Plena volume

[Bruce Plecan]

Was at PT+E for one of the tech seminars yesterday.   They had several
different versions of sheetmetal manifolds that were accessible.   2x CID,
and 3" runners, were the general theme.   Looks like the runner exists for
the sole purpose of mounting the injectors about now.
the relationship about runner to turbulence, is very dependent on cam.
there are just too many considerations.   My answer, for many of the trubo
problems is running a 0 overlap cam.
If I was designing an intake, the runners would be injector holders, and 2x
the CID.
Course then we get to TBs.

there was a nasty GN on display,  All the good parts, and looked to use 100%
of everything.  The **up pipe** and TB looked to be stock xternally.
Nothing wrong with that just shows how well the oem stuff is.  Again, given
a clean sheet of paper a monoblade would get the nod.

Bruce
looking for a better ground for the AL lining of my CSH.
my attention span problem might be neighbors TV remote changing my ideas



> This sounds like the ideal plenum may be, uh, a really big box hooked to
short runners for high rpm. Or have I totally
> missed the point.  Which brings up runner size. My guess is that runners
be more than the volume of a cylinder to have >enough to fill the cylinder.
More volume would be bad since the air column would have to rebound like a
spring when >the valve closes. Am I close?

> I'll add to this question (give Bruce something to do
> while the Medicos do their thing :)....
> How's about this for a plenum- no runners at all.   IE, the Manifold is
just a box that sits on the heads, the only > "runners" per se are the
intake ports. Port injected, not TBI. Injectors shooting right into the
heads, at the back of the >valve.

>I'm guessing this would cause lower port velocities,  possibility for "dead
air" in spots. Or No? And would you care >about the low port velocities?
Especially if,  say, you were building a 4000 RPM + forced induction  v6? :)
A plenum >like this would maximize flow...

> Tuning effects (from reversion in the runners) would be gone, obviously. I
suppose the intake ports would
> find resonance at *some* RPM.

> This would certainly make for easier packaging of a
> 1:1 or larger sized plenum.

> Later,
> Dig

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