Who has made an intake manifold?

22 May 2016

Just mocked this up to get an idea of what will fit and how i can make one. I have a lexus is200 (not my 1jz is200 but another one) the idea is to turbo it on the cheap and run it on a standalone ecu. The standard 1g fe intake manifold is plastic and looks crap and has 100’s of sensors on it and some stupid valve thing. I can make the one in the picture without to much fuss, I have a cnc mill but it wont look pretty with my adequate tig skills. At the end of the day it will work and wont leak :p

Now… has anyone else made an intake manifold from scratch? how does it go? Does it wok well? some of the examples i have seen on google have been all strange and weird shapes, some square, round etc. Does it matter so much the shape?

Comments

I could be wrong but what matters most is the how long or short are the intake runners

Yea i need to have a look at that.

Is that solid works you’re using?

If it is you have so much patience

Do you have a flow bench?

Nope

Yea, to be honest im not sure qhat im looking for, should it be as big as possible for more air or as small as possible without restricting the flow?

I can get a rough idea of tye air flow by using cad and do a flow simulation, atleast it will show high and low pressures and idea of how it moves.

I’m not an expert, but I believe the volume of air that fit’s in the manifold doesn’t really matter that much. A really big manifold will result in a laggier car since a larger space of air has to be compressed. You also don’t want to go too small because of the kind of flow you get.
Airflow has resistance on the sides of the manifold, thus lowering it’s speed. In a cross section of a tube for instance, the highest airspeed can be found in the centerline of the tube. Ideally, you want to have a laminair (I’m not sure if that’s also the english word) flow and not a turbulent flow.
Since you also want the manifold to be efficiënt when the car isn’t on boost, you’d probably want to look into narrowing the manifold diameter near the inlet ports. When you have a narrowing intake runner, the airspeed will go up. Last but not least, mostly for when you’re nog on boost, but even when you are it will help a little to look into the exact lenght from the inlet port to the throttle body. Air acts just like water, so you can have waves of resonance. With a given airspeed, you can design the intake runners to a certain lenght so that the air resonates inside the manifold at a frequency you want. The resonating means you can get a little bit more air in the cilinder so you can make more power more efficiëntly. Car makers design manifold with variable lenght runners, so they can use the resonating pulses across the rev range. When you are not going for variable length runners, you can design the intake to any RPM you want. I hope my story makes sense to you! If you have any questions, please ask them. Maybe I can answer some of them.