how much can the stock injectors take?

[kyle h.]

how far on the afc can i push the stock 450's? +1 or +2 obviously depending on rpm...

if this has been covered, please point me in the right direction. thanks

 

[BOBS90TURBO]

It depends on a lot of factors like what fuel pressure you are running etc...
And what do you have your mass set at, is it gutted, is the screw backed all the way out.


I have mine gutted(makes it run very lean) and I have a 255hp fuel pump with 6n fuel lines and an AFPR set at 45psi, I am not sure if it matters but I have a Big16g@17psi also and I have my afc highs set at +6 across and my lows at +45,+25,+15,+6,+6,+6,+6

With mine set at this, I get amost no knock(2 at most),I get good timing advance (22*),
my o2's are around 0.87v at WOT, and the most important thing(I think) is my INJP
(injection pulse) never gets over 20.00ms(I can hit 19.96ms) but thats under hard throttle

My fuel trims are
Low 117.9% (I can't figure this one out)
Mid 100.0%
High 97.6%

But remember every dsm reacts differant to sacf setting so make sure you use your logger and take your time, do not run it hard untill you have your setting nice and stoich.No knock. Check these sites out if you have not allready.

http://pocketlogger.com/index.php?pid=1gtech_trims

http://www.roadraceengineering.com/newafc.htm

 

[steve]

Bob,

You should look close at your injector duty cycle, at 6k you have 20ms total, at 7k you only have 17.1ms, at 7500 your at 16ms. If you consider 80% DC the safe max then the max injector pulse width at 6k would be 16ms, 13.7 at 7k, and 12.8ms at 7500.

Remember once you hit 100% DC there isn't any more fuel to be had at that FP.

Kyle,
On a 1G the 450's are pretty much maxed out at the stock fuel pressure with about 13-14psi boost. The SAFC can't magicly turn your 450s into something else. Get a datalogger and watch your Duty Cycle that's how you'll know when your done.

Steve

 

[kyle h.]

so the best way to exploit the stock injectors would probably be to increase the fuel pressure. right?


yesterday i was messing around with them, and increased them by +1 on the high throttle setting and my high fuel trim actually went leaner. so i put em back and im rocking it lean for a while.

but i am running 17psi, 2gmas, stock fuel/turbo/etc... and im pulling 20* usually. 3 counts of knock.

 

[antero]

The stock 450cc injectors on 1G AWD turbo cars are running *lower* than rated fuel pressure. Because of the reduced fuel pressure, this makes the 450cc injectors more like 410cc injectors. Buy a fuel pressure regulator and bump it back up to 43.5 psi to get your 450cc rating, or bump up the fuel pressure more to make them equivalent to 500cc.

Here's a calculator for you figure out what target fuel pressure you need to do this.
http://www.stealth316.com/2-air-fuel-flow.htm

 

[Blue92]

I've seen a guy make 340 horse at the wheels with stock injectors and a adj fpr.

 

[kyle h.]

i think im going to get an afpr first, since they are cheaper, a used b&m one or something, i already have a gauge. cold evenings i dont get much if any knock, while on hot days i get up too 27 counts.

im using a 1g with the 2g mas, but i would like to get 550s, to pull my afc % back down, so i can get better timing

make sense?

 

[kyle h.]

p.s. my settings on the afc are....

low thr: +18% @ 1000rpm, +17% @ 1800 rpm, and then a faster decrease to +6% around 3000rpm.

high thr: +7% up to 3000rpm, +13% @ 4000 and so on, ending with 18% @ 7000rpm.

max d/c i've seen with this setup was 106%

3rd & 4th gear pulls on a cool even i was at 93% at the last WOT rpms.

I think if I up the fuel pressure it will allow me to run better (less knock) during the hot days.