I dont know about 2.5x the volumn but have a look at some V8 supercars and
the like, they all run huge inlet tract volumn, that is after the filter.
Air speed is only relevant when the air passes the fuel jets or fuel
injectors, and in the case of carby's when it passes the chokes. This is
where air speed is most critical. This ensues correct atomisation of the
fuel.
The idea of having a huge airbox is effectively to have "no restriction" on
the engine intake side to maximise the amount of air that can be taken into
the cylinders. This is most evident when you throttle a motor and it
suddenly require vastly greater amounts of air.
With a turbo engine the idea is to have this volumn of air, so as to
minimise the lag in putting air into the motor. However this can be two
fold. If you have a very small turbo and a very large plenum it may
increase the lag, however for most systems the larger the better. The Ford
Escort 4x4 get an extra 20kW by spacing the plenum out by 20mm.
Hope this helps
Chris
mark krawczuk writes:
> hi, my brother is doing a efi setup ona 360 chrysler, and the guy from
> CAPA and MOTEC both said to have a air box about the size of cubic inches
> of the engine.
> to have a box 2.5 times the engine volume would have to absolutely
> humungus, on this type of engine.. i totally disagree that haviing a box
> cannot be oversize ( e.g "the air intake system cannot be oversized"
> (pp120).). what about
>
> air speed amongst otther things?
>
> mark k
> >
> ----- Original Message -----
> From: "Mr-Freeze" <[EMAIL PROTECTED]>
> To: <[EMAIL PROTECTED]>
> Sent: Tuesday, June 18, 2002 3:49 PM
> Subject: Re: AirBoxes!!!!! !
>
>
> > good quote there Errol
> > How true too
> >
> > Peter
> > ----- Original Message -----
> > From: "E Smith" <[EMAIL PROTECTED]>
> > To: <[EMAIL PROTECTED]>
> > Sent: Tuesday, June 18, 2002 8:37 AM
> > Subject: RE: AirBoxes!!!!! !
> >
> >
> > > Nat,
> > > Plenum volume should be at least 2.5 times engine capacity (ie 5 litres
> > for
> > > a 2 litre engine). If a small plenum is used, the wall of the plenum
> > > opposite the ram tubes should taper towards the intake furthest from the
> > > inlet. The distance from the ram tube mouth to the opposing wall of the
> > > plenum should be a minimum of 1.5 times the ram tube ID to minimise air
> > flow
> > > disturbance into the tubes. A good example of a plenum is the
> "Technicar"
> > > air plenum on Alfa's with Webers-Dellorto's although it doesn't use ram
> > > tubes. A quote worth noting is by Julian Edgar in 21st century
> performance
> > > "the air intake system cannot be oversized" (pp120).
> > > Cheers
> > > Feral Errol
> > > [EMAIL PROTECTED]
> > > http://www.datrats.com.au/
> > >
> > > -----Original Message-----
> > > From: [EMAIL PROTECTED]
> > > [mailto:[EMAIL PROTECTED]]On Behalf Of nat P.
> > > Sent: Tuesday, 18 June 2002 1:29 AM
> > > To: [EMAIL PROTECTED]
> > > Subject: AirBoxes!!!!! !
> > >
> > > Morning all!!!!
> > >
> > > Has anyone made an airbox for twin webbers? I was
> > > taking to an engineer friend who said that they have
> > > to be a certain size so to feed enough air to each
> > > carb(I knew that one!!!) BUT he also said that if its
> > > too big, you can get trubulance(spell!!)! Which is
> > > bad! I was going to get one made out of alloy due it's
> > > lightness! But I cant seem to find anyone who wants
> > > the job, Due to the fact that it has to incorparate
> > > ram tubes!
> > >
> > > Anyone want to make one? OR know who does OR know
> > > where I can get one?
> > >
> > > I know Errol has one on a EFI setup but where did that
> > > come from??
> > >
> > > Cheers NAT
> > >
> > > Any help would in good help!!!
> > >
> > > http://www.sold.com.au - SOLD.com.au
> > > - Find yourself a bargain!
> > >
> > >
> >
> >
>
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