injection angles

[ericemir]

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..

Same story of my LNF, I am just sharing what I did that removed about 90% of my total knock. I repositioned my knock sensors so that the pig tail was at the 9'oclock position and knock went from 4-5 degrees to 1 - 2 in literally 2 or 3 cells compared to almost every damn cell I hit above idle.

[gmtech16450yz]

Ok so my buddy rethought his calculations and realized there's no reason to divide by 2. He explained it to me and it actually made sense, so I'm trusting his formula, until somebody else tells us we're doing this totally wrong! (Which is quite possible.)

So, these are the numbers I come up with at 7k rpm...

6 m/s injects for 252 degrees
8 m/s injects for 336*
10 m/s injects for 420*

Holy cr@p that changes things a little bit! That means if you start injecting at the stock 360* point, and your injection time is 6 m/s, at 7k rpm your injection will stop at 108* before TDC. If your ign timing is around 25*, that gives enough time for the fuel to fully atomize before the spark fires. This proves out in real life because we know 6 m/s runs great at 7k rpm.

If your injection time is 8 m/s, start time is 360*, at 7k your stop time is now 24* BTDC. Hmmm, looks like we might be spraying fuel on our spark?

If your injection time is 10 m/s, start time is still 360*, at 7k the stop time is 60 degrees AFTER TDC! So we've sprayed fuel all the way through our spark time, and down into the power stroke. How could it possibly run right? We know this in real world results because 10 m/s WILL result in massive injection window misfires.

Even if you max out the injection angle table at 431*, a 10 m/s injection time will STILL have the injector closing at around 10*BTDC. Not too good if you're trying to run your ign timing at 25* BTDC huh? And we haven't even talked about what that effect that chamber pressure does to the injector fuel pressures. It's no wonder we're getting the high side pressures up around 3k psi for everything to work right. This also proves what we (or at least I) have known for a long time, E47 is the ONLY way to run an LNF. Not E10, and CERTAINLY not full E85.

Lemme know if any of you guys see something wrong with these calculations. I'm no math expert, and some of this stuff is over my head. I'm more of a real world guy than a theorize and calculate guy! Most of these numbers are just proving out what we've been figuring out on the streets and dyno's anyway. At least it gives value to what we've already known or guessed was happening.


BTW, I just did this log this morning, I thought I'd throw it on here to show why they're using EFR turbo's on the Indy cars...



Look at the friggin boost line! It's damn near vertical! It looks like from when I went full throttle (pedal) to when it hit 28.5 psi took about 300 m/s. The throttle wasn't even fully open yet. I think it was over 25 psi when the throttle was only at 80 or 90%. What a crying shame that these turbos have been so hard to get. It would be so awesome to have dozens more of these on LNF's. Going from no boost to 30 psi in about half a second is pretty amazing.

[|V3nom|]

This also proves what we (or at least I) have known for a long time, E47 is the ONLY way to run an LNF. Not E10, and CERTAINLY not full E85.

what if e10 is all i have, am i just SOL?!?!?!

[cobaltssoverbooster]

Precisely sol

[gmtech16450yz]

Interesting study here...
http://www.eurojournals.com/ejsr_25_2_05.pdf

The study was done on Hydrogen fuel, but the data is very relevant to what we're talking about here. They mentioned the interaction between injection timing and ign timing, and the fact that power drops off significantly when it's injecting too close to the spark event. That's what we're seeing as "Injection window misfiring". Nice to see the efficiency differences other than getting too close to the spark event were not that big. I was wondering if keeping the injection time retarded closer to the spark event was better for mpg's, like around freeway cruise areas. There's so little fuel required at freeway cruise that the injection duration isn't an issue like it is at WOT. Anyone do a lot of freeway commuting that wants to experiment with injection angles and mpg? Dammit Tom (Iambroke) why did you sell that Cobalt?!!! Oh, that's right, you got a bad@ss Camaro instead.

[cobaltssoverbooster]

to bad that camaro is not a v8 lnf twin turbo that would be beast

[Iam Broke]

snip... Dammit Tom (Iambroke) why did you sell that Cobalt?!!! Oh, that's right, you got a bad@ss Camaro instead.

Thought I quit lurking around here didncha? lol.

[oldskool]

This has been another great read - thanks to all who contribute to threads like these!

[projectlnf]

yeah thats all i have is e10... but i am spraying meth... lol thanks to everyone who has helped me out with this im going to try and do some testing with this.


i kind of did the other day and i noticed when i get up high in rpm i miss fired because i had my injection angle to far forward.



ericemir- i have had mine clocked at 9 oclock for around 2 months now so i dont know whats going on.. no miss fires but i get knock in a couple cylinders and then timing gets about 15* and it just vanishes immediately

[projectlnf]

well i have been fooling around with these tables a bit and i have noticed when you advance your timing and you get a little bit of knock you can take the injection angle and make it sooner and it will get rid of most of the knock im still in the process of playing with these tables, im doing it little by little. and i did notice that the tables in the high rpm's DO NOT like to be adjusted it miss fires like crazy lol.

[rnjmur]

Ok so my buddy rethought his calculations and realized there's no reason to divide by 2. He explained it to me and it actually made sense, so I'm trusting his formula, until somebody else tells us we're doing this totally wrong! (Which is quite possible.)

So, these are the numbers I come up with at 7k rpm...

6 m/s injects for 252 degrees
8 m/s injects for 336*
10 m/s injects for 420*

Holy cr@p that changes things a little bit! That means if you start injecting at the stock 360* point, and your injection time is 6 m/s, at 7k rpm your injection will stop at 108* before TDC. If your ign timing is around 25*, that gives enough time for the fuel to fully atomize before the spark fires. This proves out in real life because we know 6 m/s runs great at 7k rpm.

If your injection time is 8 m/s, start time is 360*, at 7k your stop time is now 24* BTDC. Hmmm, looks like we might be spraying fuel on our spark?

If your injection time is 10 m/s, start time is still 360*, at 7k the stop time is 60 degrees AFTER TDC! So we've sprayed fuel all the way through our spark time, and down into the power stroke. How could it possibly run right? We know this in real world results because 10 m/s WILL result in massive injection window misfires.

Even if you max out the injection angle table at 431*, a 10 m/s injection time will STILL have the injector closing at around 10*BTDC. Not too good if you're trying to run your ign timing at 25* BTDC huh? And we haven't even talked about what that effect that chamber pressure does to the injector fuel pressures. It's no wonder we're getting the high side pressures up around 3k psi for everything to work right. This also proves what we (or at least I) have known for a long time, E47 is the ONLY way to run an LNF. Not E10, and CERTAINLY not full E85.

Lemme know if any of you guys see something wrong with these calculations. I'm no math expert, and some of this stuff is over my head. I'm more of a real world guy than a theorize and calculate guy! Most of these numbers are just proving out what we've been figuring out on the streets and dyno's anyway. At least it gives value to what we've already known or guessed was happening.


BTW, I just did this log this morning, I thought I'd throw it on here to show why they're using EFR turbo's on the Indy cars...



Look at the friggin boost line! It's damn near vertical! It looks like from when I went full throttle (pedal) to when it hit 28.5 psi took about 300 m/s. The throttle wasn't even fully open yet. I think it was over 25 psi when the throttle was only at 80 or 90%. What a crying shame that these turbos have been so hard to get. It would be so awesome to have dozens more of these on LNF's. Going from no boost to 30 psi in about half a second is pretty amazing.

This all sounds right to me. Dividing by 2 doesn't make any sense mathmatically unless you are using 720 degrees for your calculation (which you could also do).

[|V3nom|]

can the injection angles help with low-mid rpm knock? seems like i get knock just from driving around town. also when i rev it a little from a stop while idling it knocks like 1.4. can injection timing save the day?!

[cobaltssoverbooster]

move it and find out

[|V3nom|]

ill have to try it out and see if it works.

[|V3nom|]

can anyone explain what each table in the fueling section is for? id like to start trying them out to work on a knock issue but the explanation that hpt gives for each is far from concisive. i have no idea what a hom or what its for lol.

[|V3nom|]

no answer? are there any books, software, etc that explain what this stuff is and how to use it?

[|V3nom|]

how about an explanation for each part individually.

[projectlnf]

sorry i have been extremly busy with work.. but i just got back into tuning my lnf cuz i strated to see knock when it was colder outside but ill see what i can do with these injection angles and let ya know

[projectlnf]

bringing this thread back!!

wondering when hom double intake kicks in? anyone know??

[projectlnf]

ok so i have got alot of mine moved now and it seems to pull waayyyy better with my cam adjustments and timing advance its crazy how hard this thing pulls up to redline and it just holds it and keeps going with it.