Fair enough. So still leaves to ask what pressure do i want it to open at? For those levels of boost?

 

I'm running slightly higher boost levels and the FP 18psi works great for me.

 

For running 22-24# peak boost, either the stock actuator, or a Forge WGA is your best bet. The FP 18# actuator, on the other hand, is not the ideal choice for running 22# peak pressure. Definitely you wouldn´t want a 22# actuator if you are just going to be running 22-24# peak.IMO for running moderate boost levels, such as 22-24#, the stock piece will do the job just fine. Just preload the spring to 18-19#.

 

Huge imagination here... Like when I need to preload it, do I just step on it really hard and apply body weight, and then lift and flow with it...?

How do I preload a WGA spring. I refer to preloading as in motorcycle terms. I'm not preloading for a jump am I... I see... well then haven't the slightest... I should know this.

Oh, and these spring rates, are they when the WGA is opening? or is this full open? Lets say I didn't want to preload it?

Thanks in advance

 

You can't change your spring rate by adding pre-load. They are by definition different beasts.

Your Spring rate of your wastegate determines the amount of boost the wastegate will stabilize at. A wastegate removes exhaust pre-turbine to control the amount of pressure/flow to the turbine wheel and thus limiting the amount of boost. The wastegate has a pressure reference port and a diaphram that allow a boost reference (from IM) to push against the force of the spring until it is overcome. When the spring pressure is overcome the wastegate flapper will lift off its seat and bypass (waste) exhaust pre-turbine. Getting higher pressure wastegate actuators will allow you to run more boost.

Pre-load is increasing the amount of pressure that is applied to the flapper against the seat. Similar to seat pressure on a valve spring. It is different than the actual spring pressure of the spring. If the spring isn't progressive...and it's linear then your spring pressure cannot be altered by adjusting the rod for pre-load. FYI...most actuators are linear spring rates.

To adjust pre-load: shorten your rod that connects the flapper arm to the wastegate diaphragm. You shorten it by loosening the lock nut, turning the tab with the hole in it (tighten), and then re-tightening the lock nut. FP has a nice video for you to see how this works.

In my experience with the stock 9 turbo and the FP Red... I put it as much preload as possible. I tried running little to no preload and the wastegate leaks very badly...making it impossible to see spool under 6k lol. I'm currently running FP's highest pressure actuator maxed out for preload. It works.

 

So what would the preload be on a stock WGA then to help it hold the higher boost?

 

To get a quantitative value... you would have to measure the length you displaced the wastegate arm and measure the force generated from that amount of displacement. Then find the motion ratio of the pivot point on the wastegate flapper. Then make a generalization about the applied load from the flapper on the turbine housing depending upon surface area contact. From that you could determine the amount of "pre-load" pressure that is applied to the flapper.

Or like most people do... they measure their pre-load by the number of turns they turn their turnbuckle. For example...I turned my 4.5 turns. On my Red... it's maxed out.

For a stock turbo trying to hit more boost... I would crank it all the way down. The SAFETY concern is overboost at lower engine speeds... this all depends upon your boost control system.

 

Ok, so is this to say shorten the rod, or lengthen the rod? I have also seen a 17psi actuator, possible better choice?

 

I've seen a few 22lb wastegates and they work fine