RB25 vtc vs no vtc

[eh?]

I don't think I've seen any post up a comparo of vtc vs no vtc on here or any of the aussie sites, so here it is.



Disabling of vtc was accomplished just by pulling the connector off. With VTC off Peak TQ is relatively unaffected, however you can see the huge *mid range* torque advantage of having it on. Also what you can't see is the ~1psi difference in boost with vtc on having the advantage.

You guys should check to make sure your vtc solenoid is powered, I know there's been more than a few who didn't know it wasn't wired up.

[Darius]

Nice work! It is great to finally have concrete dyno proof to support all the internet information that has been floating around regarding this topic. I have always read that it was better for low to mid-range torque to have it plugged in and didn't help peak torque because, well, it disengages at ~4700 rpm. Hopefully, all those with RB25/30's will take the time and make the effort to keep the VTC functioning instead of writing it off as a negligible feature.

[StricNyne]

heh, mine is off, i should turn it on i guess. when did he have it engaged, mine is wired in through a external switch, i think its 2000- 4500 or around there

[eh?]

Nice work! It is great to finally have concrete dyno proof to support all the internet information that has been floating around regarding this topic. I have always read that it was better for low to mid-range torque to have it plugged in and didn't help peak torque because, well, it disengages at ~4700 rpm. Hopefully, all those with RB25/30's will take the time and make the effort to keep the VTC functioning instead of writing it off as a negligible feature.

The next step is to move the turn off point to 5500 or so. On the last dyno tuning session I did there seems to be a bump in Torque in the later rpm band. Hopefully I'll remember to mess with it with the new turbo.

[jetdriver]

What turbo are you using during that test? Where does it make full boost and what psi is that? The dip from the vtc de-energizing is throwing me off, and I can't tell when the wastegate opens. The smoother lines represent the 5500 turn off point, correct? Thanks for sharing!

[eh?]

Boost was about 14psi on runs 2 and 3 and 16psi on the rest. turbo is 62-1 t3 with full boost about 4700, a lot slower than it should be due to my "custom" .82ar housing.

I was also tuning boost control so disregard the dips in run 2 and 3, they are from the boost control over correcting. There are no longer any big dips in the other dynos just little oscillations that I need to tune out. But no the other lines are just vtc off at 5000. Hard to see but the comparison is really between runs 7 and 8.