Originally posted by Keyser:
I pinned the secondaries and it sucked terribly. The turbo fell right on it's ass. It would take at least an hour of playing with timing to get back close to where I now and I don't know what that would do for daily driving. The secondaries are staying. Once the motor is fully broken in, I'll switch to synthetic, go iridium plugs and try again. Likely I'll get 399.8 or something. Right now I kept getting a slight ignition drop right at the peak and I tried 2 different plugs. I might have reached the top of the ignition system. I'm gapped at .025 on NGK TR6 right now.



This is an obvious consequence!

No matter what b*llsh|t people say about secondaries not being usefull or being too much of a restriction, it doesn't take away the fact that it is the low-rpm restriction that causes intake velocity to increase! Consequently at those optimum rpms the momentum of the fast moving column of air causes the cylinders to fill enough that you get a slight pressurization...in NA form! With a turbo it just magnifies it until you are boosting so much air that the secondaries become too much of a restriction at that rpm. At low rpm your turbo doesn't fully spool with low exhaust volumes, it can't help pressurize the cylinder much and is in effect a restriction of its own. Once the turbo makes a little positive pressure it enhances the secondaries and makes it a bit easier to fill the cylinders.
As far as high rpm restriction, as long as the intake ports are opened enough then you will get plenty of air past the secondaries as long as they are opened. There will not be much of a difference in the horsepower just by removing the secondaries with your turbo. It would take an enlargement of the intake runners as in another extrude hone pass in order to make a noticeable difference.
Remember, the engine requires much less air at low rpm than at high rpm even if the clinders are in a positive state of pressure.

Former owner of '99 CSVT - Silver #222/2760 356/334 wHP/TQ at 10psi on pump gas! See My Mods '05 Volvo S40 Turbo 5 AWD with 6spd, Passion Red '06 Mazda5 Touring, 5spd,MTX, Black