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TIAL WG Efficacy?

Any easy way to test this?
Planning on buying a couple of WGs (38mm MVS) that are currently set at 1.4 bar.
It has three springs in it. Copper, Maroon and Brown.
Now the TIAL website only rates the brown at 0.3 bar, but does not list the others by themselves. However, by looking at the other combintations have determined the Copper to be 0.5 and the Maroon to be 0.6 bar.

So if I remove the other two and only run the copper (and not buy a Beige which is 0.5 bar) I want to make sure it regularly opens at 0.5 bar.

Thanks!
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Old 04-16-2010, 12:44 PM
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jcc,
You need a very accurate air pressure regulator running off an air compressor. Set the regulator to .5Bar (~7.35psi) and feed the air pressure to the pressure side of the wastegate, keeping the wastegate vent line open (vented to atmosphere). You may have to have to engine running at idle to test this since some wastegates use some of the exhaust pressure to open the wastegate valve.
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'85 930 Factory Special Wishes Flachbau
Werk I Zuffenhausen 3.3l/330BHP Engine with Sonderwunsch Cams, FabSpeed Headers, Kokeln IC, Twin Plugged Electromotive Crankfire, Tial Wastegate(0.8 Bar), K27 Hybrid Turbo, Ruf Twin-tip Muffler, Fikse FM-5's 8&10x17, 8:41 R&P
Old 04-17-2010, 05:56 AM
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Quote:
Originally Posted by WERK I View Post
jcc,
You may have to have to engine running at idle to test this since some wastegates use some of the exhaust pressure to open the wastegate valve.
Is this true for the stock wastegate?

Thanks

Jim
Old 04-17-2010, 07:38 AM
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That should work.

See http://www.youtube.com/watch?v=LStlqe64m4M

Last edited by 911st; 04-17-2010 at 08:26 AM..
Old 04-17-2010, 08:17 AM
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Quote:
Originally Posted by jimmcc View Post
Is this true for the stock wastegate?

Thanks

Jim
According to the Porsche Technical Manual, they test it on the exhaust with the engine running.
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Old 04-17-2010, 02:37 PM
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Quote:
Originally Posted by jimmcc View Post
Is this true for the stock wastegate?

Thanks

Jim
Yes. It's somewhat of an additive affect with exhaust pressure adding to the air pressure needed to open the WG. If you want relatively accurate results, you should do the test on the car with the engine running.

As an example, with a stock .8bar spring and the WG off the car, typically you need in the neighborhood of 15psi to open the valve.
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Old 04-17-2010, 07:21 PM
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Seems it would be easier to test the WG on the car by listening or feeling when the WG valve starts to open if the car is running instead of removing it and watching the valve's opening visually on a test bench.

I am far from a WG expert but if exhaust pressure were a factor then to be accurate we would probably have to test it on a dyno at full boost as pressure in the exhaust before the turbo can be 50% - 70% or more of boost pressure and probably increases with HP and or RPM.

By the WG's design, pressure is against the head of what is basically an exhaust valve but the key is that pressure it trying to make it past the valve seat. I do not think the pressure against the top the the valve actually pushes the valve in any way to change or restrict its opening pressure.

Again, I do not know for sure but I suspect the factory procedure might be more one of convenience.

I am thinking there are two things basically relevant to what boost a WG will retain. One is the spring tension, the other is the capacity of the WG vent. If it more open than Porsche expected like with out its connection fittings, it will take more pressure to open the WG. This might be why it could take more pressure on a bench to open it.
Old 04-18-2010, 08:50 AM
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Quote:
Originally Posted by 911st View Post
Seems it would be easier to test the WG on the car by listening or feeling when the WG valve starts to open if the car is running instead of removing it and watching the valve's opening visually on a test bench.

I am far from a WG expert but if exhaust pressure were a factor then to be accurate we would probably have to test it on a dyno at full boost as pressure in the exhaust before the turbo can be 50% - 70% or more of boost pressure and probably increases with HP and or RPM.

By the WG's design, pressure is against the head of what is basically an exhaust valve but the key is that pressure it trying to make it past the valve seat. I do not think the pressure against the top the the valve actually pushes the valve in any way to change or restrict its opening pressure.

Again, I do not know for sure but I suspect the factory procedure might be more one of convenience.

I am thinking there are two things basically relevant to what boost a WG will retain. One is the spring tension, the other is the capacity of the WG vent. If it more open than Porsche expected like with out its connection fittings, it will take more pressure to open the WG. This might be why it could take more pressure on a bench to open it.
If you've ever tested a WG yourself and done a little research, you'll find that exhaust pressure does have an effect. When I bought my Tial a long time ago and tested it on the bench, I was concerned that it wasn't opening fully at the given spring tension. It was the Tial technical service people that confirmed the exhaust pressure part of the equation.
I suspect that the condition of the WG valve guide will have a lot to do with how much air pressure may be needed to open it aginst the stated spring pressure. A worn guide does allow some pressure to pass. These things aren't rocket science cutting-edge technology, unfortunately.
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Old 04-18-2010, 12:48 PM
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What did you see from your Tial?

I had to buy .7 bar to maintain about .8 to .85 bar with my shorty headers.

Makes sense if the guide is adding friction it could effect opening and boost.

I am still not getting that the exhaust pressure is a variable in when the WG opens. I do not recall any mention as to this was made in the video I linked to above so please have patience with me on this.

If exhaust pressure is a variable it seems it would make for boost spikes until just before the exhaust pressure is released.

If the exhaust pressure is not a variable, then boost would be more stable.

Again, I have not studied WG's so this is a new area to me. I need to do some study on this.

Thx.
Old 04-18-2010, 01:44 PM
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If you take the spring out of the wastegate... exhaust pressure just might push the valve open.
So if it does then putting a spring back in isn't going to stop exhaust pressure from pushing on the valve.
Seems to me exhaust pressure would still be helping it open.
Old 04-18-2010, 02:36 PM
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That helps.

I had it backwards.

The exhaust pressure is trying to push the WG open. Thus, it is pushing against the surface area of the valve head and trying to open it.

I am wondering if testing on a bench or at idle installed is just a check to see if it is functioning and a rough check as to boost level.

There seems to be other variables like the quality of the WG tube connection to the exhaust manifold, spring rate, surface area of the valve, turbo configuration...

Probably the only real test is on boost with a boost gauge in place.

Thx
Old 04-18-2010, 03:18 PM
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Found something about the quality of the WG tube connection.

See page two at : http://www.turbosmartdirect.com/install/Ultragate.pdf

They note:

Symmetrical Mounting: Best way

Angled Mounting: Good way (stock Porsche)

90 Degree Mounting: Poor flow (B&B style header's?)

Less Than 90 deg Mounting: not recommended.

Last edited by 911st; 04-18-2010 at 03:38 PM..
Old 04-18-2010, 03:26 PM
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Quote:
Originally Posted by 911st View Post
That helps.

I had it backwards.

The exhaust pressure is trying to push the WG open. Thus, it is pushing against the surface area of the valve head and trying to open it.

I am wondering if testing on a bench or at idle installed is just a check to see if it is functioning and a rough check as to boost level.

There seems to be other variables like the quality of the WG tube connection to the exhaust manifold, spring rate, surface area of the valve, turbo configuration...

Probably the only real test is on boost with a boost gauge in place.

Thx
Now you're getting it!
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Old 04-18-2010, 04:09 PM
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