I often hear talk of wastegates and blowoff valves. I'm pretty bored, so I thought i'd just post here to see if anyone could give me a description of these? I'm "pretty sure" the wastegate goes before the turbo, on the exhaust, and controls the boost. When the set boost is reached, it opens(?) and exhaust is diverted into the downpipe, thus limiting the boost the turbo gets. The blowoff value "I think" goes inline with the pressurized air - right after the turbo, or right after the intercooler, if you're 'cooled. This bleeds off the pressure when you're shifting, or letting off the throttle, etc, and prevents the turbo from clattering.

Is ANY of that right? Thanks

 

That's pretty accurate. The waste-gate is a valve in the turbine houseing that opens when there is enough boost pressure and the exhaust gas released into the down-pipe. The blow off valve is positioned between the comp out pipe and the comp in pipe. When it is actuated due to a large pressure difference due to the throttle being closed it blows boost back into the inlet so the compressor wheel speed does not decrease dramatically. When the blow-off valve does not work That's the clattering or chattering sound that you hear.

 

you can see one on my discharge tube on my site at:

http://darcom.home.texas.net/

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388 SuperRam, DFI, Vortech R trim ,N.O.S.,alki injection,
Dart sportmansII heads,50 pound injectors, Headman full headers
duel 3' exhaust,and Flowmasters, Ford nine inch with 370's
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