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I was wondering, at what RPM does the TURBO'S compressor wheel have to spin to charge...

a T3, a T4, a T-25, a T66 ?

No one can answer that. Depends on what size trim on each turbo, compression, displacement, backpressure. Also do you mean full boost or when it begins to spool?

This isn't the kind of question that lends itself to a straight answer as there are too many variables involved.

I'm assuming you're trying to relate this to spool for each turbo, in which case you are looking at it wrong. Bigger turbos don't have to reach higher turbine revs to make boost - they just require more exhaust energy to move the turbine.

But, to answer your question - they all start to build pressure at roughly 50,000 compressor RPM. (some earlier, some a little later)

Do you know when spooling would start?
And..
Do you know when it would get to full boost?

Thanks

I am putting a t 25 on my car an am pretty sure that it will spool to 6spi (full boost for me) at about 2500rpm. A freind of mine has a 2g talon awd and his boosts to 18 psi at about 3000 rpm. It does not hold well at that high of course. I mean it does not have much "top" end at high boost. But for my application I can boost 6 psi all day long and not really tax the turbcharger. As far as the others...I used to own a dodge with a t3, and it would pick up boost at about 3000 rpm. Don't know how much it was boosting (no gauges or education on turbo's at the time I owned it).