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LeeW
Samba Member
Joined: September 23, 2019
Posts: 18
Location: Cincinnati
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 Posted: Mon Jan 30, 2023 2:58 pm Post subject: Draw through turbo question |
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Hi guys,
I'm finishing up my draw through turbo but I'm having issues with my wastegate.
The wastegate line is running to the turbo like normal but since the external wastegate isn't holding vacuum it's causing a problem with idle and tuning. I've tried 2 new wastegates and they both do the same thing.
Could I run a check valve? Since it leaks vacuum I doubt it would hold a bunch of pressure on the gate? |
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madmike
Samba Member
Joined: July 11, 2005
Posts: 5292
Location: Atlanta,Michigan
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| Posted: Mon Jan 30, 2023 3:57 pm Post subject: Re: Draw through turbo question |
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Hey Lee, sounds like the diaphragm is Kput ,can u post a photo of the set up? I'm a Visual kind of guy  I have a 'Tial' made in Michigan, but ya know what, the fleeBay one works just as good
_________________
'Black Ice'Drag Buggy 'Turbo'
Rail Buggy 1915 turbo
76 Drag/Street bug 2180cc 'Turbo' 11:85 @113 mph"If I go any faster I'll burn up the Hamster" ,gets 28 mpg. also 10/09/22 11.90 @115 mph
"If I'm ever on Life Support,UNPLUG Me, Then Plug me back In see if that Works" |
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LeeW
Samba Member
Joined: September 23, 2019
Posts: 18
Location: Cincinnati
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| Posted: Mon Jan 30, 2023 4:43 pm Post subject: Re: Draw through turbo question |
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| madmike wrote: |
| Hey Lee, sounds like the diaphragm is Kput ,can u post a photo of the set up? I'm a Visual kind of guy I have a 'Tial' made in Michigan, but ya know what, the fleeBay one works just as good |
I've tried 2 different brand new ones and the same thing. The diaphragm is good the both leak around the shaft. |
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Dauz
Samba Member
Joined: January 05, 2010
Posts: 1791
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| Posted: Mon Jan 30, 2023 4:50 pm Post subject: Re: Draw through turbo question |
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How does a wastegate affect idle and tuning? All it does is bleed off exhaust pressure before the turbine to control boost at whatever the strength of the installed SPRING. A boost controller augments the 'signal' to the wastegate to also affect when it opens. Vacuum doesn't hold the WG closed.. it's mechanical (spring)
Troubleshoot your idle and tuning normally, A/F ratio, spark, ignition timing, set valves, check for intake leaks etc. |
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LeeW
Samba Member
Joined: September 23, 2019
Posts: 18
Location: Cincinnati
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| Posted: Mon Jan 30, 2023 4:53 pm Post subject: Re: Draw through turbo question |
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| Dauz wrote: |
How does a wastegate affect idle and tuning? All it does is bleed off exhaust pressure before the turbine to control boost at whatever the strength of the installed SPRING. A boost controller augments the 'signal' to the wastegate to also affect when it opens.
Troubleshoot your idle and tuning normally, A/F ratio, spark, ignition timing, set valves, check for intake leaks etc. |
It's a draw through system so the boost reference line to the wastegate is also full vacuum. It's a 3/16 line that's leaking a ton of vacuum. |
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madmike
Samba Member
Joined: July 11, 2005
Posts: 5292
Location: Atlanta,Michigan
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| Posted: Mon Jan 30, 2023 5:25 pm Post subject: Re: Draw through turbo question |
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Im thinkin u have it hooked up wrong,, pic will show us,,, I'd go out and snap a pic of mine but it's like 9* outside  Cheers,Mike
_________________
'Black Ice'Drag Buggy 'Turbo'
Rail Buggy 1915 turbo
76 Drag/Street bug 2180cc 'Turbo' 11:85 @113 mph"If I go any faster I'll burn up the Hamster" ,gets 28 mpg. also 10/09/22 11.90 @115 mph
"If I'm ever on Life Support,UNPLUG Me, Then Plug me back In see if that Works" |
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LeeW
Samba Member
Joined: September 23, 2019
Posts: 18
Location: Cincinnati
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| Posted: Mon Jan 30, 2023 5:37 pm Post subject: Re: Draw through turbo question |
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| madmike wrote: |
| Im thinkin u have it hooked up wrong,, pic will show us,,, I'd go out and snap a pic of mine but it's like 9* outside Cheers,Mike |
It's just a direct line from the compressor housing to the lower port on the wastegate. Can't see how I could get that wrong. It's off of the car right now so I can't get a picture. |
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raymon covey
Samba Member
Joined: April 30, 2005
Posts: 189
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| Posted: Mon Jan 30, 2023 8:21 pm Post subject: Re: Draw through turbo question |
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| Unhook line and just use spring. |
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Stripped66
Samba Member
Joined: May 31, 2005
Posts: 3470
Location: Charleston, SC
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| Posted: Tue Jan 31, 2023 5:52 am Post subject: Re: Draw through turbo question |
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| LeeW wrote: |
I've tried 2 different brand new ones and the same thing. The diaphragm is good the both leak around the shaft. |
That's peculiar that you've had 2 new ones leak like that. For the sake of being thorough, you're bench-testing this with compressed air? You've confirmed the diaphragm is air-tight by pressurizing the top-chamber of each wastegate? You've used thread-sealant on the hose-fittings for both the boost-reference (at the turbo) and wastegate? If all of that checks out, then maybe consider a wastegate that's higher quality.
_________________
| 66brm wrote: |
| Bodacious wrote: |
| Why not just make a custom set of wires with a Y splice in them. Then you could just run one distributor. |
I don't think electrickery works that way |
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Dauz
Samba Member
Joined: January 05, 2010
Posts: 1791
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| Posted: Tue Jan 31, 2023 5:53 pm Post subject: Re: Draw through turbo question |
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| LeeW wrote: |
| Dauz wrote: |
How does a wastegate affect idle and tuning? All it does is bleed off exhaust pressure before the turbine to control boost at whatever the strength of the installed SPRING. A boost controller augments the 'signal' to the wastegate to also affect when it opens.
Troubleshoot your idle and tuning normally, A/F ratio, spark, ignition timing, set valves, check for intake leaks etc. |
It's a draw through system so the boost reference line to the wastegate is also full vacuum. It's a 3/16 line that's leaking a ton of vacuum. |
What?!!! The reference port is AFTER the compressor. That's why they call it a MAP.. manifold absolute pressure |
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madmike
Samba Member
Joined: July 11, 2005
Posts: 5292
Location: Atlanta,Michigan
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| Posted: Tue Jan 31, 2023 6:09 pm Post subject: Re: Draw through turbo question |
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Like right here?
_________________
'Black Ice'Drag Buggy 'Turbo'
Rail Buggy 1915 turbo
76 Drag/Street bug 2180cc 'Turbo' 11:85 @113 mph"If I go any faster I'll burn up the Hamster" ,gets 28 mpg. also 10/09/22 11.90 @115 mph
"If I'm ever on Life Support,UNPLUG Me, Then Plug me back In see if that Works" |
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Dauz
Samba Member
Joined: January 05, 2010
Posts: 1791
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| Posted: Tue Jan 31, 2023 6:22 pm Post subject: Re: Draw through turbo question |
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Or these
blow-through / draw through has nothing to do with it. Wastegate has nothing to do with your idle either. |
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madmike
Samba Member
Joined: July 11, 2005
Posts: 5292
Location: Atlanta,Michigan
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| Posted: Tue Jan 31, 2023 7:00 pm Post subject: Re: Draw through turbo question |
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[img]https://www.thesamba.com/vw/gallery/pix/2364221.jpg[/imgI prefer a 'T'
_________________
'Black Ice'Drag Buggy 'Turbo'
Rail Buggy 1915 turbo
76 Drag/Street bug 2180cc 'Turbo' 11:85 @113 mph"If I go any faster I'll burn up the Hamster" ,gets 28 mpg. also 10/09/22 11.90 @115 mph
"If I'm ever on Life Support,UNPLUG Me, Then Plug me back In see if that Works" |
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Stripped66
Samba Member
Joined: May 31, 2005
Posts: 3470
Location: Charleston, SC
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| Posted: Wed Feb 01, 2023 7:57 am Post subject: Re: Draw through turbo question |
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| Dauz wrote: |
blow-through / draw through has nothing to do with it. Wastegate has nothing to do with your idle either. |
The problem is that the actuator of the wastegate is leaking around the valve-stem. At closed throttle when the manifold is drawing high-vacuum, he appears to have a significant vacuum leak from the wastegate actuator.
_________________
| 66brm wrote: |
| Bodacious wrote: |
| Why not just make a custom set of wires with a Y splice in them. Then you could just run one distributor. |
I don't think electrickery works that way |
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I Ride Sand
Samba Member
Joined: June 07, 2012
Posts: 567
Location: utah
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| Posted: Wed Feb 01, 2023 4:55 pm Post subject: Re: Draw through turbo question |
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if the diaphragm is leaking, its not actuating either. they are reliant on a pressure differential to function but if they are unintentionally self equalizing.....
Is there a manual boost controller involved? they are just a metered leak. are you sure its actually working under boost or is it just using spring pressure to regulate?
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Just a dirty coyote playing in the desert.
now where'd that dirty badger run off to? |
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panel
Samba Member
Joined: December 02, 2001
Posts: 1091
Location: Victoria B.C. Canada
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| Posted: Wed Feb 01, 2023 10:26 pm Post subject: Re: Draw through turbo question |
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LeeW ......I've played with draw through and blow through , FI etc. Just thinking here , but wouldn't the WG just be leaking exhaust ? Shouldn't cause a vacuum leak  Yes the vacuum line is hooked up to it but you could un plug it from the WG , plug the manifold at idle to see where your vacuum leak is. Don't drive/boost like this or you'd have no control over it (overboost) etc.
What kind/brand/model and size etc is the wastegate ?
Let us know how ya make out.
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My '65-Subaru EJ20 Turbo conversion |
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Dauz
Samba Member
Joined: January 05, 2010
Posts: 1791
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| Posted: Thu Feb 02, 2023 12:19 pm Post subject: Re: Draw through turbo question |
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| panel wrote: |
LeeW ......I've played with draw through and blow through , FI etc. Just thinking here , but wouldn't the WG just be leaking exhaust ? Shouldn't cause a vacuum leak Yes the vacuum line is hooked up to it but you could un plug it from the WG , plug the manifold at idle to see where your vacuum leak is. Don't drive/boost like this or you'd have no control over it (overboost) etc.
What kind/brand/model and size etc is the wastegate ?
Let us know how ya make out. |
Thank you. What I've been trying to say but here it was said more gracefully. Agree with everything except the overboost part. The spring is lighter than any boost controller and will open early. I have never used a spring heavier than to allow more than 15lbs. boost. A boost controller augments the MAP signal to the WG and "delays" its' opening to allow more pounds per square inch. However, sometimes 'where' the wastegate is placed in the exhaust can create boost creep.
It's been said several times that "the actuator is leaking at the shaft." At what indication? How is this "vacuum leak" even being validated? WHY is the wastegate being blamed for idle and tuning?
Again, all the WG does is regulate boost, it won't affect idle, tuning, etc. UNLESS someone stuck the 02 sensor in the WG outlet bypass in an EFI setup and sent all sorts of skewed output to the ECU. But that is not the case. |
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BFB
Samba Member
Joined: November 03, 2014
Posts: 1762
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| Posted: Sat Feb 04, 2023 2:53 pm Post subject: Re: Draw through turbo question |
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To answer OP’s question directly, yes use a one way valve in the the line. On a blow through the compressor outlet / intake will have vacuum, not so on blow through. And the blow off valve , just like a manual boost controller , have to be able to vent the boost pressure otherwise the waste gate will continue to stay open longer than it should. You can have small leaks on the pressure side of a turbo and the turbo still keep up, ie a water injection system run from boost pressure ( works on drawthrough, not on blowthrough btw ) different story if it’s draw though “boost side” leaks can be vacuum leaks too. You also need to use a one way valve if your running a boost referenced fuel pressure regulator otherwise the you’ll pull vacuum on it and cause your fuel pressure to drop on drawthrough system. Whether that waste gate leak has anything to do with your idle or not who knows, but yes waste gates absolutely do leak, whether through the shaft or an actual vent hole.
_________________
Forced induction can overcome a lot of obsticles that gets in it's way
"You are the Engineer and the Mechanic.
Build it your way not the way someone else does it. Their way might not work for you." - clonebug
An interesting thing happens in forums where everyone starts parroting the same thing and "common knowledge" takes over.
“ The monkey see monkey do mentality seems to run deep in VW people. "Gene Berg said it was so 30 years ago so thats the way it is" “ - bdkw1 |
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Dauz
Samba Member
Joined: January 05, 2010
Posts: 1791
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| Posted: Sun Feb 05, 2023 8:53 pm Post subject: Re: Draw through turbo question |
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| BFB wrote: |
| To answer OP’s question directly, yes use a one way valve in the the line. On a blow through the compressor outlet / intake will have vacuum, not so on blow through. And the blow off valve , just like a manual boost controller , have to be able to vent the boost pressure otherwise the waste gate will continue to stay open longer than it should. You can have small leaks on the pressure side of a turbo and the turbo still keep up, ie a water injection system run from boost pressure ( works on drawthrough, not on blowthrough btw ) different story if it’s draw though “boost side” leaks can be vacuum leaks too. You also need to use a one way valve if your running a boost referenced fuel pressure regulator otherwise the you’ll pull vacuum on it and cause your fuel pressure to drop on drawthrough system. Whether that waste gate leak has anything to do with your idle or not who knows, but yes waste gates absolutely do leak, whether through the shaft or an actual vent hole. |
what the actual f*ck? |
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