Calculating Cross Sectional Area

[86rocco]

If people let me know what they would like to see in a spreadsheet, I might be convinced to give it a go.

[jfholm]

Ed,
That would be absolutely a great Christmas present! Personally I would like to see one that would calculate each corner from radius and each one separately. My corner radii are not always the same radius so it would be nice to calculate each corner on it's own merits. It would also be neat to be able to capture about five or six different areas along to port at different depths in from the intake manifold surface. Have each area post it's area so you could see it in a chart. Then have it average the whole port so you get the average area. Then calculate the port volume from that and the length of the port and what the velocity would be. Other than that I don't need much beyond this "simple" spreadsheet I described.

John

[Flash]

OK thanks guys, it all clear now.

Was just mixing up Radius and Diameter and the numbers that they represent.

[86rocco]

John,
That doesn't sound like too tall an order. The computer I'm at right now doesn't have Excel on it so hopefully this will tide you over until I get the spreadsheet done.


BTW, in case anyone's wondering where the 0.2146 comes from, it's (4 - Pi)/4 rounded off to 4 decimal places. If you look at my earlier posts in this thread, you can probably figure out why that number is used.

[86rocco]

John,
I've been giving this a bit more thought, how's this sound. First thing one valve per port, NO multi valve ports. Cross sectional areas at the valve seat, the port entry and 3 (maybe more) intermediate sections, more or less the blue lines on the diagram below. I think you should be able to get a reasonable estimate of average CSA from this.

For the port volume I'd also need the distance between the sections along the port center line i.e. the length of the red line between each blue line. The precision of the volume estimate is likely going to be much lower than than the average CSA estimate as there are too many unaccounted for variables, things like the volume of the valve guide boss etc. Whether or not this gives a volume estimate you could describe as "reasonable" remains to be seen and of course would also depend on your idea of what constitutes reasonable.

[jfholm]

John,
I've been giving this a bit more thought, how's this sound. First thing one valve per port, NO multi valve ports. Cross sectional areas at the valve seat, the port entry and 3 (maybe more) intermediate sections, more or less the blue lines on the diagram below. I think you should be able to get a reasonable estimate of average CSA from this.

For the port volume I'd also need the distance between the sections along the port center line i.e. the length of the red line between each blue line. The precision of the volume estimate is likely going to be much lower than than the average CSA estimate as there are too many unaccounted for variables, things like the volume of the valve guide boss etc. Whether or not this gives a volume estimate you could describe as "reasonable" remains to be seen and of course would also depend on your idea of what constitutes reasonable.

The areas at the blue lines are right on where I usually check! Man you are good. You are right about estimating the volume but we could also have an area where you could manually input the volume from an actual measurement. That would be a very useful tool to have.

Thanks
John

[86rocco]

If nothing else, it'll be an interesting exercise to see how good (or bad) the volume estimate actually is. I'll have a working prototype spreadsheet up in the next few days and once it's up you can let me know what you think of it and what features like to add or modify.

[Brucepts]

Great project guys!!!

[86rocco]

You can find a first draft of my CSA calculator HERE.