With injectors there is always a dilema.
In non turbo/compressor engines.

1
At low refs you want a good running engine/drivable - this means that only a small amount of fuel injected At high refs/full power you want the maximum fuel injection that your engine can cope with. Large capacity injector & long open time If you use injectors that give you maximum power (air/fuel mix with large capacity injectors) at high refs the open time at low refs is to short for the injector to cope with -> give to much/unregular fuel. Engine does not run that well al low speed/refs.

2
At low speed/cold engine you want the injectors near to the valves - thats why a EFI cylinder head is modified with a cutout For max power you want a better fuel anotomisation - injector further away from the valves.
Plus some other facts to consider.


Factory injection systems like the Fiesta EFI 4 injectors are a compromise.
Injectors near vales & driveable in town but not big enough injectors to give the max power (ideal & max air/fuel mix) your engine can cope with.

With 8 injectors you can use the 4 front ones for drivability at low speed and the 4 back ones for full throttle
But you can also combine the front and back ones.

Megasquirt 3 has the capabilty to individualy control 8 injectors - let say below 2500 refs use the front ones, 2500-3250 that use back 4, above 3250 use all 8. You can control and therefore optimise the opentime & amount of fuel per injector and in total. Now you get the best of both - good drivability at low speed and max power when needed.

Motorbikes are ahead of car engines in using this thechnology.

I hope this explains why more is bettter - in this case . . .

Hans

----- Original Message ----- From: "Matthew Wastell" <[email protected]>
To: <[email protected]>
Sent: Saturday, July 16, 2011 10:35 AM
Subject: Re: [Quantum Owners] Re: more fettling


Stupid question maybe, but how does 8 injectors help with power compared with 4 suitably sized injectors?

M



On 15 Jul 2011, at 18:37, jin <[email protected]> wrote:

i had been considering bike carbs, its probably what ill do next if
all goes to plan

maybe a winter project?

On Jul 15, 2:08 pm, "hansdefauwes" <[email protected]> wrote:
How about bike throttle bodies?
Suzuki GSXR 600/700 (the latest models have 8 injectors!!) or Kawasaki ZX6R

Cheaper and dedicated throttle bodies & more power than the fiesta EFI.
Especialy if you use the 8 injectors - 4 for stationary/low ref & all 8 when
power is needed.

Hans



----- Original Message -----
From: "jin" <[email protected]>
To: "Quantum Owners Group" <[email protected]>
Sent: Friday, July 15, 2011 7:25 AM
Subject: [Quantum Owners] Re: more fettling

I would mate

But im running a carburettor LOL

I just wanted to know that im not way too rich or lean

Some nice looking products on that website though and im one step
closer if I do want to go EFI since I now have an oxygen sensor
already plumbed in.

Best regards

Justin

On Jul 14, 11:08 pm, "hansdefauwes" <[email protected]> wrote:
Have you considered using a MegaSquirt for ECU?http://www.msextra.com
orhttp://www.bs-autotune.nl/pics/KdFi/kdFi20V1320English.pdfexactly the
same as a Megasquirt 2 but a cheaper version.

With it you can tune your engine to what it can give.
It integrates the AFR, water/air temp sensors, MAP, TPC etc. and you can
than tune/optimise the injection time, ingnition specs etc.

Hans

----- Original Message -----
From: "jin" <[email protected]>
To: "Quantum Owners Group" <[email protected]>
Sent: Thursday, July 14, 2011 11:22 PM
Subject: [Quantum Owners] more fettling

i loosely wired up the AFR gauge into the rover to get a baseline
setting, also handy as I'm using a rover / Bosch sensor too

after driving the rover for a week I've concluded that its taught me
not a great deal ;)

well that's not strictly true but i found out no matter what i do to
the car i can not get the gauge to step into the "normal range" with
it just sitting at the end of the lean scale (no wonder its got no
power )

all wired in
[IMG]http://i120.photobucket.com/albums/o192/jindal/DSC01738.jpg[/IMG]

so after wiring it into the gauge i was happy to see it sitting to the
end of the normal range towards the rich during cruising

[IMG]http://i120.photobucket.com/albums/o192/jindal/DSC01745.jpg[/IMG]

a little richer under more acceleration

[IMG]http://i120.photobucket.com/albums/o192/jindal/DSC01746.jpg[/IMG]

and lean on the over run

[IMG]http://i120.photobucket.com/albums/o192/jindal/DSC01743.jpg[/IMG]

this is pretty much spot on, especially since its a narrow band AFR
gauge and sensor so its not detecting anything way out either end of
the scale, so for a first attempt at carb jetting its spot on

other things I've noted though is it goes haywire with the choke out
and can go lean at WOT before the fueling catches up as the revs rise,
ill either need to change the pump jet or accept that a carb is still
hit and miss at best.

I've a matching vac gauge to go in next to it tomorrow so i should get
a good idea as to what the engine is up to.

other news, I've replaced the stat for a lower one, but first the stat
housing looked a bit shabby

[IMG]http://i120.photobucket.com/albums/o192/jindal/DSC01733.jpg[/IMG]
[IMG]http://i120.photobucket.com/albums/o192/jindal/DSC01734.jpg[/IMG]

so i blasted it

[IMG]http://i120.photobucket.com/albums/o192/jindal/DSC01735.jpg[/IMG]
[IMG]http://i120.photobucket.com/albums/o192/jindal/DSC01736.jpg[/IMG]

like new

painted the hose ends with tick polyurethane paint to prevent pitting
and seal some old minor pits

[IMG]http://i120.photobucket.com/albums/o192/jindal/DSC01737.jpg[/IMG]

engine seems a touch cooler now so smiles all round

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