[Blown353]

Wastegate springs: if you want 10 psi of boost, you need to run 10 psi springs in each wastegate. As far as them not working, where do you have their reference pressure line coming from? Typically you hook the wastegates ports via hose to fittings directly on the compressor housing outlets. You can also reference off the intake piping or the hat, anywhere before the carb is OK. Do you have any kind of boost controller, manual or electronic? That may be your problem, either not functioning, not set correctly, or plumbed incorrectly.

As for your carb sticking problem, what it sounds like is happening is exactly like you describe, residual boost in the hat/intake piping after letting off. What this does is pressurize the bowls of the carb and will blow extra fuel out the idle circuit. With the throttle closed this makes things very rich and can cause the engine to die. This isn't a problem when you're in the throttle because manifold pressure under the carb should be the same as pressure above the carb, but this will definately cause problems once you let out, such as going dead rich and killing the engine when you back out of boost. It won't shove any extra fuel out the boosters as the boosters are above the throttle plates and will see the same pressure the bowls do

What you can do to check for this is run 2 pressure gauges-- one below the carb (say from the manifold vac or PCV port on the carb) and one pressure gauge hooked to the hat. Go for a ride, step on it, and then back off and watch for a boost differential, i.e. the pressure in the hat being greater than manifold pressure. As soon as you back out of the throttle you'll want as close to 0 psi in the intake piping as you can, otherwise the differential pressures will cause a rich condition as the pressure in the hat (and therefore the bowls) will dump extra fuel into the engine.

I am not a blowthrough turbo guru, but I see a potential way around this is to run a centrifugal supercharger style surge valve that keeps the intake piping open to atmosphere under cruise and closes when you step on the throttle and vacuum drops; this way when you back out of the throttle, the valve goes full open, dumping the intake tract and bowls to atmosphere, relieving all pressure in the bowls. This should alleviate the rich condition when coming down from boost. What I don't understand is your BOV should be doing the same job, but not staying open at cruise as a surge valve would.

The HKS BOV's are adjustable, you may have too much spring tension in it; i.e. it only dumps down to say 5 psi and then closes, which may leave just enough boost in the bowls to flood the car when you back out of it. With the blowthrough I'd say you want it to start opening at say 0.5-1 psi of pressure to minimize the amount of pressure the carb will see when you back off the throttle.

Hopefully someone with blowthrough turbo experience will chime in as I'd like to know the real solution to the problem, my workthrough is just an "in my head" visualization of the problem. I've had centrifugal supercharger experience (both blowthrough and EFI) and turbo experience (EFI), but never blowthrough turbo experience.

Troy