Advice requested for choosing aftermarket EFI system

[Huw Scourfield]

Robert, my opinions:-
1 Multi- tothed crank sensors, if the engine is not likely to  be subject to
rapid speed fluctuatations(as in your application) then you are unlikely to
see any benefit, however if this is a "free "addition i would include it.
2 Direct fire, definiately better as far as losses, possible failure points
are concerned.
3 Sequential or semi sequential "should" give better mpg figures, but the
differences will be small.
4 Only run on 97 octane if the engine needs it, if it's a low comp unit then
there will not be any advantages.
5 Map would be my choice for accuracy and response, espcially for a low tune
engine.Tps can be used also, for accell fuelling alone.
    Huw
----- Original Message -----
From: Robert
To: DIY_EFI at lists.diy-efi.org
Sent: 02 January 2002 04:53
Subject: Advice requested for choosing aftermarket EFI system


Hi All,
    I'm trying to decide on an aftermarket engine management system for my
Motorhome, since I'm not learned enough to design my own, and there are
several good commercial units available. I have, however designed and am
currently testing a stand alone controller for the transmission. When I've
got the bugs worked out of it, the next step is to install an engine
management system that will allow me complete control of the engine.

    The subject is on a '92 Ford Super Duty chassis, 7.5L EFI V8, E4OD
transmission, 17,000 lb GVW. With the exception of a Banks "Power Pack" 4 in
1 long tube primary header exhaust and free flow intake system, and an
"Aurora" high output inductive discharge ignition system, the engine is, and
will likely remain stock. Ignition pick up is distributor hall effect sensor
to a remote TFI module. It uses batch fired injectors mounted in the
individual intake ports, 2 banks, 4 of 24 lb/hr injectors per bank.

    Normal operating range is between 1800 and 3000 RPM, but will
occasionally pull down to 1500, and rev to 3600 to shift.

    This is not a high performance application, but rather a low compression
( 8.5:1 ) slow turning engine that will run heavily loaded much of the time.
The object is to tune for best power under heavy load, and best economy at
cruise, economy having a slightly higher priority.  Emissions issues are not
a concern.

    I had originally only considered SDS www.sdsefi.com . They have a good
reputation, and product support is without equal, but it lacks some features
I would like, so I've been researching Halltech, Electromotive TEC II, and
DTA. They are all fairly similar, but are different enough that I'm finding
making comparisons a bit difficult.

    I'd really appreciate some opinions on experiences any of you may have
had with any of these manufacturers, as well as what features would be best
suited to my application. These questions, posed to some of the dealers were
met with unsatisfactory responses, or no response at all. They are as
follows.

Given the application;

1 - Is there any advantage in multi toothed crank angle sensors or 4 magnet
crank angle sensors as opposed to the stock hall effect distributor pick up?

2 - Is there any advantage to direct fire, waste spark ( 4 coils ) ignition
as opposed to distributor?

3 - Is there any advantage to sequential,  "semi-sequential"  ( cylinders
paired for ignition with paired injectors),  or batch fired every engine
revolution, as opposed to batch fired on alternate engine revolutions?

4 - Is there any advantage in tuning for use with 92 octane fuel as opposed
to 87?

5 - Would it be better to use MAP, or TPS for load sensing?

Thanks in advance.
Robert

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