Adjusting wastegate spring pressure

[pistonbroke]

My AEM tru boost has an adjustment option to change the wastegate spring pressure. It apparently helps with turbo spool time.

 

As seen here,

 

http://www.youtube.com/user/AEMpowerTV#p/c/B4534133ED01A9D3/2/aDzx2oW0cak

 

I've not played about with this part of the gauge, and as far as I'm aware, it still set at 1psi. The video suggests setting it a couple of psi below the known wastegate spring pressure, but I've no idea what this is.

 

I'm a bit confused with the whole spring pressure thing, and it's a bit over my head.

 

So my question is this, is it worth me fettling with this option, or should I just leave it be.?

[JamieP]

Stock tt setups run actuators to open the wastegate, i dont think this will work for you.

[pistonbroke]

Hmm, my issue is since having hybrids fitted, I've had new actuators too. I think they must be a bit stiffer than the originals, as I'm not seeing full boost in 1st gear. All the other gears are fine. I don't get the second turbo rush until about 5500rpm in 1st, though occasionally, I don't get it at all.

 

The way the boost controller plumbs in, IIRC, is that one of the actuators is blocked off one end, with the controller plumbed into the turbo and the other end of the actuator (where the AEM manual would say plumb to the wastegate). If this actuator is running off a pressure level as the spring would, my thought process is that adjusting the spring pressure on the controller would have the same effect......or am I way off?

[jevansio]

Isn't this just the GAIN setting on other boost controllers?

 

It basically controls how hard the boost comes on.

 

Low settings (1 PSI) the solenoid is operated smoothly (opening the wastgate well before target boost) to achieve the target boost level (maybe at a loss of a bit of spool)

 

High settings, the solenoid is held open until just before target boost is reached (hence the gain in spool as in lower settings the wastegte would actually be already open in an attempt to control boost), then at the last minute the solenoid is driven like buggary. This obviously has the effect that it is possible to over shoot your boost target, then oscilations may occur as the boost sways back and forth (overshooting & undershooting) as the controller attepmts to stabilse the boost.

 

In general you want it set as high as you can (to achive best spool) BUT not so you get overboost, boost spike just as the turbo has spooled, or that oscilation effect)

 

I'm betting that number is the boost level under which the solenoid is held open (hence the wastegate is held shut), it should be set to a number under the spring pressure, if set over the spring pressure it will boost to oblivion.

 

 

 

You can imagine it like a car being accelerated to exactly 60mph, you can either hold you foot on the accelerator but ease off before you approach 60 in an attempt to smoothly hit it perfect (low setting above), or hold you foot flat until you get to 59mph, then by the time you come off you're past 60mph so you hit the brakes, then you drop back down so you accelerate again (high setting above also illustrating the oscilation affect)

Edited June 26, 2010 by jevansio (see edit history)

[chazuk]

http://www.aemeurope.com/varius/BoostVideo.php

 

Third video down , shows a live setup of the wastegate spring setting.

[pistonbroke]

That video I posted shows the spring pressure being adjusted with the results on a rolling road. I'll have a play with it later.

 

I'll put it on 10psi and see if it makes any difference to the boosting.

[pistonbroke]

Seems to have had no effect at all. Maybe i'll resign to the chance its one of the perks of steel hybrids.

[Homer]

Wouldn't that setting only work on an external wastegate setup? It does just sounds like gain adjustment as Jay has mentioned.