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kondzi
Joined: 02 Jul 2018
Posts: 494
Location: Poland/EU
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 Posted: Fri Sep 03, 2021 3:49 am Post subject: |
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Need to check in my garage, I have 3.2 engine on stand and 3.6 in 964 
The insulation was to prevent heat soak AFAIK.
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Konrad
'89 951 US
'88 Mustang 5.0 LX Convertible (factory specs)
'84 911 Carrera 3.2 RoW (factory specs)
'81 931 RoW (TBD)
'81 Ford Capri 2.8i (factory specs)
'79 Ford Capri 2.9 (heavily modded) |
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Cedric
Joined: 27 Aug 2004
Posts: 2806
Location: Sweden
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| Posted: Fri Sep 03, 2021 3:50 am Post subject: |
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| kondzi wrote: | 911 aircooled CHT shows 160-190 celsius normally, but there are heat insulation washers inbetween. The other thing is this is different type of plastic obviously, designed for durability, not for ease of 3D printing  |
Yes this is a factor some people dont seem to be aware about. Injection molded plastics for a typical manifold is probably in PA66 GF30 (30% glass fiber), which is also nylon, but have a heat deflection temperature of maybe 250 or 260 degrees, compared to FDM printed nylon CF at around 100-190 degC, so its way less stiff at higher temperatures, and thats before we talk ageing. Im not saying printing isnt doable, im just saying its not the same material as you see under the bonnet on production cars, hence we often need to make printed things a bit beefier, reinforcements, beefier flanges etc.
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1980 924 Turbo
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Juho
Joined: 03 Oct 2018
Posts: 392
Location: Finland
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| Posted: Fri Sep 03, 2021 4:50 pm Post subject: |
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| Ok i did more research... Ive made a combo with gaskets material (have to make own gaskets) and spacer that will give ALOT heat insulation and should protect the flange enough. I think it will give so much heat insulation that i could use a cheaper material for the manifold |
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morghen
Joined: 21 Jan 2005
Posts: 9095
Location: Romania
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| Posted: Mon Sep 06, 2021 6:07 pm Post subject: |
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Look into PHENOLIC for insluation.
Dont underestimate the heat coming from the 924 engine.
Peak temperatures wont do much but sustained temperatures at the, or above the glass transition point will deform your parts..ask me how i know
Also, you'll have to be very clever about fixing these parts on the engine as there is such a thing as plastic relaxation....meaning you tighten a bolt on plastic to 6Nm....the next day its 3, the next day its 1Nm. You tigthen it back to 6Nm and the next day its 3Nm...and so on.
You cant effectively clamp thermo-plastic parts.
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Cedric
Joined: 27 Aug 2004
Posts: 2806
Location: Sweden
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| Posted: Mon Sep 06, 2021 6:55 pm Post subject: |
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| morghen wrote: | Look into PHENOLIC for insluation.
Dont underestimate the heat coming from the 924 engine.
Peak temperatures wont do much but sustained temperatures at the, or above the glass transition point will deform your parts..ask me how i know
Also, you'll have to be very clever about fixing these parts on the engine as there is such a thing as plastic relaxation....meaning you tighten a bolt on plastic to 6Nm....the next day its 3, the next day its 1Nm. You tigthen it back to 6Nm and the next day its 3Nm...and so on.
You cant effectively clamp thermo-plastic parts. |
Hence why many plastic designs have metal sleeves in the holes, so the screws can be tightened down fully and not relax and loosen the clamping force over time.
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1980 924 Turbo
www.instagram.com/garagecedric/ |
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Juho
Joined: 03 Oct 2018
Posts: 392
Location: Finland
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| Posted: Mon Sep 06, 2021 7:11 pm Post subject: |
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| going to to bakelite sheet 8mm thickness and diy thermal insulation gaskets |
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Juho
Joined: 03 Oct 2018
Posts: 392
Location: Finland
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| Posted: Sat Sep 18, 2021 10:42 pm Post subject: |
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New design |
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Juho
Joined: 03 Oct 2018
Posts: 392
Location: Finland
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| Posted: Tue Sep 28, 2021 4:11 pm Post subject: |
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Some update, phenolic spacers arrived in country today, im taking a cnc course in school where i can hopefully make those but if not im just going to drill and dremel them...
Looking at a gasket material but i would have to buy it a very large sheet for just 2 gasket it isnt really worth. |
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Juho
Joined: 03 Oct 2018
Posts: 392
Location: Finland
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| Posted: Wed Feb 09, 2022 8:41 pm Post subject: |
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Modeled some new, i think these will introdouce more air to the head, been super busy with fsae, really havent had time for my personal projects.... also super annying to transfer stuff from my personal fusion 360 to school one |
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Cedric
Joined: 27 Aug 2004
Posts: 2806
Location: Sweden
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| Posted: Sat Feb 12, 2022 6:27 am Post subject: |
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It will surely flow well, but the runners do seem long, i think you will need to think about how to support them, maybe with a similar bracket as the orignal manifold. Maybe it would be better to shorten them as much as possible to get the weight/throttle closer to the block and use the trumpet to get the desired length. Fun project though, there are several who runs printed itbs out there.
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1980 924 Turbo
www.instagram.com/garagecedric/ |
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Juho
Joined: 03 Oct 2018
Posts: 392
Location: Finland
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| Posted: Sat Feb 12, 2022 6:13 pm Post subject: |
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| I think im going to go with the latest runners i showed, my only concern atm is the torque downing bolts, im afraid that the heat expansion will overtime loosen the bolts but i hope my 8mm bakelite spacers will fix that problem |
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Juho
Joined: 03 Oct 2018
Posts: 392
Location: Finland
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| Posted: Sat Feb 12, 2022 8:11 pm Post subject: |
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Hmmmm makes me think long vs short runners |
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Mike9311
Joined: 14 Dec 2004
Posts: 1798
Location: Chicago-ish
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| Posted: Sun Feb 13, 2022 12:18 am Post subject: |
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Its been popular with the carbon fiber manifolds to sleeve the bolt holes with metal although in the case of carbon you have to be mindful of the reactance of the materials with each other. Then you could use a larger washer on the bolt to go against the plastic to spread the load across the plastic.
Even more involved would be to use a double washer with a curved or wave spring in between the two washers.
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1980 931 since 1989
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1982 931 Red Resurrection - 951 IC
1982 931 parts car / resurrection?
1980 924 NA (R&D lightweight)
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Cedric
Joined: 27 Aug 2004
Posts: 2806
Location: Sweden
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| Posted: Sun Feb 13, 2022 12:58 am Post subject: |
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In the oem world its super common to have a steel sleeve in the hole to get consistent screw tension. You should really consider that.
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1980 924 Turbo
www.instagram.com/garagecedric/ |
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924 FAQ (Technical)
