injection angles

[projectlnf]

sorry if i sound dumb but i have been reading up on direct injection, and i was seeing that we can make alot more power with changing the injection angle at what our injectors start to open and i was just wanting a little more input.


1- has anyone tried to mess with these
2- is the how is the angle determined ( is it 240 degrees from tdc?)

those are my main questions i was just curious after i read a document on

http://www.hotrod.com/techarticles/e...e/viewall.html

[cobaltssoverbooster]

Iirc the numbers are based of of a 720* rotation with 360 being tdc compression

[projectlnf]

Iirc the numbers are based of of a 720* rotation with 360 being tdc compression

have you tried messing with them at all? im sure we can make a little bit of hidden power in those tables. and i was wondering if our motors do get alot of fuel knock. would we be able to reduce that by telling the injector to open later?

[cobaltssoverbooster]

have you tried messing with them at all? im sure we can make a little bit of hidden power in those tables. and i was wondering if our motors do get alot of fuel knock. would we be able to reduce that by telling the injector to open later?

Yea mine aren't stock. The usual change is to help the car get fuel up top.

[projectlnf]

Yea mine aren't stock. The usual change is to help the car get fuel up top.

i see and is that just if you are leaning out? main reason im asking is because i see alot of knock mid range.. but once i hit probably around 4500rpm or higher it goes away? and i have noticed that the fuel angle starts early down in those rpms? i was maybe thinking its fuel knock..

[cobaltssoverbooster]

with big turbo or full e tunes we tend to not neccessarily run out of fuel but what happens Partially is that the injection window is too small for the application thus once you hit maximum window the injectors get held open. this makes a puddle in the cylinder and causes missfires that dont register codes but are definately noticable by ear and feel.

this by all means does not always fix the situation but it does help some.
remember because of the direct injection fuel will not be sprayed during the exhaust stroke and most of overlap. the fuel would be dumped straight into the exhaust in that case.

[projectlnf]

with big turbo or full e tunes we tend to not neccessarily run out of fuel but what happens Partially is that the injection window is too small for the application thus once you hit maximum window the injectors get held open. this makes a puddle in the cylinder and causes missfires that dont register codes but are definately noticable by ear and feel.

this by all means does not always fix the situation but it does help some.
remember because of the direct injection fuel will not be sprayed during the exhaust stroke and most of overlap. the fuel would be dumped straight into the exhaust in that case.

ahhhh i seeee so mainly it is used for E tunes

[cobaltssoverbooster]

Sorta yea it's used for minor fuel flow issues

[gmtech16450yz]

As far as the injector timing tables go, zero is TDC compression. 360 is TDC between exhaust and intake strokes. The lowest numbers, 240 would be late injection, 120 degrees down the intake stroke.

Put all the cells in those tables at 240 and you'll be able to see and feel what injection window misfires are all about. I guaranty if you put 240 in the high rpm, high load cells you'll get injection window misfiring. Put 240 in the entire table and the entire rpm range will feel and run like cr@p.

The max value you can put in those tables is 431. That would be 71 degrees BEFORE TDC between the exhaust and intake strokes. That's as far as you can go when trying to get more fuel in at high rpm's with E85 and/or big turbos. You really need to watch where your exhaust cam timing is though since you'll be starting injecting when both the intake and exhaust valves are open. (re-read that, this is complicated chit!)

As I've said before, these tables ALL INTERACT. If you're advancing the cr@p out of your ign timing and cam timing tables, you need to work on the injection timing tables also. For the most part, if you want to be lazy, you'll have the best luck by raising the numbers in the injection timing tables. There's almost no reason to lower them with the fuels and mods most of us are doing. In other words, it's not too likely that you're gonna want your injection start to be later than stock.

Here's another little tidbit to drive you guys crazy... Many of you are having A/C on idle issues. Part of the solution is getting enough airflow in the cells that are active when the A/C is on, but another factor is the injection timing. Put 240 in the cells around where the A/C runs and see how badly it idles and surges. Hint- 360 is a nice number for E47/E85 tunes in those particular cells. A/C idle CAN be made as smooth as A/C off idle. And you CAN tune it so turning the A/C on and off is not even noticeable. It just takes time to get the happy balance between ALL these tables.

[cobaltssoverbooster]

I was off by 360....been a while

[projectlnf]

As far as the injector timing tables go, zero is TDC compression. 360 is TDC between exhaust and intake strokes. The lowest numbers, 240 would be late injection, 120 degrees down the intake stroke.

Put all the cells in those tables at 240 and you'll be able to see and feel what injection window misfires are all about. I guaranty if you put 240 in the high rpm, high load cells you'll get injection window misfiring. Put 240 in the entire table and the entire rpm range will feel and run like cr@p.

The max value you can put in those tables is 431. That would be 71 degrees BEFORE TDC between the exhaust and intake strokes. That's as far as you can go when trying to get more fuel in at high rpm's with E85 and/or big turbos. You really need to watch where your exhaust cam timing is though since you'll be starting injecting when both the intake and exhaust valves are open. (re-read that, this is complicated chit!)

As I've said before, these tables ALL INTERACT. If you're advancing the cr@p out of your ign timing and cam timing tables, you need to work on the injection timing tables also. For the most part, if you want to be lazy, you'll have the best luck by raising the numbers in the injection timing tables. There's almost no reason to lower them with the fuels and mods most of us are doing. In other words, it's not too likely that you're gonna want your injection start to be later than stock.

Here's another little tidbit to drive you guys crazy... Many of you are having A/C on idle issues. Part of the solution is getting enough airflow in the cells that are active when the A/C is on, but another factor is the injection timing. Put 240 in the cells around where the A/C runs and see how badly it idles and surges. Hint- 360 is a nice number for E47/E85 tunes in those particular cells. A/C idle CAN be made as smooth as A/C off idle. And you CAN tune it so turning the A/C on and off is not even noticeable. It just takes time to get the happy balance between ALL these tables.

thank you man

yeah i kinda noticed a big drag down when i turn my ac on and every now and then the timing would shoot up and then drop back down its weird but im still working with optimum spark tables im freustrated with those so i will changed them one day and get frustrated and then leave them alone for a day or two lol

[projectlnf]

and i forgot to mention cuz i dont know alot about the injections terms. what does each table mean for instance the

HOM SINGLE LOW- when does this com into play
HOM SINGLE HIGH- same thing when does it come into play


HOM DOUBLE INTAKE AND THE DOUBLE COMP.

i know the double intake and double comp is used when the injector is sprayed 2 times during the stroke. but how do we know which ones to use to get more fuel at the top of the rpm.


basically i just want to know what the terms mean and when it comes into play. i have never really dealt with any of this as im normally tuning subarus and i never had access to the injection times or double intake

[gmtech16450yz]

I was off by 360....been a while

No problem, some of these numbers can drive you crazy anyway! At one point I kept thinking "why is 360 earlier than 240?" It makes sense when you realize it's how many degrees BEFORE TDC. I don't know why I even wondered about that, it's just like ign timing after all. Duh. If this stuff doesn't make your head hurt sometimes you're just weird.

Here's one for the math experts or Engineers out there (Tom, where are you?)...

Can somebody do the math on how many milliseconds equals how many crank degrees on our motors at a certain rpm? If somebody can figure that out, then we could do the actual math on when the injection needs to start for the specific injector pulse width and rpm we're running at. That's not a difficult problem, the information to figure it out is out there, I'm just not very good at math like that! I want somebody to tell me at 7000rpm / 7ms injector on time equals X amount of crank degrees. If we knew that, we'd know EXACTLY when the injection STOPS, which for us working with Direct Injection is as important, if not more important than when it starts.

(I figured I'd bold that so it's easier for somebody to notice it and figure it out!) Like I mentioned with experimenting with putting 240 degrees in the injection angle tables causing massive misfiring, changing the start time is the reason but it's actually the STOP time that causes the misfiring. Here's my hypothetical numbers and what I'm hoping to get a better grasp on- If you open the injector at 240 degrees, and at 7k rpm it takes 6ms for the piston to move 120 degrees, that means in that situation the injection STOP time would be around 120 degrees, or 60 degrees INTO the compression stroke. Make sense? If those numbers were correct (which they're not since I made them up!), we would then know that we'd need to START the injector opening at about 300 degrees to insure the injection would STOP around BTD or 180 degrees.

Which leads me to another question, why are the injection angles so early at idle? I know from experimenting that it runs WAY better with them early, but it doesn't really make sense to me why that would be.

Lol, I bet you guys never saw me ask so many questions and not be able to understand so many things!

[projectlnf]

No problem, some of these numbers can drive you crazy anyway! At one point I kept thinking "why is 360 earlier than 240?" It makes sense when you realize it's how many degrees BEFORE TDC. I don't know why I even wondered about that, it's just like ign timing after all. Duh. If this stuff doesn't make your head hurt sometimes you're just weird.

Here's one for the math experts or Engineers out there (Tom, where are you?)...

Can somebody do the math on how many milliseconds equals how many crank degrees on our motors at a certain rpm? If somebody can figure that out, then we could do the actual math on when the injection needs to start for the specific injector pulse width and rpm we're running at. That's not a difficult problem, the information to figure it out is out there, I'm just not very good at math like that! I want somebody to tell me at 7000rpm / 7ms injector on time equals X amount of crank degrees. If we knew that, we'd know EXACTLY when the injection STOPS, which for us working with Direct Injection is as important, if not more important than when it starts.

(I figured I'd bold that so it's easier for somebody to notice it and figure it out!) Like I mentioned with experimenting with putting 240 degrees in the injection angle tables causing massive misfiring, changing the start time is the reason but it's actually the STOP time that causes the misfiring. Here's my hypothetical numbers and what I'm hoping to get a better grasp on- If you open the injector at 240 degrees, and at 7k rpm it takes 6ms for the piston to move 120 degrees, that means in that situation the injection STOP time would be around 120 degrees, or 60 degrees INTO the compression stroke. Make sense? If those numbers were correct (which they're not since I made them up!), we would then know that we'd need to START the injector opening at about 300 degrees to insure the injection would STOP around BTD or 180 degrees.

Which leads me to another question, why are the injection angles so early at idle? I know from experimenting that it runs WAY better with them early, but it doesn't really make sense to me why that would be.

Lol, I bet you guys never saw me ask so many questions and not be able to understand so many things!

actually i have never seen you ask that many questions lol ive always gone by what you and CBSSOB has said and played around with my tables a little cuz i know every engine is different so obviously i have to play around with them a little.

looks like i brought up a good thread!

i know my main thought on these injection angles were to get rid of fuel knock (which i have heard these engines have alot of if we start tuning big numbers)

id love to see tom come up with some way of telling us how to do this and maybe we can even get a histogram to show us when they open and when they close.. ( doubt that because it happens so quick lol) but it could be possible with some math and alot of time im guessing?

[gmtech16450yz]

and i forgot to mention cuz i dont know alot about the injections terms. what does each table mean for instance the

HOM SINGLE LOW- when does this com into play
HOM SINGLE HIGH- same thing when does it come into play


HOM DOUBLE INTAKE AND THE DOUBLE COMP.

i know the double intake and double comp is used when the injector is sprayed 2 times during the stroke. but how do we know which ones to use to get more fuel at the top of the rpm.


basically i just want to know what the terms mean and when it comes into play. i have never really dealt with any of this as im normally tuning subarus and i never had access to the injection times or double intake

http://www.hptuners.com/forum/showth...865#post249865

Post 14 in case it doesn't go right to it. Basically Chris told us it only uses the Hom Low table. I've seen the high table tuned though, not sure why. I've never experimented to see which one it actually uses. It would be easy enough, putting 240 in the whole table is VERY obvious when you drive it. Put 240 in the low table, then the high table and that would tell us which one it uses. I just never bothered to do that. What I did is combined the two, taking the more advanced or higher numbers from both, then making that combination table both high and low.

[gmtech16450yz]

My buddy here at work helped me figure this out!

Take rpm, divide it by 2. (EDIT- DO NOT divide by two.) This gives the number of injection events for one cylinder.
Multiply that number by 360 (degrees)
Then divide by 60,000 to convert revolutions per minute to revolutions per millisecond.
This number equals degrees per millisecond.
Multiply this number by your injector pulse width and you'll get the amount of crank degrees that the injector is spraying. Hopefully! lol.

This is what I came up with in some real quick calculations...
At 7000rpm-
6 millisecond injector pulse width injects for 126 degrees.
8 m/s injects for 168*
10 m/s injects for 210*.

This is what I wanted to see. Now we can figure out EXACTLY where in the piston travel the injection has to STOP to avoid injection window misfires. Stock injection angle (start time) at high load, high rpm is 360*. 6 m/s is ok at 7000rpm, 10 m/s is not. My initial guess at this is we need to make sure the injection STOPS somewhere around 180* or BDC. Could it be that simple? You simply don't want to have an injection happening into when the piston is on it's way back up?

More thinking needed, I'll let my brain cool off for awhile and think about this again later!

[cobaltssoverbooster]

I usually just help people get started safely instead of teach ing the complicated stuff, hence I was off 360 its been a while since I've helped with the advanced stuff. I still read to keep current though.

[projectlnf]

My buddy here at work helped me figure this out!

Take rpm, divide it by 2. This gives the number of injection events for one cylinder.
Multiply that number by 360 (degrees)
Then divide by 60,000 to convert revolutions per minute to revolutions per millisecond.
This number equals degrees per millisecond.
Multiply this number by your injector pulse width and you'll get the amount of crank degrees that the injector is spraying. Hopefully! lol.

This is what I came up with in some real quick calculations...
At 7000rpm-
6 millisecond injector pulse width injects for 126 degrees.
8 m/s injects for 168*
10 m/s injects for 210*.

This is what I wanted to see. Now we can figure out EXACTLY where in the piston travel the injection has to STOP to avoid injection window misfires. Stock injection angle (start time) at high load, high rpm is 360*. 6 m/s is ok at 7000rpm, 10 m/s is not. My initial guess at this is we need to make sure the injection STOPS somewhere around 180* or BDC. Could it be that simple? You simply don't want to have an injection happening into when the piston is on it's way back up?

More thinking needed, I'll let my brain cool off for awhile and think about this again later!

ok so just trying to get some math down and how we can figure out exactly how long our injectors are open.. ive been looking at the fueling tables i see that the INJ PULSE MULTIPLIER is increasing our injection time right?

im only guessing this because at 6ms at 6500 rpm the multiplier looks like it is increasing the time its open if my math is right. if you do the math up above for 6500/2=3250*360=1,170,000/60,000=19.5... now if im right i would multiply this by the 0.9574585 in the inj pule multiplier table correct? cuz that equals 18.6704408... is that the crank degrees the injector is open for?

[cobaltssoverbooster]

Mind blown u lost me

[projectlnf]

Mind blown u lost me

lol i have been mind blown since i started to "TRY" to figure this out!

its some crazy math that i have gotten myself into.

but if we can get this down we might be able to get the injection windows closer, stop fuel knock, and then once someone does come out with a new injector for these cars tune for those! better to start early than trying to figure it out all in one day!

another thing i was wondering... i have scaled my load axis in most of my tables to fit the load im actually pulling. like the load in most tables only go to 215 i have adjusted that to read 240's. but i wanted to ask with stock load axis being 215 and we actually hit above that.. does the ecu still go off of the 215 or does it compensate and adjust for higher load?