Yes, just the blue as you start cracking right at 15psi. As such, you have zero control of boost via the WG at anything below 15psi as it it fully shut below that value. Based on your readings, you also have limited WG travel at .32" (8.1mm) for some reason. I am assuming the WG valve would open further with greater pressure beyond that of the 26psi you publish. I found with the Blue spring the WG valve does not fully open till about 32psi. You should be seeing 10-11mm of travel from closed to open. The free travel of the IVM WG is just under .749" (19mm) according to Tial.

 

Tial said we don't need anywhere close to the full range of the wg opening so I don't think it is a concern. The more preload there is on the wastegate the less travel there is but it's not a limiting factor for the 997tt

 

I've only put a few kms on the car so lots of tweaking left but I verified that as expected with the boost controller off it makes 14.2 psi as shown on the hks peak hold, about 0.5 psi lower on the AP, which is pretty consistent with my previous measurements.

 

Lucky you! You don't have to change the spring. Mine was 20plus psi on wastegate alone before I changed the spring...

 

What do you make now with the HKS off?

 

14.5psi was the highest reading in the Cobb datalog, at the higher rpms. That is with some preload on the wastegate so that cracking pressure was 11ish iirc

 

Just a little update: car has been running pretty well this summer, just chasing down some gremlins. I think I've finally beaten them but hopefully not jinxing myself. After I changed the springs in the wastegate actuators I've been tweaking the boost curve. Car was running well but not completely consistent and I started to hear a little rattle noise at low rpm if I accelerated in 2nd gear. Just brief sound like metal on metal. To make a very long story short, the inboard nut that holds the wastegate arm in the "trunnion" of the wastegate kept on coming loose. This was on the passenger side only...problem is there is no access with regular tools, even short wrenches because the wastegate lever goes behind the header. Anyway, I found a right angle opening wrench and then discovered these things called "crowfoot wrenches". I didn't end up buying the crowfoot ones but after taking the heatshield off I was able to get the small right angle wrench in place to tighten the inboard nut so it wouldn't keep coming loose and altering the wastegate pressure on one side when that happened.
I also tightened the wastegate actuator "caps" as they weren't quite as tight as they should have been...I think they might be the source of the rattle at certain rpms with load on the car.

Anyway, the car now drives much better. Amazing what you get used to after driving for a while. It's the low end immediacy that was suffering a bit although I didn't realize it. Now the car feels more responsive and the logs are better. In low 70s today with full tank of gas and 21ish psi max I did 60-100 in 2.8s with ZERO knock sensor activity. A couple of pulls this evening reminded me why I fell in love with the Xonas, lol.

I will keep on logging and slowly increasing the boost for just a little more zoom and then done. I'd love to crank it up to 24-25psi but some recent posts in other threads mentioned 35-40k USD for an engine build and it just seems like diminishing returns for me at this point. Maybe it wouldn't be so pricey without the 3.8L upgrade but damn that's too rich for my blood. Wouldn't put me in the poorhouse but for sure into the doghouse.

My wing has been acting up so I bought the EB Werks fixed wing set. Nice that they let you borrow the Durametric Pro cable to disable the wing. Just had to put a deposit down for it. Hopefully get to that this weekend.

Been kinda quiet around here, hopefully people are enjoying their cars...

 

Bogg,
Sounds like the car is running well!

I was on this thread a couple months back when I was trying out different ethanol blends with different tunes in my car. I went up to e25 and didn't really get a whole lot of extra performance. But here's an interesting factoid- I bought a set a AMT Forged monoblock alloy wheels for my car...they are crazy light at around 16 lbs front and 22 lbs rear. The car is lots faster with the light wheels in 60-100 and 60-130 pulls. 60-100 dropped from 3.25 to 3.1 seconds, and 60-130 dropped from 7.5 to 7.25 seconds. Very similar density altitude as my prior test runs. It also feels way lighter and sharper. I was running GT3 wheels which are relatively heavy. I've read about the critical importance of rotational weight- apparently there is certainly validity to the benefits of reducing it!

My next possible move may be to get rid of my 3.5" core GMG intercoolers and go for do88 big packs or AMS 5.5" coolers with associated larger plumbing and y-pipe. That may be good for 1-2 tenths as well..?? Otherwise my car is running flawlessly. I've been driving it a lot.

Keep enjoy the car!

 

Thanks. I may have jinxed myself...car runs great but now I hear a "ticking" noise which is loud enough to reflect off buildings and other cars. Not rpm related and not there at idle. Seems to be speed related...like when a kid puts a card between the spokes of the bike wheel and the ticking gets faster as the speed gets higher. I may have to look for cards in my rims or something, lol.

 

Interesting about the light wheels. I've dreamed about "deep dish" rims for years...I'll have to make sure they are lightweight when I decide to pull the trigger on a set.

I recommend the Big Pack. I previously had the .2 intercoolers on my 68vtgs and the big pack keeps temps down waaay better. With your built engine and interest in staying on pump gas I'd give serious thought to upgrading to Xonas the next time your engine is down for whatever reason (plugs, injectors, etc...)….

 

that weird ticking is usually an exhaust manifold leak. Check your bolts for proper torque.

 

thanks for the tip...I read something similar. Better this than a failing timing belt tensioner etc...

 

My header bolts were all ok - I checked up to 17ftlbs and none were loose. Turns out it was a piece of metal or nail in my tire. noise gone now!
the only other noise I hear is a little "rattle" at low rpm when going from part throttle to more than part throttle. I think it's the heatshield and I see that one of the clips/bolts is missing.

 

One of my goals for the Xona setup was a 75-110mph time of 3.3ish seconds. Start in 4th gear at 74mph and floor it. This simulates a roll race scenario. Proto 63s did it in 4.3s, Champion 68s did it in 3.7s. Today with half tank of gas and outside temp of 65F the pull took 2.99s! Very pleased. Repeat value was 3.0s so this wasn't a one-off run.

 

Can you post images of your current EBC configuration?