#### naughtika

##### OzVR4 Stalker

they should've provided you with the other dyno graphs..

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they should've provided you with the other dyno graphs..

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- #22

i was paying for a tune as cheaply as i could, not the dyno, the dyno was solely to show the before and after. Ill ask anyway though.

There is a question that have been floating on my head about the maximum psi of our TD03 turbos. I have gone through this thread and this thread and I read that each turbo can handle 15psi, this is correct, right? If so, that is a total of 30psi together.

So, this is the question. Why is it that most of us have set our boost below 15psi only while both turbos can produce up to 30psi? That is only 1/4 (7.5psi) boost level out of 15psi on each turbo.

Am I missing something??? I am confused!!!

Please someone else explain this better than I have!

At 15 PSI of boost (~30psi Absolute), the turbo is essentially holding pressure on the outlet of 2x the inlet pressure, if that inlet pressure is at sea level (~15psi Absolute)

Although you have 2 turbos, this maximum pressure ratio does not change, and therefore the outlet pressure will only get to 2x inlet pressure.

It doesn't matter how many turbos you run in parallel (assuming all the same turbo) this will always remain true.

If one turbo produces more than the other, the other will slow down (because it cannot support the pressure ratio) and as a result, flow less air. Because less air is flowing, the pressure ratio then drops back.

If, on the other hand you had one turbo which fed the inlet of the 2nd turbo, you would have the opposite.

Because the pressure ratio across the first compressor was 2:1, the inlet pressure to the second turbo is then ~30psi Absolute (or 15psi boost). Supporting a pressure ratio of 2:1, the maximum pressure on the outlet of the 2nd turbo should be ~60psi absolute. The down side of course is that the maximum flow rate is still only what the one turbo can provide.

Exactly the same principle as having batteries in series or parallel. In parallel you double the current capacity but maintain the same voltage. In series, you double the voltage but maintain the same current capacity.

Just swap current for flow and voltage for pressure and you have turbos.

In theory at least

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