Hey guys, I just saw this in the FI section, and they said they will most likely do testing to see if there are any gains with an NA s2000. I know I saw that one thread where wadzii bored out his IM to fit the bigger TB, and it didn't see any gains at all so i'm wondering if this manifold would net any gains. It would be a nice peice if it gained a few ponies, and the Magnus IM's always look great.

https://www.s2ki.com/forums/index.php?showt...&#entry20183901

I just thought I would post that here so the NA guys can have a little hope for a nice intake manifold that might give some gains.

 

Thanks. I would have missed it in the FI subforum...

 

Why hasn't anyone made an all motor intake manifold yet?

 

How would an NA IM differ from an FI IM?

 

^
Peak torque and throttle response.

 

I think gernby meant how would there be a difference between actual manifolds, since H22toF20 said why hasn't anyone made an all motor manifold yet?.

I don't see how they would make specific manifolds though, thats why i'm curious why they only posted in the FI section, and not here also.

 

Yes, I meant how the actual manifold would differ (dimensions, shape, etc.).

 

it has to do with velocity of air and volume...FI cars lean a little more towards volume and alittle less towards velocity simply cause they can get away with being....well this isnt the right word, but "sloppy" or "loose" with the design since they have something forcing air in.

also with the manifold you want to bring a balance to things, such as TB opening diameter, rounding edges for smooth flow ect. there are also things like runner length to consider, plenum volume ect. all of those are different between, or should be different between a FI car and NA car

 

For N/A engines the Intake Manifold must provide good driveablity at low and high engine speeds and loads and also good power.
An IM for FI engines must take care of good air and pressure distribution to all cylinders.

In detail:
for a NA engine the VE (volumetric efficiency) is the key for torque and combined with engine speed torque = power.
The torque curve on an diagram is a good indicator for the VE that is loaded into the cylinders (if AFR is always the same of course).
For NA engines the torque curve has several peaks and pitts. This is due to secondary pumping effects inside the engine - mainly inside the bolt on parts like intake and exhaust manifolds, but also within the engine itself like the cam angles.

The Intake manifold is built of three several areas:
- the intake runners,
- the plenum chamber
- the venturi chamber with the Throttle Body

Part 1:
The inner diameter and lenght of the intake runners have an effect at the acceleration and velocity of the air that is sucked inside the cylinder. The smaller the diameter, the higher the acceleration and air speed. This is good for low end torque, because the high air speed contains more energy and helps filling the cylinders when the intake valve is closing.
At higher engine speeds, the small diameters are restrictions of the already high air velocity. For better power at high engine speeds bigger runner diameters are better.
The runner lenghts must be tuned precisely so that that the oscillations inside
of it causes the pressure waves running back with the speed of sound inside the runners into the plenum chamber where they are reflected backwards inside the runners again. The next time the Intake opens, this pressure wave appears just before the valve. It works like a organ pipe. The effects are harmonic oscillations. These harmonic waves have different frequencies and therefore different engine speeds where this scavenging effects will provide more air inside the cylinders.

Part 2:
The plenum chamber collects all low and high pressure waves and if it has the right volume it works as an Helmholtz resonator. Means, that the high pressure waves from one cylinder arriving at the plenum chamber can support the loading effect in other cylinders. It depends on the number of cylinders, the firing order and the overall volume of the plenum chamber. Also the distance of the wall that faces the runners to the funnels is important.
Finally the throttle response is influenced by the plenum chamber volume. Imagine a very large chamber that is connected between the intake runners and the throttle. It'll take a long time between the throttle movement and an effect inside the engine, because the chamber volume must be filled up again.
For FI engines a bigger volume is better, because the chamber collects compressed air and can provide it very quick if needed.

Part 3:
The Throttle Body and venturi camber (or RAM Pipe) must be tuned together to stabilize the airflow inside and after the TB. The airspeed should be constant (nearly) in the vicinity of the throttle so that scavenging effects have no influence on it.

 

I don't think they are making two different manifolds....