Kevin Jewer
DSM Wiseman
- 1,464
- 277
- Jul 25, 2002
-
LaRue,
Ohio
Everyone knows that the bigger the WG valve is, the more likely it is to blow open. (Pressure times Area = Force) Especially on internals with weak actuator springs, and some leverage gained in the flapper arm system. I did a quick experiment since I was in a position to do so. Here is what I found.
I'm on a borrowed 16g setup with a 34mm internal and stock type actuator, but still using the manifold mounted external. I disconnected the internal actuator's vac line. I would see 24 psi falling to ~19 by redline, and 36-37 lb/min airflow. As an experiment I wired the internal WG shut, and it held 24 psi, sometimes dropping to 23, and airflow was at almost 40 pounds per minute across the whole gear, meaning it was opening before boost started to fall. (I'm assuming thats because a certain amount of air in equals a certain amount of air out, and that is what creates the pressure to blow it open. RPM isnt much of a factor if airflow is flatline across the gear.) Thats the highest airflow I have ever seen since I borrowed the 16g. I still ran the same 12.0s at 113-114s, but I did so without having to flog the tranny, though short times sucked that night.
I had previously speculated that the boost was dropping simply because the motor was outflowing the turbo, since I'm relatively well modded. I guess not
Moral of the story, I wouldnt run an internal again, unless it has at least an 18-20 pound spring in it, since I run at least 20 on pump anyway. Going external was a good investment, and I'm gald its behind me. Of course now the issue is my external has the highest available spring at 13 pounds, and the Profec B can only double that.... Dammit.
Just thought I'd share
I'm on a borrowed 16g setup with a 34mm internal and stock type actuator, but still using the manifold mounted external. I disconnected the internal actuator's vac line. I would see 24 psi falling to ~19 by redline, and 36-37 lb/min airflow. As an experiment I wired the internal WG shut, and it held 24 psi, sometimes dropping to 23, and airflow was at almost 40 pounds per minute across the whole gear, meaning it was opening before boost started to fall. (I'm assuming thats because a certain amount of air in equals a certain amount of air out, and that is what creates the pressure to blow it open. RPM isnt much of a factor if airflow is flatline across the gear.) Thats the highest airflow I have ever seen since I borrowed the 16g. I still ran the same 12.0s at 113-114s, but I did so without having to flog the tranny, though short times sucked that night.
I had previously speculated that the boost was dropping simply because the motor was outflowing the turbo, since I'm relatively well modded. I guess not
Moral of the story, I wouldnt run an internal again, unless it has at least an 18-20 pound spring in it, since I run at least 20 on pump anyway. Going external was a good investment, and I'm gald its behind me. Of course now the issue is my external has the highest available spring at 13 pounds, and the Profec B can only double that.... Dammit.
Just thought I'd share