Good rpm to shift at?

[MarusGTR]

Well Skym you might be right as usual; Looking at the diagram and how a boost controller works I can't see how removing the restrictor could be beneficial...

Basically instead of giving small pulses to the wastegate you're jamming a crap load of air into them. Basically removing the restrictor should, if I'm interpreting this correctly, reduce boost with a stock ECU. As for my AFR it could be because of the EPROM that was burned off sight unseen by Robin Almasi. Since the ECU controls the solenoid, it could have been tuned for a setup without restrictor and surge the wastegates with unrestricted pressure instead of PWMing the line.

[Skym]

Not sure about being correct, but thank you for your kind words.

Without doing testing on a bench or car (adjustable valve), it's only a rough guess at best. That's based on what one sees as the result of removing the restrictor (could be that the boost duty maps on ECU are set for a higher boost level), fitting adjustable valve. Should always back what you read on internet with your own testing, calculations, etc to confirm, especially if it's from the internet. Some info is correct, some isn't and by testing you find out. It's more of a guide in the right direction (starting point).

Can't go any lower than spring pressure on internal wastegate actuators. For stock R32 RB26DETT internal wastegate actuators that's 9.94psi-11.36psi when tested on bench. That varying spring pressure can be why some cars produce more hp (high psi = leaner A/F ratio) than others on production line.

More air = overcome wastegate spring pressure and wastegate opens on back of turbo (can test this on bench with pressure / boost gauge T'd in and vacuum hose, air compressor)

Less air = takes longer to overcome spring pressure and wastegate stays shut a little bit longer and boost spikes (rise in boost level) and then wastegate opens (what a boost controller does and controls when, how fast, etc the wastegate opens to control shape of boost curve).

I'm thinking restrictor helps with back pressure to boost control solenoid, which helps it to maintain a straight boost curve, helps to bring boost on earlier by restricting air to internal wastegate actuators. Like I said above, only a rough guess and could be wrong.

There's a few boost duty maps on stock ECU, one for knock, one main boost duty map. They look like the fuel, ignition maps (load, rpm).

[Dragon Humper]

The restrictor limits the amount of signal pressure that the solenoid is bleeding off from the wastegate cans.

Basically, the diaphragm and the spring play a balance game in the can. Add signal pressure (from the charged side of the intake) and the diaphragm pushes on the spring to relieve exhaust gasses before the turbine, lowering the boost. Remove signal pressure and the boost goes up. Remove all pressure and the spring will hold the wastegate shut untill the pressure becomes too great between the engine and turbine and the flapper valve cracks open against the spring (on the stock cans that is about 20-24psi depending on the condition of the can).

A manual boost controler (a good one anyway) will block all boost signal to the cans untill you get to within 3-4psi of target to cut down on spool time. It can make a dramatic difference.

The factory solenoid is a glorified bleed valve, removing the restrictor let's it bleed more, raising the boost.



Jon.

[bourquetc]

7500-7700rpm shift and 6800rpm launch