Thanks for the story book,
N/A manifold's (well in NZ) have a butterfly system in the manifold
which mechanically opens at 4,500 rpm, why 4,5000 rpm, this rev range
is suited to the cam profile. So there is a huge restriction in the
manifold until 4,500.
Yes the WRX manifolds are much better and bigger, you should also
keep the injectors and use them, modify the air intake to get the
MOST airflow, and replace the fuel pump and you will then be away
laughing.
I am not sure that I follow your pre-cooler idea fully though, if you
have a decent intercooler this mod would make hardly any difference.
Dan
--- In BC-BFLegacyWorks@y..., "Sam & Beth Barrett" <LEVATHIAN@s...>
wrote:
> I think one could replace the manifold, perhaps with a custom
jobbie, and do
> very well.
>
> The manifold we have (in the U.S.A.) is crappy. I've had it off
once and was
> appalled at the guts of the thing. Then I went to a local
dealership, and
> took a look-see under the hood of the WRX and I would dare say the
rex's
> manifold is a HUGE improvement. It looks like the pipes are closer
to equal
> length (on the WRX) and are twisted (in a good way), to provide a
more equal
> airflow. However, this should only make a significant difference
with N/A
> engines. When the manifold is pressurized by a turbo, the length of
the
> tube, angulation, and such, doesn't make as big a difference -
because it's
> pressurized (once the turbo has engaged, and effectively compressed
the air
> between the turbine and the valves that is).
>
> Now if that intake went under the manifold as the WRX does, it
would also
> position itself nicely for a pre-cooler mounted up front, as it is
facing
> the front of the car squarely, naturally. Finding a way around the
radiator
> would be a challenge, but with a little madrel bent tubing, easily
overcome.
> For the N/A types, I would leave it as is (bending around the top,
not going
> under the manifold). Everytime you introduce a new angulation, or
increase
> an angle, to a intake header you are effectively making it more
difficult
> for the engine to pull that air in. From what I understand, front
mounted
> INTER-coolers are hellatiously lagg-ey because there is sooo much
tubing,
> and a larger cooler to pressurize (volume). A pre-cooler would make
more
> sense to me; give the turbo some cooler air to start with, and
finish it off
> with an inter-cooler before it hits the last of the manifold,
valves, etc.
> There is no doubt in my mind that our N/A manifolds are crappy and
should be
> replaced by something with more equal length tubing, better
distribution,
> less jagged bends, polished, finished properly etc. If it were not
for the
> fact I'm saving my lunch money to buy and re-build a EJ22T - it
would be one
> of the first things I might change for the N/A engine.
>
> I have yet to have proven any of these theories, and that is
exactly what
> they are at the moment. I haven't had the opportunity to really
hash this
> stuff out with a Subaru turbo genius to see if I'm at all correct.
If you
> are, or know someone who is, have them get in contact with me. I'd
like to
> talk to someone who has "been there" with front mount intercoolers,
> pre-coolers, etc.
>
> So tell me what you think.
>
> Sorry about the stream of consciousness post. I've been thinking
about this
> for some time now...
>
> -Sambo
>
> -----Original Message-----
> From: daniel.wilson@d... [mailto:daniel.wilson@d...]
> Sent: Wednesday, May 16, 2001 6:52 PM
> To: BC-BFLegacyWorks@y...
> Subject: [BC-BFLegacyWorks] Re: Question for Dan
>
>
> Sure would be an improvement.
>
> I am not sure that you will be able to get a decent size pipe under
> the manifold and around the power steering reservoir, just have a
> look, you may need to get another reservoir (not sure though on your
> models)
>
> Dan
>
> --- In BC-BFLegacyWorks@y..., acroxford@h... wrote:
> > True, in production almost everything is a compromise. I think I
> may
> > bolt this TDO5 on and try the expansion tube trick and also
> eliminate
> > any obstruction to the air flow that is already coming from under
> the
> > fender to help with the lag problem. I would think it would be an
> > improvement over the RHB4 IHI that is on there now at high boost
it
> is
> > really working.
> >
>
>
>
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