Direct Injection Systems

[SpdFreak]

Subscribed (2thumbs)

 

[ericrapp]

Very interesting Ziggo thank you for the insight!

 

[trufanatic]

Sticky!

 

[tru-boost]

Injector duty cycle is [SIZE=-1]the percentage of time the injector is supplied with power.

Injector pulse width is [/SIZE] the time during which the injector is powered.


Explanation

if this is the case and our cars are at 45% duty cycle they are MAXED !
a DI car can only inject through about half of the combustion cycle. that would not be good news. sure if you up the fuel pressure you can get more fuel into the motor in the same amount of time, but that is only good for so much.

for the AFR itis also true that what is considered dangerously lean on most cars is not that bad on a DI car. because of the way the injection works and the fact that the injectors dont spray non stop the car is much less likely to detonate. 13 even 14:1 is scary on a normal injection car, but in all honesty it isnt scary on a DI engine. i would still take comfort with a 12:1 on my street/strip car though.

 

[dparm1984]

Well I don't know if all of that holds true for GDI...but I know if an injector is running at more than 80% duty cycle it will perform poorly and wear out fast.

 

[dkswim]

europen car has the lean burn. has something to do with better quality of gas, and when you burn lean a certin type of emision goes up but with the cleener fuel and diffrent type of cat it ends up clean

 

[killerMS3]

Very interesting Ziggo thank you for the insight!

+1

 

[Ziggo]

europen car has the lean burn. has something to do with better quality of gas, and when you burn lean a certin type of emision goes up but with the cleener fuel and diffrent type of cat it ends up clean

When you run lean the excess oxygen combines with the prevalent gas in air, nitrogen, and forms various nitrogen oxides, which are the main precursor to smog. The Europeans have a special catalytic converter capable of breaking down the NOx, but it gets fouled by sulfur. The US used to have lower (higher parts per million allowed) sulfur standards for gasoline than Europe, but I don't know if this is true anymore. I know the diesel standard was recently increased significantly, but don't know about gasoline. Running lean reduces power output, fuel consumption and thus CO2 emissions but CO2 is really a non issue, despite what the hysterical environmental weenies would have you believe. NOx (nitrogen oxides) however do cause smog, which leads to a number of respiratory health problems not to mention atheistics.

 

[RXMmazdaspeed]

subscribing for when i have a little more time.....
looks like a lot of good info just breezing through it real quick. thanks.

 

[Mid_Life_Crisis]

NOx (nitrogen oxides) however do cause smog, which leads to a number of respiratory health problems not to mention atheistics.

NOx leads to not believing in God?

 

[dparm1984]

I think he meant aesthetics, lol.

 

[mrlilguy157]

lol. ya'll are crazy. i like all the input now. sorry, I haven't been browsing this forums lately.

I'm impressed with Ziggo.... looks like he's done a bit of research too.

 

[Mid_Life_Crisis]

I think he meant aesthetics, lol.

I knew what he meant. I just couldn't resist being a wiseass.
Of course I can't help but be reminded of the old joke about the dyslexic, agnostic, insomniac who lies awake at night wondering if there is a dog.

Apologies for the threadjack. I'll stop.

 

[dkswim]

the europen cars dont lean burn all the time it is only during low load conditions like say idling, crusing down the road, and decellarating times when you dont need the fuel to aid in cooling.

 

[Ziggo]

I knew what he meant. I just couldn't resist being a wiseass.
Of course I can't help but be reminded of the old joke about the dyslexic, agnostic, insomniac who lies awake at night wondering if there is a dog.

Apologies for the threadjack. I'll stop.

I deserved it, spellcheck!=correct *smacks head*

 

[matsuda]

Sigh...

Lots of confusion here!

I've said it before and I'll say it again:

Lean burn (or stratified charge) mode does NOT apply to the Mazda DISI engine. This engine NEVER uses a A/F ratio leaner than stoichiometric under any steady operating condition (cruise, idle, etc.)

As far as A/F ratios are concerned, think of this engine no differently than you would a port inected engine. If anything, the cooling effect of the direct injection may allow for a SLIGHTLY leaner A/F ratio under some operating conditions but that's about it.