24 or 26lb injectors?

[awesomeame]

2002 L36/M5 camaro...

hit the dyno today since my winter mods...last year i got 177.5 hp on only exhaust, and i've since installed a lid & cam 210/210 .507/.507 111ls 107ic and today i dynoed 193hp [img]graemlins/bs.gif[/img]

pulled the air filter out & dynoed 180hp. so the dyno guys said i'm obviously running way lean, 'cause i'm allowing more airflow and the injectors just can't keep up to the added airflow. the graph gets all bumpy from 4500rpm up, but is smooth from 0-4500.

so what size injectors should i get? LT1 24 lbs or LS1 26lbs? (if those numbers are wrong correct me) both the lt1 & ls1 injectors will fit my current intake/fuel rail right?

help

--matt

[Timmy]

they will both fit your rail and i would say go with the 26. I have the 24lb with a 210/220 512/512 @115 lsa and im starting to run a little lean too.

[awesomeame]

any ideas if our stock computer handle the 26lb injectors?

--matt

[Timmy]

it might run rough for the first day, but it will adjust itself.

[awesomeame]

no offense timmy [img]smile.gif[/img] but anyone else have an opinion on this?

--matt

[Zooomer]

On our stroked GT putting down 248WHP NA we run the 24 pounders which we tested and they flowed 24.9 actual. We then use a mini-AFC to dial in the AF.

[Nachius]

Some LS1s have 28.8 # injectors, If you have a way to fully tune I don't see how the bigger injectors would actually hurt?

[Turbo V6 Camaro]

nah go with 57# you know plan for the future ;)

i would say 26, that will alow for a little shoot off go go jusice or little boost

[OneQuickV6]

Go with the LT1 if you have to have one or the other. The LS1 has a different connector as I recall. And some LS1 injectors had 28.8# some had 26.4#. The PCM will try to take care of some of it, but on this big of a jump, it will still be pig rich. A tune would be a good addition to either injector.

[AllTheGoodNamesAreGone]

wow.. 193 huh? I dunno.. I dont think you need new injectors..

I would try tuning the beast before you go any further..

what was yoru AF?? what was your injector pulse rate?? are you getting knock??

have you upgraded your fuel pump?

injectors IMO are the wrong way to go.. I dont belive for a second that you are maxing the stockers out with that setup..

I would also try and trouble shoot some stuff too..

becuase I made 197 HP with a lid, headers, exhaust, and rocker arms..

[John_D.]

I would agree. Typically a jagged dyno line indicates a lean condition, but not necessarily. You need to know the actual a/f ratio.

And even if you were lean, it is just as likely (maybe more) to be fuel pump pressure falling off, as it is to be the injectors maxing out.

LS1 28.8's, at LS1 pressure, are about the same as 24's when running at our pressure.

I run Accel 24's. Getting the idle so it's not way rich was a problem. 26's would be even more difficult. If you can get some tuning, then maybe...

I am probably around 250rwhp with the blower. (I say probably because I was a bit over 230rwhp running way lean at 16:1 and 17:1 a/f, and solved that problem, but haven't dyno'd it again) I'm getting by on 24's, although I am boosting the fuel pressure a bit too with the fmu and the kenne-bell boost-a-pump.

Ideally you need to know fuel pressure (4500-6000 rpms), o2 voltages and/or wideband a/f ratio, and injector pulsewidths, in order to come up with a solution.

[awesomeame]

o2 voltages are ~830 millivolts with the pulsewidths hitting around 20-22ms. i have no idea on the fuel pressure...thanks for the input guys!

btw, the only wideband o2 guys even remotely near me are agostino racing engines, and they "don't have the software to support your vehicle" :(

--matt

[1998silverbird]

I have 24lb injectors and 28 lb LS1 injectors for sale if you want them.. To get the full 28lb you need to adjust your Fuel pressure..

[John_D.]

Yeah, if you're hitting 20-22 ms on the high end of the rpms, then you're running out of injector. This table shows the msec's at different rpms:
http://engine.firebirdv6.com/pulsewidth.html

The .830 o2 voltage says lean too... Even after you get the injectors, fuel pressure will still be iffy too.

[AllTheGoodNamesAreGone]

IMHO pump it and see what happens..