Carbon & Aluminium Intake Manifold

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Carbon & Aluminium Intake Manifold

Carbon & Aluminium Intake Manifold

Author	Message
toolchimp	toolchimp posted 10 Years Ago HOT Topic Details
Group: Forum Members Posts: 5, Visits: 194	I am in the process of designing and making a carbon and aluminium intake manifold for my V8 powered kit car. I have a design that has been through the flow analysis loops and the runner to runner mass flow distribution looks good, so I could set about the construction. I knew making the runners would be the most tricky part, so I decided to start with them. Ideally, these would be a continuous tube (i.e. not two halves bonded together) with a carefully defined cross sectional area and shape, blending from a rectangle at the port to a circle at the plenum. A good surface finish on the inner face is beneficial for minimum pressure drop, but I also want a good cosmetic finish on the outside as it will be very noticeable when the bonnet is up! I devised a lost wax method of making these parts and set about making a mould for the 8 off wax plugs. Given the accuracy I needed, I decided the master pattern had to be CNC machined, so I spent some months designing and building such a machine. This will be used for other parts of the car, so it was not just a one-off for this plug! This was the first part I cut on the machine so there were a few teething troubles, but the PU tooling board is easy enough to repair with car body filler and re-machine. These are the lighter coloured regions in the pictures: A couple of layers of Pattern Coat along with guide coat and progressively finer grits of wet and dry, followed by polishing soon saw the finished master. This has shrinkage allowances added to it in order to compensate for the down stream processes The first attempt at a mould for the waxes was using an all plaster arrangement. This proved to be a dead end as the extremely porous plaster 'drank' the liquid wax before it could freeze! I therefore reverted to a silicone-plaster 'mother mould' technique using additive cure silicone as the tooling face. A plasticine dam was built around the part before pouring the first of two halves of the silicone. The box structure then allows the plaster to be poured. Note the black 'dots' are registration marks for the two halves of the plaster mould. The process can be repeated for the second half From here, I could then cast my first wax plugs. I moulded it over a piece of dowel to act as a handle during lay up After all this effort, I was finally able to lay up the runner itself. The schedule was 2 layers of gel coat, followed by 4 layers of 7.5 oz/sq.yd biaxial carbon sleeve and high temperature lamination resin. The stack was consolidated with a coated heatshrink before curing at room temperature. Once cured, I could post-cure the part, during which time the wax also melted out as planned. There were a few issues with the first part - the finish on the wax wasn't great due to moisture still in the plaster (despite a week of drying time), runs in the gel coat (a little to liberal with the application) and trying to figure the best way of rolling the sleeve into place whilst getting the weave straight meant that the both the internal and external finish left a lot to be desired, but I am hopeful the next parts will be much better. This part was sectioned to check the lay up and there were some very small inclusions in the thickness of the wall (a hazard of not consolidating under vacuum) and a couple of air bubbles under the gel coat (I will use a roller next time!) but overall, I am pleased with the result so far - it certainly seems strong enough for my needs! Eight more to go then!
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FLD	FLD posted 10 Years Ago Post Details
Group: Forum Members Posts: 468, Visits: 2.7K	Awesome! There's a serious amount of work there.
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bmxarmy	bmxarmy posted 10 Years Ago HOT Post Details
Group: Forum Members Posts: 3, Visits: 380	Fantastic work! What is the power plant for the car going to be? Can you explain the coated heat shrink a little better? I look forward to seeing your progress on the project! Thanks for sharing
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toolchimp	toolchimp posted 10 Years Ago HOT Post Details
Group: Forum Members Posts: 5, Visits: 194	Thanks for the comments. The engine is a 302 cu.in. (technically 306 cu.in. after the rebuild) / 5.0l Ford Small Block V8. The intake is matched to the ports on the aftermarket cylinder heads so will also support stroking it out to a 353cu.in., should the urge arise! The heatshrink is transparent and coated with release agent on the inside to allow it to be peeled off after the part has cured. I purchased it from here: http://www.sollercomposites.com/composites/carbon%20fiber%20sleeves.html#Shrink It did not come off as easily as I anticipated in a couple of places, but I suspect I had overheated it trying to get it pulled down uniformly (the heatshrink is very thin and when it touches the wet resin, it takes more heat to fully shrink). I did manage to get it all off successfully though. I will report back on the next parts when I have had another try at it!
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BlackNDecker	BlackNDecker posted 10 Years Ago Post Details
Group: Forum Members Posts: 92, Visits: 251	Fabulous work! How are you planning to attach the runners to the plenum?
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toolchimp	toolchimp posted 10 Years Ago HOT Post Details
Group: Forum Members Posts: 5, Visits: 194	The area where the runners meet the plenum will be billet aluminium so I will be using a semi-flexible adhesive at the joint. I need to be careful that I electrically isolate the carbon from the aluminium to minimise the chance of galvanic corrosion. I work with electric machines for electric and hybrid cars and we use a very thin (0.17mm) but mechanically tough insulating paper to keep high voltage away from chassis potential so I will probably incorporate this into the joint.
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bmxarmy	bmxarmy posted 10 Years Ago HOT Post Details
Group: Forum Members Posts: 3, Visits: 380	Any updates on this project?
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