AW: AW: Intake manifold construction, intercoolers

[Rausch, Bernd]

I want to keep it simple, like Bruce is suggesting, that means 6 TB is
out of question. I do not have problems with idle or part throttle (mild
cam). At WOT, a 6 butterfly system is worse then a butterfly at the
plenum because you have the shafts and plates directly in front of the
intake port.

A good point was to insulate the plenum from the heat of the head, I
will do this with CF runners or with short silicone hoses in the
runners.

Bernd

-----Ursprüngliche Nachricht-----
Von: Bruce [mailto:nacelp at bright.net]
Gesendet: Dienstag, 4. Dezember 2001 19:08
An: diy_efi at diy-efi.org
Betreff: Re: AW: Intake manifold construction, intercoolers



From: "Bernd Felsche" <bernie at innovative.iinet.net.au>
Subject: Re: AW: Intake manifold construction, intercoolers
> Rausch, Bernd tapped away at the keyboard with:
> > the complete intake manifold with plenum and intake runners will
> > be custom fabricated. So I am open for various suggestions.
> In that case, having separate throttles is even more attractive.

Heck, then make it a 7 butterfly system.  Or even 8.

> > I do not understand why integrating the IC in the plenum hurts
> > throttle response. In a "classic" setup I have the IC before the
> > throttle body, with extra piping and manifolds on the IC, so
> > throttle response should become even better.
> The plenum volume; that between the throttle valve and the intake
> valve determines how quickly a pressure change can occur to change
> airflow.

If you just happen to be ignoring the turbo having to spool up or down
as
the case may be.

> > I thought individual throttle-bodies are normally used for engines
> > with long duration cams to avoid cross-flow and get better
> > idle/part throttle response ? I want to avoid the extra work (and
> > money) integrating 6 TB´s and linkage.
> Individual throttles are used where throttle response is required or
> where there's no common plenum.

Or when looking for complex answers to simple guestions.

> I envisage a common throttle plate with separate butterflies on a
> common shaft (per side in a Vee engine). It's simple machining to
> bore some suitable holes through a sandwich of two long aluminium
> plates, machine a shaft and to make some butterflies. The throttle
> cable enters what is the post-IC distribution box and pulls on a
> lever attached to the butterfly shaft. A spring counters the cable
> to close the butterflies.

Till you start worring about the drill wandering and wind up with the
throttle shaft being offset too much, or worse yet, not at all.  You'll
want
it offset so that if the throttle return spring breaks the throttles
close
rather then remain open.

> If the runners leave at opposite sides of the air distribution box,
> then a relay link can mirror the motion for an identical setup of
> throttles on the opposite side. There are only two throttle bodies;
> each with 3 butterflies on a common shaft.

then you'll also want a by-pass adjustment for each butterfly to really
balance out the air flow at idle.

> A competent machinist can probably make all the throttle parts in
> less than a day using a lathe and bench drill in addition to some
> hand tools. A milling machine would be useful but not essential.
> Especially useful for creating the lip against which the butterflies
> close on each half of the throttle plate sandwich, and for chasing a
> groove for the butterfly shaft and its bushes. (Don't skimp on the
> bushes - the shaft has to be quite thin in places and could be bent
> by a backfire, causing it to stick subsequently.)

Now you want thinning of the butterfly shafts too?.
Shall we chrome all the bearing surfaces, or run the shaft on ball
bearings,
and incorporate seals into all 12-14-16 throttle shaft bearings?.

> Each throttle plate sandwich, complete with butterflies and spring
> can be held together with screws through one plate tapped into the
> other.
> Don't let the price of commercial units fool you into thinking the
> parts are hard to make.
> If you want to, you can attach the spigots for the inlet runners
> directly to the throttle plates and use the plates as a side of the
> distribution box.

Or use *mirrored* runners and have all 6 butterflies in a row.

Simplicity is the key to design.
I'll stick with my earlier statements.
It's much more important to have the plenum so that each cylinder feeds
freely from it and not having one runner wall at the end of a large
column
of air.  The one good thing about the SDS refered to intake fabrication
was
that they continued the plenum past the last cylinder's runner wall.

As soon as the machine shop is done with my manifold I'll get back with
on
what really works in the real world rather then just day dreaming or
quoting
theory
Bruce

> --
> Bernd Felsche - Innovative Reckoning, Perth, Western Australia


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