[DeTomaso] efi horse power gain

Tue Aug 11 21:24:19 EDT 2009

Boyd,

You know a lot already.

It seems like you are well on your way. I really don't think you'd be  
happy with anything but the FAST XFI.
:-)
Just kidding.... go for it. It does seem like the latest and greatest.  
As you indicate, I assure you that it will have more features than you  
will use, but it will certainly be flexible, just like the TEC3r and  
others.

Regarding vacuum... it depends. As I pointed out in a previous email,  
I use ONLY the #2 runner with my IR EFI on my Pantera for the brake  
booster. I was told by many experts that this would NOT work, but it  
does. Now... if I had a really radical cam with next to no vacuum at  
idle, then maybe it would be another story.

My recommendation is try it first and if it doesn't work, then you  
have two options.
Tie all the runners together in a plenum (which you should do anyway  
with a decent IR system), which has been discussed ad nauseam, or go  
with a small electrical vacuum pump to give you enough vacuum. If  
you're going to use a 'street' cam, I'll bet you'll be fine.

Sensors are useless without 'vacuum assist'? Hmmm... I don't know what  
that means....

Should you go with a throttle body and injectors or an individual  
runner manifold? Up to you...

At the risk of repeating everything...

1) Low and mid range HP and TQ will be better
2) Drivability will be better, even with a radical camshaft
3) DON'T FORGET THE BLING FACTOR!
4) It looks really cool
5) Everyone (well, almost everyone) will be jealous
6) Your air cleaner will cover up the single throttle body and nobody  
will every know what kind of cool sh*t you have underneath!
7) It'll start and you can drive away without blipping the throttle or  
wondering when the choke is going to shut off

I really think you're getting your head around the whole issue. Keep  
asking questions if you've got any.

Regards,
Kirby

On 11 Aug 2009, at 6:53 PM, boyd casey wrote:

> 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
> "
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> 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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