Intake manifold construction, intercoolers

[Kelly McCrystle]

 Yes, openings in the intake system after the Air Flow
Meter will allow un-metered air to enter the system
and will cause among other things High Idle or a
hunting idle.  Therefore it is likely that the hose
was cracked previously and that led to the high idle. 


Kelly M
'91 FJ80 

--- Bruce <nacelp at bright.net> wrote:
> 
> From: "James Montebello"
> <jamesm at undeadminion.bom.conru.com>
> Subject: Re: Intake manifold construction,
> intercoolers
> > Thanks for completely omitting the section of my
> post where I discussed
> > the other compromises, Bruce. :-)
> 
> Was just trying to tighen up what I wanted to
> blather about.
> Hmm, I thought I had included a brutal snippage
> comment, but in double
> checking, it's not there, that was an error.
> 
> > Yes, all things include compromises.  My point
> was, ONE tradeoff in the
> > "one big plenum" approach v. an IR setup is
> simplicity v. throttle
> > response.  There are other tradeoffs.  One big
> plenum not only makes the
> > throttle construction easier, but it also allows
> you to use MAP without
> > heavy filtering (or a MAP plenum).  It allows you
> to use MAF if you
> > desire, unless you make another plenum "above" the
> throttles in the IR
> > setup, where you get the nice airflow without the
> compromise of losing
> > throttle response.
> > None of this is new.  IR setups were around
> decades ago.  I've driven cars
> > that were swapped between single
> plenum/single-throttle setups and IR
> > setups.  Throttle response is most definitely
> improved, so it's not just
> > theory.  However, the IR setup is more complicated
> in many ways.  Whether
> > its all worth the effort is up to the guy spending
> the money.
> 
> But, when worded like this it apprears you stating
> it as a universal truth.
> I have no doubt that in some applications there
> perferred compromises.
> 
> > And while you're blathering about drivetrain
> theory, you should mention
> > CVT, where you can tune for a very high but narrow
> torque peak using 30-50
> > year old knowlege to get >150hp/liter out of a
> two-valve setup, and let
> > the CVT hold it on that torque peak.  Nice, once
> someone figures out how
> > to deliver 500+lb/ft through a CVT.  Audi seems to
> have figured out
> > 250lb/ft.  Of course, now we've traded off a
> simple engine for a
> > complicated transmission.
> 
> I just find myself limited to what's actually
> available.  Life's just
> complicated enough handling what we have already
> without further
> complicating things with what ifs.
> Bruce
> 
>  Note:  The sender is not responsible for your
> interest or lack thereof in
> the contents of this posting.  The Warning is
> included in part to ensure
> that people who ARE NOT LIKE ME are in no way
> offended or disadvantaged.
> 
> 
> > james montebello
> 
> > On Wed, 5 Dec 2001, Bruce wrote:
> > > Speaking from experience or from theory?.
> > > While you can ignore other issues, when you're
> discussing an individual
> > > item, when you do put it into practice thou,
> what happens?.   There is
> alot
> > > more going on, when you crack the gas then the
> intake valve looking at
> the
> > > manifold.
> > >    Your multi butterfly set up *might* have
> better transistional stuff.
> > > But,  if you  compromise it's plenum area then
> you'll fall down *big
> time*
> > > on WOT.
> > > Then we get into air calculations.
> > >   If we're using any plenums, then we're going
> to have a *choke point*
> > > somewhere anyway.  For either a MAF or MAP
> system.  the MAP spikes are
> so
> > > serious that you need averaging of them to make
> a worth while signal out
> of
> > > them anyway.  The MAF is self explainatory.
> > >   Then comes into issue are the matters of AE. 
> With a longer column of
> air
> > > the lesser the need for AE.    That can be a
> good thing, since we get
> more
> > > to give the engine what it needs, rather then a
> calculaton based on TPS.
> > > But that leads to fly by wire throttles which
> have to be a better answer
> > > anyway.  With them you can keep the airflow
> optimised per rpm, per rate
> of
> > > accleration.  Hmmm, maybe a (3-4", pre turbo)
> slide like an old SU has
> isn't
> > > such a bad idea after all............
> > >
> > > Then we have to figure in the various drivetrain
> issues.  Autos being
> alot
> > > more forgiving then manuals.  With the converter
> to act as a huge
> dampner,
> > > we can get the slippage to work for us.  Given
> enough slippage to get us
> to
> > > peak torque, where would all this lag even be an
> issue.
> > > Bruce
> > >     Still cruising in 80s (and earlier)
> technology......
> > >     Still looking for this *new* stuff
> everyone's talking about.
> > >
> > >
> > >
> > > From: "James Montebello"
> <jamesm at undeadminion.bom.conru.com>
> > > Subject: Re: Intake manifold construction,
> intercoolers
> > > > This is true, but with one big caveat, already
> mentioned several
> times:
> > > > throttle response with one "big-arsed" plenum
> and one throttle will be
> > > > pretty awful.
> > > > james montebello
> 
> 
>
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