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Old 03-31-2006, 03:04 PM   #1
shvrdavid
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Default Porting Question

I was wondering how many of the people on here port their own cylinder heads?

I am still working on mine and decieded to post a few pictures of the progress so far.



I still need to cut the inside of the seats, still waiting on that size cutter...

Actually they need a lot more work...

I am curious to hear everyones input on my work so far...

right now the flow numbers are at about 20% over stock on the intake and 10% over on the exhaust at .421 lift...

Hopefully I can get the numbers to 25 and 15 by cutting the inside of the seats larger, maybe more...

I plan on using Cosworths new cams with these heads..

Thanks for looking, comments and suggestions please...
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Old 04-01-2006, 01:33 AM   #2
reddevil
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I am porting mine....slowly..... They are just old 2.2 heads, but damn I removed alot of material so far....
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Old 04-01-2006, 11:01 AM   #3
herewegoagain
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Try one of the technical forums, this is for Proven Power Bragging.
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Old 04-02-2006, 01:56 AM   #4
Hopper
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What type of flow bench do you have?

How are you going to cut the seats and valves?
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Old 04-02-2006, 11:14 AM   #5
shvrdavid
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Ok Hopper, I will explain.

I knew that someone would ask me what type of bench I have...
I made it myself, it really isn't that hard to make one, and most people all ready have most of the stuff lying around...

It won't tell true cfm, but it will tell percentage of increase, or decrease, that you make... You can get the charts for the MAF you use and convert the readings to cfm, but it wont be as accurate as a flow bench is...

Here is a list of what you will need...

A vacuum source, dont laugh, a dustbuster is enough...
A good vacuum gauge that is acurate at low levels, can either be mechanical or you can use a map sensor. I use a map sensor..
A mass air flow sensor, I use a bosch 3" sensor
power supplies for maf and map
meters for map and maf

Some list, you will need a few other things to go along with this that will be in the decription.

Set the head up with the valves at about 2/3 of the lift you are going to run. you can hold the in place with a jig or use orings on the stems to hold them.
You will end up checking about every .1 of valve lift, but 2/3 is a good starting point...
Get a piece of pipe about the same size as the bore of the engine. and put in on the head in the same position as the cyinder would go. I use pcv pipe and made tabs so it clips into the head bolt holes, and you double sided foam tape to seal it to the head. (You need to have pipe to simulate cylinder wall shrouding.) Drill a hole in the side of the the pipe to insert a nipple into it to read the vacuum drop in the pipe... More on this later...

Now fab up some thing so you can mount the MAF to either the pipe or the intake side of the head... On Scooby heads you should also have the tumbler housing on the head to flow it...

For flowing the intake, the MAF goes onto the intake side, apply vacuum to the pipe that mocks up the cylinder wall, have the vacumm gauge hooked to it as well... adjust you vacuum in pipe until it is a stable 1" vacuum drop..
record your MAF reading...

To flow the exhaust, just fip it around so the MAF is on the cylinder side and pull vacuum out the exhaust port...

After doing this, and rechecking everything numerous times, you will have your base readings...

I have had many people laugh at my setup, until the see the numbers of the heads that are flowed after porting them...

If you are worried about messing up your heads, you can take molds of the stock ports and then make clay ports to experiment with untill you get the flow you want...

After you are done porting your heads, have them flowed on a good flow bench, it will run you about 200 dollars at most racing shops for a 4 cylinder..
You need to make sure that they are flowing evenly after porting them...

Now onto cutting the valve seats...

There are a few companies that make really good cutters for hardened valve seats...
Two that come to mind are http://newaymfg.com/ and http://www.goodson.com/

Neway has a picture of the setup on there main page...
You can get any style scutter you want from either company...

I preffer Goodson cutters...

Let me know if you have anymore questions about porting your heads, I have been porting heads for all sorts of things for over 20 years...
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Old 04-02-2006, 01:42 PM   #6
Hopper
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Very Good!

I fabricated a Flow bench. I use 6 vacuum motors with a variable transformer to control depression, and a Flow Quick

I use a VR-7000 to cut my valves

The reason I ask about the seats, because stones are Stone Age. I go to a shop to cut my seats, but I have been thinking about using my Bridgeport to start cutting them. Itís time consuming with the mill, verses a floating head.
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Old 04-02-2006, 04:10 PM   #7
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Stones are fine on cast iron, but they don't work on hardened seats very well...

Check out the two companies I put links up for... The cutters are not the fastest way to do it, but they are very good at it... If you take your time doing the seats, you don't even have to lap them in... I am sure you can get the stuff to use the cutters with your mill, that would make it a quick job, and be very accurate...
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Old 04-03-2006, 03:59 PM   #8
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nice thread. good info hopper and david.
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Old 04-09-2006, 04:43 PM   #9
shvrdavid
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I am updating the picture of the heads I am working on...

Here is the intake side so far, seats still need cut...

It appears the cutter is on backorder...


Comments ???
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Old 04-09-2006, 05:10 PM   #10
Hopper
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I know you spent a lot of time on the sharp edge between the two ports, but, remove it. Make it round. Think of an airplane wing.
With that sharp edge youíll have a lot or turbulence between the two ports.

Flow the intake port, while you have the vacuum source there, flow a small string in the port and watch what it will do.
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Old 04-09-2006, 06:09 PM   #11
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Interesting thought, I will try it and see if it creates more turbulance than it is worth...
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Old 04-09-2006, 11:27 PM   #12
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Ok, now I am totally confused... I tried the string trick to see where in fact the turbulence is in the intake tract of the heads.. I found it at the typical places that I thought I would. Around the valve for one... The odd one is the turbulence on the outside of the port wall.. I know , my diagram sucks, but I will explain what I found..

The brown line on the ports doesn't make any sense to me at all, the air lifts off the port wall after going thru the tumbler delete... It must have something to do with the tubulence at the injector... I am going to clay the area and see what mods I can do to the deletes to get this area to flow better... If you put the string anywhere near the middle of the port, there is turbulence, but the turbulence is up at the injector area... The divider does not seem to cause any ill effects.. After the air gets past the turbulnce from the injector, it finds a path and sticks to it.. I also noticed that if you increase the air speed thru the port, the air starts to rotate down the runner towards the valve... I wish that I would have done this to the heads before they were ported, it would be interesting to see the difference...

More to follow another day... Thanks for suggesting the string idea, it gave me some things to think about...
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Old 04-10-2006, 08:03 AM   #13
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Quote:
Originally Posted by shvrdavid
If you put the string anywhere near the middle of the port, there is turbulence, but the turbulence is up at the injector area...
having a bit of tumble/swirl in that area is probably not a bad thing at all... it may give back more in terms of fuel distribution than it takes away in terms of mass flow rate.

in any event thanks for sharing your results.

-ken
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Old 04-13-2006, 02:22 AM   #14
Hopper
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Port flow will favor a side in the port. Our ports favor the cylinder side. UN shrouding the combustion wall will help flow. Do you have a manometer? If so you can probe around and see high and low spots.

Leave your work for now, or just break the edge.

If you pay shipping both ways, Iíll flow one cylinder for you, and give you a print out. I have stock charts; we can compare your work. If so just the right head, it needs to be finished. Let me know.
Good luck.
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Old 04-13-2006, 02:26 AM   #15
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Is there an injector in the TGV? Looks like it formed a cone around it, just like the guide and the valve. Your picture looks fine. Did you do work in the TGV?
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Old 04-13-2006, 12:49 PM   #16
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FWIW, Dan Paramour of DPR gave me a port job that looks a lot like this, with a knife edge you could shave with.

The string experiment and diagram of your findings are interesting... thanks for going to all that trouble.

How hard would it be for you to find someone's stock heads to perform the same test on? I agree that the ensuing data comparison would be valuable. And a side-by-side with a radial edge head would be interesting.

Really nice job... very impressive work! Your decades of experience are showing. What's your tolerance for uniformity across cylinders? Any pics of the other side?
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Old 04-13-2006, 08:43 PM   #17
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Quote:
Originally Posted by ka mano
FWIW, Dan Paramour of DPR gave me a port job that looks a lot like this, with a knife edge you could shave with.

The string experiment and diagram of your findings are interesting... thanks for going to all that trouble.

How hard would it be for you to find someone's stock heads to perform the same test on? I agree that the ensuing data comparison would be valuable. And a side-by-side with a radial edge head would be interesting.

Really nice job... very impressive work! Your decades of experience are showing. What's your tolerance for uniformity across cylinders? Any pics of the other side?
I have seen some of Dans work, He is very good at what he does...

Here is a picture of all 4 of the intake ports...


I am still in the process of measuring them to see what else needs to be done to them to even them out...
I am sure they will need a little more work to even them out...
I want all 4 of them to be as close to equal as possible...

Then it will be off to the exhaust ports... They need some serious work to get them to flow... The factory bowls are very restrictive...

With a turbo engine I like to get the exhaust side to flow as much as possible.. Normally aspirated likes a split from intake to exhaust side... Somewhere around 30% more on the intakes.. A turbo totally changes that, you want as much flow as possible out the exhaust side... If I cant get it close enough to what I want with the stock valve sizes, I may put oversized valves on just the exhaust side... I have set up a few, turbo 4 valve heads for motorcycles, that the exhaust side out flowed the intake... Not sure how that would work with the displacement of the scooby...

After that, the chambers need some work as well...

I am not in a real big hurry to get them done, but they are getting there...

I am like most people, more projects to do than time permits...
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Old 04-16-2006, 11:32 AM   #18
ka mano
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Impressive! IMO ported heads are one of the most visually pleasing parts of our engines.

What are the downsides from taking out so much material? Is there loss of intake charge velocity making tuning difficult at low rev?

It'd be cool to see pics of the exhaust side. Thanks for posting up these cool pics.
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Old 04-17-2006, 10:22 PM   #19
shvrdavid
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Quote:
Originally Posted by ka mano
Impressive! IMO ported heads are one of the most visually pleasing parts of our engines.

What are the downsides from taking out so much material? Is there loss of intake charge velocity making tuning difficult at low rev?

It'd be cool to see pics of the exhaust side. Thanks for posting up these cool pics.
To answer your question about removing that much material...

As you have found with your car, you have to raise the idle to keep the port velocity stable... With a low port velocity, the fuel does not distribute very well... The injector does its best job of atomizing the fuel, but the low velocity can not keep it suspended in the airflow... The fuel will literally fall out of the air and bunch back together... That is part of the problem with the idle in your engine... The second part of it is the duration.. Low duration cams ,like the stock ones in most engines, open the valve as late as possible to promote a high port velocity... To better explain it, there will be a partial vacuum in the cylinder when it opens... The vacumm can be created in two different ways, the first is opening the valve after the piston starts to go down on the intake stroke, and the second is the close timing of the exhaust valve that scavenges a vacuum in the cylinder..

With a high duration cam, the intake valve opens before the piston gets to top dead center, typically about 30 degress in a turbo engine.. To make matters worse, the exhaust valve may not close until 20 to 30 degress after top dead center... This point when both valves is open is called overlap... The wider the overlap window, the worse it will idle... At low rpms the overlap eliminates the creation of vacuum in the cylinder, until the exhaust valve closes... At high rpms it works totally different... The late closing of the exhaust valve actually creates a vacuum due to the charge velocity in the exhaust port...

Now back to the larger intake port at higher rpms...

We all know that increased port volume and decreased velocity hurts low rpm power. You would be suprised how many people dont understand how the larger port creates more top end power... I will give an easy explaination for it that doesn't cover all of it... Before I go into it keep in mind that you can do the same thing with smaller ports, but it is much harder to explain...

Just about everyone has felt the air coming out a a blow gun... It comes out fast, or does it... Believe it or not, air in an intake manifold exceeds that speed by 4000rpm in most engines.. The biggest difference is that it is starting and stopping a lot... Guess what happens to air when it exceeds about .6 mach... Stumped? An easy way to explain it is that it stops acting like air and acts more like a liquid... And the liquid fuel doesn't want to turn corners at that speed, it will go strait and hit the port wall... If there is any change in port diameter, it creates a massive amount of turbulence at that speed...

This is where the larger port comes in... With a larger port, the air doesn't have to go as fast to fill the cylinder... ie it takes fewer full intake ports to fill the cylinder.. This extends the rpm range that is under .6 mach... Combine that with a high duration cam, which to a point lowers port velocity, and you can spin even higher without exceeding .6 mach...

From what I figured out, a stock STI engine reaches .6 mach about 6500 rpm... The heads on your engine with the cams you have should reach it about 8000 rpm... I figured this at 24 psi...

Keep in mind that 1 mach, the speed of sound, is affected by pressure and a little by temp... .6 mach in a manifold is different at vacuum than it is with 30psi of boost... Pressure increases the speed of sound... That is part of the reason engines respond so well to forced induction...

I will post pics of the exhaust side after I do a little more to them...
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Old 04-18-2006, 01:42 PM   #20
sponaugle
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Speaking of idle and port/cams:

I have been street driving Steve's car (ka mano), which has the DPR complete racing port job, larger valves, and the stage 2 cams.

Stable combustion at idle occurs right around 1000-1100 rpm, but the trick is getting the car to keep the idle there. Using the Accessport (or Ecutek), I can raise the target idle points to say 1100 rpm, however this leaves one problem.

If you jump off the gas, as the rpms are falling and the TPS is less then 1.6%, the ecu waits for the RPMs to fall below the target idle point before it starts idle control. Once it starts this idle control, it sets the idle motors to 32% duty cycle and starts a feedback loop. In the case of the large port/cam setup, to idle at 1100rpm, you typically need about 68-75% duty cycle on the idle motor.

Unfortunatly, neither the Access Port nor the EcuTek expose a 'Starting Idle Duty Cycle Map' that would allow you to change the starting point. Since the car starts at such a low duty cycle, it takes the car about 5 seconds to get the idle back under control. During that time, the car is barly hanging on at 500-700rpm, and often dies.

The simple solution is the use the throttle cable adjustment to crack the throttle body open just a bit, so the resulting duty cycles are brought down closer to 32%. I have made this change, and the off gas idle pickup is much better, and the RPMs don't fall below 900-1000 during idle engagement.

The more ideal solution would be to drill a very small hole in the throttle plate to offset the difference needed. I may do this once I determine the right size hole needed.

Once these starting duty cycle maps get exposed, it will make idle control much better for these large cam setups!

Jeff Sponaugle
PDXTuning.com
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Old 04-18-2006, 06:31 PM   #21
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Quote:
Originally Posted by shvrdavid
From what I figured out, a stock STI engine reaches .6 mach about 6500 rpm... The heads on your engine with the cams you have should reach it about 8000 rpm... I figured this at 24 psi...
I will post pics of the exhaust side after I do a little more to them...
I'm curious about the method used to determine the intake mach index. Were you using something akin to:

http://www.btinternet.com/~mezporting/machcalc.html, or were your adjusting the speed of sound based on temperature assumptions?

I am suspecious of the math used on most of these internet sites, as they use a linear reduction for the effect of lift vs valve size. (Translation, if the lift were to double, the velocity is cut in half). That is obvously an incorrect model, as list past 1/4 of the valve diameter additional lift does not add significant flow.

Jeff
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Old 04-18-2006, 08:01 PM   #22
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This site has just about every formula you need to figure out baselines for just about anything

http://www.rbracing-rsr.com/calculations.htm

Temp has a much smaller effect on an intake charge speed than pressure does...

There are even more formulas, I will look around and see what I can find for you, it will save me a ton of typing...

I don't have much experience with the Accessport... Can you force a fixed map value with it at a preset value, ie rpm? I have gone nuts trying to get large cams to idle for very similar reasons with other types of computers... Not sure how the subaru computer deals with idle maps... FYI may ecutek reflash will hunt and sometimes stall... I can relate to that, and I have considered a bleed hole... You may want to get a valve for controling the air for a fish tank and experiment with a controlled vacuum leak to find the correct size of the hole... Different pcv valves can also add or subtract to the bleed...
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Old 04-20-2006, 12:07 PM   #23
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Quote:
Originally Posted by shvrdavid
This site has just about every formula you need to figure out baselines for just about anything

http://www.rbracing-rsr.com/calculations.htm

Temp has a much smaller effect on an intake charge speed than pressure does...

There are even more formulas, I will look around and see what I can find for you, it will save me a ton of typing...

I don't have much experience with the Accessport... Can you force a fixed map value with it at a preset value, ie rpm? I have gone nuts trying to get large cams to idle for very similar reasons with other types of computers... Not sure how the subaru computer deals with idle maps... FYI may ecutek reflash will hunt and sometimes stall... I can relate to that, and I have considered a bleed hole... You may want to get a valve for controling the air for a fish tank and experiment with a controlled vacuum leak to find the correct size of the hole... Different pcv valves can also add or subtract to the bleed...
Interesting... This site uses the exact same javascript code as the other site I posted about. Take a look:

Code:
<SCRIPT LANGUAGE="JavaScript">
//rbracing-rsr.com
<!-- Begin
var piston;
var valve;
var rpm;
var stroke;
var lift;
var numvalve;
var injlbhr;
var temp1, temp2, temp3, temp4, temp5, temp6, temp7, temp8, temp9, temp10, temp11, temp12, temp13, temp14;
var result1, result2;
function create(form){
piston = form.pistdiam.value;
valve = form.valvdiam.value;
rpm = form.rev.value;
stroke = form.strok.value;
lift = form.lft.value;
numvalv = form.numv.value;
temp1 = piston / 2;
temp2 = temp1 * temp1;
temp3 = temp2 * 3.1416;
temp4 = valve / 2;
temp5 = temp4 * temp4;
temp6 = temp5 * 3.1416;
temp15 = temp6 * numvalv;
temp7 = temp3 / temp15;
temp8 = rpm * stroke;
temp9 = temp8 / 12;
temp10 = (lift * 1) / (valve * 1);
temp11 = temp10 * 1.5;
temp12 = temp11 * 34793;
temp13 = (temp9 * 1) / (temp12 * 1);
temp14 = (temp7 * 1) * (temp13 * 1);
result1 = roundOff(temp14, 3);
result2 = result1 / 1000;
text = "<HEAD><TITLE>Inlet Valve Mach Index</TITLE>";
text += "</HEAD><BODY BGCOLOR=#0000FF TEXT=#FFFFFF>";
text += "<font face=arial size=-1><CENTER>";
text += "Inlet Valve Speed of Sound (MACH) Index</CENTER><P>";
text += "Your bore size is " +form.pistdiam.value;
text += " inches with a stroke of " +form.strok.value+ " inches ";
text += "and has ";
text += form.numv.value;
text += "  inlet valves with a diameter of " +form.valvdiam.value;
text += " inches. Running a valve lift of " +form.lft.value;
text+= " inches at " +form.rev.value;
text+= " RPM, the inlet valve mach index is " +result2;
text+= " .  The mach index for maximum volumetric efficiency is .6";
text+= " .  Beyond .6 the volumetric efficiency falls off. ";
text+= " As the mach index rises beyond .6 the volumetric efficiency can be increased by later inlet valve closings (60 to 90 degrees ABDC).</font><P>";
text += "<center><form><input type=button onClick='self.close()' ";
text += "value='Close Window'></form></center></font>";
resultsWindow=window.open("", "displayWindow", "toolbar=no,menubar=no,scrollbar=yes,resizable=yes,width=320,height=350")
resultsWindow.document.writeln(text);
resultsWindow.document.close();
As you can see from this code, it was clearly written by someone somewhat math challenged. Take a look at the temp1 to temp 3 calculations, then look at the temp 4 to temp 6. Then look at temp7, and you can clearly see that temp 7 divides temp 3 by the scaled temp 6. That means the division by 2 and multiplication by PI are cancled out. Those are wasted steps.

Also, if you trace the code, the ending calculation for the Mach Index is as follows:
Code:
           Db^2           Rpm * Stroke(in ft) 
N =     --------  *    --------------------------
          n*Dv^2         (lift/valve) * 1.5 * 34793
The more commonly used estimate is based on the following formula:

Code:
            Db^2           2 * Rpm * Stroke 
N =      --------  *    --------------------------
            n*Dv^2         Speed of Sound
Assuming the speed of sound is the same for both equations ( ) , the first equation would expland to (using the speed of sound as 66000 ft/sec)

Code:
        Db^2        2 * Rpm * Stroke(in ft) 
N =   --------  *  -------------------------------
       n*Dv^2       (lift/valve) * 1.5 * 34793 * 2

which reduces to 

        Db^2        2 * Rpm * Stroke(in ft)              1    
N =   --------  *   -----------------------  *  ------------------
        N*Dv^2        Speed of sound            (lift/valve) * 1.58
In other words, the author here has used the standard equation, and scaled it based on the amount of lift compared to valve diameter. The standard equation is for a port of fixed size, so the derating based on lift would result in the following:

If lift = 1/8 valve diameter, velocity would be 5X of an open port.
If lift = 1/4 valve diameter, velocity would be 2.5X of an open port.
If lift = 1/2 valve diameter, velocity would be 1.2X of an open port.
If lift = valve diameter, velocity would be .63X an open port.

Thus this equation indicated if the valve is open .63 times the valve diameter, the flow is equal to an open port.

I'm not sure where this constant comes from. It is my understanding that valve flow does not increase much beyond about 25% open.

Any comments about this? I could email the author of the page.


Jeff
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Old 04-20-2006, 02:01 PM   #24
drees
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Quote:
Originally Posted by Hopper
I know you spent a lot of time on the sharp edge between the two ports, but, remove it. Make it round. Think of an airplane wing.
With that sharp edge youíll have a lot or turbulence between the two ports.
I would think the same thing - Rounded on the intake ports, sharp on the exhaust side. Probably should flow bench both setups to be sure!
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Old 04-20-2006, 09:39 PM   #25
shvrdavid
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Quote:
Originally Posted by sponaugle
Interesting... This site uses the exact same javascript code as the other site I posted about. Take a look:


The more commonly used estimate is based on the following formula:

Code:
            Db^2           2 * Rpm * Stroke 
N =      --------  *    --------------------------
            n*Dv^2         Speed of Sound
Assuming the speed of sound is the same for both equations ( ) , the first equation would expland to (using the speed of sound as 66000 ft/sec)

Code:
        Db^2        2 * Rpm * Stroke(in ft) 
N =   --------  *  -------------------------------
       n*Dv^2       (lift/valve) * 1.5 * 34793 * 2

which reduces to 

        Db^2        2 * Rpm * Stroke(in ft)              1    
N =   --------  *   -----------------------  *  ------------------
        N*Dv^2        Speed of sound            (lift/valve) * 1.58


Any comments about this? I could email the author of the page.


Jeff
I know that a lot of people use this equation to figure it out...

The first error I see in it is the basis of the speed of sound...

The speed of sound is: 331.6 m/s (1088 ft/s) at 0 deg. C in dry air
That comes out to 65280... at zero degress with 0 humidity...
I don't know about you, but that just isn't possible with our engines...

So what is the speed of sound in our engines???

Put your thinking caps on, this gets complicated...



Did I loose anybody...

R = the universal gas constant = 8.814 J/mol K
T = the absolute temp (in Kelvin)
M = the molecular weight of air in this instance = 28.95 for dry air
y = characteristic of specific gas (air)

Do you see where this is going... My engine doesn't run on air alone...
Gasoline, water, and alcohol are also in this air flowing thru the engine
The molecular weights in the column of air drastically effect its well over 66000.

Temperature also raises the speed os sound as well... I wish my intercooler took the air to 0 degrees...


Temperature affects the speed of sound as well

Here is one formula to figure that out...

Vsound = 331.4 +0.6t where t is the temp in celcius and the speed is in meters per second... Remember the 331.4 is 0 degrees 0 humidity...

There are flaws in just about every way to figure out the speed of air in a port...

The equations used in these java scripts are a close approximation.

Try figuring out the speed of sound for the air fuel mixture in our intakes at 30 psi of boost at 200 or so degrees.... It complicated.... I came up with just shy of 1200 fps... 72000 not 66000... If anyone else gets the same answer, let me know.... That would make us either both right, or both wrong....

As far as the flow versus lift maxing out at 25%, are you referring to 25% lift versus valve diameter? If you are, that is another debated subject as well...

When you figure that out, the valve is open in the head on a flow bench...

The math that figured that out (Chrysler did this research in the 60's) also came up to other conclusions that disproved this..

Ram effect from the valves opening and closing and the length of the intake runner can change the lift that it is most efficient... or which side of the lift curve is most efficient...

Gotta run, later guys... edited for major typo's

Last edited by shvrdavid; 04-20-2006 at 10:06 PM.
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