wastegate pressure

[fregisr]

for you guys running an FMIC piping and all, if your piping doesn't have a nipple for your wastegate signals, what are my alternatives? Is there a t or y that I can split the pressure off the rubber hose nearby the throttle? I need help

[9240sx]

T it off the BOV vaccum line.

[karmakaze]

or have a nipple welded on.

[Dori Dori]

T it off the BOV vaccum line.

That's a bad idea since the BOV will most likely be getting its vaccum from the cold side. Nice way to overboost.

[Dori Dori]

or have a nipple welded on.

+1. Have your hot pipe modified.

[240SicknessX]

i dont have an sr but to keep my wastegate signal line short i tapped a 1\4in barbed fitting into the compressor outlet of my t04e. If you know how, and have the equpiment you can do this if you find an appropriate spot. Its an alternative to having a nipple welded on your hotpipe if you dont have that kind of access. I did this to keep the wastegate line short running to the tial 38. (better wastegate responce then running your pressure source from the intake manifold.)

DO PROCEED WITH CAUTION: if you mess up with your drill and tap you will either have to step up a size which might be too big or have the hole that you drilled welded shut and try again. ahhh just have a nipple weled on your hotpipe, its easier and less chance of messing with your compressor housing.

[stevesrt4]

you can use one of the nipples from the throttle body... i have the top right going to the wga the top left to my bov and the bottom to my boost gage... works for me. good luck.

[9240sx]

Iv been running mine like this for years,And never had a problem with it.I did notice faster spool up time running like this,then with it on the hotpipie.How would you overboost running it like this???

[Dori Dori]

If you know how a turbo and wastegate work you'd understand why its important (for proper boost control) to get the wastegate signal as close to the compressor as possible. I'm not hear to school sarcastic know-it-alls so reseach it yourself if you really want to know. X1000000000000000000^3 lolllerz n00b omg hahaha.

[HardcorePS13]

If you know how a turbo and wastegate work you'd understand why its important (for proper boost control) to get the wastegate signal as close to the compressor as possible. I'm not hear to school sarcastic know-it-alls so reseach it yourself if you really want to know. X1000000000000000000^3 lolllerz n00b omg hahaha.

So taking the pressure signal from the cold pipe is a bad idea even though that is how the OEM setup is configured? Need I mention the fuel pressure is regulated off of actual manifold pressure as well.

Running it off the cold side gives you post intercooler pressures, or the actual pressure the engine is running at. It's nothing crazy or obscene, it's actually ideal IMO.

[Blown240sx]

^^^^ Sounds about right to me ^^^^

[Dori Dori]

Yes, because OEM setups have incorperated this setup, it is ideal. So are soft spring rates, high ride heights, rocker arms, and small intercoolers. Awesome logic!!!!
Modified by Dori Dori at 4:22 AM 2/1/2006

[Dori Dori]

Look, you can get the signal from any preassure source, even the brake booster line if you wanted to. I said, and it is 100% absolutely correct, for proper boost control - no spikes, no overboosting - get your signal from as close to the compressor as possible. Read Maximum Boost, page 147 - 148. Pressure from the cold side is fine but you CAN run into problems like off throttle engine bucking or boost spiking although your boost response will be better. This is obvious since the pressure will be delayed to the wastegate.

Unless unusual circumstances dictate, hook the wastegate signal to the compressor outlet and call it a day.

[virus77]

I just dripped a hole in my hotpipe about a 6 inches from my turbo and cut off a vacuum nipple from an old carburator for the fitting since I had tons laying around. I attached the fitting into the hole and jb welded it for a seal, hasn't failed in two years. you can use spare vacuum nipples of your intake manifold or any parts you have laying around.

On a side note if you dont have a boost controller this is going to effectivly reduce your boost around 2 psi so take that into consideration when doing it. So if you have a stock SR turbo you will only boost like 5 psi.

[stevesrt4]

Iv been running mine like this for years,And never had a problem with it.I did notice faster spool up time running like this,then with it on the hotpipie.How would you overboost running it like this???

Pressure will build in the system as you accelerate. As I said above, the sensor for my WGA is tapped into the intake manifold just after the throttle body. (like yours) When the signal gets to the WGA it then causes the waste gate to open and maintain pressure at the level set by the WGA. That delay can only be a issue if there is a spike high enough to cause predetination... On the 2.0 motor that more than likely won't happen I'm on the t-2small and not having any issues with spike... IMO it's fine. But what do I know, I'm new to the sr. maybe the sr is completely diffrent from any other turbo motor out there.

[240SicknessX]

dori dori is trying to say the compressor outlet is the best place to put your wastegate signal line because it is the first area of your intake system that sees atmospheric pressure increase. You want your wastegate signal line closest to your wastegate, the longer the line, the more air volume that is in the line and the longer it takes for the wastegate to respond. In your particular instance it may not differ to your observations whether you have your wastegate source on the intake manifold or the compressor outlet because of your setup. Start increasing boost and altering other varibles and see if your intake manifold wastegate pressure source will work or is ideal.

the fpr vac line goes to the manifold becuase that is the actual pressure that the engine see's.

i run my boost gauge off the intake manifold, wastegate signal line off the compressor housing.

[HardcorePS13]

Look, you can get the signal from any preassure source, even the brake booster line if you wanted to. I said, and it is 100% absolutely correct, for proper boost control - no spikes, no overboosting - get your signal from as close to the compressor as possible. Read Maximum Boost, page 147 - 148. Pressure from the cold side is fine but you CAN run into problems like off throttle engine bucking or boost spiking although your boost response will be better. This is obvious since the pressure will be delayed to the wastegate.

Corky Bell's book is not the end all to turbocharger performance. It was written so long ago that it has passed it's prime.

Off throttle bucking? The BOV is open, how exactly is the engine going to buck as a result of the wastegate's position being open or closed given that the turbocharger is despooling regardless.

Boost spiking? Right, if you don't run any sort of blow off valve. Kinda hard for a small turbo to overpressurize intercooler piping with a 30mm hole in it.

[virus77]

how does a blow off valve stop a car from boost spiking?

[Dori Dori]

how does a blow off valve stop a car from boost spiking?

Well, many factory bypass valves are made to leak at high boost preassures to prevent spikes from damaging the engine...a fail-safe. I doubt mr. hardcore even meant to bring factory bypass valves into the discussion since he did say BOV. Relief Valves also exist to perform the same function but again, nobody's talking about that.
Modified by Dori Dori at 2:30 PM 2/2/2006

[Dori Dori]

Corky Bell's book is not the end all to turbocharger performance. It was written so long ago that it has passed its prime.

Regardless of whether or not this is true, the wastegate theory presented is still accurate today since wastegate functionality has stayed the same. Period.

Off throttle bucking? The BOV is open, how exactly is the engine going to buck as a result of the wastegate's position being open or closed given that the turbocharger is despooling regardless.

Despooling. Nice. Did you make that word up yesterday or find it in some uber-discreet engineering book? How do I even answer this question now?

Boost spiking? Right, if you don't run any sort of blow off valve. Kinda hard for a small turbo to overpressurize intercooler piping with a 30mm hole in it.

Do you know what a boost spike is? How does "overpressurizing" intercooler piping even occur? Are we now talking about the wall strength of our aluminum pipes, couplings, or intercoolers here haha. And if your BOV bleeds off boost before it makes it to your intake manifold to regulate boost spiking, you'd have a complete and utter disregard for the life of your turbo. If a spiking problem did exist, that'd be a bad way to deal with it. That or you'd be running a factory bypass valve, which wouldn't be called a BOV at all.
Modified by Dori Dori at 3:05 PM 2/2/2006