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I'm catching up a bit late to a discussion that took place last week - have been on a holiday. As the discussion concluded, getting things right with the BTM and associated tricks isn't simple but not overly difficult either. Just need some time, patience and basic tools.
To add to the earlier discussion, I just wanted to note that most (if not all) pressure valves do bleed into the atmosphere. It is just that the amount is very insignificant. I recall the SMC valve I'm using is spec'd at 1 liter per minute with 8bar operating pressure.
Another VERY important thing to note about the pressure valves is that the ones I have tested are very linear in operation by means of transmitting the increased pressure from the input to the output of the valve. But unfortunately it is not like that the other way around: Once the pressure at the output has reached the level set with the valve, that level will stabilize. The problem is that it may remain stabile even if the pressure at the input DOES GO DOWN! This can lead into a situation (closed throttle for example) where the BTM is still retarding even though the boost's down already - you DO NOT wan't that to happen! This is a problem only if the pneumatic circuit at the output is a closed one, i.e. there's nothing there that consumes the air. This is exactly the case with the BTM!
Checking what your valve does is very simple: attach a pressure gauge to the output of the pressure valve. Introduce pressure into the input of the valve. Note the pressure reading at the gauge. Now disconnect the pressure source. Look at the gauge: still got that pressure in there? If so, you need the following fix...
My suggestion: the "right" way of connecting the hose terminals into the pressure control valve is by using sealing tape at the threads. That's ok for the input side. But I recommend skipping the tape at the output threads. This will create a very small leak which will bleed the "ghost" pressure left in the hose into the atmosphere. With this trick the output will follow the falling pressure at the input with no delay at all.
Jouko
My Saab Turbo Project - timing issues
, Mon, 9 Jul 2001 10:23:22, Sun, 8 Jul 2001 19:57:49
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