[DeTomaso] efi horse power gain

Tue Aug 11 19:53:28 EDT 2009

When it comes to vacuum I am like Sgt. Schultz, "I know nothing!"  But from
what I have read there seems to be a a very Strong correlation between
deficiencies in Vacuum and Weber stack style efi Units. I don't understand
the mechanical processes involved with  generating and maintaining a
sufficient level of vacuum but something to do with the design of the Weber
stack setup interferes with having sufficient vacuum to operate some of the
various devices that require vacuum. The Fast XFI ecu has the largest
number  optional  devices  and sensors ( that I know of) that can be run or
controlled by the fast XFI and   apparently  a number of them are useless
without sufficient  vacuum assist. I have even read that one may( literally)
run in problems  with braking  due to insufficient vacuum for the brakes. I
can't remember where I read it and I hate quoting something without be able
to cite the source but I seem to recall a brake vacuum booster being highly
recommended if one was considering a weber style  stack EFI setup.I have
nominal vacuum powered items on my car so I know even less then the average
Pantera owner, but apparently the fast XFI has among its optional interfaces
( automatic transmission interfaces,  waste gate controls, ac controls ,
Idle controls ) here is a partial list from one of their web sites : Quote
from Hot Rod magazine "
This is a list of some off the other optional features and sensors. This is
not a comprehensive list and some of the items are not really relevant  to
Pantera applications.
The partial list is as follows:

   - Fast XFI Dual Sync Distributor
   - Fan - Fuel Pump and control Harness
   - XIM Ignition Module
   - TCU Transmission controller and adapter harness.
   - Fuel Injectors
   - Fuel Pump
   - Throttle body
   - Coil on Plug ignition applications

Some of the popular options are:
Traction Control
PC Free  "Internal Channel Data logging up to 30 Minutes of  data recording
with out a computer.
Additional PC Free data logging of accelerometer, EGT,  Fuel pressure and
oil pressure.
(it is almost like an aircraft's black box)
It also has an available Digital LED touch screen. With this module
installed in your dash board or glove compartment  you would be able to
adjust  and calibrate the operating parameters by touch right from the
drivers seat while you are driving  instead of having to plug in a lap top
to make adjustments.
With the addition of the XIM Ignition module  it can be adapted to the Ford
Modular transmission,  GM LS1 and new Hemi transmissions.
And with the addition of the  Transmission control unit ( obviously not  a
benefit to  a Pantera  owner) it can be utilized to work with GM, Ford, and
Chrysler  electronically controlled transmissions.
I know there is more I am missing and all this taken in conjunction with the
ability to control  up to 16 injectors and 5 map sensors makes me believe
the biggest problem would be coming up with an engine advanced enough to be
able to use theses optional sensors and controls and the PHD in tuning you
would need in order to utilize it all!
It would be great for a supercharged or twin turbo  DOHC  32 valve  16 spark
plug 16 injector 12,000 rpm  engine. with  a six speed paddle shifter and
F1 trans axle ( and a complete pit crew and bank roll to keep it all
running).
 Either that or just buy it like most other american consumers and have ten
times the power that I could ever use but be able to brag about it even
though they never drive it
 I guess it's still better to have allot more then you need then a little
bit less then you need. Especially if the price is the same.  Apparently if
you don't buy all the extras the price is close to the price of the average
systems on the market.  And it is human nature to want the latest and
greatest  even if you will never use it.
I have to admit is sounds like a bad ass set up.

Boyd
"

On Tue, Aug 11, 2009 at 4:42 PM, Kirby Schrader <kirby.schrader at gmail.com>wrote:

> Well, what can I say...
>
> It works to combine them. I can _prove_ it by measuring the manifold
> pressure at the plenum on my car.
>
> Why are companies like TWM using this technique if it doesn't/shouldn't
> work?
>
> Either the explanation is wrong or the conclusion is wrong. Or both.
>
> Let's not ignore the proven facts. If I did that in my job, I'd have
> been fired decades ago.
>
> Kirby
>
> On Tue, Aug 11, 2009 at 2:59 PM, <JDeRyke at aol.com> wrote:
> > In a message dated 8/11/09 8:02:16 AM, kirby.schrader at gmail.com writes:
> >
> > I have no idea how each cylinder's vacuum pulse can cancel out each
> other.
> > That
> > means one pulse would be negative (vacuum) and the other positive
> > (pressure).....
> >
> > Correct- the strong pulses going back & forth thru an IR manifold are
> indeed
> > positive and negative, as the pressure wave oscillates between the intake
> > valve and the ram-tube top. As one intake opens and starts a negative
> wave
> > downward, the preceding cylinder has just closed and starts a positive
> wave
> > back out. I found the net from combining cylinders is zero. It's so
> > prevalent that experts suggest using a fairly long piece of rubber tubing
> to
> > connect a single intake port to a vacuum advance, so the rubber's normal
> > pliability will dampen the pulses. Using metal lines is the worst- as I
> > found. My vacuum with Webers wouldn't accumulate until I added a check
> valve
> > like is in the power brake booster. But maybe the rules change with EFI-
> > dunno; haven't tried it yet. FWIW- J Deryke
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