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MLM

ITB M42

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After a bit of experimentation vacforming a skin of ABS seems to be an excellent way of sealing the mdf mold. It in effect gives me both male or a female mold depending which side of the ABS i use.

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Also trying the first wet layup to see how it will work out. So far so good for a fiberglassing noob

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Hopefully the second half will get machined up soon.

Let me know how this all works out and what you think the costs would be to make a second airbox. I am starting a very similar project for a mates rally car.

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Let me know how this all works out and what you think the costs would be to make a second airbox. I am starting a very similar project for a mates rally car.

Will do, may depend on the option you would want ie just the box or with backing plate f-glass or carbon etc Will be able to be more specific once ive made this one

looking good matt!

Cheers Heath, want one for the puggy?..

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Will do, may depend on the option you would want ie just the box or with backing plate f-glass or carbon etc Will be able to be more specific once ive made this one

Would be good as just with Glass.

I would also like the backing plate with the trumpets.

Cheers

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Second half of the mold completed today, had a few hicups on this one where the cnc decided to eat the part but came out in the end ok.

As before i have skinned it in ABS as a mold sealant and release surface. As i was at it i pulled a couple of extra skins off and assembled them to establish part lines and create a prototype for mock-up. All in all quite chuffed with the result so far.

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Mdf molds back to back. The section in the middle between the lines and abs skin is part of the mold only and wont be present in the part.

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Completed prototype

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Entry downward facing

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Engine side. Most of this face will be replaced with a aluminium backing plate which will have the trumpets passing through it. The whole lot will be sealed and clipped together with overcenter style clips fitted into the 4 recesses.

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thats sweet man, good work.

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12:57pm

Carbon fibre arrived this morning after 5 weeks from the US. At the time it was cheaper but since then its been popping up on trademe for the same price!

At least it has now arrived. Also will be trying a different technique to mold the parts using cling film and a fridge compressor. More on that later if it works...

Carbon spec 2x2 3k Twill.

ADDED @ 8 PM

Ok so couldnt wait till the weekend so i have decided to have a practice run. Here is a pic of the setup. Its a complete guess/seat of the pants experiment. Fridge compressor is providing vacuum to the bag to press the fiberglass together. A technique called vacuum consolidation so my second attempt at fiberglassing just went high tech, sort of..

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Looks ok so far. Will have a final result in an hour..

Edited by MLM

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Results:

post-3850-1311064835.jpg

That worked out mint! The part pulled into all the nooks and crannies, cured and released perfectly from the mold. The inside finish is mirror like thanks to the ABS and the exterior is fairly smooth from the glad wrap. Nothing 10 minutes with sand paper wouldnt sort out. The excess around the edge will be cut away once fully hardened to reveal the final part. I may even use this one as a base for the carbon fibre.

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Cheers Heath,

Seeing as the inside came out with such a good finish im considering making a tool from the abs mold. More work and a bit more expence (maybe $100) but then i would have parts with the perfect finish on the outside where you want it. A shiny inside is a but arse about face. Plus the extra work would probably be saved in trying to make the outside perfect. Be a shame to go to all this effort and the have a part which looks average on the outside cos i couldnt be bothered.

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+2 .. loving the DIYP (Do It Yourself Properly) attitude

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Ok, so today is carbon day.

Over the week I made a mold, which didn't end up costing anything as I had enough materials. The mold turned out to be quite testing of my patience but the end result was ok.

From there I have now just completed the first (and my first) carbon layer. Damn this stuff is tricky to work with. No only is it harder to form into shape due to its greater stiffness but also if using it for cosmetic reasons like i am you need the weave to sit well. Not an easy thing. so my first attempt is good but not perfect. Im still happy though.

Work area with second mold hooked up to fridge compressor vacuum pump

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Carbon in place. looks a bit ratty but will trim up ok

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Not perfect but pretty good weave layout.

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From here I will let it cure before adding more layers (1 carbon 1-2 glass). Then fingers crossed I will have a blingy carbon part which looks and functions well.

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Very nice! You can make me one now ;)

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Nice! :) ..

Ive been looking into the flow dynamics of trumpets and internal (to the box) trumpet length .. Some interesting discussion around staggered lengths to circumvent vortext intruption due to firing order / backpressure of each cylinder. Also learnt that the air follows the walls of the trumpt and has a dead spot in the center. Mucking any of this up obviously causes power loss etc.

I wish I was a bit more skilled with fluid dynamics software to even use it.

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Nice! :) ..

Ive been looking into the flow dynamics of trumpets and internal (to the box) trumpet length .. Some interesting discussion around staggered lengths to circumvent vortext intruption due to firing order / backpressure of each cylinder. Also learnt that the air follows the walls of the trumpt and has a dead spot in the center. Mucking any of this up obviously causes power loss etc.

I wish I was a bit more skilled with fluid dynamics software to even use it.

Playing with the trumpets is a big no no, they're tuned from factory the way they are, loss of power and torque will be inevitable. But you already no this :)

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Done.

post-3850-1312188665.jpg

Im reasonably happy with my first carbon part. Issues are the resin has cured with a slight cloudy white colour which is inconsistant. You can sort of see it in the picture. There are ways around this which i may try. For an underbonnet component though it hardly matters as it only really shows when light hits it the right way. Still noticable however which bugs the perfectionist in me.

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Nice! :) ..

Ive been looking into the flow dynamics of trumpets and internal (to the box) trumpet length .. Some interesting discussion around staggered lengths to circumvent vortext intruption due to firing order / backpressure of each cylinder. Also learnt that the air follows the walls of the trumpt and has a dead spot in the center. Mucking any of this up obviously causes power loss etc.

I wish I was a bit more skilled with fluid dynamics software to even use it.

The more I learn about the fluid flow analisis the more realise how much is still best guess not absolute accuracy. Still, i believe that you can use intellegence and a bit of intuition to get better results.

The discussions you mention would be good to be part of. Inlet length impacts torque, trumpets change effective length, taper angles are critical etc . Bit of a mine field really. I chose stagered trumpets in terms of location not length so the trumpet behind the leading trumpet is not drawing turbulent air created by that leading trumpet. In its shadow if you like. Analisis an logic says it should work..

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