Originally Posted by duder01
The GTX aero doesn't improve spool-up, per se. The idea was to make a higher flowing, more efficient wheel in the same size package as the older GT stuff.
However, you could improve spool if you look at it slightly differently. If you had a "regular" GT3076R, and replaced it with the GTX3071R you would have a 5mm smaller wheel...hence faster spool-up.
And, you get the same / slightly higher max flow. And higher compressor efficiency, leading to lower charge-air temps, hence higher midrange torque and the ability to run more timing.
You'd also get better transient response too (which doesn't show up on a map or dyno graph). Cruising along at part throttle, if you go to WOT immediately, the turbo will respond faster and you'll get more torque "on demand."
Don't get me wrong. I'm not secretly wishing for a bad result for this turbo.
It's logical to expect it to perform better than the old 3076 due to the smaller compressor wheel. It's just that the old 3071 already had a smaller compressor wheel and had only marginally better response (yes I know that this is subjective, but it's my opinion based off of driving one). That's why I'm waiting for results as well, but I doubt that the gains over the old 3076 will be easy to quantify.