[quote author=Dagnut link=topic=7977.msg96025#msg96025 date=1214582269]
yeah your right its probably wron to say it spools the turbo ..the exhaust gases do that ovbiously but it does recircualte already compressed air which your losing if you dump to atmosphere....probably makes feck all difference but thats what i was told and it makes sense..why would subaru recircualte the air when its much easier just to dump it...BUT does the BOV just replace the secondary wastegate? in which case it wouldn't matter??
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To the best of my knowledge, there is only one wastegate. If you look at your intercooler, the wastegate is just to the right of the intercooler with a pipe that leads to the inlet of the primary turbo. To install a bov, you need to take the wastegate off, block the pipe leading to the primary turbo, then attach the bov. If you take the B4 up to 5 or 6,000 revs and change gear you can hear the wastegate dump the boost into the inlet. The sound comes from the pressure equalising on both sides of the wastgate, so in essence the air being dumped is the same pressure as the inlet is already before you changed gear... if that makes sense... so maybe there is no problem with having a bov??? The only thing i can think of is that subaru thought there was no point in wasting the air that has already been filtered?? but maybe someone that actually knows would clarify....
I would like to know if any1 here knows for sure, what way does it bring in the second turbo?? When using the primary turbo, all exhaust gas goes through the primary but when switching and using the second turbo, does all the exhaust gas travel through the second turbo only or do the turbos work together and the exhaust gases split? I know when i'm going through the vod, my boost goes from 0.6 on the primary down to about 0.3 as the second turbo comes in and then shoots back up to 0.8 as the exhaust gases are traveling fast enough at those revs to spool the secondary turbo very quickly