924Board.org

[Hugo]

you have a air regulator on your vacuumline to the wastegate?, how does this increase boost pressure? If I remember it correctly from some of the old posts I studied. If i understand the thing about adjusting the air/vacuumline wideness it can only increase a faster or slower spoolup, not a higher boost. this would require a bleed. by lowering the pressure on the control line the wastegate will open later thus allowing the turbo to spool up longer. please correct me if I'm wrong. I'm looking to build on a restrictor with solonoid valve and adjusting the rod length from the actuator. Thanks

[Lizard]

the Variable Boost Controller is what you are talking about, it limits the air going to the wastegate so that it takes more air to actually open the wastegate,

so you could push 10 PSI but the VBC would only allow 7psi to get through to open the wastegate
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3 928s,

[CMXXXI]

If I understand your question/explanation, I think you have thing sort of backwards. The wastegate works by having the turbo's boost pressure act on the top of the wastegate's diaphragm & piston. When the pressure gets high enough, the diaphragm/piston presses down on a valve (looks much like an engine intake/exhaust valve) and opens the port the valve seals. With this port open, it allows exhaust gasses to flow not only through the turbo (which provides boost), but to also bypass the turbo completely and get dumped through the wastegate directly into the exhaust pipe (which will reduce boost or maintain it at a constant, controlled/lowered pressure).

The regulator works by changing the amount of boost pressure that is allowed to act on the wastegate diaphragm/piston. Reduce the pressure on the diaphragm/piston you will prevent the diaphragm from moving (as far/quickly) and increase the amount of exhaust gasses passing through the turbo (compared to what would flow through with the wastgate open), thus increasing the effective boost to the engine.

This clarify things at all, or did I miss the point all-together?
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'79 Eurospec 931

[Hugo]

When I was reading the following page I got confused:
http://www.xmission.com/~dempsey/perform/
It was this part:
Restrictor (or Orifice)
A restrictor is a simple vacuum connector with one twist: inside the connector is a brass insert with a small hole in it. The purpose of a restrictor is to delay the time required for vacuum (or boost) to travel through the connector. Why would you want to do this? In our case it helps speed turbo response. By now you've probably noticed that when you floor it the maximum boost level goes high and then settles back down to the preset level. This overshoot is called the boost spike. You can directly control the size of the boost spike by using a larger or smaller orifice in the restrictor: the bigger the restrictor's hole, the smaller the spike; the smaller the hole, the bigger the spike.

So It seemed to me that the mini air regulator not working with the ball and spring (like a boost controller) would actually work like a restriktor by making the hole where the air should pass thru smaller thus creating a pressure build up on one side of the regulator. and according to the text creating a spike and then leveling off. So any clearer???

[Joes924Racer]

Man Id like to get parts together for a turbo this year.
Can honestly say I would trade on of my 924 cars
for a complete turbo motor. If I get both new cars.
Of course not the bahama mama.
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1979 porsche 924 Na
1980 porsche Turbo 931GT Replica
Have u ever driven a turbo.