<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by BauleyCivic &raquo;</TD></TR><TR><TD CLASS="quote">A MBC or retarding timing won't solve any of this? This is just how greddy kits (or turbo's with internal wastegates for that matter) are?</TD></TR></TABLE>

Hmm.. my T3 Super 60 w/ Internal WG doesn't seem to have any spiking issues. I hit full boost, which is about 5.5psi (for now at least ), at about 3000-3200rpm and it holds to redline. This is on a D16Z6 with Hondata S200B. I'm also running a Joe P. MBC set on the lowest/loosest setting, if that makes any difference.

 

i'm gunna bet $10 that if you hooked your wastegate actuator to a manifold vaccum port you'd see a nice steady Xpsi across the rpm range.

i'm betting right now you have your wastegate connected to the compressor housing.

 

Wouldn't hooking up the wastegate to your intake manifold give you a more accurate boost reading too? How different is it to hook it up to the manifold than the turbo compressor housing?

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by ComputerJLT &raquo;</TD></TR><TR><TD CLASS="quote">i'm gunna bet $10 that if you hooked your wastegate actuator to a manifold vaccum port you'd see a nice steady Xpsi across the rpm range.

i'm betting right now you have your wastegate connected to the compressor housing.</TD></TR></TABLE>

thats right
i have been trying to tell him

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by ComputerJLT &raquo;</TD></TR><TR><TD CLASS="quote">i'm gunna bet $10 that if you hooked your wastegate actuator to a manifold vaccum port you'd see a nice steady Xpsi across the rpm range.

i'm betting right now you have your wastegate connected to the compressor housing.</TD></TR></TABLE>

Thats how it is for me...should I T it off of the manifold?

 

got the dyno pics up finally

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by BauleyCivic &raquo;</TD></TR><TR><TD CLASS="quote">

Thats how it is for me...should I T it off of the manifold?</TD></TR></TABLE>

i would like to know this to

 

**YES**. You should absolutely connect the wastegate actuator to the intake manifold. Intake manifold pressure is what is really important. There are a lot of obstacles between a turbo and the intake manifold, resulting in substantial loss of pressure. There's the piping, intercooler, and worst of all.. the throttle. With my properly connected wastegate (and properly working BOV), I can make full boost at a small percentage of full throttle. This means that that the pressure in my charge pipes is a lot higher than the pressure in my intake manifold. But I don't care about pressure in my charge pipes!

When you let off the gas, the throttle closes and the BOV vents the excess pressure. But the turbo is still spinning like crazy (producing pressure). If you have the wastegate vacuum connected "ahead" of the throttle body, then the wastegate needlessly pops open every time you let off the gas due to a pressure spike in the charge pipes. That's a lot of additional wear and tear on the actuator, especially on a daily driver.

There's a lot of really illegit turbo "bashing" going on this thread. If the wastegate isn't even connected properly, *of course* boost is going to plummet. About the worst aspect of an internal wastegate is that it tends to dump back into the exhaust stream a little sooner than it should. Other than that, they're fine. Especially at the power levels anyone with a Greddy kit is making. Assuming the wastegate actuator is connected properly, if problems still exist then the actuator needs to be repaired/replaced.

As for the compressor map, who cares if an 18G is out of it's efficiency range at 5 psi? 5 psi is hardly what engineers had in mind for just about any turbo when it was designed. Boost doesn't kill motors, POWER and POOR TUNING kills motors.

 

How do you know for sure if the actuator is screwed up? I just installed a Greddy 18G kit on my B16A3 Del Sol, and it will boost sometimes. At first the actuator arm was not on the exhaust flap. After I fixed that problem, it ran fine. After a few minutes of driving there was no boost to be found. I highly doubt there is a leak in the I.C. or charge pipes. Also I know the turbo is good. Why is boost only coming on sometimes, and not staying on? Also what are the leading causes of boost creep. Keep in mind I dont do turbos often, so I am in the shadows when trying to diagnose any problems.

 

Your problems do sound related to the wastegate actuator. If you have a bike pump, you can hook it to the actuator vacuum line and see if it is working correctly. IMO, if the actuator is doubtful then replace it. Actuators are plentiful, cheap, and easy to install. They're also pretty reliable if you get one in good working order. It's an extremely important part of your turbo system, as it prevents overboosting and blown motors.

 

I have a greddy kit on a b16 in a 99 si.

My tdo5 internal wg is attached to the first charge pipe, about 2 inches away from the turbo.

With no boost controller, i boost to 5psi at 3800, and continue to build as much as 7-8pounds as i approach redline.

I put on a greddy profec b, and now i run at 7 pounds by 4000, and then it holds fairly well untill around 7000rpm in fourth or fifth gear and it creeps up.

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by ComputerJLT &raquo;</TD></TR><TR><TD CLASS="quote">i'm gunna bet $10 that if you hooked your wastegate actuator to a manifold vaccum port you'd see a nice steady Xpsi across the rpm range.

i'm betting right now you have your wastegate connected to the compressor housing.</TD></TR></TABLE>

See I thought about this forever. And ever. And ever. It makes no difference in my setup. When i use the boost controller, the actual computer controlled unit has a tube that i connected to my intake manifold.

There is a wire that goes from the computer controlled unit to a physical unit in my engine bay that inturrupts the flow of air from the first charge pipe to the wastegate. It fakes out the wastegate based on an electrical signal sent from a computer that is taking readings only from my intake manifold, past the throttle body.

There is 0 difference in my cars behavior from when i turn off the boostcontroller, and when i have it on. I know what your saying might be right, but i have thought and tried this on my car and in my limited (read: very limited) experience, it made zero difference