OKRX-7

Okay, I didn't have a pill in the turbo pre-control line so I through a needle valve in there and now have gotten it up to 8-8.5 psi on the primary without playing with the valve. I didn't get a chance to slave one in on the wastegate so I am getting boost creep on the secondary. But it looks like it may have been caused by not having a pill in the line.

OKRX-7

Okay, update since this morning. I am now running about 9-7-10, oddly enough I no longer get the creep I used to get. Now when I hit 10 after awhile it starts dropping down slowly but I doubt I hit 9psi before I am about on the redline.

The only thing that concerns me is that my needle valve is like half a turn away from being closed. I am afraid I will be only 1/4 turn open by the time I actually run 10 on the primary, anyone else have experiance with this?

OKRX-7

Taken from Rob Robinette's site in reguard to the Turbo Precontrol. As I said I am set between 1/2 and one full turn open. I see Rob ran around 1/8 open so I still need to restrict my needle valve some more to see a full ten on the primary. Unless anything else changes I am going to consider this problem...

Solved!


I did this and it works but it takes some work to get the valve set right. I now have have a much smaller boost spike when the second turbo comes on line. I have the valve set at just a little more than 1/8 turn out from fully closed (very restrictive). The more you open it the more it pre-spools (more boost spike), the more you close it the less it pre-spools (more boost dip). Adjust it to balance the boost drop and boost spike that occurs at 4500 rpm.
This valve is much more sensitive than the boost valve. A very small turn will greatly affect the pre-spool. It is tough to get the right amount of pre-spool to balance the boost dip vs. spike. When the precontrol valve opens the boost from the primary turbo will drop because the precontrol valve acts like a wastegate, exhaust is diverted away from the primary turbo. Realize that adjusting the pre-spool will also raise and lower your primary boost because of the way the precontrol valve acts like a small wastegate. The more you open the valve (more pre-spool) the lower the primary (<4500 RPM) boost will be, close the valve and primary boost will go up. The bottom line is that there is a complex relationship between primary boost and the boost spike at 4500 RPM. If you have problems setting the pre-spool valve you can easily re-insert the restrictor pill.