after some massive tuning on the fuel side this weekend, i got the duty cycle below 100% on the stock stage 2 stuff, no 2.8.

how? 100 octane.

running 10.7 a/f down low, up top, it was running 11.5 this is the only way i could get it below 100%

in short. gm's performance division sucks. point blank. how they warranty this is beyond me.

this was done on a dyno. 257 to the tire on the 3.1 pulley. just beware. to those running small pulley's on 42's. shift at 6500, or run the risk of locking the injectors, and suffering another post of "i blew my ****"

 

Nice numbers!

I assume this time is was a mustang dyno!

 

I have seen some S2 logs that would give you nightmares.

 

What does Octane have to do with your injectors duty cycle?

 

oh trust me, i have my own that makes me cry.


octane, being higher gives you the ability to run it leaner. leaner = less duty cycle.

 

Well...

Why couldn't you pull full back if you are tuning?

You don't need to run a 10 a/f or even 11 a/f...why did you think you needed higher octane just to go leaner? you could run 12s and be absolutely fine with a 3.1 inch pulley or even possibly 2.8 inch pulley if your IATs aren't as high (thinking that you don't need to run richer in order to cool down combustion chamber temperatures).

What was the air fuel ratio BEFORE you tuned it? What was the duty cycle BEFORE you tuned it?

 

Didn't y'all read the post that says that our A/F ratios need to be in the 11's to be safe?

 

In what condition though?

 

I still believe you are reading the numbers incorrectly.

Im digging as best i can to find the info i remember reading.

but it all just doesnt add up.
GM would be committing financial suicide by warrantying something running at 120IDC.
it just doesnt make any sense.
I also believe if we were truely running gm tunes at that IDC, we would have seen stage 2 cobalts popping engine parts.

to my knowledge we havent had 1 stock or GM stage 2 engine blow.

 

according to the tech 2, 2nd gear on my race map was 17.0 m/sec.


im going to finish my stage two stuff.

why did i run the race gas? protection, pure and simple. nothing more nothing less then that. i like to have a cushion under me when im doing some extreme things. plus with the timing i was running, it was good to have it.

also, something else that leads me to believe this is true. is the simple fact at 6700 rpms. the LM1 was doing a rocket launch from 11.4, to 12.2 at 7k rpms.

what does this tell me? the injectors can't handle it. this might be an isolated case, i shall find out tomorrow for sure. but i did try 3 different sensors. all the same results.

 

12.2 is not bad...

Stop thinking in the mind of "I need to run the same a/f ratio as everyone" and compare it to

- What are your IATs?
- How much timing are you running?
- What are your EGTs?

And an assortment of other factors.

You could be running 12s just for the fact that you might not NEED to run any richer.

Do you have an actual duty cycle %?

 

you're talking to me like i am new to tuning cars, or forced induction tuning.

maybe i am reading it wrong.

my way of tuning is usually the opposite of other people in general.

tuning is an art form. either you have it, and they call you van goh. or you don't have it, and call you a 3 year old with finger paints and a freshly painted white wall in moms kitchen.


im somewhere in the middle. every car is different, and must be treated as such. my tune on my car may not work on someone else's.

im not trying to come off as a dick, so please don't take it as such. just a long drawn out sleepless weekend so im a bit edgy.

i can post the logs later

 

I think I'm just not understanding the thread...i dont know

I'm tired.

 

Question: Say we're talking stage II and that's all, why can't we just run an adjustable FPR or something like that and accomplish our AFR needs that way?

Edit: I know injector size is very important and must be matched with your setup, but you don't need to go past a certain point either. There are many ways to solve the problem; which way would you suggest NJHK?

 

Why dont you just answer what adam asked you instead of trying to make a come back with it, he is asking you logical questions to try and help you.

 

Area47:

When are you shifting at? Are you seeing on the datalog that the AFR 12.2 occured at 7k possible just as you let off of the throttle? I'm just curious. If that's the case then that would be fine.

From what I see everyone in this thread is right so far. 11-12 AFR is a good starting point for a FI car and 12.2 AFR isn't bad, it just needs to be monitored.

IMHO, I wouldn't tune your car with the basis being to lower IDC because then you're having to change AFR to suit the injectors when it should be the other way around. IMO, I would select the proper injectors, and possibly even up the fuel pressure a bit to lower the IDC and then tune for the proper AFR with max power in mind.

Sorry if I am misunderstanding your post just giving my .02

Edit: I will like to see the datalog when you post it out of curiousity.

 

You can't run a Adjustable Fuel Pressure Regulator because you have a Return-less fuel system UNLESS you were to convert it over. Currently, your rail has no provisions for a Fuel Pressure Regulator and there is no line to return fuel back to the fuel tank.

Thank You

 

Ahh....dumb on my part...I'm still learning about this car, just got it a month ago. I should've known as the Cavalier ECOTECs were the same way, my bad.

 

Actually...

All J-bodies run with a Return Fuel System. They aren't returnless.

 

Maybe I'm missing the whole point of this, actually I'm sure I am but if your concerned about the IDC then why not just go with a larger injector to bring down your IDC?

 

I try to follow the S2 discussions since i have this installed on my car, sighlently - up until now. I have a suggestion: email GM directly about the IDC/AF Ratio/IAT temps.

http://www.gm.com/gmcomjsp/contactus/

I would do it, but i dont have the knowledge that you guys have. And 2, i dont have the ability to send readouts/logs/graphs that you guys with HPT do. Pin the tough questions to them. Ask them if they feel its a ticking time bomb. Ask them how they can warranty such items. Direct them to this site to express the concerns that people have. The worst that can happen is that you never get a reply back. Although that would be really bad for customer service. Just my .02

 

i plan on getting larger injectors.



the lean spike was at 6800.

iat's? 62 degree's. give or take a couple.

timing, stock gm timing. 25-26 degree's
egt's not a clue, dont have the gauge in the car yet.


sorry for my snappy post, going on a total of 6 hours of sleep in two days tends to make me a bit cranky

 

Just remember that More timing = Higher temps I would not run that much timing unless you have a hedder back exhaust without a cat.

 

whoa whoa......
25-26 degrees of timing on gm stock?

that doesnt sound right?

 

I did the same as you when I first got HPTuners. I got the injectors below 100% around a 12.0 A/F ratio. Thats a stock stage 2 pulley I/H/E and the 42 lb/hr injectors.
Its the fact that they run extrememly rich, go static and stay open and A/F ratio steadily climbs. What amazes me is the fact they designed Stage 3 with a 2.99" pulley, 8K possible rev limit and a dry 50 shot of nitrous, all with 42lb/hr injectors.
If you are talking about EGT temps, you got it backwards. More timing means lower temps. After you have A/F dialed in, you tune for knock with a pyro, when the pyro increases, its the PCM pulling timing and you know you have knock. Very useful on vehicles that you can't scan for knock with.