200 CFM Research

[bruce]

[wfolarry]

Perhaps even a new topic title devoted only to Pipemax 101
I would like to see that too. There is a lot of valuable info in that program that you could use to make adjustments when porting your heads.

[larrycavan]

[maxracesoftware]

its the busiest time of the Year for me,
our NHRA Division Races are about to start in Februrary
and in succession in months afterwards.
A lot of Port Work and Dyno Time is promised out,
so it puts my PipeMax development time further off.

Still i'm constantly working on upgrading PipeMax
in any spare time i get...currently working
on both 3.7 and 4.0 versions at the same time
as they are interelated.

3.7 will replace 3.6xp2 version and have new look
with new Inputs... like ability to input
Flow Data and then PipeMax calculates tons of Data from those inputs. Will create Flow Sheets from Inputs.
3.7 will include FlowBench Program inside

3.7 will be in the Main Screen and 3.6xp2 version will be
in 2nd Screen..so that version 3.7 is 2 versions in one
and a little backwards compatible.
This will be a "Tabbed-style" Program with a little
look like Mac OS-10 and Windows combined Interface.

3.7=Weather Inputs, CamShaft Lobe Profile inputs,
Wrist-Pin Offset, Carb or Induction CFM Rating Inputs,
Header Piper Thickness, Intake Port CenterLine Length,
Engine Type, Camshaft type, Block & Head Material Input,
various Port CSA inputs, and more

Also ability to Save Output or Input Data as .PDF File
plus many more Print Screen and Print Data options.

3.6xp2 and 3.7 are "Entry-Level" Programs

--------------------------------------------------


4.0=Major upgrade..Professional Program.

4.0= Start of Full Engine Simulation Program
Graphs,Charts,Video,animations,Sound,etc.
Will also have a Windows/Mac OS-10 Style Interface

4.0=will include 3 main Tabbed Screens,
3.6xp2, 3.7, and new 4.0 versions,
a 3 in one Program....and backwards compatible,
and convert 3.7 and earlier Files to 4.0

Too many improvements and features to list now
but you will be able to download both 3.7 and 4.0
from my Website. They will be real versions
but run in Demo Mode until Unlocked by Password.


i won't be Posting often until i finish these
2 Programs. Hopefully 3.7 in 2 more Months or less
and 4.0 about a Month or so afterwards 3.7

[larrycavan]

Port Area Calculations - Some thought on the matter.

This post is more or less thinking this through and typing as I go....so bare with me! I'm doin the best I can to explain my thinking...you can pick it apart as you so choose. I'm open minded and willing to learn / discuss things. Being nearly 52 years old now, I'm well past the age where I once knew everything... :laugh:

Let's use the 4.528 [circumference / perimeter] value from above and go from there.

THE PROBLEM

Different formuation methods derive different area calculations from the same circumference value.

Using 4.528" we can arrive at 3 different area calculations. It varies depending upon the shape we choose to make from 4.528" curcumference.

Circle area = 1.633 sq.In.
Square area = 1.281 sq.in
Triange area = 1.138 sq.in [shown just for example]

Generally we're going to have port shapes of circular, square or rectangular. All I can say is take your pick and use the formula that you feel best represents you actual port.

What are we after here anyway?

Using formulated methods we're trying to discover a correct cross sectional area and air speed for a given port and a given RPM of the engine.

We can formulate the average port area.

Average_CSA = Port_Volume_CC / (Port_CenterLine_Length * 16.387)

We can formulate the mean velocity from the average port area and our flowbench derived CFM.

FPS = ( Flow_CFM * 2.4 ) / Average_CSA

We already know the area formulas yield different results. What else do we know?

We know the accuracy of our flowbench cannot be 100% verified.

We can only compare it to another through calibration plates and conclude that our bench reads the same as another bench that we "believe" to be accurate for whatever reason [ see Pass Around Plates Thread]

We know the pitot we use to measure air speed takes up area in the port we're measureing. As such we should probably subtract the area of the pitot from the area of our port.

Ultimately we have a handful of non-exact methods from which we're trying to correlate an exact value.

There is not even a uniform agreement on port air speeds for all engines. Some types like wicked fast ports that would give other engines absolute fits. We have a thread going on over on Speedtalk where that's being discussed.

When it comes right down to it, the best you can do is to work within the paramaters of the accuracy you feel your methods & equipment provide you.

When it comes to porting heads for internal combusion engines, you have as much opportunity to discover something about the likes / dislikes of the engine you're working on as the next guy.

I'll end my dribble with this statement. I really like and very much appreciate the thinking and approach 200cfm shows in his posts. In this thread alone, he's addressed the CSA calculation from 3 different approaches. That, IMO, is the type of a guy that will not only accomplish something but learn and enlighten others along the way!

JMO

Larry C

[thomasvaught-1]

Quote:

"Rocco...Tom....Tony....where are ya?"

Had a few computer glitches and could not log on for a few days, but Bruce got me fixed up last night.

Tom V.

[larrycavan]

Tom,

Do your PMs work now?

[thomasvaught-1]

Larry, I am back under a new log-on so any previous PMs are gone.

Send me a PM and I will see if I get it with the new log-on which is:
thomasvaught-1

Tom V.

[bruce]

I have no idea why "new" shows up in red in any posts ???

Maybe that's just on my computer?



Edited By bruce on 1200933688

[thomasvaught-1]

Red lettering is gone now Bruce

Tom V.

[200cfm]

Larry, I believe you are correct in the pitot probe itself consuming up some of the port space and hence altering the internal CSA. I think I will start subtracting the CSA of the probe dimensions when using the math. And since the probe has to infuence the area space I believe one could assume the the port velocities are going to be less than the observed pitot reading. Wonder what a valid correction factor might be for velocity that could account for the pitot probe csa influence?

Today I remade one of my port enty plates. This version 2 should be an improvement because the first entry plate was rather thick (3/4) and I noticed as I opened up the port wall from entry back to pushrod turn the entry plate radius no longer gasket matched the port. The new entry plate is thinner with a full 1/4" radius (paint brush wood handle split down the middle) for the air to roll over into the port and matches the modified port entry dimensions.

[200cfm]

Ran some tests this week mostly to educate myself on air behavior. Have learned that the design and choice of the radius inlet does affect and may schew the readings. Last week I made up a nice radius for cylinder port 3. This week I wanted to make lift comparisons to cylinder port 1 and was using the first version wood 3/4 thick radius for port 1. Comparison between the ports was fine at lower lifts but widen alot at upper lifts. Thought I had found a "super port design" but when I made a clay radius the upper lift numbers fell back. That got me thinking. The thickness and radi is swinging things. The clay though was rather tedious to stay glued and would pull over on high lifts so I have decided to make up a radius plate similiar to the version 2 model for port 1 and test compare again. But I dislike the work involved in making special inlet radius for every port especially when they are enlarged and the original radius no longer matches up the port.

What are others using for air to port entry transistions? Are you seeing variations on different models. What should be a standard design. Thanks.

[200cfm]

The new made up port entry plates were doing fine but I ran into one port today that layed down on high lifts and gave a "scream sound." Thought at first I had ported it wrong or shaped it differently. Decided to retest with some new modeling clay I bought at a craft shop. Shaped up some clay to the entry radius to the reworked port entry section and the scream sound went away and the higher lifts fell right in line with the other ports. Appears the roof entry was over hanging the entry plate and set up a sharp edge that somehow skewed the air entry. If a intake to head mismatch behaves like this flow could really be hurt on high lifts. So now I am thinking of using clay for any port entry that is not a perfect fit for the entry plates.

[106-1194218389]

I will use the port entry plates and then use clay to make them fit properly. Much faster than using 100% clay. JMO though

John

[200cfm]

I tested the 1.780" heads this weekend after a lot of shop time and porting. Never reached 200 cfm and the cam could only reach up to .422 lift but I had a blast. Went a best of 11.043 @ 119.47