me and a friend of mine want to try and make a couple intake manifolds for our cars. does anyone know the formula, on how long to make the runners, plennum ect...one is a 280z and i have a b-series, thanks.

 

there is no specific "formula" sorry.

 

Exactly 15.35" long runners with a 1" dia. plenum.

 

thats for the Bseries right?

the Z should me [(9/7)pi(r of cyl)^3(2d of runners)(# of cyls)] / 23*rpm

good luck

 

You forgot the number e in there between the pi and the (r of cyl).

 

i thought it was similar to building a header, having a scavaging effect...it its pretty much build it and see if it works or what?

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by k24em2 &raquo;</TD></TR><TR><TD CLASS="quote">You forgot the number e in there between the pi and the (r of cyl).</TD></TR></TABLE>

right sorry, you need a DE with e^(kt) in there also...lol

 

thanks DICK!

 

There are a couple calculators available out there. I tried to get them both into a spreadsheet but haven't had the best of luck.

Basically you choose a cross-sectional area to get the peak torque location, and choose runner length to get a harmonic boost at some point in the band. The plenum should be 1.2-1.5 times the engine displacement. These are just thumb rules, of course.

Here is the calculator for CSA:

http://www.rbracing-rsr.com/runnertorquecalc.html

This thread gives some good thumb rules and insight:

http://www.team-integra.net/se...D=471

Good luck.

 

cool thanks thats all i needed, was that soo hard?