Designing my own 2g intake manifold with CFD

[kthackst]

Well my big build coming up this summer and no 2g Magnus intake manifold yet. So I have decided to design my own. Plus knowing the best aluminum fab guy on in the central PA region helps, shoutout to Erbified Motorsports (he is a supporting freelancer so I should be able to do that). Being from an engineering background I have always been sceptical of a lot of the intake manifolds on the market. Mailbox style, smashed runners, and tight right angle bends.

I want this to be a thread detailing the methodology and design process of my intake manifold. Questions and discussions are welcome, please keep it nice. I will be using CFD to make the first revision since it will give me a 1000 times better design without wasting material, time and cost. I use the program at home and my lunch break when a license is available. Work projects definitely trump this. If i don't update for a while it will be because of work demands.

I will start by saying I have an ebay Venom intake manifold on my car right now. The goal will be how much better than the Venom can I make this new one. Also make it manufacturable.

So i did some preliminary runs on the Venom manifold. Here are some pics below. I have plenty of pictures and CFD runs not shown. I don't want a overload of information.

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[steve]

Did you model what the flow looks like when each runner is the only active one?
It would also be interesting to see what things look like when one runner stops flowing and next one in sequence starts flowing.

 

[007jimmy]

Are you basing this manifold on the venom design? I have read that the venom intake flows pretty well compared to other SMIM. Intersted to see the results. Keep us posted.

 

[TSiAWD666]

What plenum size and runner length? How do you tune those for resonance for your given engine? I recall those details discussed in the last engine building book I read and am wondering if you're ready with those calculations.

 

[kthackst]

@steve - I have run each runner individual to see how well each is balanced in relation to each other. I have the pictures but they don't show much since the difference is slight but its is there ~10 difference% over all the runners. The next step will be a dynamic run which will see how the airflow reacts to each cylinder opening and closing. This will be more difficult and take a good bit of time setting up correctly.

@077Jimmy - No I am not basing it on the Venom design. I have already seen some pinching of flow in the Venom design that I do not like. This pinch of flow will happen on all intake manifolds that crush a round tube to a rectangular section at the flange. Now I just have the proof I was looking for. I am not saying the Venom is bad just this sheet metal design does exhibit pinching of flow at the entrance of the runners. I'll post pictures of this "pinched flow" of this later. One of my major goals would be to minimize this.

@TSiAWD666 - Plenum size and runner length will be decided on from the CFD program results. I need to run my basic design first. Hopefully on Friday I should have some CFD results on my first design revision to share.

 

[snowborder714]

Do you plan on designing this intake for big power/flow, for fast air, etc.?

 

[kthackst]

Do you plan on designing this intake for big power/flow, for fast air, etc.?

Yes I hope to be pushing 60-70 lbs/min this summer. The goal of this manifold to maximize efficiency, smooth flow, and high flow. So in theory it should be an upgrade for anything.