AdrianH
|
| posted on 1/4/10 at 07:20 AM |
|
|
Injection question on timing
This is a general question..
Do the injectors squirt at a fixed angle on the crank rotation regardless of rpm.
I know that the 'on' time can vary depending on the amount of fuel needed, but wondering if they always on at a fixed point in the intake
stroke?
If so anyone know what the angle may be?
Cheers
Adrian
Why do I have to make the tools to finish the job? More time then money.
|
|
|
|
|
StrikerChris
|
| posted on 1/4/10 at 07:53 AM |
|
|
that is a very general question!i haven't got a clue but it wouldn't suprise me if the modern stuff alters the timing now to be ultra
efficient with emissions etc.if they alter the angle air hits the turbo i'm sure a mili second here and there is programmed into the fuel
cycle.doubt an early rover does tho...
|
|
|
turbodisplay
|
| posted on 1/4/10 at 08:22 AM |
|
|
early injetion used a fixed point in the cycle, when the sync pulse was recieved, usually tdc.
Moderen systems aim to inject fuel so the injector closes just before the intake valve closes.
Powerwise gain is very low when engine is up to temp.
Darren
|
NOTE:This user is registered as a LocostBuilders trader and may offer commercial services to other users
|
snapper
|
| posted on 1/4/10 at 08:28 AM |
|
|
Interesting question this one, I have seen CGI representations of fuel injection which fires the injector before the inlet valve opens, the timing of
the injection is then dependent on maybe 2 things, the inlet valve opening point which is fixed on building the engine by crank degrees and cam inlet
valve opening point BTDC.
Port velocity would i think increase with engine revs perhaps meaning that the injectors need to fire a little earlier. Injector duration would need
to be set to complete before inlet valve opening or you might get stand off similar to what you get with high duration cams and carbs.
I eat to survive
I drink to forget
I breath to pi55 my ex wife off (and now my ex partner)
|
|
|
turbodisplay
|
| posted on 1/4/10 at 09:57 AM |
|
|
In old batch fire, the fuel acually sits arround the inlet valve until it opens.
My eu did this and it ran fine, using every 6th pip from the edis to squirt fuel. The real difference is when the engine is cold, and low rpm, more
fuel enrichment is required, as it does not mix as well.
Most pre 95 cars were batch fire.
Darren
|
NOTE:This user is registered as a LocostBuilders trader and may offer commercial services to other users
|
MikeRJ
|
| posted on 1/4/10 at 11:38 AM |
|
|
Sequential injection is only worthwhile at low engine speeds anyway, as the engine speed goes up the injection pulses get so long they all start to
overlap and it's effectively non-sequential after that.
In terms of power, the injector timing isn't very important, it's mainly to help emissions and economy.
[Edited on 1/4/10 by MikeRJ]
|
|
|
AdrianH
|
| posted on 1/4/10 at 02:21 PM |
|
|
The reason for the basic question was to try and figure if an old CFI ECU could have an external box added to take the injector pulses out to fire 4
iinjectors.
The eleconics is rel simple to do the add on box would use an engine position sensor to switch each injecter in turn.
Adrian
Why do I have to make the tools to finish the job? More time then money.
|
|
|
AdrianH
|
| posted on 1/4/10 at 03:09 PM |
|
|
The reason for the basic question was to try and figure if an old CFI ECU could have an external box added to take the injector pulses out to fire 4
iinjectors.
The eleconics is rel simple to do the add on box would use an engine position sensor to switch each injecter in turn.
Adrian
Why do I have to make the tools to finish the job? More time then money.
|
|
|
