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Re: Is this a good deal?



If a little is good
more is better
then too much should be about enough.

The intake tract is full of compromises.
Which compromise you want to take is what you do (meaning anyone).

If the intake runners are you're limiting factor then you *in theory* can
run any intake tract you want.
Jus son't be surprised if it don't run worth dodo.

The intke tract lenghts, volumes, and if wet considerations must be mad for
that.
You can have too much cam, valve curtain area, cam lift, Throttle body cross
sectional area, compression, yada yada.
Grumpy
----- Original Message -----
From: Squash <realsquash@yahoo.com>
To: <gmecm@diy-efi.org>
Sent: Tuesday, May 23, 2000 11:00 AM
Subject: Re: Is this a good deal?


> I don't get this argument.  If your engine takes 750cfm to run at WOT/5000
rpm, and 500cfm at
> WOT/3500 rpm, how can a 750cfm TB be better than a 900cfm at anything but
WOT/5000?  Anything
> under 5000 rpm and you are over-sized with a 750cfm unit, right?  Is a
900cfm unit at WOT/3500
> worse than a 750cfm unit at WOT/3500?  Or WOT/2000?
>
> Squash
>
> --- JTesta1966@aol.com wrote:
> > In a message dated 5/23/00 2:15:25 AM Eastern Daylight Time,
bob@tecmark.com
> > writes:
> >
> > << Reason for this is that I came across a "Air Research" aftermarket
TBI
> >  system for about $300 - includes the controller (set with buttons on
front
> >  and small LCD display, no laptop connection), BIG MAF sensor, *900* CFM
> >  throttle body (4 barrel) with 4, 85lb/hr injectors which shoot in from
the
> >  side,  >>
> >
> > Too big is bad in NA engines as they rely on the vacuum for airflow. a
> > injected car might be less suseptible, but still need a certin airflow
to
> > keep the air/fuel flowing in the right direction. A TB too large will
> > possibly create positive pressure in the manifold (depending on your RPM
> > range) and hinder actual airflow into the cylinders. This is more
important
> > on carbed engines where you need the pressure differential to make
gasoline
> > flow out of the carb, but I'd haveta think it'd make a difference in an
> > injected engine as well. maybe you can use a throttle stop to limit the
> > available CFM until the motor is built to require the 900cfm you have
> > available. An olds engine wont rev that high, their not known for their
> > bottom ends....I build a few pretty healthy Rocket 350's and did a
decent
> > amount of research on what works with them. Assuming you have a healthy
403,
> > which wont see much duty above 6500RPM you'd want more like a 700-750CFM
TB
> > to assure proper airflow. maybe you could fabricate a stop at a little
more
> > than 3/4 throttle, and scale the TPS to make THAT point WOT.
> >
> > ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> > Jim Testa
TType86 on
> > #BuickGN
> > ASE Master Technician
> > buick.fiendish.net:6667
> > L1 Advanced Engine Performance                          NJ Lic MV
Inspector
> > jtesta1966@aol.com                                  NJ Lic Emission
Repair
> > Tech
> > http://members.aol.com/jtesta1966/buick.htm
>
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>
> =====
> Trains, Trucks, and EFI at http://www.trailrunners4x4.org/users/realsquash
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