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Re: [T3] Injector interchangability?

And the dance begins.
The crate has arrived or shall we say landed.

"....the whole world , Chico. And everything in it."

David V. Nelson
1969 Fastback FI (no matter what!)

----- Original Message ----- 
From: "Jim Adney" <jadney@vwtype3.org>
To: <type3@vwtype3.org>
Sent: Monday, December 01, 2003 12:08 PM
Subject: Re: [T3] Injector interchangability?

> On 30 Nov 2003 at 23:04, David V.N. wrote:
> > From: "Jim Adney" <jadney@vwtype3.org>
> >  > fuel. At some point the PS will max out, however, and then there will
> > no
> > > additional fuel as the airflow continues to increase. So you are lean.
> > >
> > > If you try to cure this by just increasing the fuel pressure you can
> > > things work right at some point, but the mixture at 36psi will be 20%
> > and
> > > the PS will still be maxed out.
> >
> > A "ramping" regulator has been suggested to take this into account.
> > That is,using a microswitch,(or something similar),a higher pressure
> > could be "activated" at some pre-set throttle position.I think I've
heard of
> > such a thing being used in turbo application.
> The problem with this is that the PS is already ramping the fuel delivery
> the low demand end. What you need is a pressure ramp that starts just as
the PS
> ramp stops (when it maxes out) which will be pretty hard to accomplish.
> better solution is to find a PS that has a wider range, or a PS/throttle
> combination which has a wider range, and a brain that understands this new
> combination.
> > > > >In my opinion, It MIGHT be possible to upgrade our FI to that of a
> > > > >different car IF we also upgraded the throttle body either by
> > out the
> > > > >throat diameter to that of the other car, or by using the throttle
> > > > from that car.
> > > >
> > > > Is the porsche d-jet THAT dissimiliar?The internal volume doesn't
> > to be that different. (The porsche bieng slightly larger)
> > >
> > > Internal volume has nothing to do with it. It's simply the throat
> > and
> > > possibly a small effect from the air cleaner flow properties. I don't
> > what
> > > the relative throat diameters are, or what effects that might have.
> >
> > I am assuming that you're referring to air velocity past the port for
> > MPC.
> > Hmmmmm.If the relative diameters of the throat are close then perhaps
> > only a matter of placeing the sensing port of the MPC at a distance that
> > approximates the distance inside a T3.
> Virtually all the pressure drop occurs across the throttle body. Once past
> point I think we can safely assume that the whole intake air distributor
is at
> the same pressure. Air velocity inside the IAD doesn't really matter much,
> there will be a velocity-dependent pressure drop between the IAD and the
> combustion chambers for which the FI system needs to have built in
> compensation.
> You still need to get a PS that has a wider range. This means a wider
range of
> input pressures (vacuums, actually) with the usual range of outputs, since
> suspect that ALL the D-Jet PSs have the same output range.
> Then you have to adjust the brain, or find a different brain, which
responds to
> the usual PS outputs with proportionally wider injector pulses (or find
> injectors which put out proportionally more fuel for the same inputs.
> So it just might be possible to do with a different PS and different
> Finding the right combination of parts would be the tough part, and it's
> even certain that an appropriate combination already exists. I'll agree,
> however, that there are enough options out there that it should be
possible to
> come close.
> -- 
> Jim Adney
> jadney@vwtype3.org
> Madison, WI 53711-3054
> ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> List info at http://www.vwtype3.org/list | mailto:gregm@vwtype3.org

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