Chris Johnson 00 T/A

Okay, so, I'm currently running 32.5# injectors now, and think I need more.

My IPW's are at about 3ms, and my WOT's reach an average max of 22-23MS.

I'd like to drop that down some, so that I'm not a the limit of my injectors.

What size should I look at?

I *expect* to be pushing about 460-470 to the wheels when I'm done.

Add 15% for MN6 and I'm at ~530 flywheel or so.

I have a 'hook up' for Lucas injectors, and can get any size I need. Would 36# or 38# be better? 42#?

Way down the line, I expect to juice the car as well. I'd expect a wet shot, but, if I have the ability to run a smaller dry shot, that would be nice.

TIA,

Louis

iTrader: (7)

Chris, go with the 42s, and look up Godspeeds xcel chart for injector sizing on LS1edit.

sununix69

I am not sure why you are not getting feul cap deliv. through those injectors, how do you know they are the limiting factor....

Have plenty of pees with 422 and 427 pushing over 600 to the wheels, running 36# injectors..

32# is WAY plenty for 500 or so Crank HP

Chris Johnson 00 T/A

Okay, two different answers.

Whats the deal here?

Am I fine with my IPW's? Could I use larger injectors? If so, what size?

<img border="0" title="" alt="[Eek!]" src="gr_eek2.gif" />

RyanJ

by hook up, i assume you can steal...ahem...get these for reeeaaall cheap. why not upgrade? go with 38's or 42's and use edit as louis said.

Chris Johnson 00 T/A

no smart ***, not 'steal' <img border="0" title="" alt="[Razz]" src="gr_tounge.gif" /> but, it's almost as good of a deal <img border="0" title="" alt="[Smile]" src="gr_stretch.gif" />

The PCM will be tuned shortly after I install these things. I hope my ARC2 can lean the car out to the point where I can at least move it <img border="0" title="" alt="[Smile]" src="gr_stretch.gif" />

Colonel

The injectors you have now are fine for 470RWHP. Just make sure the fuel pressure is actually getting to them. (I would invest in a pillar mounted FP gauge if you don't already have one.)

RyanJ

If you are worried about fuel pressure and sticking with those injectors, you could splice in an adj. regulator outside the tank (replacing the in-tank regulator i believe) and pump up the pressure. Andy used to run like 70psi when he sprayed.

Ryan

Colonel

Right, but you still, of course, have to ensure that you maintain enough volume to the regulator in order to hold the desired PSI.

TanRchy

At ls1speed.com the 37#, 38# and the 42.5# are all the same price so why not get the 42's? I know YOU have the hookup but is there anything wrong with this philosophy?

Gene

How do you determine injector size. Would a 99 with heads and cam need bigger? Ive got SVO 30lbs now but some people tell me they are all wrong for a LS1. Need help.

red ws6 99

Go to www.rceng.com they have an online calculator. bsfc should be ~.5 for a NA car, .6 for turbo. Injector duty cycle max of .8 or 80% ontime you can go higher but risk damaging the injector (you will get a lot more flow at 100% of course). BHP in the equation is the flywheel horsepower. RWHP say 20% lower for A4 and 15% lower for M6. That should get you in the ball park. The reason some people dont like the 42 lb injectors is the fact that they are non linear. They flow a lot at low end and taper off quick on the top. Some people dont like SVO injectors because they have a different flow pattern than the stock injectors. Plenty of people run them.

Hope that helps.

Gary

Pro Stock John

iTrader: (34)

I know you have had some tuning/engine problems so I don't blame you for thinking about bigger injectors.

Remember when evaluating injectors that we stand alone at our 58psi vs the 40-45psi for LT1's and Mustangs.

I'm moving this thread to external engine where we house all the fuel threads.

I'd run 36's...

I run 2000 GTP injectors which are like 39's in my car and they are overkill.

If the injectors get bigger they get harder to calibrate.

Racetronix

iTrader: (2)

Try this company's on-line calculator....
http://www.rceng.com/technical.htm#WORKSHEET

Chris Johnson 00 T/A

PSJ: I'm running the same GTP injectors you are, and I know that there has been a debate on what they *REALLY* are.

I was told that they are 32.5's at 58-60PSI.

Do you have other information that they are larger?

I'm still going off of what my IPW's are at idle and WOT.

My PCM is still under the assumption that I have stock 2000 injectors in the car.

ChrisB

</font><blockquote><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><hr /><font size="2" face="Verdana, Helvetica, sans-serif">Originally posted by Chris Johnson 00 T/A:
<strong>I'm still going off of what my IPW's are at idle and WOT.

My PCM is still under the assumption that I have stock 2000 injectors in the car.</strong></font><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif">Those two situations are mutually exclusive. You can't tell much of anything from your pulsewidths if your injectors are not programmed correctly. All you know is that your computer *thinks* you are maxing out stock injectors.

Chris

RyanJ

</font><blockquote><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><hr /><font size="2" face="Verdana, Helvetica, sans-serif">Originally posted by Colonel:
<strong>Right, but you still, of course, have to ensure that you maintain enough volume to the regulator in order to hold the desired PSI.</strong></font><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif">a collective 'Duh' falls over the crowd. <img border="0" title="" alt="[Big Grin]" src="gr_grin.gif" /> j/k

Yes, a nice racetronix setup would be best for pushing that much pressure. but you should be fine with the inj. at that point.

you should be at about 89% duty cycle with 32.5# inj. and .5 BSFC. If you use a lot of fuel (.55bsfc), which is likely, that puts you closer to 95%. i see why you want to step up. (all this is at 58psi FP, btw). at 65psi and .55bsfc youre down to 90% and at 70 youre at 88% or so. target should be around 80-90% i think with some room to spare and your bsfc is probably around .5-.55. anyway..just FYI, at .55bsfc and 58psi with 38# inj.'s you're only at 82% and the same inj. with 70spi is at 75%. just remember to have enough volume to push it at 70psi.

i could be wrong on the calculations, also.

red ws6 99

A little more injector could not hurt. Also remember that when you crank the pressure up your injectors flow more but your pumps flow rate decreases. A stock pump is really not designed to for 450 rwhp so it would be a good idea to replace it with a gs340 (good for 500 rwhp in a turbo charger application probably 550-600 NA) or racetronix.

Gary

Colonel

"I'm moving this thread to external engine where we house all the fuel threads."

Looks like it's still here to me. <img border="0" title="" alt="[Confused]" src="images/icons/confused.gif" />

Pro Stock John

iTrader: (34)

Harlan said they were about 39.5 lb injectors.

I can go about 610rwhp with these at 80% duty cycle.