designed for:

2nd harmonic at 9500
3rd harmonic at 7300
4th harmonic at 5500

plenum volume is ideal for an engine displacement of 2 liters

throttle body is 90mm (Q45)

 

quite the tease! this looks very well thought out!

 

one word comes to mind!

Amazing!

 

Looks good!

 

What is a Harmonic? How do you calculate what Plenum volume should be? Hope you don't mind the questions

 

looks bitchin.

 

A harmonic is the point that a pressure pulse i is reflected back into the runner in time with the opening of the intake valve. Plenum volume is much simpler there is no exact correct volume making it smaller or bigger is a compromise. The rule of thumb is between 1 an 2 times engine volume mine is over 4000cc's so its on the large side which is better for power but worse for throttle response and spool

 

couldn't you design a plenum shape that helps increase throttle response and spool but does not compromise power by being too small? i have a couple ideas, but would not be able to prove them without building a prototype and testing it, but i'm confident it can be done.

you have obviously put a lot of thought into this project.

 

sure just make it variable volume, other than that the short answer is no

 

by "variable volume" do you mean tapered? i want the long answer!

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Ben-NSI &raquo;</TD></TR><TR><TD CLASS="quote">designed for:

2nd harmonic at 9500
3rd harmonic at 7300
4th harmonic at 5500

plenum volume is ideal for an engine displacement of 2 liters</TD></TR></TABLE>

Calculating the Helmholtz resonance is easy, but how did you determine the "ideal" plenum volume? I've studied intake design for years and I have never seen a proven formula for the perfect size, just ballpark guidelines and minimum sizes.

Please share the methodology for finding the "ideal" size.

 

When you calculated Plenum volume did you include or exclude the volume of the runners inside the plenum? Thanks, this is great info

 

my calculation did not include the bells in the manifold as those are part of the runners and not part of the plenum

 

I would also like to know how you figured this to be the ideal size.

 

what ever fits in the engine bay is the ideal size.............. actually that holds true with alot of stuff people make because some of the stuff u come up with using that theory is rediculous and would not fit very well.


mike


Modified by all_motor_mike at 9:40 PM 4/1/2008

 

looks real nice. i thought it was good looking and then i noticed it was an s2k, and now its better!

 

Looks great!!!
9500rpm, nice!!!

 

would a manifold like this work well for FI. if so sign me up i need one.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by all_motor_mike &raquo;</TD></TR><TR><TD CLASS="quote">what ever fits in the engine bay is the ideal size.............. actually that holds true with alot of stuff people make because some of the stuff u come up with using that theory is rediculous and would not fit very well.

mike
Modified by all_motor_mike at 9:40 PM 4/1/2008</TD></TR></TABLE>

I agree with that. I would like to see the use (on a honda engine) of the dual plenum manifolds that can be seen on Audis.

 

sweet

 

its specifically for FI applications although it would work well on NA setups as well

 

I still would like to see your long answer.

 

i called dibs on the long answer a few posts up... i'm always interested in learning theory on this stuff.

 

Why are the velocity stacks protruding so much into the plenum? Seem a bit like overkill to me. The air that flows behind the stacks will have trouble getting into the runners.

Justin

 

i too was thinking they were sitting a bit high.............. usually u want them about 3/4" at most of the plenum floor because thats where ur fast moving air is........... or so ive heard.


mike