AW: Intake manifold construction, intercoolers

[Rausch, Bernd]

OK, I understand what you mean. The air going out of the core is bent to
the intake runner with the open valve. Tis is why I want to have a
rather big plenum.
But when you have a normal intercooler, the air is bent going inwards
and again going outwards. That is the same effect, even worse with
intercooler with the piping 90deg to the airflow, like the most
intercoolers.

I did not mean meachanical stress when comparing na to turbocharged
engines. I did mean airflow plays the same role with a turbocharged
engine, maybe is even more important because the air is denser. It is
right that the plenum pressure is helping to push the piston down, but
this has nothing to do with airflow. At the exhaust stroke, backpressure
is much higher that in a na engine.

Best regards,
Bernd


-----Ursprüngliche Nachricht-----
Von: Bruce [mailto:nacelp at bright.net]
Gesendet: Dienstag, 4. Dezember 2001 20:22
An: diy_efi at diy-efi.org
Betreff: Re: Intake manifold construction, intercoolers



From: "Rausch, Bernd" <br at rnt.de>
Subject: AW: Intake manifold construction, intercoolers
> I have the information on intercooler size from
> http://www.spearcointercoolers.com. The core is 2-171.
>  This is a road/track car, and I am going to use two big
> radiators(12"x16") to cool the liquid.
> The plenum will be made of aluminium, only the runners will be CF.
> I do not want to have the air going thru a 4.5 core and then want it
to
> bend
> immediately. This is with the stock plenum without intercooler. My
> plenum will be straight, like on my ascii drawing below.

For any one valve to be drawing air, the air will have to be bent to
feed it
from any area other then the I/C area directly above the port.


> And I do not see flow in a turbocharged application very different
from
> a n/a. The air is even denser in a turbo application, so flow losses
are
> higher. Of course you can crank up the boost, but you are loosing
> efficiency and going to have more backpressure this way.

In a N/A your waiting for atmospheric pressure to fill the void as the
piston moves down.  In a boosted motor, the plenum pressure is helping
to
push the piston down.  In a N/A engine, there are all sorts of wave
activities, that can help or HURT cylinder filling, and that is about
mute
when in boost.
  If you think these issues are minor then look at the rod failure
differences between the two types of motors then
Bruce

> Best regards,
> Bernd
>
> Von: Bruce [mailto:nacelp at bright.net]
> Betreff: Re: Intake manifold construction, intercoolers

> From: "Rausch, Bernd" <br at rnt.de>
> Subject: AW: Intake manifold construction, intercoolers
> > thanks for your response. Your input (and that of others, of
course)is
> > really welcome. But I disagree in several points:
> > I want to use one Spearco air/liquid intercooler per side
(V-engine),
> > this IC is 4.5"x4.5"x10" and rated for 700cfm each. The engine will
> need
> > about 800-850cfm for 650hp.
> > With the IC in the plenum, I will actually cool the plenum and gain
IC
> > area this way (normally with a hot plenum and runners you heat your
> > intake charge). I thought about building carbon intake runners, to
> > insulate the runners and the plenum from the heat of the cylinder
> head.
>
> You going to use a total of 4.5x9x10 for cooling an engine of 650 HP?.
> Is this a dragster, or just for really short bursts of speed?.
> what are your plans for cooling the liquid?.
> CF for a large ehough plenum to hold all this is going to need some
> serious ribbing to prevent a sneeze from rupturing it.
> > I want to make big plenums, about 1,5L *after* the core
(displacement
> of the engine is 3L total). So the core will not straighten the flow
to
much.
> Your going to have the air going thru a 4.5 core and then want it to
> bend
> immediately?.  Ugh, OK, I don't see it happening that way, but it's
your
> decision.
> > Think of it this way: If I use the same IC (of which I assume that
it
> is the right size for the application) with a "classic" setup
> > (IC->TB->plenum), all I am doing is to avoid the transition form the
> > intercooler core to a 2,5" pipe and the transition from the pipe to
> the manifold (and a 90deg bend, since my TB is mounted on the side of
the
> > plenum)!

> Me thinks your toooo concerned about an elbow.  Is it some really
small
> radius?.
> Again, I think your thinking in N/A terms, not T/C
> Bruce

> > Best regards,
> > Bernd

> > Von: Bruce [mailto:nacelp at bright.net]
> > Betreff: Re: Intake manifold construction, intercoolers
> > Any intercooler that you use in the plenum, would either be too
small
> to be effective, or need fluids that are really cold.  you'll also be
> losing the surface area of the piping for heat transfer.  With the in
plenum
> > cooler, you also be exposing it to the heat of the manifold, thru
all
> it mounts, and you libel to losing alot  of cooling effect to cooling
the
> manifold.
> > For a plenum to be effective the opening intake valve must be able
to
> draw against the plenum, having the finning in the plenum is going to
> **straighten** the air flow, and so the opening valve is going to have
to
*try* and
> have this air change direction, rather then drawing against a rather
> turbulent chamber of waves, and air movement.  BTW, this is the same
set
up as
> > International Harvester uses on some of it's deisel applications,
but
> they are extremely low rpm motors.  They also have an area above the
I/C
that
> is about equal to the area below it.  I think you'd have to have a
really
huge
> plenum for any kind of free reving motor to really work,  in the IH
version they
> use coolant in the I/C so as to just reduce the high peaks of air
temp..
> >   I think it's a stop gap measure, and limited in practical
application.
> > For a diesel tractor working in the fields it's OK.
> >   I had choices of 2.5 and 3.0" piping for the front mount I/C in my
> GN, and after some investigation think my original thoughts of using
the
> 3" are best.  Trading a little off idle / low rpm response for cooler
> ultimate flow should be worth while.  I'm lucky in so far as mine is
an
> automatic trannied car, so I can tolerate the lack of really down low
torque
> since converter slippage with be absorbing that loss anyway, or rather
> allowing the engine to rev thru that zone in a lightly loaded state.
> >   Huge preturbo plumbing, large post turbo, as much I/C as can be
> > fitted, and calibrate as necessary.   then finalize the hardware to
> best use the above.  At least that's the way I'm headed.
> > Bruce

> > From: "Rausch, Bernd" br at rnt.de
> > Subject: Intake manifold construction, intercoolers
> > > Thanks for the responses I got, I have some additional questions:
> > > At the moment, I have an air/air intercooler per side (twinturbo V
> > > engine). I have per side: three 90deg bends, about 2m piping, two
> > > intercooler mandifolds with 90deg bends and four silicone hoses.
> > > I am thinking of welding an air/liquid intercooler core from
Spearco
> > > directly in the intake plenum. The throttle body will be upstream
of
> > the intercooler. With this construction I can exit the turbo in a
> straigt line, with an expanding pipe of about 0.4m to the throttle
body. I
> > will only need one hose (turbo has a flange at the outlet). This
setup
> will save me five 90deg bends, 1.6m piping, three silicone hoses and
two
> > > manifolds at the intercooler per side.
> > >
> > >       TB   IC     intake runners
> > >        |---------|------------|
> > >        |   ||    |------------|
> > > -------|   ||    |
> > >  ->    /   ||    |------------|
> > > -------|   ||    |------------|
> > >        |   ||    |
> > >        |   ||    |------------|
> > >        |---------|------------|
> > >
> > > -Is there any downside of this setup ?
> > > -How do I calculate intake plenum volume ? Only the volume on the
> > > downstream side of the intercooler or the complete plenum
including
> > > intercooler ?
> > > Any help would be appreciated.
> > > Bernd


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