requires a lot of time on both a wet and dry flow bench, as well as dyno testing and track time. A lot of small shops don’t have a flow bench or a dyno to do development work and testing on their engines. They have to rely on experience and feedback from their customers to determine what works on the track or drag strip. Consequently, they may not be getting as much power out of their engines as they could.

Special Valve Seat Cutters
To address this issue, Mondello has put his nearly 50 years of experience in reworking performance cylinder heads into his own line of high performance valve seat cutters. The “Joe Mondello Signature Series Infinite Flow Valve Seat Cutters” feature all of Mondello’s tricks for improving airflow, velocity and power. The valve seat cutters feature multiple valve angles that are proven to significantly improve airflow and power over a single angle or three-angle valve seat cutter. Mondello says his multi-angle cutters typically increase airflow 10 to 20 cfm by just adding and changing the angles on the valve seats.

However, Mondello urges caution and care when using a cutter that is designed for a certain application. “My exhaust seat cutters go from a primary seat into a full radius below that seat, but they’re only recommended for exhaust seats, not intake seats. A lot of guys will also use them to cut the intake valve seat because it shows an 8 to 10 cfm increase in airflow on a flow bench. But when you look at the actual airflow pattern on a wet flow bench, the profile that was developed for the exhaust seat causes bad fuel shear and turbulence in the valve bowl and seat area. That’s why I offer different profiles for the intake seats.”

Of course, putting a radius on the intake seat is nothing new, and a lot of guys have been doing it for years because it increases airflow. But Mondello says bigger airflow numbers don’t necessarily translate into more power. It depends on what happens to the air/fuel mixture as it enters the combustion chamber.

“My valve seat cutters are designed to improve airflow, throttle response and horsepower, and they can be used on heads for street cars as well as a race car. Either way, you’re going to get better results than a simple three-angle valve job,” he says.

Mondello says that when cutting a full radius on exhaust seats, it is better to use a seat with a straight ID rather than a seat with a taper ID. With the straight ID, you can form the full radius up to the primary seat without having to worry about running into the bottom taper or leaving a ridge at the bottom of the seat. “I use an 86 degree radius undercut blade (IFT 86R6B-HP) to cut the very bottom of the seat and to clean out that little ring or any deformation that might be left from the seat cutter.”

Mondello’s product line includes a new exhaust seat cutter for heads with smaller valves like those from BMW and Audi, and will soon add a cutter for the intake seats. He also has cutters specially-designed for Harley intake and exhaust valve seats.

Besides making more power, cutting additional angles on the valve seats allows a shop to charge more for a valve job. “It’s a value-added service that improves performance, so why not charge more for it?” asks Mondello.

Important Ratios
Another factor that has a huge impact on airflow through the valve port and seat is the ratio of the size of the valve opening to the size of the throat area just below the base of the valve seat (as measured from the largest area at the bottom of the valve seat). The number one rule here, says Mondello, is having the optimum ratio that maximizes air velocity through the “primary choke” area in the valve bowl just under the seat.

“A lot of the aftermarket performance heads today are typically made with a 91 to 92 percent throat area, which, in my opinion, is too big,” says Mondello. “To get maximum velocity and airflow, the ratio needs to be a little smaller. On many heads, a throat dimension-to-valve size percentage of 86-1/2 to 89 flows best. On Harley motorcycle heads, we use 89 percent. On big displacement high flow V8 racing heads with valve sizes from 2.100˝ to 2.25˝, we may go as high as 90 to 91 percent. We try to keep the choke area as small as we can so it will flow efficiently and improve velocity in the port runner.”

He explains, “If you have big ports in a cylinder head but only a so-so valve seat, the head won’t flow as well as it could. Engines run on velocity, not cfm airflow numbers. The right valve angles will have a supercharging effect that really helps ram more air and fuel into the cylinder. That’s what gives you instant throttle response instead of a bog when you stomp down on the gas pedal.”

Mondello says a bowl cutter should be used to achieve the proper percentage for the valve-to-throat dimension size. Even if a performance engine has to run under a “no porting” rule, the bowl area under the seat can be cleaned up to improve airflow. Reworking this area can often improve airflow an additional 8 to 14 cfm.

Is Good Quality Valve Work Possible With Outdated Equipment?
Mondello chastises shops that are still using old, worn-out equipment to do what they call “performance” valve jobs. “It isn’t really performance work if the equipment can’t hold tight tolerances,” he says. “A tolerance of a couple thousandths of an inch is not close enough when performance valve work requires holding tolerances to tenths of a thousandth. The valve-and-seat machine bearings and pilots have to be in good condition.”

The concentricity of the valve seats to the valve guides is critical not only for proper valve seating and sealing, but also for the longevity of the valves. Misalignment between the valves and seats forces the valve stem to flex every time the valve seats. Eventually, this can lead to metal fatigue and valve failure. So the seats have to be as concentric to the guides as possible.

Mondello said the valve guide pilots that some shops use have too much play for accurate valve work. A valve-to-guide tolerance of .0004˝ is too much for performance work. It should be down around .0002˝ or less. One way to achieve that is to use a high-pressure lubricant on the pilot. Mondello prefers a lubricant called CMD-3, which can handle up to 50,000 psi. The same lubricant can also be used on a dead pilot to take slop out of the valve cutting system.

Chatter is another problem that can ruin a performance valve job. Chatter can be caused by three things: too much play in the pilot (or to the guide if the valve-and-seat machine uses a live pilot versus a dead pilot) or the speed of the cutter. However another culprit may be the casue and have nothing to do with the pilot or the cutter: examine how level your machine actually is compared to what you think it is.

“If your valve-and-seat machine is off-kilter just a bit, the valve seat cutter can chatter when it cuts the seat,” Mondello explains. “When was the last time you leveled your machine? More importantly, when was the last time you leveled your level?”

The Living Legend continues: “Many people don’t know that a level is not flat on the bottom. It has a bow in it. Most people also don’t know how to check their level. You can’t accurately level your valve-and-seat machine if the level you are using is off. When you set your level, make sure the little level is always to your left. If you turn it around, you will get a different reading.”

Mondello says using a lubricant when cutting hard seats will also reduce chatter. He uses a 2020 Mondello Signature Series cutting fluid for this purpose, and 2030 Mondello Signature Series fluidwhen refacing titanium and stainless steel valves.

Seat Materials
The type of seat material used will depend on the application. Racers running titanium valves typically use a beryllium-copper alloy seat, or one of the new beryllium-free copper-nickel alloys. Beryllium-copper and copper-nickel seats have a high rate of thermal conductivity, and are a must for high revving, high power engines with titanium valves.

Mondello says one of his favorite materials for valve seats is powder metal. He says he uses powder metal seats from a leading U.S. manufacturer in many of the heads he rebuilds. He likes the powder metal seats for a variety of reasons: they have great machinability when they are new, they produce very little chatter when you cut them, they have built-in lubricity for the valves, they hold up well, and they are made in the USA.

Mondello urges engine builders to be very vigilant about their suppliers, because in his opinion, not all manufacturers pay close enough attention to their alloys. Consequently, the hardness of the seats may vary greatly even within the same size seat.

Interference Fit
Keeping the seats in is just as important as the angles that are cut on the seats. Mondello says one of the most common problems he sees are engine builders not using the proper press fit when they install valve seats. “You should always preheat aluminum heads and freeze the seats prior to installing them (Mondello does not recommend preheating iron heads).

I recommend .005˝ to .0065˝ of interference when installing seats in a cast iron head, and .0065˝ to .007˝ in an aluminum head, unless the seats are Beryllium Copper, in which case I recommend .004˝ to .0045˝ of interference fit. Some guys tell me .007˝ to .0065˝ of interference in an aluminum head is too much. But you know what? I’ve never had a seat drop out, not even after an engine got too hot and overheated.”

Mondello says to achieve a good fit, you need a good hole (correct dimensions, smooth finish and no distortion or damage to the seat counterbore). You also have to use a lubricant when driving in the seat.

“I don’t believe in using locking compound on valve seats. It interferes with the heat transfer. All you need is a little assembly lube,” he says.

Mondello says shape is important too. “The valve seat should also have a chamfer on the bottom edge. If you’re finding your seats are straight cut with a flat bottom. You need to put a bevel on those seats before you install them. And regardless of what type of seat you are installing, always use a pilot and driver. Some guys will just beat the seats in using a driver and a puck. That’s asking for trouble. Use a pilot to align the seat so it goes in straight.”

Mondello cautions against using excessive heat when preheating a cylinder head to install new seats. “You only need to heat the head up to about 160 to 180 degrees F. If you get it too hot, say 200 to 250 degrees F, the guides can move around and change the alignment between the guide and seat. When we do Harley heads, we preheat the head on an electric stove. You can also use a hot plate or a torch for the same purpose.”

To be sure, Mondello urges precision. “Use an infrared thermometer to check the temperature. We put the seats in a freezer while the head is being warmed up. That makes it very easy to install the seats. You can almost drop them into place.”

Mondello says you have to install the valve guides before you do the seats. The position of the guides determines the position of the seats, so once the guides are in place, they can be used to pilot the position of the seats.

“On Harley heads, we drive the valve guides into the head from the top (from the spring seats). On most other V8 heads, we also drive the guides in from the top (spring seat side). On early 396/427 Chevys where the guide exhaust guide is stepped, you have to drive out the old exhaust guide from the combustion chamber. New intake and exhaust guides can then be driven in from the top side.”

The key to performance valve work, therefore, is knowing the angles, having a valve-and-seat machine that’s in good condition and can maintain tight tolerances, and paying attention to details.

replacing worn valve guides

http://www.enginebuildermag.com/2003/12 ... ditioning/

http://www.calgaryfieros.com/OSGdocs/va ... seals.html

https://www.youtube.com/watch?v=PR8cDaum7ss

http://www.hthoward.co.uk/engine-machin ... -sleeving/

http://www.hotrodlane.cc/New%20LS%20Lin ... inding.htm
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related threads, with info you might need
IF YOU CAN,T SMOKE THE TIRES AT WILL,FROM A 60 MPH ROLLING START YOUR ENGINE NEEDS MORE WORK!!"!
IF YOU CAN , YOU NEED BETTER TIRES AND YOUR SUSPENSION NEEDS MORE WORK!!
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Re: valve seat angles and air flow

Postby 87vette81big » January 18th, 2013, 8:22 am

Thanks Grumpy !
I am going to have to speed read your article here, leaving for work soon.
I will read in depth this evening.
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Re: valve seat angles and air flow

Postby Indycars » January 18th, 2013, 9:55 am


Is D1 and D2 correct???

I wonder how many think that D1 is measured
at the margin on the valve?

valveseat2.jpg


Important Ratios
Another factor that has a huge impact on airflow through the valve port and seat is the ratio of the size of the valve opening to the size of the throat area just below the base of the valve seat (as measured from the largest area at the bottom of the valve seat). The number one rule here, says Mondello, is having the optimum ratio that maximizes air velocity through the “primary choke” area in the valve bowl just under the seat.

“A lot of the aftermarket performance heads today are typically made with a 91 to 92 percent throat area, which, in my opinion, is too big,” says Mondello. “To get maximum velocity and airflow, the ratio needs to be a little smaller. On many heads, a throat dimension-to-valve size percentage of 86-1/2 to 89 flows best. On Harley motorcycle heads, we use 89 percent. On big displacement high flow V8 racing heads with valve sizes from 2.100˝ to 2.25˝, we may go as high as 90 to 91 percent. We try to keep the choke area as small as we can so it will flow efficiently and improve velocity in the port runner.”


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Re: valve seat angles and air flow

Postby grumpyvette » January 18th, 2013, 4:25 pm

not only the valve angles. the back cut and the valve diameter effect flow but the shape and finish on the valve will effect your results, most performance valves are reduced in diameter for the first 3/4" behind the valves head to reduce the flow restriction

http://www.hipermath.com//engines/intake_valve_size

http://www.austincc.edu/wkibbe/headdesign.htm

http://www.trickflow.com/articles/18degree_hp/

http://www.trickflow.com/articles/dynod ... _heads.asp

http://www.chevyhiperformance.com/techa ... and_heads/

http://www.chevyhiperformance.com/tech/ ... ewall.html

http://www.popularhotrodding.com/engine ... ewall.html

http://www.popularhotrodding.com/tech/0 ... ewall.html
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the purpose of the chart is to give you a fairly realistic starting point to select a cams lobe separation angle 'lsa'
keep in mind , with a given duration, as the LSA gets tighter the overlap tends to increase and exhaust scavenging becomes more effective at filling the cylinders, its that more effective scavenging during the overlap that allows the more effective fill of the cylinders, and the longer the stroke, and larger the displacement the more effective that scavenging needs to be to effectively sweep the previous charge of burnt exhaust gases from the cylinder,replacing them with a fresh charge, keep in mind the valve size is limited, so the curtain area gets restrictive as the displacement and stroke increase especially when you consider that at something like 6000rpm, the cylinders need to fill, ignite, and push out the exhaust gases 50 TIMES A SECOND
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viewtopic.php?f=52&t=1070

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IF YOU CAN,T SMOKE THE TIRES AT WILL,FROM A 60 MPH ROLLING START YOUR ENGINE NEEDS MORE WORK!!"!
IF YOU CAN , YOU NEED BETTER TIRES AND YOUR SUSPENSION NEEDS MORE WORK!!
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Re: valve seat angles and air flow

Postby 87vette81big » January 19th, 2013, 12:01 am

Just Awesome Reading Grumpy.
3 hours reading your provided links & I have learned more about cylinder head airflow characteristics, valve to seat throat sizing, multiple seat angle valvejobs, valve backcuts, ect than I have read - learned in the last 20 years.

I own my own valve grinding equipment. As Joe Mondello would say, Its stone age.
SIOUX Valve grinder #624 wet coolant cooled. & #1710 electric seat grinding(stone) machine.
Have practiced since 1999.
Both are very good machines yet. 3 & 4 angle seat cuts are what i typically perform on my own heads & a few others I do for friends that ask me to.
One of my old bosses died while working in his GM dealership. New owner cam in. He was going to throw the Sioux equipment in the garbage dumpster.
I intervened, pulled out $100 & gave to the Moron new boss. Loaded the valvegrinder & seat grinder into my 1973 Lincoln Mark IV.
I was about 29 years old then.
Both are working nicely.
I can not do full radius valvejobs like on a Sunnen or Serdi, but I can hold seat concentric to .001" or less every time. I own a Jewled seat runout gauge.
Did not take too much to fix both after sitting in that old GM garage backroom unused for nearly 30 years.
I bought New Sioux Pilots of .340. 341. .342, .343. .373,.374, .375. A large assorment of stones & cut to shape with my Diamond stone seat dresser.
All solid pilots bought.
Ball bearing mandrels for stone holders.
Its a different kind of fun & nice challenge I enjoy every time I do a valvejob on a set of SBC, Pontiac, Olds, or other engine.
It was the exact same pieces of equipment my late friend Bill used back in the 1960's & 1970's while working as a Chevrolet Master Mechanic.
He taught me how to use them each.
And art of 3 angle valvejobs ( Boxing them in ).

Its interesting, when I stop by my friend Steve S. auto & diesel machine shop, his $10K Sunnen head machine( fixed pilot) carbide cutters is idle.
Not broken.
On another workbench he is grinding the seats by hand with an electric Kwik Way stone seat grinder.
I asked him why several times.
Answers back, "I don't know Brian, I just like refinishing seats this way yet as I did 25 years ago when I opened this shop".
Shows off to me the mirror finish & 3 angle cuts made, Sunnen seat runout gauge confirms .0002 to .0005 inch concentric.
"What do You think ? AHHHHHHHH its just Ok Steve, I can do better.......let me show ya.......

BR
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Re: valve seat angles and air flow

Postby grumpyvette » January 19th, 2013, 9:32 am

IF YOU CAN,T SMOKE THE TIRES AT WILL,FROM A 60 MPH ROLLING START YOUR ENGINE NEEDS MORE WORK!!"!
IF YOU CAN , YOU NEED BETTER TIRES AND YOUR SUSPENSION NEEDS MORE WORK!!
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Re: valve seat angles and air flow

Postby Indycars » January 19th, 2013, 1:18 pm

87vette81big wrote:He taught me how to use them each.
And art of 3 angle valvejobs ( Boxing them in ).

BR


By "boxing them in", do you cut the seat first and then come back and cut the angles above and below it. Which determines where you actually place the seat.

Rick
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Re: valve seat angles and air flow

Postby 87vette81big » January 19th, 2013, 6:59 pm

Indycars wrote:
87vette81big wrote:He taught me how to use them each.
And art of 3 angle valvejobs ( Boxing them in ).

BR


By "boxing them in", do you cut the seat first and then come back and cut the angles above and below it. Which determines where you actually place the seat.



Yes Rick, You cut your main angle in 1st. Most of the time its a 45 degree seat angle on most cylinder heads. Pontiac & Olds & few others used 30 degree intake seats. Oddy enough a 1977 to 1979 Olds 403 engine uses a 30 degree Exhaust seat with a 45 degree intake seat.
After cutting in the main seat, I usually cut in the top blend angle. Afterwards I finish with an undercut or lower blend angle.
By careful grinding of blend angles, you can actually raise or lower the seat height of that valveseat intentional. Takes constant checking with a depth gauge or similar. Adjustments of + or - .015" height can be accomplished. If the main seat angle gets to narrow to my liking, I go back & touch it up for a few seconds with dressing stone ( I like Ruby Red most of the time). The original Sioux grinding stones are the very best to use ( blueish gray color), cut fast & precise with virtually no stone wheel holder vibration. The Ball Bearing stone wheel driver is turning around 20,000 RPMs under moderate cutting load pressure applied.
Much of experience is gained in feel from sound of grinding process, vibration feedback through your fingers & wrists, & experience learned from grinding different diameter seats & different seat materials.

Its fun. If you love to tinker & learn, its worth trying out yourself grinding valves & seats the OLD SCHOOL WAY.
Afterwards you gain much respect for the old Veteran Mechanics & Racers that did all their own engine builds & machine work in house.
Even better when you get similar results as they did on the street & track.
Grumpy's article & links provided me with new insight to try different ideas next time I do a valvejob for high performance street or track usage.

I still have not found a single professional engine builder with a Serdi or Sunnen Head machine to cut full radius valveseats.
The reason why is because some of those specialized cutters cost $500 to over $1K each.
Real hard to find an honest machinist too here in IL. My friend Steve with his auto & diesel machine shop is an exception.
Most will take your $$ & give you back junk that won't ever win a race.
Why I was determined to learn more always.
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Re: valve seat angles and air flow

Postby Indycars » January 19th, 2013, 7:38 pm


I see the old valve grinders occasionally on Craigslist, is this the type of equipment you are using??? I've used those stones way back in the early seventies when I attended Vo-Tech school for 1/2 day as part of my junior and senior years in high school.

Please post some pictures of your setup. Those pics would explain alot about the equipment you are using. Maybe if Grumpy and myself said Pretty Please several times you might be able to post a short tutorials with more pics to show the rest of us how we might do this and skip a few of the mistakes you had to make in the beginning to get where you are today.

How much would you estimate you had to spend on your setup??? Of course taking into account that you bought the original setup for $100.

So here is my 1st PRETTY PLEASE.........Grumpy and anyone else that would like to see a tutorial please post your PRETTY Pleases also !!!

Just the kinda operation that a small home garage might be able to make room for. There is no way I can add a lathe or mill.....but maybe valve seat equipment.

So here is my 2nd PRETTY PLEASE....... anyone else out there!!!

I really enjoy those things that I can do myself, instead of taking it to the professional, even if I don't get that last 2 HP!!!

Rick
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- Check Out My Dart SHP Engine Project: viewtopic.php?f=69&t=3814
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Re: valve seat angles and air flow

Postby 87vette81big » January 19th, 2013, 8:38 pm

Indycars wrote:
I see the old valve grinders occasionally on Craigslist, is this the type of equipment you are using??? I've used those stones way back in the early seventies when I attended Vo-Tech school for 1/2 day as part of my junior and senior years in high school.

Please post some pictures of your setup. Those pics would explain alot about the equipment you are using. Maybe if Grumpy and myself said Pretty Please several times you might be able to post a short tutorials with more pics to show the rest of us how we might do this and skip a few of the mistakes you had to make in the beginning to get where you are today.

How much would you estimate you had to spend on your setup??? Of course taking into account that you bought the original setup for $100.

So here is my 1st PRETTY PLEASE.........Grumpy and anyone else that would like to see a tutorial please post your PRETTY Pleases also !!!

Just the kinda operation that a small home garage might be able to make room for. There is no way I can add a lathe or mill.....but maybe valve seat equipment.

So here is my 2nd PRETTY PLEASE....... anyone else out there!!!

I really enjoy those things that I can do myself, instead of taking it to the professional, even if I don't get that last 2 HP!!!



Yes Rick.
Ok.
Give me some time. Even if it takes me several months to make a tutorial for Grumpys Forum here.
Its going to be somewhat difficult to relate all easily.
Some may scoff because its done the old school way.
But it works yet today still.
One important aspect is making sure the valveguides in good condition yet before starting a quality valvejob. Any slop, bellmouthing, taper of the guide ID, you won't have good results, seat runout gauge will tell all when checked. Close to "0.000" as possible is the goal.
Last valvejob I did was on the wife's 1999 Honda CRV. A fuel injector failed on Cylinder #3 and it ran lean in that cylinder way too long. An exhaust valve failed, a pie shaped section of the valve face fell off and blew down into the exhaust system. New Exhaust valve purchased & I went to work. That was the late fall of 2011.
I used to do valvejobs maybe 8 to 20 times per year with headgasket sidejobs at night & few small time racers with SBC engines. Times were good still. No recession, no bama dude.

I would pay up to $800 for the valvegrinder machine itself. The seat grinder equipment if all there & in excellent condition with nice assortment of pilots & grinding stones with Diamond tool stone wheel dresser ( adjust diamond cutting angle to face stones from 0 degrees to 90 degrees) - I would pay up to $600 or $700.
You have to be careful looking around to buy, many items are lost or broken today, sellers have no idea whats supposed to be with each, some dishonest, ect.
I see valve grinding equipment on ebay on occasion. The Sioux #624 valve grinder weighs in around 225 lbs, real heavy to move, Real cast iron construction like an old South Bend Lathe is made. The seat machine grinder is in a nice heavy gauge metal box, Sioux painted them Orange, someone repainted my box Blue, everything weighs about 60lbs.
In my other garage. I am like Grumpy before he built his Big Garage a few years back. Someday soon I hope. Keep working hard.

I do have a sidejob going on Rick, 1999 Chevy Venture minivan, 3.4L V6.
Blew #2 fire ring in the front bank headgasket. Both heads are off earlier this week. Getting resurfaced. Maybe I will do a valvejob on them. Minivan ran Ok but temp gauge ran away after driving for 10 minutes. Combustion Block leak tester kit I have confirmed problems. Disassembly revealed problem culprit.

Brian
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Re: valve seat angles and air flow

Postby Indycars » January 20th, 2013, 11:11 am


Looking forward to your posting a tutorial! I know how time consuming they can be, I wrote the one below on port matching. Sounds like you are pretty busy, several irons in the fire.

A good set of photos of the equipment would go along ways towards helping to identify a complete setup, so one would know what to look for.


Port Matching Procedure (Step-by-Step Guide with Pictures)
viewtopic.php?f=55&t=5378

Rick
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- Check Out My Dart SHP Engine Project: viewtopic.php?f=69&t=3814
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Re: valve seat angles and air flow

Postby 87vette81big » January 20th, 2013, 11:56 am

Indycars wrote:
Looking forward to your posting a tutorial! I know how time consuming they can be, I wrote the one below on port matching. Sounds like you are pretty busy, several irons in the fire.

A good set of photos of the equipment would go along ways towards helping to identify a complete setup, so one would know what to look for.


Port Matching Procedure (Step-by-Step Guide with Pictures)
viewtopic.php?f=55&t=5378



Yes Rick.
I have a real hard time taking close up photos with my current Kodak 8.1 mega Pixel camera (2007 vintage).
I can do, but the slightest movement of my hands or arms makes for blurry pictures.
With wife & kids & still new to us farmhouse on 5 acres, I have to plan ahead for my own personal ESCAPE TIME..... :D
I wish the crazy lady living here before did not knock down the 2 story barn that was here. Was about a 50 X 60 foot base.
For a small town guy like me......it would have been Hotrod Heaven to me.
Research carefully for your Valveguide equipment of your own.
Siuox, Kwik-Way, Black & Decker- Snap On are most common available used for good deals.
Also, pilots, mandrel drivers, electric angular drivers are dedicated parts per manufacture. Keep this in mind.
All are still supported by aftermarket specialty machine shop suppliers- jobber warehouses.
K-line & Atlas machine are my personal favorites when I need items.
All Souix Pilots have .385" inch diameter tops above the lower pilot section that inserts into the valveguide.
Unique from anyone else. When you have your setup, treat with lots of TLC. A dropped pilot on the concrete floor can ruin it, take it out of end to end trueness. Parallelism. Pilot guides are precision ground to + or - .00005' inches, or 50 millionths of an inch.

Brian
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Re: valve seat angles and air flow

Postby grumpyvette » April 2nd, 2013, 6:21 pm

IDEAL FLOW FLUX another critical intake pumping process parameter that has been discovered over the years of ENGINE PRO SOFTWARE DEVELOPMENT is the maximum intake flow per unit of area that can be obtained on the flow bench when tested at 28 inches of H20 .
This value is calculated using the intake throat minimum cross sectional area (CSA) which is usually located just up stream of the intake valve seat insert or seat ring.
Image
obviously you will need to carefully port match some intakes to some head ports due to the wide variation in sizes and shapes
Image
Image
Image
the valve seat throat area as a percentage of the intake valve diameter effects the port flow rate, yes the port cross section and angle also effect flow rates and larger valves and larger throat areas with less restriction obviously have some potentially lower flow restriction.
max piston speed for long term durability obviously depends on the rotating assembly your using its displacement (bore/stroke) and rod length, component quality and weight,you should select intake components that at least match and ideally exceed the intake port flow potential and valve train components used in the build will effect results but the general consensus puts max piston and valve control speeds in a 383 with its 3.75" stroke with a hydraulic valve train, at or slightly below 6300rpm in most builds.
obviously shaft rockers and rev kits with extra spring load rates on a hydraulic roller cam can be used to slightly boost that limitation.
at 6300rpm, a 383 with its approximately 48 cubic inches of cylinder volume, will require about 90 cubic feet per minute of air flow per cylinder to maximize power potential.
now obviously your effective cam duration compression and the valve curtain area , and lift duration will effect the flow rate.
the average guy sees that and thinks WOW! my heads are rated at lets say 240 cfm and says , NO PROBLEM, but he forgets at 6300rpm the valves probably opening and closing 53 times A SECOND and the valves only open for maybe 235 of the 720 degrees in the cycle or 1/3rd of the time so that 240 cfm is already at in theory nearer to 80 cfm of effective flow.
thats why you find engines require port flow rates above about 260cfm to feed a 383 at that rpm level, and having headers designed to effectively scavenge or help draw in the next intake charge can only help efficiency
Image
notice volumetric efficiency and the power curve tend to follow each other rather closely
The calculation of the CSA must also include the flow area lost to the intake valve stem.
the CSA equations are included below.
InFlux=InCFM/CSA

For example, for an intake port that flows 500CFM@28inch H2O and has a minimum CSA of 4.00 square inch, the calculated InFlux would be 125 CFM/in^2. Years ago SuperFlow performed the following calculations to determine that the maximum "ideal" value for InFlux@28 inch H2O was146.0 CFM/in^2. This value is still published today in all the SuperFlow flowbench manuals.
Bernoulli's equation from elementary fluid dynamics can be used to convert a pressure head of 28 inch H2O to an equivalent velocity for dry air.

Bernoulli's equation: 0.5*RHO* Velocity^2/GC=DeltaP

Where: RHO=0.07633 lbm/ft^3(@Motorsports Standard Day)
GC=32.174 ft-lbm/lbf/sec^2(gravitational constant)
deltaP=28 inches H2O

Rearranging to solve for Velocity (ft/sec) and adding some unit conversion constants:

Velocity=(144*deltaP * GC* 14.696/ (406.78*0.5*RHO)) ^0.5=350.4 ft.sec

And finally, if the air is moving at 350.4 ft/sec through an area of 1.0 square inch, the resultant ideal InFlux would be:

Ideal InFlux = (.350.4 ft/sec) * (60 sec/min) * (1 in ^2)/(144in ^ 2ft^2)=146 CFM/in^2


For years cylinder head porters have been chasing this illusive 146 CFM/in^2 value. The SuperFlow calculation is absolutely correct for an "ideal" frictionless orifice with no dump or expansion losses. In the real world of IC engine intake ports, there is an intake runner with rough or smooth walls, a valve guide and turns, and an intake valve stem and valve head that all result in friction losses. And a real dump lossas the air slows down after the valve seat throat and expands to fill the cylinder bore.

Maximum Flow Flux

Research has shown below that there are simple ways to estimate these pressure and velocity losses. The techniques shown below use industrial stands from the theory of flow in a pipe. These standard equations are used for all types of fluid flow systems, in all kinds of applications. The equations use loss coefficients to relate pressure drops to velocity heads.

For example, the typical friction loss in a short pipe might be equivalent to a 0.6 velocity head The loss coefficient for a dump loss normally includes how abrupt the area change is and for typical racing engine geometry would be about 0.8 velocity heads. Using a total loss coefficient of 1.4 would reduce the 146 CFM/in^2 value as follows:

Max InFlux= 146 * (406.78 -1.4 * 28)/ 406.78= 131.9 CFM/in^2


The use of 132 CFM/in^2 for the maximum intake port flow flux would seem to be a reasonable number that cylinder head porters should be able to achieve. However, in the real world of racing cylinder heads the current (circa 2004) "best" or "benchmark" levels of InFlux appear to be:

* Max InFlux =133 CFM/in^2 for a single intake valve and
* Max InFlux=137 CFMin^2 for two-intake valve configurations


The use of two-intake valves must substantially reduce the dump loss as the air enters the combustion chamber and cylinder, as the friction losses in the intake ports would seem to be similar between these two intake port configurations.


Cross-sectional Area-CSA

Typically, the minimum Cross-sectional Area at the valve throat (CSA) is calculated using the number of valves (NInV), intake valve diameter (InVD), throat percentage (Throat%) and valve stem diameter (VSTD). The equation for calculating the CSA in this fashion is:

CSA= NInV * ((InVD * Throat%/100) ^2- VSTD ^2)/4



Sample Calculation:
NInV=1
InVD= 2.52
Throat%=92.3%
VSTD=5/16=.3125
CSA=4.172

The graph below can be used to quickly determine the "benchmark" intake port flow CFM @ 28 inch H2O for a single intake valve based on:

* Max InFlux = 133 CFM/in^2
* Range of intake valve diameters from 1.90 to 2.60 inch with a 5/16 inch valve stem
*Range of Throat% from 87.0 to 93.0%

Image

combining the info posted a 383 sbc has 47.8 cubic inches per cylinder divided by 2.02=23.7 on the chart above, so youll find cams in the correct duration range having a tight 105-108 lSA most efficient at filling the cylinders in many combos,

lets say we build a 496 big block with 2.19" intake valves,
496 divided by 8=62 cubic inches per cylinder, divided by 2.19=28.3. now look at the chart! you find youll need a rather tight 101-103 LSA


Image

you might also find these useful

viewtopic.php?f=52&t=333

http://www.rbracing-rsr.com/runnertorquecalc.html

http://www.wallaceracing.com/max-rpm2.php

http://carprogrammer.com/Z28/CylinderHe ... _notes.htm

viewtopic.php?f=52&t=462

viewtopic.php?f=52&t=1070

http://www.wallaceracing.com/ca-calc.php
IF YOU CAN,T SMOKE THE TIRES AT WILL,FROM A 60 MPH ROLLING START YOUR ENGINE NEEDS MORE WORK!!"!
IF YOU CAN , YOU NEED BETTER TIRES AND YOUR SUSPENSION NEEDS MORE WORK!!
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Re: valve seat angles and air flow

Postby Indycars » April 4th, 2013, 8:22 am

Bernoulli's equation: 0.5*RHO* Velocity^2/GC=DeltaP

Where: RHO=0.07633 lbm/ft^3(@Motorsports Standard Day)
GC=32.174 ft-lbm/lbf/sec^2(gravitational constant)
deltaP=28 inches H2O


RHO is the abbreviation for the Greek Letter ρ


This stands for "Air Density". Usually stated at some "Standard Temperature & Pressure", in
this case it's "Motorsports Standard Day". I'm not sure what the exact temperature & pressure
is for this standard, I could not find anything on it. Usually it's around 60°F at sea level or
14.7 psi. Maybe it's stated in the book "The HP Chain", where Grumpy is getting this info.

So One Cubic Foot of air weighs .07633 lbs/ft^3, so the air in a 10 foot square room weights
76.33 lbs. That's right, 10 x 10 x 10 = 1000 OR 1000 * .07633 = 76.33

The other three variables are somewhat familiar to most of us and that's the effects of
Gravity, normally seen at 32.2 feet/sec^2. "deltaP" is the difference in
pressure from one location compared to another. In this situation it's a comparison
between inside the intake port to atmospheric pressure. The third variable is Velocity
or speed, and we all know that one!

That's as far as I've gotten thru the entire post at this time. Hopefully that may clear
up some of the confusion.

Rick
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Re: valve seat angles and air flow

Postby Indycars » April 4th, 2013, 3:21 pm

Cross-sectional Area-CSA

Typically, the minimum Cross-sectional Area at the valve throat (CSA) is calculated using the number of valves (NInV), intake valve diameter (InVD), throat percentage (Throat%) and valve stem diameter (VSTD). The equation for calculating the CSA in this fashion is:

(1)CSA= NInV * ((InVD * Throat%/100) ^2- VSTD ^2)/4

Sample Calculation:
NInV=1
InVD= 2.52
Throat%=92.3%
VSTD=5/16=.3125
CSA=4.172

(3)The graph below can be used to quickly determine the "benchmark" intake port flow CFM @ 28 inch H2O for a single intake valve based on:

(2)* Max InFlux = 133 CFM/in^2
* Range of intake valve diameters from 1.90 to 2.60 inch with a 5/16 inch valve stem
*Range of Throat% from 87.0 to 93.0%



Several things don't make sense from the above information.

(1) When I do this calculation I get 133, yet it says CSA = 4.172. It maybe
just a coincidence, but "133" is shown as the Max InFlux.

(2) The Max InFlux from the information above my quotation says Max InFlow
should be between 133 to 146 CFM/in²

(3) The graph directly below has to do with the LSA of a camshaft, is this the
correct graph ???

Rick
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Re: valve seat angles and air flow

Postby grumpyvette » April 4th, 2013, 8:20 pm

Don,t confuse air flow rates and air flow volume, remember a flow bench measures air flow thru a port at a constant 28" of water rated vacuum, yet an engine has 720 degrees of rotation cycle of which you might have 230 deg.-260 degs. of effective valve lift offering air flow potential and at a constantly changing vacuum or pressure thru the valve curtain.
Four barrel carburetors are usually rated for flow at a pressure drop of 1.5" of mercury, further screwing up any easy cross reference.
a piston reaches max velocity at near 90 degrees from TDC and that can produce vacuum readings near 60" of vacuum, but most of the piston travel produced less vacuum.
lets do some real world math comparison
that 133cfm per square inches of port cross sectional area, represents the max theoretically achievable flow rate, and I don,t think its meant to include the restriction the valve stem or valve guide represent, its merely a guide showing that increasing the valve size,and the throat area under the valve seat, potentially has the ability to significantly increase the port flow potential
a typical 383 sbc would usually use a cylinder head with a 1206 size intake port which is 1.31 "x 2.2" and a 2.02" valve , max piston speed near 6400rpm for that size engine and stroke on most 383 engines
a 383 has roughly 48 cubic inches of displacement per cylinder and thats roughly 2.89 sq inches of port cross sectional area at best , feeding a 383 sbc spinning at 6400rpm. theres 3200 intake strokes so you in theory have 153600 cubic inches , or a bit less of potential air/fuel mix or 153600/1728=88.8 cubic feet per minute of air flow in a port, max theoretically achievable.
think about that, 88.8 x 8 cylinders is 710cfm, thats one reason a 750cfm rated carb seems to work well on a properly built street/strip 383 sbc.
88.8 cubic feet of fuel/air mix per minute per port,/2.9 in sq inches of area means theres roughly 31.7 cubic feet per minute per square inch of port area, and a 2.02 intake valve with a 90% diameter throat area would have about a 2.9 sq inch area of flow, so your looking at the same potential flow, speeds in port and throat.

133cfm x 2.9 square inches=372 max cfm, for a open port without a valve, but add in a a valve stem and guide sticking into the port that’s 8mm in diameter and that’s in that port has about 2”, in length minimum has about a .62 -.80 square inch of area restricting port flow, so your down to 2.0- 2.28 x 133= or near 303 cfm, now you look at the chart (remember its for theoretical max flow , not what youll see but what the ideal port could in theory flow if everything was perfect,and while its useful as a guide its hardly reflecting real numbers youll see on a flow bench.
Image
Image and we see it predicts a max flow for a 2.02” valve with a 90% throat in that range, IF the valves lift exceeds about .25% of the valve diameter at full lift, its curtain area equals or exceeds the seat throat cross sectional area.
Image
this corresponds rather well with the best published cylinder head flow numbers for sbc heads with that size port which rarely exceed 300cfm rated flow.
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