Wojo7

So I've been going back and forth with this boost issue and I am pretty sure I've tracked it down to the wastegate so I figured I'd start a new thread. My almost new TiAl 46mm wastegate is leaking past the valve stem ALOT. I've tried heating the valve to 500 degrees to see if the tolerances get better and the leaking slows down but there is no difference hot or cold. I contacted TiAl and they say it's normal but I really can't see how any boost controller could accurately run this valve. TiAl says the exhaust gas pressure is supposed to assist in the valve opening, my thoughts are if that's the case wouldn't it just burp some exhaust gas and fall closed again if the diaphragm couldn't hold it open on its own? Every log I have since installing this wastegate has a jagged spiked boost curve, I've tried several controllers, manual and electronic with no luck, has anyone else experienced this problem with this wastegate?

Tom M'Guinn

I have a 46mm tial and it holds boost perfectly steady with the Profec B controller. I've never seen or felt any signs of it leaking like that...

Wojo7

How much boost are you running? Do you know the spring rate? I just ordered two more springs, 8.7 psi and 7.4 psi. The 10 psi spring is too much, the valve is not cracking till 12.5 psi and doesn't open to 3/4 till 15 psi. TiAl says the valve needs back pressure on the cross over to help the valve open. im not sure how much pressure is behind the valve, But they are saying it should be close to manifold pressure.

Bill

I have a Tial 46 and it holds 22psi perfectly steady with an Apexi boost controller. Logged using both Zeitronics and Rogue loggers.

Tom M'Guinn

I've been running about 18-20, but have had it as high as 25 without issues (without wastegate issues anyway). I have 2 springs in there that create 1 bar of spring pressure, although the actual boost will go as low as 13psi if I turn the boost down all the way. What are you using for boost control? Can you just try another wastegate to see if that's really the culprit?

https://rennlist.com/forums/944-turb...e-process.html

Wojo7

I am gonna put the stock gate back in and see what happens, the .9 bar spring is the one that was in the tial when I bought it, without any control just a hose from the banjo bolt to the side of the gate I would spike at 17 psi. Currently I'm using an innovate scg-1, I thought for sure it was the control but I can't explain why it will not produce a smooth curve when it is running off just the spring. This is a screenshot of the boost curve with a 15 psi spring running straight from the hard pipe. The blue line being boost, the peaks are over 19 psi.

E-man930

Have you pulled the top of the Tial apart?

JacRyann

Let's back up a bit and get more info:

1. WHAT is leaking past the valve-stem? Exhaust or pressure from diaphragm?
2. Does the diaphragm hold the valve open indefinitely?
3. How do you have the wastegate installed & configured?



This wastegate has the opposite action as the stock one, so the bottom of the wastegate should be connected to crossover pipe and the dump goes out the side. With the wastegate closed, I can't see how anything can leak past the valve-stem anyway since the valve is closed.

The pressure port is on the side and where you hook up the boost-solenoid. The wide oscillation is a clue that needs more data to explain.

Just for giggles, I've had the stock as well as Tial gates running up to 25-27psi without any problems. Electronic control is the only way for flat boost-curve, even the Tial will drop boost in the upper-RPMs with a manual controller.

Wojo7

The signal air is is leaking through the valve stem, TiAl tech support says its normal and designed to leak, I could not get them to say how much it's supposed to leak, they just said " a bit ".

The diaphragm most definitely does not hold the valve open when the air is removed from the bottom port, it instantly falls closed, TiAl says this too is normal.

The wastegate is installed the same as the photo, inlet on bottom, dump on side.
I've tried a few methods to control boost including EBC but none have been great. It just seems like the valve is way too lazy to be accurate.
I've noticed in previous posts that it seems they work well at somewhat higher boost pressures which makes sense since the more boost you run the less work the wastegate has to do.

kev951

how about , best way to bench test a tail 46 mm dual port wastegate??

E-man930

The top of the wastegates do not leak unless the diaphragm is torn or distorted by being pinched in between the top and bottom cover.