TEXAS TREY

Nice fabrication on the QSV.

DblTrbl

Nice concept and build!

I would like to see the comparison with the same converter. The stall of the converter is a huge factor in how fast spool comes up. As you know, the more load there is on the engine at a given RPM, the faster it will spool. Also a looser converter will allow more RPM and speed up spool. Could you also add engine RPM to the dyno chart? Might be interesting to see that.

V8KILR

I have swapped back to the same 3800rpm converter so here is that dyno sheet. The run was started earlier so still not apples to apples but that's often the case with dyno sheets. I don't have any rpm info. The QSV run is the red one. Converter is slipping from around 100-160kmh due to more torque on QSV run.

DblTrbl

BTW, very nice HP numbers. Must be a fun little car.

I'm not seeing as much difference in this comparison. The converter seems to have been a bigger factor after all. If your engine management logs RPM and boost over time, that might actually be a better indicator of the effectiveness.

Is that a T3 flange?

Is the spring strong enough to overcome the exhaust pressure even at the start? If not, maybe move the shaft closer to the center of the flap.

Don't get me wrong, I really like what you've done. I would love to improve my spool time so I can be on the converter less time.

So I'm guessing the boost is fed back directly to the wastegate actuator to open the flap once there is enough boost to overcome the spring pressure. Very slick.

V8KILR

Thanks, it is awesome fun on the street. Boost comes in very early with just part throttle making it very responsive on the street.

The higher the stall, the less the benefit of the QSV will be. That's because you are closer to the peak torque/boost where the turbo works well just by itself. A 5000rpm stall would probably show very little difference on the dyno sheet.

I tried doing some logging but the car was wheel spinning on the dyno from around 70-190kmh, making the rpm numbers useless. Also logs showed that the dyno guy was feeding in the throttle and didn't get to 100% until 65kmh. I probably need to use a hub dyno to get better rpm data.

The shaft is a 1/3 the flap width as that's where the center of pressure is. With the shaft in the center (first attempt), it struggles to open smoothly due to the force on the flap. I have videoed it opening and it only opens once it gets the boost pressure from the turbo.

It starts opening at 6psi and fully open by 11psi. If I held it closed to higher boost using a solenoid, the gains would be better then what is shown so far. Based on similar setups opening it around 15psi might work best.