Drawing copressor maps, IHI RHF6

[jfallen]

I had a bit of free time today so I thought I’d finish off drawing the IHI RHF6 compressor map I started the other day. I started to draw this map firstly because I wanted to see how this compressor would look fitted to a CA18DET looking for 260kw at the motor, at 20PSi (P/R of 2.4,) and secondly as an exercise to see if I could do it. I used figures obtained from the turbo calculator spreadsheet I’ve written to select this compressor as a possible choice.
The RHF6 compressor is used in the VF23 turbocharger used on the Mazda BP18 GTR motor seen in that Familia 323 GTR from the group A days and in a current Nissan truck. It features a 65mm Exducer, 52mm Inducer, with a Trim of 64.0. It has a maximum flow of 17m^4/minute, (46lbs/min) along with maximum rotational speed of 140,000rpm.

Currently IHI only offer their compressor maps in this not so user-friendly form:
link

Step 1 Highlight the flow line of the compressor you wish to draw a map for. You don’t have to do this, but it makes life easier in the next step.


Step 2 Draw up a grid using an appropriate scale. Make sure to use a setsquare, ruler and pencil, as you will make a mistake. Try to use most of the page, with the drawing in he middle.
Once the grid is drawn up, place small dots on your grid that correspond with the flow line on the other chart. It’s easiest I find to plot the points where lines intersect as it’s more accurate and there are plenty of these points.
It should now look something like this:


Step 3 Keep this as an original and take a few photocopies. On the photocopies using a set of French curves start drawing the lines of equal speed. This is a trial and error kind of thing, but you’ll know when you’ve got it right. It just looks correct.
It should now look something like this:


Step 4 Take another set of photocopies and keep your final from the previous step as an original. Using your set of French curves start placing the efficiency islands on the map. Mine is a little to the left and the peak efficiency island (in this case) should slope more towards the top right hand corner. I plan to redraw from this step which wont be too much effort as I’ve kept originals of each step.
It should now look something like this:


Step 5 Now all that is left of is to finish off the map by adding in the labels so that a viewer knows what they’re looking at.
It should now look something like this:


I hope you’ve found this useful as a guide to plotting your own compressor maps, should you ever feel the desire to do so.

Cheers
Jordan

[chris davey]

You must spread some Reputation around before giving it to jfallen again

Good thread