M20 intake manifold design thread

[B C]

A few of us here are interested in designing an intake manifold for an M20, and a few have already started working on them. 

SOME DISCLAIMERS

UNLESS YOU ARE A NERD, THIS WILL BE AN IMMENSELY BORING THREAD FOR YOU.
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1) I do not know everything, especially when it comes to unsteady flow dynamics.

2) I have done a lot of research on intake design over the last 13 years in my free time, but I am still nowhere near an authority/expert on the subject. It is just one that fascinates me and I may have an unhealthy level of interest in it.

 

3) I DO know that even when playing with advanced maths and analysis, that there are still 9302934021 things that aren't being accounted for, or cannot be predicted. If you have done well, and get lucky, you may find yourself in the ballpark of where you need to be. Real world testing, when possible, trumps mathematical analysis all day everyday and 3.14 times on Sunday

 

4) Even when testing a manifold design on a flow bench, there are still at least 2814731 things that aren't being accounted for, or cannot be tested.

5) The only 100% accurate testing and analysis is performed with a manifold installed on a car with proper measurement equipment (dyno, etc)
 

6) The time, cost, and knowledge involved in thoroughly developing the ideal intake manifold is unrealistic for anything short of an F1 team, and even then, they have to draw the line somewhere.

 

7) Assumptions must be made. Whether they are good or not, you must make assumptions. If and when the end product doesnt work as intended, you must re-visit your assumptions and make adjustments.

 

Now that is through,   this thread is for us to exchange thoughts and theories about taming the crab under the hood. 

 

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[Rowleym]

Can I pre-order mine?

Haha Ill make you one but we need to finish the design! I just need to order runners. I just recently ordered 2" .125 wall 6061 t6 for my supercharger intake manifold, but we might need something different for this? not sure. 

[ClassE]

Here's my 5 minute sketch of how my previous SRI was built as a reference.

-Flange w-injector bungs (either original mani chopped or new machined)

-Velocity stacks

-Flat "plate" with round holes cut to slip stacks through - welded to flange

-Round plenum with a portion machined off to match height of plate the stacks are slipped through.

Maybe something like these would work?!? (Google searched - we'd obviously need to to determine overall runner length and such)

http://www.velocitystacksonline.com/product/B154-170

My concerns are the meet-up of the stacks and original mani (obvious material thickness difference - both for welding and esthetics) and runner length.

[frcefed]

Dtmfiberwerkz offers this manifold for $900

[Jeff]

Dtmfiberwerkz offers this manifold for $900

What is the logic in that manifold why? What does it help? And dimension's on it?

[ClassE]

Dtmfiberwerkz offers this manifold for $900

If you do some digging in that - they've never actually made one. There's acouple threads I've found on it - company advertises them and shows that as a reference but hasn't actually made one.

[industrialsized]

if you need help in the making of any parts let me know i can probably get it handled for you guys i run a fairly large machine shop so if you want something like a bunch of flanges waterjeted out i can get it done for you

 

also i'm with earl on the m4x manifolds but i guess i can just steal whatever you come up with and cut cyl 1 and 6 of to make an intake for myself

[frcefed]

If you do some digging in that - they've never actually made one. There's acouple threads I've found on it - company advertises them and shows that as a reference but hasn't actually made one.

So what would happen if I ordered one of these manifolds? Would they just be like "oh, we were kidding" haha.. not that I would order it, especially if the picture represents the actual product, seeing as it wouldn't fit an m20 and if it did, the throttle body would hit the hood.

[ClassE]

So what would happen if I ordered one of these manifolds? Would they just be like "oh, we were kidding" haha.. not that I would order it, especially if the picture represents the actual product, seeing as it wouldn't fit an m20 and if it did, the throttle body would hit the hood.

I would assume they'd do what most companies do - send an email saying the product is not available.

I wouldn't want to order one without seeing the final product anyways.

[ClassE]

Drooling:

[Earl]

Volvo?

[ClassE]

2.5T that's going into a MK2.

[B C]

Volvo?

 

 

YOU CAN COUNT

[Rowleym]

Serious note. I have plenty of materials now.

I have 2" 6061 with .125 wall.

I will be Welding 1" of tubing onto each runner, porting the piss out of it to make sure it's a smooth transition. And then from there I can weld to clean aluminum.

My plan is to make a die for a tapered inlet from the plenum, and I will use the 2" tubing.

7 degree taper? And then I will machine little radii for the first part of the velocity stack.

Or I might make a die to form a velocity stack? Not sure.

Also. I built a brake booster delete out of 1x4x4 aluminum and I think it's going to work awesome. It's installed but the car is not running yet. This leaves LOTS of room to play with. We will be doing an itb adapter soon as well.

I changed the pedal ratio to 6.2:1.

[rampelsauce]

For the prototype, you guys should be thinking about the ability to swap pieces easily. Let's say your plenum is the right size but you need to swap out your stacks, you should be able to remove them and replace them with the new pieces. The finished product should be one piece to reduce turbulence. Prototyping is always easier when you can take it all apart.

My .02

I'll powder coat the prototypes for you guys if you'd like.

[Rowleym]

For the prototype, you guys should be thinking about the ability to swap pieces easily. Let's say your plenum is the right size but you need to swap out your stacks, you should be able to remove them and replace them with the new pieces. The finished product should be one piece to reduce turbulence. Prototyping is always easier when you can take it all apart.

My .02

I'll powder coat the prototypes for you guys if you'd like.

I like the idea.

Man I just want to have a huge piece of aluminum to play with for free. Id totally have a modular intake by now haha.

I would have to say plenum design is probably the hardest part no? I think I should weld a base plate right before the stacks, and I could have the plenum bolt on and off? Man that might be a bit difficult to manufacture...

I can't wait to get these rolling!!

[B C]

one thing I would implement is a fit bolt/precision shoulder bolt screw/dowel pin for repeatable fitment when they are port matched.

I believe the S14 engines have something similar.

[Rowleym]

one thing I would implement is a fit bolt/precision shoulder bolt screw/dowel pin for repeatable fitment when they are port matched.

I believe the S14 engines have something similar.

Hmm. That makes me think I should just Cnc port the welded part.... Much easier.. 

[Rowleym]

The inside will be ported and smoothed out, but just showing how nice it is before that.

This is just the start of shaping the plenum. Just trying to get some excitement for me to finish lol

[Earl]

I think an m42 one should be next=P

[Rowleym]

I think an m42 one should be next=P

I would love to build one! Have a spare m42 laying around? Lol.

I have an e36 shell ready for mockups too.

Oh and we have 5 e30's now...

Anyone interested in a lsx e30 with a zf 5 speed? I wonder how much I could sell one for..

Holy tangent.

Also that was my first ever intake runner weld. And that's welding cast alum(not cleaned even) to 6061. I'd say it turned out well! The rest of the runners look even better.

The next manifolds will be welded with some actual cast rod. Cronatron 510t I believe it's called. And more time will be out into prep.

I'm thinking sand blast an powder coat? Or wrinkle coat?

[Jeff]

how is this going any updates?

[Rowleym]

Zero updates from me. But hey I have a good start and I might be able to finish it but one question.

I can mock it up using an eta head right?

And hey Jeff wanna help me design to manufacture some velocity stacks? Haven't found a cheap way to build them yet ha.

Sent from my iPhone using Tapatalk

[B C]

Update: m20 manifolds look like crabs

[HipMF]

Does that make you Mr Crabs?

[Jeff]

Sure we can do that