I just had wrxboy2003 fab me up a 3-inch midpipe that runs from my HKS DP to my stock muffler on my 94 Legacy SS. (Thanks again, Nate.) On my drive back north from Shakopee I noticed a fluttering sound coming from the vicinity of my DP when going 60% Throttle position to WOT in between 2500 and 4000rpm. I've heard this before, but the new DP makes it VERY noticeable. What is this noise? Is it wastegate flutter? If so, what exactly is wastegate flutter? Is it compressor surge? Is it dangerous to my turbo? Like I said, it's made this sound before, it's just more noticeable, now. I know other Legacy owners with upgraded turbos have mentioned this sound, too. A bit about my car: 94 Legacy SS with IHI VF-8 turbo, JDM Slanty TMIC, 3-inch TBE reduced to stock (2.25in) at the muffler. The DP has similar characteristics to the stock DP in that there is no wastegate opening. It's just a flat plate and the wastegate exhausts are immediately forced into the regular exhaust stream instead of using a bellmouth or divorced wastegate pipe. Thanks, -Greg
wastegate flutter. just the little flapper flapping arround trying to control boost. unless the car was bucking.....
I agree. After doing some more reading on legacycentral I'm pretty sure it's nothing more than wastegate flutter. Like I said, I'd heard this previously, but now with the DP opened up I can hear it much better. Just like I can hear the sweet, sweet music of spool-up. AWDImprezaL, what kind of BOV? Is it a true BOV, or something akin to a WRX BPV... I'm interested.
