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AFD660's Avatar
 
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Wastegate operation

I just installed a .7 bar spring to replace my 1bar spring. I have a question though.

Is there a way to test for proper operation of the wastegate? and what am I to look for during the test. lol..

Thanks

Jonathon
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1984 930... Andial intercooler, GT35R, Zork tube, RarlyL8 wastegate pipe
Old 06-16-2010, 08:06 PM
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Simply slowly apply air to the lower wastegate port and read how much it takes for the wastegate to open, .7 bar spring should require .7 Bar air pressure to open.

Cole
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Cole - 80 930 "The Old Sled"
Mods: TurboKraft Custom IC, 934 Headers, GSX 61, Zork, Port Work, SC Cams, Air Mod Fuel Dist Relocated, Water Meth Injection, BL WUR, MSD 6530, Greddy EBC, Synapse Bov, Short 2nd & 3rd with 8:37 R&P, Wevo Shifter, Coupling, and Mounts, MTX-L SSI-4, Big Brakes, Rebel Coilovers, Bilstein Sports.
Old 06-17-2010, 06:43 AM
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Quote:
Originally Posted by cole930 View Post
Simply slowly apply air to the lower wastegate port and read how much it takes for the wastegate to open, .7 bar spring should require .7 Bar air pressure to open.

Cole
Let me just add one little piece to this. Provided your WG is in good condition with minimal blow-by through the valve guide and/or seat, Coles advice will hold true. You may find that when bench testing, air pressure in excess of the stated spring will be needed to open the valve due to air leakage past the guide (in the neighborhood of .8 or .9 bar of pressure to open it). But when in the car the exhaust pressure has an additive affect to the boost air pressure and it will open just fine at .7.

I found that to be the case years ago when testing my Tial before installing. My old stock WG took almost 15 psi to open with a .8 bar spring on the bench (and I could hear the air blowing by), but it worked just fine in the car.
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Old 06-17-2010, 10:19 AM
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Picky, picky, picky !!!!!!!


I would like to add to my last post.

"The above testing procedure of wastegate opening pressure, only applies, when the wastegate being tested has been properly maintained and is in proper working order prior too preforming said test."

My apologies for assuming those preforming this procedure would have some idea of what they were doing.

Cole
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Mods: TurboKraft Custom IC, 934 Headers, GSX 61, Zork, Port Work, SC Cams, Air Mod Fuel Dist Relocated, Water Meth Injection, BL WUR, MSD 6530, Greddy EBC, Synapse Bov, Short 2nd & 3rd with 8:37 R&P, Wevo Shifter, Coupling, and Mounts, MTX-L SSI-4, Big Brakes, Rebel Coilovers, Bilstein Sports.
Old 06-17-2010, 12:26 PM
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Quote:
Originally Posted by cole930 View Post
Picky, picky, picky !!!!!!!


I would like to add to my last post.

"The above testing procedure of wastegate opening pressure, only applies, when the wastegate being tested has been properly maintained and is in proper working order prior too preforming said test."

My apologies for assuming those preforming this procedure would have some idea of what they were doing.

Cole
My middle initial is "A"...stands for Alan. Sometimes I think my folks actually meant for the A to stand for Anal....

Just trying to protect you from litigation when Jonathon fires back with: "I put .7bar to the WG and she don't open! WTF!"
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Old 06-17-2010, 02:12 PM
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There may be other factors at work. For some reason when I put a new .7 bar tial on my B&B system it would pull over .8 bar with a k27-7200.

Thus, the valve might open on a bench test at .7 bar bit you might get more boost in real life if you WG circuit is not ideal.

Best to have a good gage arched directly to the manifold after the throttle plate and before the intake valves.
Old 06-17-2010, 03:40 PM
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When I've bench tested my stock wastegate in the way described it hasn't just opened by itself. The diaphragm allows it to open at the appropriate pressure but it has required quite significant pressure on the face of the valve. Mine works fine on the car (0.8bar in my case).

David
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1984 ROW 930 - Stock except Rarlyl8 1-out, Andial IC, Air Pump delete, Carrera & Setrab Coolers, 0.8bar & LM-2
Old 06-17-2010, 04:01 PM
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They all start opening or lifting the valve off the seat about .2 before the stated bar level for a given spring... as long as the valve guide isn't worn and everything else works right.
They have to do that so they can be open all the way at .8bar if thats what it takes to keep the boost pressure from going over that.

If you want a .8bar wastegate spring to keep the wastegate valve closed below .8bar so there is less turbo lag.. then you need a good manual or electronic boost controller.
Old 06-17-2010, 05:07 PM
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I think this is the key phrase here. With a small diameter pipe from the headers to the WG, this will allow overboost unless it is replaced with a larger one. I had this problem with my HFS until I did this...

Quote:
Originally Posted by 911st View Post
There may be other factors at work. For some reason when I put a new .7 bar tial on my B&B system it would pull over .8 bar with a k27-7200.

Thus, the valve might open on a bench test at .7 bar bit you might get more boost in real life if you WG circuit is not ideal.
Old 06-17-2010, 05:14 PM
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I am not sure what I experienced is termed over-boost or not.

With the K27-7200, the Tial just ran at a higher than spec level. I have long suspected that is how the B&B's make part of there power gain --from tricking the WG with a less than ideal angle. Most of us were going to the Tial to ensure better boost management at the time.

I am staring to believe that is the best place to put a WG on a shorty header system as that is where the volume of the secondary tubes have to restrict down almost by half to enter the turbo. But that is another discussion.

I did however latter experience boost creep that did create an over-boost condition when I went to one of the early HF prototypes. In that case even with my .7 bar Tial, boost would creep up to 1.1 bar. Probably as noted because the WG circuit was to small.

Jim makes a good point about using an EBC ! It can keep the WG from leaking before target boost level is reached. Not sure but I think it needs to be the type that has a set up procedure or logic that learns the boost curve. This locks boost down until the target is reached and then opens is just as much is needed to maintain said boost.

That was one of the selling points of the EBC's years ago. That they added power right where you needed it. The difference between relying on the WG spring and using the EBC could be seen on a dyno. The kink in the TQ curve as the boost target was reached could better be seen.

I found the EBC effective enough that I was actually able to tame my over-boost issue from the early HF (big compressor/small turbine) and hold boost at 1 bar.

Did not make sense to me but that is what it seemed to do.
Old 06-17-2010, 05:40 PM
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WTF... I PUT IN A .7 SPRING AND IT DIDNT OPEN AT .7... THANKS FOR NOTHING COLE...hahaha.. Just kidding..


I tested it and it worked just fine it seems. Thanks for the testing procedure guys..Now I have to get the 4 snapped off studs on the muffler side taken out and replaced before I change to the RarlyL8 wastegate muffler. Anybody have a ballpark figure it'll cost for the snapped stud removal?

Jonathon
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Old 06-17-2010, 06:24 PM
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Jeeze guys, I think the original question was how to test for proper operation. That's all. Then off we go talking about boost creep, EBC's, pipe diameter from the header, etc. OK, I know we're all great reservoirs of information and eager to share. I'm just as guilty in doing the mind-dump. So Jonathon, more information than you can assimilate in one sitting? :-)
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Old 06-17-2010, 07:54 PM
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Jonathon,

I can tell your going to fit right in with this deviant band of misfits. Most of those who have replied to your thread are on the FBI most wanted list.
Just mention John Walsh and watch them scatter

Cole
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Mods: TurboKraft Custom IC, 934 Headers, GSX 61, Zork, Port Work, SC Cams, Air Mod Fuel Dist Relocated, Water Meth Injection, BL WUR, MSD 6530, Greddy EBC, Synapse Bov, Short 2nd & 3rd with 8:37 R&P, Wevo Shifter, Coupling, and Mounts, MTX-L SSI-4, Big Brakes, Rebel Coilovers, Bilstein Sports.

Last edited by cole930; 06-18-2010 at 11:43 AM..
Old 06-18-2010, 11:40 AM
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