This is what I think I feel is happening:
When the boost controller is turned off, the wastegate spring progressively opens (mechanically) even as full boost is still building. Therefore some of the boost leaks out and it takes longer to spool up. With the controller on, the gate stays completely shut until desired pressure is reached, at which point it vents only whatever's needed to maintain what's dialed in. Am I right or wrong?
It DEFINITELY feels like 10 psi off the wastegate spring is much much lazier that similar boost with the profec on.

 

correct

 

Thanks. Yay, I'm smart!

 

Hey interesting, thanks for bringing this up. EBC is now moving up my list of modifications with this new information

 

No problem, pretty cool. Makes a huge difference especially with a lazy turbo at boost levels below it's efficiency, such as mine.

 

the duty cycle of the boost control solenoid determines how quickly it opens and the responsiveness of the turbo to an extent. higher duty cycle = opens later and more quickly, with hopefully less lag but a higher risk of boost creep. lower duty cycle = opens sooner, possibly less responsive but not likely to boost creep if you have a properly sized wastegate.

 

Less lag is great, but from what I hear high boost at lower rpms (< 3000) is more likely to blow an engine? Or do you just have to adjust the settings so it comes on progressively? Im really interested in a profec b and this is one thing I was concerned about.

 

having a EBC wont actually make a big turbo spool earlier in the rev range like 3000 rpm or below. It START to spool (actually build +ve pressure) at the same time with or without the EBC. The advantage of having the EBC and having the gain tuned is that it will actually reach you max boost quicker, hence you will feel a greater rush when you come on boost up to your max boost. So as an example, lets say your turbo used to start make +ve pressure at say 4000 rpm and reach max boost of 20psi at 5000rpm. If you add and EBC you still start to make +ve pressure at the same 4000 rpm but you make the 20 psi by 4600rpm instead of 5000rpm.

As torquesouth said it is because the EBC solenoid is keeping the pressure away from the wastegate. Without the EBC the pressure runnng straight to the wastegate the wastegate spring would progressively open as the pressure/boost build up which in fact cause the wastegate to start opening up and bleeding of the exhaust gas "prematurely" hence slowing your spool to max boost. With an EBC, the solenoid stays closed until the max boost is reached then it opens up instantly and the pressure hits the wastegate at once making it open up rather quickly, as compared the slow bleed off without the EBC.

 

But be aware when using the gain function on your EBC, if set too high it will cause overboost, which we know what that can cause. A little overboost isnt bad its actually helpfull in giving you that initial start up kick when coming on boost, so if you set you EBC to 20psi and you tune the gain you can get it to go to 22psi per say for a very breif moment without causing damage and still giving that little extra kick and then back down to a steady 20psi. The scramble boost works on the same concept. But if you have the gain too high and it spikes to 30psi..then you are very likely screwed.

 

Very well put Andrew. And I also find that sometimes when you set the gain high it spikes early but boost falls on top end (?). And with a huge wastegate there is not much worry of boost creep due to late opening. One thing's for sure, I don't have to worry about boost at 3000 rpm with the big fatty snail...

 

How you finding the T88? Liking the new car and the power. Whats the mod list on the new machine?

 

Actually it's another T78.
Very similar setup to the last, just bigger primaries (850/1600) and tuned for a little more boost (can go up to 20 psi on C12). It feels the same on the 12 psi I run on the street and track so far, just much louder (almost 4" exhaust all the way). Very nice to drive one again, just like before it's my true daily driven transportation.

 

More so with the wastegate and turbo combination you have.
The Greddy Profec gain setting loves to be a lot on the positive side.

 

With that being said...

Do you believe dual wastegates are more responsive than a single?

Say dual 36mm vs single 60mm?

 

True. I couldn't beleive the difference when you tweaked it on the white car. I remember the high boost wasn't working at first because I had it too low...