CMS,
The whirr you are hearing, as some have eluded to, is from the turbo spooling up. I have 2 T5's and both have this sound. One of these cars i recently changed my air filter from stock to the K&N type and noticed immediately that the whirr loudness increased (even my wife noticed, asking me that day if the car was ok). Next time you hear it look at you turbo gage and you will notice as the turbo needle increase (Boost) then the whirr sound increases. Mine is loudest just after the boost passes the center. Once the boost returns more or less to nominal the sounds dissapears.

I have the same kind of sound on my mazda RX7 turbo too.

Jeff
1994 854 T5
1994 855 T5
1987 Mazda RX7 Turbo

The famous 850 whistle!...This has been debated for literally years here on brickboard with many a suggestion, but never a definitive answer given or agreed on. Others have referred to it as the mysterious whistling noise. It happens on 850s regardless if they are Turbo or not. For example, it happens on my '94 N/A, but only in cold weather. Something others have noticed as well (cold weather). Some have suggested the Turbo, others a vacumn leak, others wind noise from a specific cavity in the engine compartment. It does appear to come from the right front area and I have just accepted it as an anomily of the car....and years later it still remains a mystery!

I'd guess turbo noise. Or as the Italians say when talking about engines, "at's a no noise, at's a sound she make."

I hear it on my '95 855t with 77,000 miles but only during the first few minutes when cold. After that it's very quiet. I don't beleive it's a problem and I kind of like it. Like the straight cut alloy timing gears in my Moto Guzzi LeMans.
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H
ppy Motoring, Erwin in Memphis, '95855t