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Old 08-26-2009, 10:31 AM
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Default Wastegate question

I am finishing up (I hope) my DIY rear mount. I have a Turbosmart 50mm progate. I want to get advise as to were to plumb my wastegate sensing line. Should I plumb it to my turbo compressor outlet, or all the way to the front of the car to the front of my TB, or right into the intake manifold behind the TB. I would think the best place would be right into the manifold or right in front of the TB. That way you are trying to sense after any piping and intercooler restrictions. I would like to place it in the intake manifold after the TB but I am worried how it will react when the TB is closed after a WOT pass. If it is after the TB, the wastegate will shut and the Blow off will open. Will this cause the turbo to speed up? If it is before the TB then it should open until the blow off blows off the pressure, can this cause the turbo to stop suddenly or even spool backwards due to the pressure in the cold air piping before the blow off finishes blowing off?

Wich way should I set it up and why?
Old 08-26-2009, 02:10 PM
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I plumbed mine off a fitting on the compressor housing. In my opinion, the benefits of having the WG referenced off the intake are offset by the lag time in the 12' of vac line front to rear. I had a 10psi WG spring and saw 9.7psi at the engine, perfectly flat boost curve. You can also use a Hallman, or Electronic boost controller to raise the boost if needed. Good luck.
Old 08-26-2009, 03:26 PM
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I agree with Egash, But you have to be careful because the boost mesurment would be way differant. I had my gate referance to the back of the intake and I had alot more lag and boost was not flat. Now after I put it on the compressor housing boost is solid no drop at all and lag was reduce. But the only thing is I run 15-17 psi depending on how I feel I have the boost controller set at 10 psi there is a 7 psi differance between my reading out back and at the intake. I also hook up a second boost guage to verify the readings from the eboost 2. Im not saying you should see a huge diffrance but just becareful when you start boosting. another thing is I have my bov tied into my map sensor becasue the pressures changes fast and that gives the ecu a quick reading. Because befor I had it referance to the break booster and it would stumble after I let of the gas and hpt tuners showed a funky reading from the map sensor. So a quick change and it work out just fine.
Old 08-26-2009, 06:58 PM
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I do not see what you mean with Lag. Are you talking about turbo lag that sensing at the inlet to the engine will cause the turbo to spool slower; I do not see how this could be. The waistgate should not be opening at idle, I would think. If you are talking about the time it would take to pressurize a sensing line, I can see that point, a little. It should not take long for the signal to reach the waistgate, if the size of the sensing line is kept to a minimal diameter.

I am going to go with the sensing line sensing as close to the actual intake manifold pressure as possible. This said, what are the pro's and con's of sensing before verses after the TB?
Old 08-27-2009, 10:43 PM
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Boost was not stable running the vac line on the intake due to the lenth of the line. The best mesurment would be on the intake after the tb. I stop using that method because boost would drop off and I woud get spikes. The only thing now is I have a 6-7 psi diffrance in the referance at the setting of the boostcontroler versus boost at the intake. thats why I hook up a second boost guage to verify the boost im seeing at the intake. Lag is reduce because The gate will open up at that boost level that is set. The old way the gate would open And I would loose about 3 psi and it will climb back up. My intake is a vic jr and elbow.




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