userbbc

Performance and drivability have been phenomenal after the APR upgrade. However, at certain times, mainly during acceleration, there is a very faint whistling/ringing sound that I never noticed before. It actually sounds closest to a high pitched telephone ring.

Is this normal? Is this the turbo spooling up or the diverter valve handling excess pressure?

The last turbo vehicle I'd been in was an '86 Audi 5000CS...back then, the turbo sounded more like a jet turbine...so I'm wondering what this new sound is?

BMWBig6

If it sounds like a warbling bird, yes that's the turbo. And it's normal, post-chip.

boiler127

I've heard the same noise with the GIAC ECU. It's normal.

AudiTX87

The turbo has always had a whistle to it, but its always been subtle. However, after APR I agree with you, a lot louder and kinda does sound like a ring...sounds good, no complaints here!

what program are you on?

Spacecadet_CC

I love that turbo whistle. It is way too faint on the stock car. I can't wait to get the chip!

userbbc

on the east coast so running the 93 program. Really happy about the upgrade - makes the a4 a totally different car.

on the other hand, does anyone remember turbine-sounding turbos (pretty much like a plane taking off)? Or was that tune only available on turbos of old. As I recall, the '86 Audi my parents had was an oil cooled turbo...

BMWBig6

Oh yes, I remember. My Porsche 944 turbo (951 for those in the know) sounded like a jet engine. Loved that sound, but that car had more lag than I cared for (it was a peaky creature).

whiterabbit66

What kind of performance increase are you guys noticing while driving? I mean in terms of 0-60 0-100 etc? Is the car more responsive in the higher rev ranges or mainly low down with all the extra ftlbs?

Thanks,

NJRoadFan

The MC engine (which is a popular swap into the 4000/Coupe GT) used a larger K26 turbo with longer spool up time.

ddun

the car feels like it drives effortlessly with all the torque. doesnt take much to go from a stop, passing power is adequate even without downshifting, and the top end feels less anemic, actually top end feels a lot better.

alsohttp://www.audizine.com/forum/showthread.php?t=301302