injector spray timing

N/A tech, Cold Air Intakes, Spark Plugs/wires, Cat backs, Exhaust...etc

Moderators: daewoomofo, Moderators Group

Locked
MMamdouh
Moderator
Posts: 7299
Joined: Wed Feb 18, 2004 8:33 am
Location: Cairo, Egypt
Contact:

injector spray timing

Post by MMamdouh »

i was watching an animation for a 4 stroak engine and noticed that the injectors spray fuel while the intake valve is closed... actually the timing of the spray was almost identical to the spark time... is that correct??

i am under the impression that the injector sprays fuel as the intake valve is beeing opened, this way the fuel gets distributed on the intake charge... or this is what i was told.

in the animation i could see the fuel sitting still in the intake mani and then the piston sucks the air in with the fuel... not sure if this is the best fuel mixing technique or not but that was the way in the animated video.

is their any particular reason for that timing - during the spark - or is it just a spray while the intake valve is closed... also why should the spray be at the closed valve? isn't the "spray in the intake charge" better as far as even air/fuel mixture is concerned?

need advice to fully understand how this works.

MMamdouh
Driving is the utmost fun you can have with your pants on!
Check out my ride: http://www.cardomain.com/ride/567267
Image
exist3nce
Expert
Posts: 1233
Joined: Mon Oct 25, 2004 2:24 am
Location: Toronto, Canada

Re: injector spray timing

Post by exist3nce »

MMamdouh wrote:i was watching an animation for a 4 stroak engine and noticed that the injectors spray fuel while the intake valve is closed... actually the timing of the spray was almost identical to the spark time... is that correct??

i am under the impression that the injector sprays fuel as the intake valve is beeing opened, this way the fuel gets distributed on the intake charge... or this is what i was told.

in the animation i could see the fuel sitting still in the intake mani and then the piston sucks the air in with the fuel... not sure if this is the best fuel mixing technique or not but that was the way in the animated video.

is their any particular reason for that timing - during the spark - or is it just a spray while the intake valve is closed... also why should the spray be at the closed valve? isn't the "spray in the intake charge" better as far as even air/fuel mixture is concerned?

need advice to fully understand how this works.

MMamdouh

I think the animation might be wrong. To my understanding it should spray during the intake stroke as the air is getting sucked in. Can you post the link?
Daniel
Expert
Posts: 1298
Joined: Mon May 03, 2004 8:28 am
Location: Belgium

Post by Daniel »

Maybe a path. At 3000rpm the intake stroke time (half a turn) is in theory 10 millisecond. This could be too fast for our low pressure fuel injection system to spray the correct amount of fuel. So the fuel is sprayed early and the mix is ready to be sucked. And it came even worst at higher rpm when the engine need more fuel.

Read this article http://www.babcox.com/editorial/cm/cm59726.htm to see the evolution. Our Daewoo's are half way between carburetor and direct fuel injection.
And mine is even before mid point with a semi-sequential EFI: injectors are fired in pair 1-4 & 2-3 :( .

Sorry not answering better.

Daniel
MMamdouh
Moderator
Posts: 7299
Joined: Wed Feb 18, 2004 8:33 am
Location: Cairo, Egypt
Contact:

Post by MMamdouh »

exist3nce: will post a link to the vid when i get back home.

Daniel: sounds logical to me.

MMamdouh
Driving is the utmost fun you can have with your pants on!
Check out my ride: http://www.cardomain.com/ride/567267
Image
barmanjay
Posts: 7
Joined: Sat Aug 19, 2006 8:48 pm
Location: calgary, ab
Contact:

Post by barmanjay »

That sounds about right

some earlier gm 2.0's were TBI - throttle body injected, much like an 84 corvette

a carbeurator style TB ontop of the intake plenum with a single large injector ontop of the TB spraying fuel onto the butterfly of the TB. the 84 vette had dual TB's with injectors on them.

The theory is the same,.. spraying on a closed valve and when it opens the air mixes and sucks it in.

Slightly better but still 'old technology'

gm's new turbo 2.4 ecotec is usinig a direct injected fuel system, where the injectors are injecting directly into the cylinders.
MMamdouh
Moderator
Posts: 7299
Joined: Wed Feb 18, 2004 8:33 am
Location: Cairo, Egypt
Contact:

Post by MMamdouh »

here is the link to the vid, 14.6MB

http://www.megaupload.com/?d=YELLZFHS

MMamdouh
Driving is the utmost fun you can have with your pants on!
Check out my ride: http://www.cardomain.com/ride/567267
Image
Slammed
Expert
Posts: 836
Joined: Sun Jun 20, 2004 10:02 pm
Location: CT USA

Post by Slammed »

Locked