Twin injector system?

[Daniel Ciobota]

One of the tricks I see quite often in fast efi based drag cars is a
hybrid injection setup using port injection for the lower low boost rpms
and a supplemental throttle body type injection setup for the high
boost/nitrous stages.  The system uses the conventional efi electronics
(some used custom dfi systems, but they work about the same) to fire the
port injectors, just like in a factory setup.  At boost/nitrous or
higher rpm's, those cars have a thick plate mounted usually at the top
of the lower intake manifold, which has holes drilled for additional
injectors (usually two or four).  These injectors work off a secondary
control system that varies the pulse duration on a curve tailored
according to rpm/boost.  The setup is much simpler on this second
"throttle body type" system (no idle, or part throttle curves even), but
it seems to work pretty well even on 8 second cars.  To make a
completely driveable system, you'd probably have to work on the control
system a bit.

Daniel



Barrett Flowers wrote:

> Something I have been wondering about for quite a while and maybe
> someone can shed some light on this for me. Is there a system that
> uses
> twin injectors? Say something like 2 15# or a 20#and 30# injectors?
> My idea is a fairly simple one, the smaller injector is only used at
> idle and part throttle, as rpm's increase the second injector takes
> over
> from the first, and at WOT both injectors kick in. Seems this approach
>
> wouldmeet most all the needs of a daily driver/weekend racer. If I
> remember right at 6000rpm there is ony two 6ms times for the injector
> to
> respond, and that is not much when performance is on the line. I do
> know
> that there is at least one system out that uses three extra injectors
> in
> the plenum to add extra fuel, but I thought it might just be simpler
> to
> drilla few holes in the fuel rail and intake and add a second set.
> I know this is doable, but it is pratical as well as economical?
> Would someone be willing to build a system like this so I can test it
> on
> my supercharged 600HP Corvette?
> An alternative to this is that the second set of injectors inject
> alcohol into the system, this should help reduce knock, make the
> engine
> run cooler and give added power, but will alcohol and gas mix well
> enough and work together with such a system?
> Food for thought...<smiles>
> I'm all ears...
>
>      -Barrett
> vette at disknet.com
>      1989 Carroll/S.C.A.R. Performance Corvette
>      Paxton S/C, Borla, FX-3/z51/HD Springs, Exorbitant engine mods.
>      PBM Racing heads, PBM custom cam, valves, springs, retainers,
> etc.
>      1984 S.C.A.R. Performance Corvette- Mod Engine, leather, TCI
> 700-R4
>      ICQ contact # 6317092   Owner: SCAR PERFORMANCE
>      WebPage: http://members.tripod.com/~Barrett_VETTE/index.html
>      Don't Forget To WAVE! I am.....
>      Southern Indiana, near Louisville, KY
>      Member: Ohio Valley Vette Assoc. New Albany, IN