mrpham's summer build

[Magpie]

At the moment my ITB's draw air from inside the wheel well. At Sandown final session intake temp was 48, dropped to about 32 whilst moving and was at 43 when I shut down.

QR in Nov 2016 around 1300, 46 at start, 41 whilst moving and 50 when shut down.

In discussions with my tuner there can be a slight benefit with ram air. Hopefully when I have done the mod for ram air I will get the tuner to sit in the passengers seat to adjust the tune.

[16bit]

they use to do ram air with the old 2l british touring cars.

[ndragun]

I don't have any references regards the ram air effect. I think it's a physics problem? ie. How much air can the itbs flow

There is some stuff out there - particularly around the last generation of normally aspirated F1 engines and how they draw air from the intake above the drivers head. I remember seeing something about how they do the opposite in terms of sizing; actually size the intake smaller than the runner size to slow the intake air down in the plenum and increase what is called its 'volumetric efficiency'.

Either way - cool cad drawing ;)
Can you actually print with a plastic that isn't suceptible to high heat?? I didn't know that...

[mrpham]

Velocity Stacks & Airbox - http://omgpham.com/velocity-stacks-airbox-prototyping

This is going to be a big photo dump of my latest adventures into 3D printing, both for prototyping and hopefully end usage. I purchased myself a 3D printer, Wanhao Duplicator i3, and I'll do a separate post for that soon. For now let's talk about my experiences with the intake parts I'm prototyping

I have no real knowledge in both 3D printing/modelling and engine intake theory, I'm just learning as I go, so there will be mistakes here and there. And therefore, not entirely sure if these parts/designs will make any measurable performance gains, but it's all fun anyway!

In my last post, I had just commissioned some prints of velocity stacks. Well I did some redesigns, and they*can now be found on thingiverse.com, again it's still all a work in progress and I'm not expert in the design theory.

The velocity stacks are 105mm tall and designed for Silvertop AE101 throttle bodies.




Next up was designing an airbox for the ITBs and 105mm tall stacks, I pretty much modelled it using the same external dimensions as my Pipercross filter. I did this because I know for sure that it would clear all the brake and clutch parts in the engine bay and I also wanted the ability to easily change from filter to airbox. I can and will make a better design once I have this design fitted and tested.

For the Pipercross filter and this airbox to clear the stacks, a new mounting plate needed to be made. So I chose to print out a spacer that would be sandwiched between two laser cut plates, you can see it in the previous screenshot.



Below*is my ideal design, will work on that soon.



The printed spacer for the filter mounting plate, had to be printed in multiple pieces due to the limited build volume of my printer (200mm x 200mm x 180mm).



Before doing the actual prototype print I decided to use some rubbish filament for a test print without support material, just to see how far it could go. It failed pretty quick when it got to the dome part, it recovered slightly towards the end though.




Here you can see the rear section of the airbox being printed, tried to minimise the usage of plastic and support material. This was printed at mostly 200micron layer height and the curved sections were printed at 100micron layer height, varying the layer height like this helps reduce print time as well as reduce support material for the sections with overhang.




Mid section being printed, by far the easiest part. Only needed support material for the mount flanges, this was printed at 280micron layer height.




And this is the front section being printed, all printed at 280micron layer height. This part had some design modifications to improve print-ability, also to reduce plastic usage and support material.



Since this is a prototype for test fitting, sections are glued together using*Cyanoacrylate. Final part will either be epoxied or plastic welded together, not sure yet. Or maybe just use the print as a mold for carbon fibre?




It's amazing seeing this all come together as one piece, nearly 500mm total length. So happy!





Photo trying to show the internal clearances with stacks installed, minimum distance to walls is 25mm.



Some lessons I learned during this entire print are that overhangs causes prints to look like crap. So I've made the following design changes to help reduce overhangs.

1. I added a chamfer on the inside surface to reduce the overhang angles under*the "dome", this allows me to print with minimal support material, and the chamfer being only 20% solid means I use less plastic overall.
2. The highlighted flat sections at either ends of the flange remove the overhangs and allows my printer to simply bridge that section, which my printer does very well. This makes the print look cleaner and also reduce support material.
3. I found that printing holes on a vertical plane produces nasty overhangs and causes imperfections in and around the hole, so I opted to print only dimples instead of a through-hole. This improves the finish and I can just simply drill the holes post print anyway.

I also modelled this catch can and printed it out for test fitting. Unfortunately, the filament ran out before it completed printing. Was still able to test fit though!

[97 MXV]

John I think there is a body of work out there suggesting you need a bigger plenum volume than this ? Have you seen how huge the Toyota AE111 plenum is ? Not sure what drove Toyota to make it so large. I have not studied why, so cannot shed light on it at this stage.

I don't have any references regards the ram air effect. I think it's a physics problem? ie. How much air can the itbs flow

There is some stuff out there - particularly around the last generation of normally aspirated F1 engines and how they draw air from the intake above the drivers head. I remember seeing something about how they do the opposite in terms of sizing; actually size the intake smaller than the runner size to slow the intake air down in the plenum and increase what is called its 'volumetric efficiency'.

In a 4 stroke engine, the intake size into the plenum only needs to be around half the area of the 4 ports/ram tubes in a side draft head (velocity stack sounds like a down draft descriptor for say a V engine).
Therefore perhaps making the F1 car's plenum inlet area above the driver as large as all the ports might upset aerodynamic flow over the car.

For example with a BP engine, 4 x 40mm Toyota AE101 throttle bodies have an area of 5030 mm^2, half of which is which is 2515 mm^2 which is the area of a single throttle body of 57mm.
This is close to the standard 55mm TB, and explains why anything bigger than 60-65 mm is considered larger than normal for a single TB and that 4 x 45mm Toyota AE111 throttle bodies are considered larger than normal also.

On the other hand, maybe a large inlet to a remote filter housing is good because it provides a large plenum equivalent ?

[mrpham]

I can definitely try increase the volume, would have to be through the top/bottom like the factory AE101 box. I'll try get this prototype revised and printed in the high temp plastic first, see how it goes with heat and fitment first. This box is currently 150mm x 150mm x 470mm.

I'm staying with at least a 4" inlet though, well these guys found better results with their S2000 using a larger inlet. Can always print a smaller inlet if needed

https://www.youtube.com/watch?v=hzsKLzF1xmE

https://www.youtube.com/watch?v=aki5w1kksTs&t=1140s

[bruce]

Isn't there some rule that a plenum should contain 1.5 times engine capacity of filtered air (or something like that)?

[mrpham]

Isn't there some rule that a plenum should contain 1.5 times engine capacity of filtered air (or something like that)?

If that's true, than my airbox has plenty of volume. It's roughly 8000-8500cm3, so that's at least 8L.

I'd do more research into it, but I just want to print stuff NOW! Hahahaha

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[3gress]

You need to take that piece out to your car, test fit the thing and give us some pics mate!

[mrpham]

Here you go, quick test fit last night

[3gress]

Thank you sir

I've pondered whether there'd be room enough to feed a plenum from the scuttle panel. It would take a fair whack of trial and error but food for thought perhaps?

[speed]

Here you go, quick test fit last night

Is looking good. Can't wait to read how it performs.

Thank you sir

I've pondered whether there'd be room enough to feed a plenum from the scuttle panel. It would take a fair whack of trial and error but food for thought perhaps?

Clutch master and brake lines are in the way. Certainly wouldn't get a 4 inch pipe in there easy.

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[Gladiator]

I just enjoy looking at your engine bay.


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[speed]

I really think it is the best looking engine bay on here. It's neat, practical and performance orientated.


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[mrpham]

Thank you sir

I've pondered whether there'd be room enough to feed a plenum from the scuttle panel. It would take a fair whack of trial and error but food for thought perhaps?

Would be too tricky. My plan is to use a half sized radiator and use the extra space to do a ducted cold air intake into the airbox.

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