protejay

I'd like to get some serious thoughts about these ideas

I read Jesse's thread in the tech forum about intake manifold theory. I got the basic impression that small plenums are good for torque; large for high hp. Length/design of runners has a big impact as well.

The 2nd gen plenum (or dc - dynamic chamber) is bigger than the 1st gen's. The runners are correspondingly longer. The factory rates the 2nd gen BP torque as 117ftlbs @ 4000rpm; the 1st gen's is 113ftlbs @ a higher 4500. Now there are MANY other factors at work between the 2 gen's - most importantly being ecu tuning and exhaust differences....
So, just curious - any thoughts on the fact that 2nd gen's have a larger dc (good for high rpm) and yet are rated @ more torque/lower rpm - ? Would it most likely be due to longer runners??
For that matter, despite having a larger dc its rated hp is a lower 122hp @ 6000rpm....

now for modification thoughts:

What if i were to make a hole in the front of the dc to make for a straight shot into the secondary (VICS) chamber?? Instead of the air flowing down the length of the dc, winding through the 'passage' into the secondary chamber; now all it'd have to do is flow through the throttle body and *directly* into the secondary chamber....

Would another hole in the dc adversely affect the resonance characteristics of the dc?? Esp, would it have an affect on torque??

An even better seeming idea, at least for high rpm, would be to fit curved air horns to feed VICS... cut the dc lengthwise down the middle, make 4 holes in the wall, just below the upper long runners, and plop some short fat runners in Again the question: how would it affect torque and low rpm resonance?

Anyways, i'm thinking of experimenting with the stock dc.... what would you do? If i WERE to make another hole in the dc, does the 1st idea seem like a good one? Right after the throttle body?? How big a hole? I don't have much material to work with on the 1st gen dc, so that would limit the size of the hole....but at least the air would have a straight shot. Good? Bad? Conjecture whether its good/bad?

Disclaimer: I realize cams and a standalone would optimize gains - if any - from these ideas...

spooki

withougt a degree in physics i coudnt tell you. i understand what your talking about though. maybe you should just try it.


"If i WERE to make another hole in the dc, does the 1st idea seem like a good one? Right after the throttle body??"

if you could put a butterfly valve there (in the hole you would cut) and make it your secondaries. i could see it working.

the probe throttle body (2.2l) has the secondaries in the trottle body. you could try that and see. (and take out the other secondaries of course)

spooki

i just whent and looked, the 2.2 throttel body wont match the 1.8 manifold.

"An even better seeming idea, at least for high rpm, would be to fit curved air horns to feed VICS... cut the dc lengthwise down the middle, make 4 holes in the wall, just below the upper long runners, and plop some short fat runners in Again the question: how would it affect torque and low rpm resonance?"

i have an extra manifold, and the tools to do something like that. except the curved air horns,(might have to make some).

wish you didnt live so far away........

protejay

the butterfly valve idea had crossed my mind too - just more expense/complication than i'm game for... but it *seems* it would keep the plenum's resonant abilities intact.

it may not be easily possible; but it just seems there could be a way to increase high rpm flow without compromising torque. that's the goal at least....

wish i understood airflow dynamics more - i think it'd be awesome to design intake manifolds, etc!