It makes perfect sense. The efficiency difference between my Xonas and my old vtgs is easy to see when I compare logs.
Are Pagid Yellows a good "street" replacement for stock pads? I'm still on my original pads and rotors but eventually they will need to be replaced...

 

 

Thanks for the tip on the brakes.
I'll check my driveway to make sure it's not my car in the container, lol. But seriously, what car did you buy?

 

 

cool! I'm also from the 70s (barely!)

 

Hi all, it's been a long, cold winter up here but finally got the car out for some play. With the help of Tial tech support I was able to swap the springs in the wastegate actuator to softer ones...I will detail the whole painful process later, lol.
Long story short, I think I'm on the way to some turbo happiness. Just incrementally increasing the boost now. At 15psi the 60-100mph 3rd gear pull was as fast as with my old Proto 63vtgs going ***** out, lol. At 17psi it's pulling strongly all the way up and holding boost nicely. Weather still a bit wet and cold right now so it may be a few more days before I can adjust some more. The good news is that it looks like the bog between hard 3rd to 4th gear pulls seems to have been beaten. In hindsight, I think part of it may have been setup/user error but I'm not sure. All I know is that the HKS boost controller instructions are probably wrong...it says to do a full throttle pull and use the highest value as the "baseline boost" setting. My understanding and experience showed that the controller doesn't take effect until it reaches that "baseline boost" setting and in my case that was near the high end of the rpm range so it wasn't quite right. I actually measured the wg cracking pressure (details later) and set the baseline boost setting at that level and it has worked beautifully. More details to follow..

 

A quick update - targeting 19psi and with boost in the 18-19psi range my 60-100mph 3rd gear time is 2.9-3.0s in non-optimized pulls. This is what I was getting with the Champion 68s with 22.6psi!!!

 

Bogg - which xona's did you go with?

 

The XR980 kit...I believe it is the Xona version of an a3073 turbo. I think this is the XR5756 with some alterations to get it to use the stock Porsche headers and to mate with Porsche size exhaust.

 

I just ramped up the boost to target of 21psi in the HKS controller. Now we're talking! Boost comes on smoothly and quickly with stock "offset" settings and no targeted boost increases. The Cobb logs show values about 1/2-1psi less which I assume is related to "losses" flowing through the longer piping and intercoolers to get to the sensor in the ypipe. With non-dedicated runs in cool weather I get consistent 60-100mph in 3rd of 2.8s and that's with a full tank of gas and partly uphill. Sam I will send you the logs soon! They look great.
Previously (i.e. last fall) I would always get higher boost in 4th gear pulls over 3rd gear pulls. Not anymore. Even with rapid 3-4 shifts there is no boost spike. I am not sure if I should give credit to the softer spring or the more accurate setup in the HKS. I actually measured the cracking pressure for the wastegate and used that setting in the HKS controller. The instructions give a different method but that different method never really worked for me (or others I have spoken to).
Next step is some targeted increases in boost above torque peak and that's it.
I did a 3-4 pull and let off the gas around 128mph and coasted to 130mph. Full tank of gas, slight uphill, and I didn't shift in anger. 6.6s 60-130. Not too bad. This car definitely has 5s in it on pumpgas with a few more tweaks, which rocks!

 

The HKS is such an underrated beast ... How much of a distant memory are those VTGz now?,

Log manifold pressure, it's a calculated channel but you'll find its closer to the HKS numbers than the reading before the throttle ....

btw, around 21-22 psi with 30's is when the stock fuel pumps start dropping pressure, stock ecu is a bag full of compromises and will totally miss it, gets worse when fuel is warm so you might not see it in the first or even second log .. Friendly heads up ...

 

Thanks for the tips. I have been logging manifold pressure and it is a little closer to HKS numbers. VTGs, what are those? lol. But seriously, the vtgs were awesome but the current Xona tech outshines
them at all rpms. I think I paid more for my Champion 68s than I did for just the Xona turbos without the accessories. Xonas are worth the money but they are more complicated to get setup than the vtgs.

 

You're probably right, Sam, accurately setting up the boost controller is important. Tial had said that the "optimal" setup is to have spring pressure at 60-65% of max target pressure. With the softer spring and some preload I am closer to 50%. I don't have any boost creep or spikes but I think I may have been okay by just reducing the preload on the initial spring that was in the wastegate, but there was no easy way to do that because the stems were just long enough to catch the bolt. Reducing the preload would have been a bit of work but it would have still been easier than changing the spring, lol. Hindsight is always 20/20.

 

e85+VTG is still competitive. I'm on 63.5mm VTGs, full bolt ons, and e85. full boost at 3500rpm.

60-130 in 5.88 in 70* ambient, 60-100 in 2.55

 

very competitive...if you have e85. I don't...otherwise I would have kept my 68s.
The Xonas can hit full boost a couple of 100 rpms later but I don't bring them in quite that early. Not looking to change my rods, lol.