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Mike9311
Joined: 14 Dec 2004
Posts: 1678
Location: Chicago-ish
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 Posted: Mon Mar 02, 2020 1:09 am Post subject: |
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Progress pic... will report back either tonight or tomorrow for sure
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1980 931 since 1989
1981 Ideola 931 Club Sport
1982 931 Entwicklungsfahrzeug
1979 924 NA ohne 650 mit 471
1982 931 Red Resurrection - 951 IC
1982 931 parts car / resurrection?
1980 924 NA (R&D lightweight)
1982 931 wana-be GTR race car |
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Mike9311
Joined: 14 Dec 2004
Posts: 1678
Location: Chicago-ish
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| Posted: Tue Mar 03, 2020 12:11 am Post subject: |
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Good Morning....for me anyway
Ready for some clean up in a lathe and such. Will let you all know how it fits
_________________
1980 931 since 1989
1981 Ideola 931 Club Sport
1982 931 Entwicklungsfahrzeug
1979 924 NA ohne 650 mit 471
1982 931 Red Resurrection - 951 IC
1982 931 parts car / resurrection?
1980 924 NA (R&D lightweight)
1982 931 wana-be GTR race car |
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Fasteddie313
Joined: 29 Sep 2013
Posts: 2596
Location: MI
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| Posted: Tue Mar 03, 2020 3:08 am Post subject: |
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wow..
Really coming along..
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80 Turbo - Slightly Modified |
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Mike9311
Joined: 14 Dec 2004
Posts: 1678
Location: Chicago-ish
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| Posted: Tue Mar 03, 2020 3:20 am Post subject: |
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| Fasteddie313 wrote: | wow..
Really coming along.. |
Yeah, not sure what drove me to dive so hard on this the last couple of weeks. Already spun it up with a vacuum cleaner but it needs to be cleaned up a bit and I have to think about how I want to test exactly. Something more definitive.
It fits though. Always forget how loose these housings are. Thought there was a mistake until I grabbed an actual 6.10 and it fit the same way.
_________________
1980 931 since 1989
1981 Ideola 931 Club Sport
1982 931 Entwicklungsfahrzeug
1979 924 NA ohne 650 mit 471
1982 931 Red Resurrection - 951 IC
1982 931 parts car / resurrection?
1980 924 NA (R&D lightweight)
1982 931 wana-be GTR race car |
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Fasteddie313
Joined: 29 Sep 2013
Posts: 2596
Location: MI
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| Posted: Tue Mar 03, 2020 3:40 am Post subject: |
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You mean loose as in the blade tip distance from the housing?
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80 Turbo - Slightly Modified |
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Mike9311
Joined: 14 Dec 2004
Posts: 1678
Location: Chicago-ish
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| Posted: Tue Mar 03, 2020 5:46 am Post subject: |
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| Fasteddie313 wrote: | | You mean loose as in the blade tip distance from the housing? |
Yes, but I know its for thermal expansion and its identical to the original 6.10
I just always forget how it looks to the eye 
Its amazing how close the dimensions really are considering I am comparing a plastic print. Still need to clean it up some more in a couple of spots. Then I will bolt it up
_________________
1980 931 since 1989
1981 Ideola 931 Club Sport
1982 931 Entwicklungsfahrzeug
1979 924 NA ohne 650 mit 471
1982 931 Red Resurrection - 951 IC
1982 931 parts car / resurrection?
1980 924 NA (R&D lightweight)
1982 931 wana-be GTR race car |
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Mike9311
Joined: 14 Dec 2004
Posts: 1678
Location: Chicago-ish
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| Posted: Thu Mar 05, 2020 12:36 am Post subject: |
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Been doing spin tests between original housing and this one. Not very scientific at the moment but I am comparing rpm with a laser tachometer.
Working on making up something more consistent and repeatable. So far so good though really
_________________
1980 931 since 1989
1981 Ideola 931 Club Sport
1982 931 Entwicklungsfahrzeug
1979 924 NA ohne 650 mit 471
1982 931 Red Resurrection - 951 IC
1982 931 parts car / resurrection?
1980 924 NA (R&D lightweight)
1982 931 wana-be GTR race car |
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Cedric
Joined: 27 Aug 2004
Posts: 2608
Location: Sweden
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| Posted: Thu Mar 05, 2020 5:08 pm Post subject: |
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Wheel to housing clearance is critical, mostly because of shaft motion (which is larger than you think it is). It do cost turbine efficiency to have a large gap, but its not something you can play around with if you dont know what you are doing  , sadly.
The best solution is to have an abradable coating on the inside of the turbine housing, so the wheel will rub itself into place. That can give several % of turbine efficiency, sadly theres noone doing it for reasonable money in small series.
However, one thing you can do if you ever go one to cast it for real is to talk with the caster on how to get the best possible surface roughness in the turbine scroll. It clearly affects turbine performance aswell.
ok, i will quit babbling about details, your work progress is really great. Whats the plans for going forward from here?
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1980 924 Turbo
www.instagram.com/garagecedric/ |
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Mike9311
Joined: 14 Dec 2004
Posts: 1678
Location: Chicago-ish
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| Posted: Fri Mar 06, 2020 12:50 am Post subject: |
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| Cédric wrote: | Wheel to housing clearance is critical, mostly because of shaft motion (which is larger than you think it is). It do cost turbine efficiency to have a large gap, but its not something you can play around with if you dont know what you are doing , sadly.
The best solution is to have an abradable coating on the inside of the turbine housing, so the wheel will rub itself into place. That can give several % of turbine efficiency, sadly theres noone doing it for reasonable money in small series.
However, one thing you can do if you ever go one to cast it for real is to talk with the caster on how to get the best possible surface roughness in the turbine scroll. It clearly affects turbine performance as well.
ok, i will quit babbling about details, your work progress is really great. Whats the plans for going forward from here? |
Hi Cedric, I was hoping you would chime in. The clearance is identical to the original 6.10. The turbine curvature is exactly like the original. For the scroll, in the end, I used cross section diameters and let the CAD do the work. I had the scroll scan in a layer that could be turned on and off to check throughout my tweaking. I did remove one step, as you suggested earlier (might not have been the one you meant), and I was going to see how the exhaust down-pipe looks to see if anything needs adjusting from the original.
The scroll tongue, from the exhaust manifold entrance, gently slopes up to the tongue. On the blade side, the last little bit of the scroll goes from the scroll curvature to straight across at exit or "nozzle". It exits at the same overall clearance diameter. I like that it does this since its the max 'lever arm' on the wheel. At times, I think it looks a tad odd in CAD but the print looks good. Plus, even at very low air flow the turbine responds (my so so crude testing). I still want to fillet a bit too around the tongue straight. Currently the straight is sharp to the housing at each side. Not sure if you have an example pic I could see of how it should look?
When you mentioned the tongue I just added more pics, papers, and such to my file to study as I went along. Modern examples as best I could find.
The outer housing of the scroll needs an adjustment before it goes to metal plus filleting to all the surrounding parts. The scroll was created as an offset from an earlier scroll and its thin in once spot and maybe thicker in another spot. The outside scroll is not like the original 6.10 since I was hoping to have it somewhat thinner which leads to material choice....
Two choices as of this moment, stainless 310 (CK20) or inconel 625 depending on what process I choose to make the prototype. This is decision time and I am trying to keep it local and fast since I would like to pop it on the turbo I am rebuilding for the '82 which has a hard April deadline to run
Today I am hoping to test again against the original. I printed a flange to bolt up to the housing that for better tube fitting and consistency of incoming air. ALso needed to get new reflective tape for the tach to measure rpm. The adhesive was just not working on the tape I had not to mention inlet air flow was terribly inconsistent. It was more for fun just to get an idea. Overall though I am pretty happy with how it acted when compared to the original. We will know more today. Keeping the bearings oiled though might wreak havoc on the frictional consistency and value of the test. Going to do it anyway
Weird...it wouldn't let me preview to proof read. It simply disappeared. Glad I copy clipped 
_________________
1980 931 since 1989
1981 Ideola 931 Club Sport
1982 931 Entwicklungsfahrzeug
1979 924 NA ohne 650 mit 471
1982 931 Red Resurrection - 951 IC
1982 931 parts car / resurrection?
1980 924 NA (R&D lightweight)
1982 931 wana-be GTR race car |
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Mike9311
Joined: 14 Dec 2004
Posts: 1678
Location: Chicago-ish
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| Posted: Sun Mar 08, 2020 11:35 pm Post subject: |
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Finally managed to clean up my testing a tad. Printed a flange hose adapter and compared new 3D Printed 6.10 vs the Stock 6.10 and then a Stock 4.10.
I was hoping the two 6.10's would be close. They totally were, which was great. I also knew the 4.10 would be different and how different it was...
I threaded the 6.10 printed housing. The hose adapter was fitted up nice and tight because both pieces were threaded so please ignore bolts sticking up like that...just lazy
3D Printed 6.10 Housing
https://vimeo.com/396202200
Stock 6.10
https://vimeo.com/396212356
And then the Stock 4.10 which easily doubled the rpm of the other two for the given airflow indicating what we all knew already but fun nonetheless
https://vimeo.com/396212697
EDIT: Should have printed 944 flange as well to test the larger housing from my 951S Turbo (8.11 vs 8.10 GTS too close to matter). Then we would see GTS like comparison. I still can at any time since I am rebuilding another turbo right now for the car
_________________
1980 931 since 1989
1981 Ideola 931 Club Sport
1982 931 Entwicklungsfahrzeug
1979 924 NA ohne 650 mit 471
1982 931 Red Resurrection - 951 IC
1982 931 parts car / resurrection?
1980 924 NA (R&D lightweight)
1982 931 wana-be GTR race car |
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