WG tests
 

Its been a while since I looked at my WG. So decided to do some tests. (its original with 250 K plus on it).
First after removing I saw that the soot pattern on the valve was distinctly asymmetric, all the bypass was coming out of one side. See pic.

http://forums.pelicanparts.com/uploa...1576951879.jpg

So the valve was not seating evenly.

http://forums.pelicanparts.com/uploa...1576951958.jpg

Cleaned the valve and the housing where it seats.
Next the shims I had been using (supposedly stainless steel ) had rusted and there was rust between the WG diaphragm housing and the base.

http://forums.pelicanparts.com/uploa...1576952180.jpg

Cleaned this up. Reassembled the WG without shims and tested the gate by applying pressure to the input nipple of the WG.

-Starts to open at 3 psi.
-Can see clear opening all the way around the valve and housing at 5 psi.
- Fully open at 10 to 11 psi.

Next I built an adapter to test the gate spring under simulated exhaust pressure.

PLEASE NOTE THIS DOES NOT INDICATE ANYTHING OTHER THAN A RELATIVE SPRING PRESSURE AT VARIOUS SHIM WIDTHS.



http://forums.pelicanparts.com/uploa...1576952617.jpg


http://forums.pelicanparts.com/uploa...1576952639.jpg

-No shims the WG will hold 20 psi.
-0.1 inch shims the WG will hold 23 psi.
-0.2 inch shims the WG will hold 25 to 26 psi.

Again the numbers are just that, a relative stiffening of the spring force by shimming it.

Next I am planing a test with the waste gate being controlled by applying vacuum to the nipple (to hold it closed against the exhaust ) and then switching to pressure when the car hits the required boost point to hold it.
Kind of a dual WG but without the modifications to the diaphragm chamber.
Will keep y'all posted.
Sox

Interesting because my WG operates approximately at the same pressures as yours. I had no idea it holds 20 psi tho. Since most think my low boost problem stems from too much backpressure, that means BP could be well over 20 psi. Hope to get a gauge on the crossover pipe in this week.

Mike G.

That is not holding pressure it is just the point at which it stabilizes for the amount of air I can supply. If I had a bigger compressor these numbers would be higher.
The point was to show the relative difference the shims make.
Sox

For me 1/8 shim increased approximately .2 BAR or 2.9 psi on the stock gauge. The second 1/8 shim did nothing.

Mike G.

Mike are you talking about the boost? I was talking about pressure at the WG to turbo side.
Sox

Yeah Boost!

But I am interested in the amount of turbine inlet pressure it would take to open the WG Valve.

Thanks
Mike G.

I am in the process of testing this diverter as a replacement for the CV.
Have to play with the PWM duty cycle to tune it, but seems to work.
Important: you need to introduce a leak on the down pipe to the WG, as this device will switch but not release pressure on the WG and WG will stick open.
Sox

http://forums.pelicanparts.com/uploa...1577488249.jpg

Hey, that's some awesome testing! Your WG spring might be slightly soft as Mike's doesn't start opening until 5psi. But still within spec as it doesn't open fully until 10-11psi, which is fine.

Using with check-valve manual-controller with bleed-hole should give you any boost you want, 20psi+

Electronic solenoid shouldn't need bleed hole as both NC/NO ports will connect to COM. With fast duty-cycle signal back & forth, any residual pressure between valve and WG will be bled off. Look up various Supra MKIV forums on how to connect solenoid in push/pull configuration. With EBC, such as Apexi AVC-R, you can get any boost-level you want. I've gotten 25psi with unmodified stock WG when solenoid is configured in push/pull with connection to vacuum source on one side.

So....
further testing, replaced the O2 sensor with an old busted one. I drilled a hole through it to attach a hose to it. (The ceramic in the sensor is a really hard one, busted a few drill bits on it ).
did some road tests:
-hose to WG is pinched off, so no boost control by the KRL.
-Car gets 11 psi at about 22psi at the inlet to the turbo/WG connection. (this agrees with my static finding above, 22psi is when the WG starts to leak past the valve).

Next, the Cat is just a thru pipe, so I will check the pressure pre Cat and post Cat.
I don't have any data for how high the inlet to the turbo runs on these cars. Any info is appreciated :)
If the pressure is still in the 20's past the turbo, then I will look at my muffler. It is a flow master series 40.
Sox

Pressure in downpipe and exhaust after turbo should be very low.

Pressure-ratio between turbine-inlet and intake-manifold boost-pressure is not direct or linear. At low-RPM and low boost-levels, ratio will be < 2:1. At high-RPM and high-boost, it will be > 2:1. Also varies by turbine-size with larger TurboS K26/8 turbos operating at lower ratios than K26/6.

For high-power high-boost builds greater than 300rwhp, even larger turbines are used. At stock 10-12psi boost-levels, they will operate at < 1.5:1 ratios.

When going from factory exhaust to straight-pipe config, you'll typically see an extra 1-2psi boost. IF exhaust is not too restrictive.

Tested pre cat....negligible pressure, so will not do post cat.
As it stands:
Pre Turbo 22 to 24 PSI for a 10psi boost.
WG seems to be letting go at a combination of 8psi on the gate barb and 22psi on the Valve side. (KLR is starting to divert at this point).
Pinching off the WG control line increases the 8psi to 10psi and the 22psi to 25psi.
Next will mechanically hold the WG and test. (briefly :) )
Sox

Seems like my 9 psi boost to 22 psi to crossover doesn't seem to be too far out of the ball park?? So does a stock turbo S actually achieve 11.6 psi???

Thanks

Mike G.

Yup max boost on stock TurboS is 12psi in mid-range and trails off to 8-10psi at redline.

So what was the boost pressure when the WG line was pinched off. Most state that it could go extremely high?? Mine didn't really go that much higher.

Thanks
Mike G.

Hey can you do a bleed down test? Apply 10-15 psi to the WG line sealed off and see how much or how long it takes to bleed off pressure? I'm going to give that a try too hoping that I can determine if my diaphragm has a slight tear and bleeds off at higher pressures.

Thanks
Mike G.

i'm pretty sure that vac line is supposed to be air-tight and not bleed off at all.

Yeah "if" everything is working as it should!! :D

Thanks
Mike G.

Tested pre cat....negligible pressure, so will not do post cat.
As it stands:
Pre Turbo 22 to 24 PSI for a 10psi boost.
WG seems to be letting go at a combination of 8psi on the gate barb and 22psi on the Valve side. (KLR is starting to divert at this point).
:)
Pinching off the WG control line increases the 8psi to 10psi and the 22psi to 25psi.
:)
Next will mechanically hold the WG and test. (briefly )
Sox

Geez that's it 10 psi? Even my turbo re-builder said it should completely over boost!

Thanks
Mike G.

It should but the WG is likely letting go, so that's my next step.
Your and my issues may be the same.
-low boost.
-no real back pressure post turbo outlet.
-Isolating the KLR from the WG does not increase boost significantly.

So next step for me is to prevent the WG from bypassing and make sure the Turbo has the oomph to make enough boost.

I had a similar problem years ago and IIRC it turned out to be the knock sensor telling the KLR that the engine was knocking. The KLR then retarded the ignition which ended up in low boost. Will look for that thread.
Sox