99 Black Bird T/A

iTrader: (4)

What's the rwhp limit with 02 - 28.x pound injectors?

I was planning a 346 with LS6 heads and a nice cam and assorted bolt on's etc.

I have a chance to do a Big Bore 382 or may be even 427. What are the limits of the 02 injectors?

At what point should I move to 30 or 36 pound injectors?

I do not intend to spray.

At what point do I need more than a stock fuel pump?

If the LSX intake works as well as expected and it flows more air etc, will that mean injectors that were near their limits with an LS6 intake will most likely be maxed and require upgrade?

Thanks

SMOKIN01TA

iTrader: (10)

from what ive seen, you can go 10's on #28's with 450rwhp+ but anything under 11's it seems to be a good idea to upgrade the fuel pump im going to say 450-500 is a good time to start looking to get bigger injectors, the size depends on how much further you want to go.

Nasty N8

iTrader: (33)

The stock pump and injectors are working pretty hard by 450hp. I would upgade both any more than that. We have a fuel special til Christmas.

Nate

SMOKIN01TA

iTrader: (10)

yes pump is workin hard by then but if you get a 255 pump you stock injectors should hold up a little bit more that stock.

Nasty N8

iTrader: (33)

Why is that you are still running the same pressure? The injectors are only going to spray so much at a given pressure.

Nate

SMOKIN01TA

iTrader: (10)

i have been told the lb. rating was base on the sock fuel pressure and if you change to a bigger pump the rating changes a little. just what i herd. havent really done it yet. i was assuming you can regulate the fuel pressure.

mike72678

SMOKIN01TA , you are correct . When you upgrade your fuel pump to a GSS340 or a GSS307 , you will notice a 3-8 psi increase in fuel pressure . That is why you may notice it may run rich for a couple of days which is why it is also a good idea to leave your battery disconnected for a while after you do the job so the computer will relearn the fuel curve . The PCM will notice the additional fuel and make up for it in the injector pulsewidth times after a little bit of driving .
After you upgrade to a GSS340 your 28.8 lb.per hour injectors just went from 28.8 lbs. per hour at 60psi to 30.5 lb.per hour at 60 psi .

Colonel

After you upgrade to a GSS340 your 28.8 lb.per hour injectors just went from 28.8 lbs. per hour at 60psi to 30.5 lb.per hour at 60 psi .

I don't understand this statement. Typo? 60 psi is 60 psi so why would the flow rate change if the pressure stayed the same?

28.8 lb/hr injectors can support alot more power than people think (over 500 RWHP)...SO LONG AS you maintain fuel pressure to them.

mike72678

Because your fuel pressure will increase slightly when you change the pump because it will pump more , until the computer has a chance to relearn and make it's adjustments , read my post again and you will see that I said there should be a 3-8 psi increase in fuel pressure immediately after installation .

Whoops ! I meant 30.5 at around 64 psi . Sorry , didn't see that !

gomer

iTrader: (13)

I'm on my stock 02 injectors still.. and I have been known to spray a little 75hp wet kit on top of it for a certain pesky supra around here... Stock pump too.

Colonel

mike, I don't necessarily agree that your fuel pressure will increase by using more pump if by "increasing" you mean over the stock 58 psi.

On my 9 second car I ran a 340 intank, a 255 inline, and a voltage booster that took them both up to about 18 volts. What PSI did I see?...about 58 at idle and 55 at WOT. Now I guess you could say I increased my FP since without all of the extra pump capacity my fuel pressure would have been close to zero...but I can't say that my pressure was higher than stock.

To increase the fuel pressure over stock you have to either a. overpower the fuel pressure regulator or b. bypass the the FPR and install an adjustable one.

Nasty N8

iTrader: (33)

I have also seen a 1-2 psi increase for the first couple of days on a pump change but I don`t concider that enough to say your injectors are now rated higher.

Gomer you just push everything You injectors are fine but I would be willing to bet you are way lean on those nitrous runs. Upgrade your fuel pump

Nate

mike72678

I had a 4 psi increase when I did my gss340 for a couple of days until my pcm made adjustments . When I did the swap in my mustang , I had a 6 psi boost in fuel pressure , and a 7 psi jump when I did the gss342 swap in my 90 eclipse (also rewired the pump to up the voltage).
When an injector is rated at a given amount of flow , at a specific fuel pressure and then it has a raise in pressure , doesn't that raise the flow rating on the injector ?
Just like if you put our injectors in an LT1 , they will only flow around 24 lbs. per hour .
Correct me if I am wrong , but to me this only makes sense .

99 Black Bird T/A

iTrader: (4)

Say you have enough fuel pump to keep the pressure at ~60 say a GSS340, and use an adjustable fuel pressure regulator and set it at 60, and tune according.

Will the 28.8 injector now become a ~30.5 injector?

99 Black Bird T/A

iTrader: (4)

Anyone know of a table to look up fuel pressure vs injector ratings etc?

mike72678

The injector flow rating will not chage , but if the pressure increases , then it is obviously going to flow more .

10thanvhawk

for those math intensive

http://www.mcbrooms.com/volvo/injcalcs/injcalcs.htm


my favorite,for the rest of us.. hehe

http://www.csgnetwork.com/fiflowcalc.html

lots of extras on the second choice

99 Black Bird T/A

iTrader: (4)

10th...thanks!

That's just what I needed to see...I think I'll keep the 28.6 injectors because they calculate out to ~32.5 injectors with ~56psi fuel pressure and 33.5 injectors at 60 psi. I have a GSS340 fuel pump thanks to Nasty Performance, I'll get an adjustable reg too.

Thanks for the help!

mike72678

You are using the chart incorrectly , your 28.6 are more like 24 at 43.5 psi which is what most injectors are rated at . At 56 psi , you actually only have 27's .

10thanvhawk

I agree, I have a 2001 with 28's and they were not enough with the ATI @ boost even with 65#'s of fuel pressure, I am pretty sure that GM rated the 28's at LS1 fuel pressure and NOT at 43. So I only added 7# of fuel pressure which is not much. However my new 36# act like 42# or so, since they are rated at the 43# originally. However I do see some 50# versions in my future.