Turbine housing sizing + quickspool valve

[RedBird]

basically at low engine speeds the plate is closed, forcing all the exhaust gas through the single, smaller opening, basically changing the turbo into a small turbine A/R, which spools the turbo very quickly, then as the engine speed increases the valve opens, allowing it to act like a large A/R housing, allowing for more flow and power than a smaller housing would.

[Driver_10]

basically at low engine speeds the plate is closed, forcing all the exhaust gas through the single, smaller opening, basically changing the turbo into a small turbine A/R, which spools the turbo very quickly, then as the engine speed increases the valve opens, allowing it to act like a large A/R housing, allowing for more flow and power than a smaller housing would.

(You beat me to the punch.) Yep...Thats the theory.
The real benifit of the "quick-spool" valve is being able to use an overall larger exhaust housing which would reduce breathing effort and free up hp.

However, Im changing my approach and using a fairly large exhaust housing in combination with a "divided pulse" style set of turbo headers with dual wastegates. The "divided pulse" system is ultimately more efficient and should provide better boost control. I just wont be able to run nearly as large an exhaust housing as I would with a "QS"-valve and non-divided turbo headers.

[Driver_10]

Heres a good pic that shows kinda how I intend to run the two wastegates on the "divided pulse" primary set-up...

This is not my pic BTW... but you get the picture

[Mars]

For the record on my .63 AR T3 turbine with the 60-1 compressor it spooled off idle. It was full boost 1/2 throttle accross an intersection.

I have a 3 spd. automatic TH350 though. 4500 stall.

[Driver_10]

For the record on my .63 AR T3 turbine with the 60-1 compressor it spooled off idle. It was full boost 1/2 throttle accross an intersection.

I have a 3 spd. automatic TH350 though. 4500 stall.

My .69 A.R t3 non-divided "S256" was about the same way. It did very well on my old 3400 swap and had a torque band like an SBC.

However, a moderately sized housing is restrictive at high rpms. To free up some power at higher rpms requires a larger turbine housing.

The challenge is to create an efficient system with usable low-end torque and good, flat, "mid to top range" power band. The parrasitic losses should as reduced as posible.

(Its a difficult goal, but not an impossible one)