[DeTomaso] efi horse power gain

Wed Aug 12 12:04:21 EDT 2009

See below

Mike Trusty Engineering

15119 Gorgeous View Trail

Little Rock, AR  72210

Ph:  501-224-9013

Fax: 501-421-0151

From: boyd casey <boyd411 at gmail.com>

Date: 11 August 2009 7:50:51 PM CDT

To: Kirby Schrader <kirby.schrader at gmail.com>

Cc: JDeRyke at aol.com, detomaso at realbig.com

Subject: Re: [DeTomaso] efi horse power gain

Finally like the prophet returning from the mountains after 10 years with
the ten commandments and smashing the golden lamb. The prodigal son has
returned.

[Mike Trusty] Now that there is funny, I don't care who you are.

Here are some comments to get folks thinking:

1.        It is possible to make just as much horse power with efi as it is
with a carburetor.

2.       It is possible to make just as much horse power with a carburetor
as it is with a efi system.

3.       To make that same power which approach has the most compromises
that you have to live with?

Based on the comments that have been made I think we all know that the efi
system has the potential to get closer to that still confusing statement
"you can have your cake and eat it too".  I prefer the statement describing
efi in that "it is the best of both worlds".  But a lack of understanding
and a poor application of either will result in frustration.

As you all know, every aspect of a motor is a whole list of compromises that
you have to pick and choose which you want to accept and what best fits your
situation.  This is true of the ignition systems, the exhaust systems, fuel
systems, cam selection, manifolds, pistons, combustion chambers, rod length,
radiators, etc. etc. etc.etc.  There have been books written about each of
these and their interaction with the others.  So, it will be impossible for
"anyone" to give a recommendation on which is "best".  Here are some
observations, comments and opinions for you to consider based on your
questions.

 So Mike , is the twm still your recommendation for the starting point as
far as the basis for building a weber styled  EFI?

[Mike Trusty] It depends.  There are several throttle bodies available in
the market.  I have landed with TWM and they have served me well.  But there
are limitation.  The main limitation with the TWM units is the size of the
throttle bodies available.  Something that is often overlooked is the fact
that although you have all of those beautiful throttle stacks that look like
webers, they will not flow as much air to your motor as a properly match
plenum manifold and four barrel carb.  The problem is the same with webers.
Most of the throttle bodies available are in the 48 to 50 mm size, that is
less than 2" in size.  That means that each cylinder has to draw all of its
air through that 2" hole while with a four barrel in a plenum manifold it
has four holes almost that same size(and yes I know two cylinders are
drawing at the same time).  Now again you must understand the application
and what you want to accomplish.  If it is show, bling and some go then the
bolt on weber manifolds and 50 mm throttle bodies are great.  If it is all
out performance then you need to do something else.  That is why I use 58mm
throttle bodies on the engine in my GT40 with a highly modified manifold to
flow what the throttle bodies can flow and what the engine can use.  Again,
you just build a system to fit the application.  One size does not fit all.

  Do you think that starting with  a weber intake manifold from Hall is also
the way to go?

[Mike Trusty] "always" - absolutely not.  For a system that looks totally
awesome and works extremely well which is a hard combination to get to work
together, then yeah, maybe.

 And What about the computer. Do you like the fast XFI system ? or do you
recommend something else.

[Mike Trusty] You are going to hate me but the answer is, well it depends.

Without addressing every feature of every system that is available I'll talk
in general terms.  The two system that have been talked about the most is
the FAST system and the Electromotive systems.  Here are my "opinions" on
these systems.

1.        Either will accomplish the same end.

2.       I see the FAST system being tailored more to the newer cars that
have many features that must be addressed like controlled torque converters,
transmissions, etc.  They are a plug and play system with the newer
generation cars.

3.       I think the Electromotive systems are maybe better for applications
to older machines like pre-1980 cars like the Pantera.

4.       But with the current programmers that are available, if I were
performance upgrading current generation cars I would be using a
reprogrammed stock ecu.  The current factory ecu's have much more capacity
and features than any after market unit.

5.       I'm going to start cutting my comments short or this is going to
get out of hand.

 What if someone wants to go with a super charger I would assume that the
stack system is no longer the optimal choice.

[Mike Trusty] It will not be the easiest choice to fabricate but it will
definitely have it's advantages.  The biggest performance advantage that I
see with multiple stack systems is the throttle response.  The single
throttle body units with long runners will lessen the throttle response and
make a motor less responsive.  Still have the power just not as crisp.
When you add blowers and intercoolers the problem with throttle response is
increased with a single throttle.  I don't have any data to back this up but
if you look at respected power plant builders you will see the trend.  If
all out performance is need in a boosted motor for racing then they have
individual throttles for each cylinder.  If you want good performance with
acceptable throttle response and less complexity say for a street
performance car then the single throttle system is used.

 Would you recommend  a tunnel ram throttle body  or what.

[Mike Trusty] Depends.  If you want a good running efi system you can make
that happen with a tunnel ram manifold and a single throttle body.  If you
have the budget I would prefer the multiple throttle bodies for the looks if
nothing else.  I also like the multi units for throttle reponse.

Let me point out something about multi stack systems whether they are carbs
or injection.  The single problem that has given all of them a bad rap is
improper balancing.  They must be balanced in flow and the linkage must be
so that they are progressive and open at the same rate.  In ninety nine
percent of the cases it is the lack of understanding the balancing procedure
that causes the problems.  If you have a system with a well designed linkage
system with good components you will never need to mess with it after the
initial setup.  I was visiting my best friend this weekend and we were
talking about this very thing.  He has a Lamborghini Countach that I put TWM
throttle bodies and a Electromotive Tech II system on in 1993.  He has not
touched the linkage and has never replaced the plugs.  It has thousands of
miles on it.  We walked over to it after it setting for two months.  Turned
the key, it rotated two revolution to determine where it was and started
with a perfect idle.  Try that with a stock Countach with carbs and
distributors.  That points out  the one major advantage of efi systems
especially if they have distributorless ignition included.

If the electromotive systems has but one advantage over others it is the
fact that it comes with a distributorless ignition system as part of the
standard unit and is not an add on.

 I don't want to inundate you with questions but I don't know if you are
going to fade back into the back ground and disappear before I can get  the
information I would like. 

[Mike Trusty] My day job is starting to make me fade.

Your reputation precedes you! 

[Mike Trusty] There you go being funny again and scary.

One last thing (for now) From a standpoint of looks there is no question
that the Weber stack system has the other EFI set ups beaten hands down. But
lets  say that esthetics's appeal has nothing to do with my choice. ( and it
may be the superior choice based solely on performance) I would be surprised
if the best looking was also the best performing. So if it's not the best
from a standpoint of horsepower what design is the best performing ?

[Mike Trusty] Either can be made to make the same power.  All things kept
the same regarding the motor I would prefer the multiple throttle bodies for
the better throttle response.

The  current technologies in motors are amazing but as someone pointed out,
it will be a long time before it can be applied to our Pantera motors, i.e.
direct injection.  

If someone asked me today what motor and injection system would I put in my
dream Pantera.  Forgive me Mike Drew but I would recommend a LS7 or OH MY
GOD LS9 with a reprogrammed stock ecu.  Small, light, 28 mpg and most of all
RELIABLE.

Thanks,
Boyd

On Tue, Aug 11, 2009 at 7:53 PM, boyd casey <boyd411 at gmail.com> 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

"

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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