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why arent intake manifolds designed like exhaust headers?

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why arent intake manifolds designed like exhaust headers?

 
Old 08-02-2011, 04:06 PM
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Why doesn't an intake have a collector that the TB mounts to with runners going from the collector to the head? Why isn't this more efficient/better than the standard plenum with runners?
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Old 08-02-2011, 04:09 PM
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This **** has been beaten to death.
Start searching bitch

In a nutshell: long runners with no plenum will make tons of torque and kill the topend power.
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Old 08-02-2011, 04:09 PM
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equal length tubular intake manifold FTW



Attached Thumbnails why arent intake manifolds designed like exhaust headers?-4efe_tubular_intake_manifold_4_mem_pakwheels%2528com%2529.jpg  
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Old 08-02-2011, 04:17 PM
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I'll most likely be using an equal length runner/plenum/thing with my ITBs on the BMW.

Part of the reason (as I've heard it told) why they tend to make shitty top end power is due to the fact that the pulses of air caused by the snapping shut of the intake valves can't dissipate into the plenum and be absorbed by other cylinders.

I'm going to attempt to offset this with a helmholtz resonator on each runner.
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Old 08-02-2011, 04:22 PM
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Look for discussions on why plenums are an important part of manifolds.
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Originally Posted by codrus View Post
Basically I've come over to the camp of "If something is a reliability problem on the track, just ask Andrew and do what he says".
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Old 08-02-2011, 04:26 PM
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Yes I mean something like what volcanic posted, but with a full 2 or 3 liters between the collector and throttle body.
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Old 08-02-2011, 04:27 PM
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Attached Thumbnails why arent intake manifolds designed like exhaust headers?-02phrs1_024moran23_z.jpg  
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Old 08-02-2011, 04:56 PM
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Mazda make an intake manifold for the Z5 engine that looks like an exhaust manifold

Z series is the succesor to the B series more or less
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Old 08-02-2011, 05:35 PM
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Originally Posted by Savington View Post
Look for discussions on why plenums are an important part of manifolds.
yes, you've posted it a few times now.
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Old 08-02-2011, 05:54 PM
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in reality it has a similar concept to ITB with the use of individual stacks and with proper engine management you can control how much fuel is being sent to each injector

that wiki thread has a ton of great info. what would be really cool is to create two sets of runs, short and long, and have the short ones open after a certain RPM using butterflies and a vacuum actuator

edit: if this is a track only car you can tune the length of the runners for an RPM ranage that you are constantly above

(im really excited about this thread!)
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Old 08-02-2011, 06:07 PM
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isn't that what vics already does?
Also every other vtec honda out there has this already.
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Old 08-02-2011, 06:10 PM
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vics changes volume, not length.

vtec switches to a high profile cam above 5,500 rpm.
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Old 08-02-2011, 06:12 PM
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yeah which started on the 99 engines, i guess i was talking about the 1.6l as well as implementing it on a equal length IM
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Old 08-02-2011, 06:38 PM
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Originally Posted by v01canic View Post
what would be really cool is to create two sets of runs, short and long, and have the short ones open after a certain RPM using butterflies and a vacuum actuator
Mitsubishi did this in the late 80's early 90's. Google "cyclone manifold". They came on japanese only 4g63-T's.
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Old 08-02-2011, 07:07 PM
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my sentra has one too
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Old 08-02-2011, 07:20 PM
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Originally Posted by Jeff_Ciesielski View Post
Mitsubishi did this in the late 80's early 90's. Google "cyclone manifold". They came on japanese only 4g63-T's.
And there's a lot of debate as to whether these actually do anything beneficial. Coming from DSM land I can tell you that there's much disagreement over their effectiveness and not much in the way of hard numbers (or at least last time I looked) pointing one way or the other. We have a small pile of them at the shop, and that's a direct reflection of their on again/off again popularity.
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Old 08-02-2011, 07:26 PM
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lets keep our eyes on the prize here. does anyone know why a tubular equal length intake manifold sholdnt work? we can get to the arguments of secondaries and butterflies later
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Old 08-02-2011, 07:30 PM
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Originally Posted by Braineack View Post
vics changes volume, not length.
I'm thinking hes thinking drilled out vics manifold.


Originally Posted by Faeflora View Post

Yes I mean something like what volcanic posted, but with a full 2 or 3 liters between the collector and throttle body.
If thats the case why not just toss the throttle body on the other side of the intercooler?
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Old 08-02-2011, 07:57 PM
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BTW it is not hard to fab up intake manis. I used to make some for BMWs. One time we modded some OE head flanges and plenums. Then we played with different lengths and diameters of tubing and coordinated some other hard parts like cams that modeling showed should work well. The best bits would up helping for sure, but they were not compact at all. Part of the OE compromise is for tight packaging and low cost manufacture. This was for NA application. You can get quite a bit above 100% VE at certain RPM ranges. Like passive supercharging. IIRC S2000s hit around 120% VE here and there per Honda. The key is that all the various bits need to be coordinated with one another. A wonder mani won't do much just slapped onto any engine.
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Old 08-02-2011, 08:29 PM
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Originally Posted by triple88a View Post
...why not just toss the throttle body on the other side of the intercooler?
Oooooooh! This *might* be a retarded idea, but I like the way this man thinks! Please school me.

Why not have an equal length runner/collector type intake manifold and put the throttle body way upstream to use the intake piping and/or intercooler as the plenum?
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