I have a 91 240sx fastback. Anyway, when I'm driving past 2.5 thousand rpms at WOT my engine starts to whistle like its spooling a turbo. Anyway, I get home and rev the car from a stand still no sound, except for the engine. I've had a few people tell me different things, water pump? Air leak(hoses, intake)? I'd like a few more thoughts on this please. I'd like to know incase it turns out to be a big problem. THANKS.

 

I Have the same thing as if my car is catching air like a turbo when reving down. it only does it on long drive's when the engine has been on for a long time wish i knew what it was but so far it hasent seem to be a problem but it would be nice to know what it is. I know its comming from the back of my car though