Mounting a secondary Bosch BPV to an aftercooled SC setup
Joined: Oct 2008
Posts: 4,805
Likes: 15
From: St.Petersburg/Tampa, FL
Joined: Oct 2007
Posts: 340
Likes: 9
From: West Palm Beach
I did this a while back on my Comptech Novi 1220 setup based off feedback from a few of the S2Ki SC'd legends (S2000Junky in particular) and have since been asked about it several times. I posted these pictures and a short write-up on a different forum, but figured it would be good archive information for anyone looking to do the same in the future.
My history with aftermarket BOV/BPV's on my Comptech setup ranges from the stock Bosch BPV, to a Turbosmart Dual Port, to a Tial Q, then a Tial QR, and now the Tial QR with the secondary Bosch BPV. I had compressor surge from the stock Bosch BPV and the Turbosmart Dual Port (both ports vented to atmosphere) when making 9k RPM shifts at 7 PSI. The Tial Q (with a custom 1.5" ID adapter flange to my aftercooler) solved this as it evacuated much more air volume. However once I stepped up to 16 PSI the venting noise at cruising RPM's was unbearable. I swapped to the Tial QR which is far more tame under cruising conditions, but the compressor surge at high RPM shifts was back. This is because the Bosch BPV, Turbosmart Dual Port, and Tial QR all have a 1" ID restriction at their inlets, and only so much air volume can be vented through them... this restriction causes the compressor surge.
Adding the Bosch BPV to the air pump port on the aftercooler to act as a secondary BOV/BPV allowed a second escape point for air volume to reduce the duty of the main BOV. This allows me to use a quieter main BOV like the Tial QR and avoid compressor surge at high RPM shifts. Currently I have the secondary Bosch BPV venting to atmosphere, but I might plumb it back into the intake to further reduce blowoff noise. The Bosch BPV is louder under venting than the Tial QR, but still 100x quieter than the Tial Q under cruising conditions.
Anyway, onto the info:
My history with aftermarket BOV/BPV's on my Comptech setup ranges from the stock Bosch BPV, to a Turbosmart Dual Port, to a Tial Q, then a Tial QR, and now the Tial QR with the secondary Bosch BPV. I had compressor surge from the stock Bosch BPV and the Turbosmart Dual Port (both ports vented to atmosphere) when making 9k RPM shifts at 7 PSI. The Tial Q (with a custom 1.5" ID adapter flange to my aftercooler) solved this as it evacuated much more air volume. However once I stepped up to 16 PSI the venting noise at cruising RPM's was unbearable. I swapped to the Tial QR which is far more tame under cruising conditions, but the compressor surge at high RPM shifts was back. This is because the Bosch BPV, Turbosmart Dual Port, and Tial QR all have a 1" ID restriction at their inlets, and only so much air volume can be vented through them... this restriction causes the compressor surge.
Adding the Bosch BPV to the air pump port on the aftercooler to act as a secondary BOV/BPV allowed a second escape point for air volume to reduce the duty of the main BOV. This allows me to use a quieter main BOV like the Tial QR and avoid compressor surge at high RPM shifts. Currently I have the secondary Bosch BPV venting to atmosphere, but I might plumb it back into the intake to further reduce blowoff noise. The Bosch BPV is louder under venting than the Tial QR, but still 100x quieter than the Tial Q under cruising conditions.
Anyway, onto the info:
Bringing this back from the dead, but it would be useful.
Registered User
Joined: Oct 2005
Posts: 160
Likes: 1
From: South Florida
Found it, ordered the Turbospeed dual port valve. Seems straightforward.
