Infographics & Data Visualisation

Maybe.

Have you tried plotting intake - exhaust (or whatever way round)?

I think what you want to show is "why does this engine pull in more and kick out less?".
What about a ratio of intake to exhaust and then have the engine on the X axis.

The goal of the chart is to communicate how the GT3, the 997 Cup and the 996 Mod perform with reference to the base 996. Which is why it's plotted as it is.

The ratio of intake to exhaust (whilst clearly important) is not the key theme.

The goal of the chart is to communicate how the GT3, the 997 Cup and the 996 Mod perform with reference to the base 996.

Is base 996 on that chart? Are those measurements differences from it (i.e., the percent figure on y is the comparison)? This may be obvious to car people.

One way of focusing attention on a specific thing(s) is to make the others slightly transparent. Not sure if that communicates what you want though.

Also I'd cut the y and x ranges so differences are slightly more pronounced (mostly y).

The Y axis is % of the stock heads flow at the valve lift on the X axis, if that makes sense?

The Y axis is % of the stock heads flow at the valve lift on the X axis, if that makes sense?

Absolutely none, but I don't think I'm your audience here.

You shouldn't need to be interested in engines to understand the chart, so it's a clear failure.

Performance engines need to draw air into the cylinders and then expel it again - the rate of this flow is one of the key metrics to judge how well an engine does this, and it's a key indicator of how an engine is likely to perform because the more air and fuel you can use in every combustion event the more power you are likely to be making.

The stock 996 engine is the reference frame here because that's the standard version of the car, the GT3 and the Cup are, respectively, very high performance and race engine heads.

Some people will be familiar with how a standard 996 performs, a few with a GT3, a tiny handful a 997 Cup.

Gotchya. I'm guessing you don't really want to use this plot, but: Is the aim to show that the modified 996 is more comparable to those other cars/better than unmodified? If so, I'd use raw air flow and add the unmodified 996. Then someone can easily see the differences. As it is now the viewer has to move back and forth from data points to the percentages.

Well it's not doing a very good job of showing that right now is it?

If they are referenced to the 996, does that mean these are all having twice the airflow? Or is the axis wrong?

I'd split each graph into four panels so you have each category as a separate panel with the axis the same size.
I might put the baseline on there so you can compare it, maybe.
At the moment it's confusing because the lines are similar width and I find it difficult because the colours are too similar.

What is it you're trying to show?
There's nothing wrong with stating the answer in the title of the chart.

Also, what's the thing you're trying to show? And what's good or bad?

That is what I’m trying to show, but:

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Where would three unmodified 996 fall on those? If the same spot (roughly) I can see your problem. If noticeably below, it would be good perhaps.

Or cut the low end of valve lift so theres more detail in the to end.

do you need to show the full range?
could you take a few specific valve lift values and be able to then play around with points and/or bars?

.

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Ok, so this is the standard 3.4 litre M96 engines intake and exhaust flow, in CFM, at various valve lifts:

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And this is the 96mm bore (above, from the 3.4 litre engine) plotted against the same head on a 100mm bore (3.7 litre):

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From which you can say that the exhaust is benefiting from (possibly) a degree of unshrouding.

But, otherwise - the flow is very close.

Now we plot the standard engine against the modified M96 head:

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Quite a difference to the stock head - and a much larger change than moving to a larger bore.

Now the plot shows the modified M96 head against a 997 Cup head:

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The 997 is noticeably stronger in the middle of the curve, and stronger throughout for the exhaust - much larger valves than can fit into the M96 head are hard to beat.

Here's the modified M96 vs the GT3:

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