I have been doing quite a bit of reserch on this and have hit a dead end on finding information.

WHat I know so far:

Intake Runner Length:

This has been covered fairly extensively in posts such as this one:
https://honda-tech.com/zerothread?id=1963201

This covers everything from the back of the valve to the tip of the runner entering the intake plenum.


Intake plenum volume:

Haven't been able to find out much on this subject.

I know that the more volume of air required by the motor/ unit of time the larger the intake plenum seems to be. (ie turbo vehicles benifit alot from larger plenums)


Throttle body Dia:

The selection of throttle body diameter seems to be based on the constant battle between volume and velocity of air. It seem to me that the best selection for size is the smallest possible opening that won't starve your engine of air volume at high rpm's.


Intake pipe length (CAI Length):

The only real information I can find on this is that 1.8l honda motors like the CAI length to be somewhere around 760-80mm as a ballpark to start with, then length must be tuned on the dyno to be perfected.

How did someone come up with these numbers? How does pipe diameter affect pipe length?

I know pipe length has alot to do with harmonincs, but is there a calculation to figure this out??

I'm not looking for anyones secrets, I don't want to know what sizes the ppl who have figured this out are running, I would just like to know where I can further educate myself so I can understand things better!!

I would also like some confimation, and or comments on what I think I know.

Any help would be great!! Cheers!!

 

anyone?

 

http://www.team-integra.net/se...eID=4

 

that post doesn't help him do anything other than understand flow terms.

I too would like to know what the magic equation is for a tuned length intake. in the end im thinking it has to do with the volume of intake air and matching the engine volume to the intake volume. that would explain hondas variable length manifolds and air intakes.

 

wow, lots of info, once i take it all in i'll have to come back and make some comments Thanks!

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by gibsanez &raquo;</TD></TR><TR><TD CLASS="quote">http://www.team-integra.net/se...eID=4
</TD></TR></TABLE>

 

Ok, so that was quite an awesome little read about flow theory and wet flow in the intake ports, but that's unfortunately where it ends.


anyone else have any more great info???

 

what info are you looking for??

Its been proven longer runners small plenum tend to be better for mildly built or stock 1.8/1.6 motors

bigger plenums for bigger motors...
shorter runners for turbo etc etc or very high reving motors with a ton of headwork?

I mean what general direction are you wanting this thread to go in?

 

WHat I am trying to bring togeather is the infomation to do the caculations that prove why a longer narrower tube is better for a mildly built motor than a larger tube and similar things for my other questions.

Trying to establish a backbone of variables and calculations that the community can use to help determine what is right for their motor as far as lengths and diameters.

Where We are so far:

Variables -

Flow Capacity = voulme of air(or air fuel mixture) that can pass through a given crossectional area. The capacity required is determined by the demand of the motor.

Flow Velocity = how fast the air (or air fuel mixture) is travelling. velocity is affected by the crossectional area and the length of a runner / pipe. more velocity will give you better low end and midrange power by helping with fuel atomization, but too small a crossection or too long a pipe will reduce volume and starve the motor at higher volume demand.

Crossectional area: effects flow velocity and flow capacity

Length: effects flow velocity and wave pulse harmonics

Theory's:

Ventiuri effect

D-Ports and how they affect wet flow around bends

Surface finishes, rough vs smooth polish and how it affects turbulance


We still don't have much on intake volume or CAI length.. but we are getting closer!!

Anyone else care to chime in? feel free to tell me i'm wrong if I am!!

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by IntegraType-R &raquo;</TD></TR><TR><TD CLASS="quote">what info are you looking for??
I mean what general direction are you wanting this thread to go in?</TD></TR></TABLE>

he's looking for the formula, not a am forum answer. its not that simple itr. yes, people can say long runners produce x and short produces y, but he's looking to do the math so that he can calculate the answer. i've done some im testing and every im reactes differently with every set up. its a fact. i'm in for any more valuable info. good topic op

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Rollo Lawson &raquo;</TD></TR><TR><TD CLASS="quote">

he's looking for the formula, not a am forum answer. its not that simple itr. yes, people can say long runners produce x and short produces y, but he's looking to do the math so that he can calculate the answer. i've done some im testing and every im reactes differently with every set up. its a fact. i'm in for any more valuable info. good topic op </TD></TR></TABLE>
I know..
I understand that, i didn't understand if he was just looking for regular information or trying to start a thread about where to find the perfect manifold..
i mean.. There's manifold test all over.. but its one motor i'm sure what manifold didn't work well on that motor would work well on another.. I know its not that simple or really even able to be broke down.. I'm in for results as well but i've always stuck to what i've seen work on my motor and my motor likes long runners small plenum... Its high compression, with some nice size cams and a good induction system as well as exhaust/header setup, again thats my motor.. Some joe down the block can have something simliar but his motor liks short fat runners with a huge plenum..

 

BUMP

 

Try bryan pendleton. he's the man when it comes to manifold and intake tunning and theory. Many members use his BPI velocity stack.

 

In for the possibly good read.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by DCFIVER &raquo;</TD></TR><TR><TD CLASS="quote">Try bryan pendleton. he's the man when it comes to manifold and intake tunning and theory. Many members use his BPI velocity stack.</TD></TR></TABLE>


I will have to admit that even I run a BPI stack , but it has alot to do with my experiences in the car audio field.

Using ports /w velocity stack style intakes effectively doubles your port size, allowing you to run smaller ports and smaller sub boxes and make bigger sound

 

bump for more insight

 

some SAE stuff

http://www.mne.psu.edu/me415/f....html

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by 98vtec &raquo;</TD></TR><TR><TD CLASS="quote">some SAE stuff

http://www.mne.psu.edu/me415/f....html</TD></TR></TABLE>LOL, they actually got the hp equation wrong. It's hp=tq x rpm/5252 not 5250.

Anyway, here's some simple equations for IM design.


Modified by Vengeance at 9:55 AM 9/4/2008

 

That was kinda neat, but there wasn't a whole lot of info there.

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by 98vtec &raquo;</TD></TR><TR><TD CLASS="quote">some SAE stuff

http://www.mne.psu.edu/me415/f....html</TD></TR></TABLE>

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Vengeance &raquo;</TD></TR><TR><TD CLASS="quote">simple equations for IM design.
Modified by Vengeance at 9:55 AM 9/4/2008</TD></TR></TABLE>

Awesome info, will have to finish reading it when I get home from work!!

 

Goos stuff guys. Anymore?

 

When I get a few minutes tonight I will consolidat this into the first post so it reads better