Droptopws6

iTrader: (13)

Here's what I have going on. 2002 WS6 Trans Am, I'm installing a Powerdyne supercharger kit. It comes with the FMU and external fuel pump to use factory injectors. I would like to eliminate those two items, use larger injectors and just adjust the tables with HP Tuners.

An LS1 running at most 6lbs of boost would need what size injectors?

I've researched the Powerdyne unit, how to keep it alive, make it stronger and not kill it. I also know there are far better FI units out there. I have reasons for the using this simple kit.

Any help would be greatly appreciated.

JRENIGAR

iTrader: (37)

U could probably get by with 42'ers but 60's would be optimal. Id do the racetronix kit with hot wire also. BTW I have both these items on my dd car with no problems.

YURVIEW

iTrader: (127)

http://www.rceng.com/technical.aspx

silverbullet02

iTrader: (2)

Same here...42's with Racetronix and hot wire.

Droptopws6

iTrader: (13)

Thanks for the link, it seems I may be able to even get away with the Bosch 36lb's by that link.

With the bigger injectors can I eliminate the FMU and the external fuel pump and just take care of the fueling with HP Tuners?

YURVIEW

iTrader: (127)

36# may be a stretch.... be sure to change the following in the calculation table on that link

"* Brake specific should be .45 to .50 for naturally aspirated engines,
.55 TO .60 for supercharged engines,
and .60 to .65 for turbocharged engines."

LS1 Fuel Pressure - 58 psi (NOT 43)

bmech211

Hi Droptopws6,

I agree with YURVIEW in that you may be pushing it with 36#. They're good for a little over 600hp, and the 42#'s a little over 700hp; All @ 80% duty cycle. Your mass air flow at peak torque, pushing 6psi, is around 30 lbs/min (428 cfm).

Just wanted to give you a little more data to help you out if you need it

Ciao

ZL1Killa

iTrader: (17)

Let the details be known.

36 LB/hr injectors at 43.5psi (standard rating) are ACTUALLY 41.5 LB/hr injectors at our LS1 fuel pressure of 58psi
Lets say you run 6 psi with that...
so now you are running 58psi fuel pressure with 6psi pressure all through your intake manifold etc. 58psi - 6psi = 52 psi
those 41.5# at 58psi under 6psi of boost are now actually 39.3 LB/hr

*IF you get a fuel pressure regulator (FPR) and set your atmospheric reference to 58psi you will be able to run the 36 LB/hr injectors.

*IF you do not get a FPR you will max out those 36# injectors.
A fuel pressure regulator (FPR) adjusts fuel pressure according to manifold pressure.

If you do not want the hassle of buying and installing the associated FPR and hardware for it, I HIGHLY recommend 42# injectors as that is what I used when I first ran my car with my turbo kit (long time ago). This was with no FPR and just 42# injectors with a Racetronix 255 L/hr pump installed with hotwire kit. My BSFC is higher than yours (turbo vs supercharge) but I had a 70% duty cycle

the so rated 42# injector at the standard pressure of 43.5psi is ACTUALLY a 48.5 LB/hr injector at 58psi and with 6psi of boost down to 52psi injected pressure, it is 45.9 LB/hr

ZL1Killa

iTrader: (17)

an LS1 using 30LBs/min of air with forced induction?? making 600 and 700HP? bullshit...come on...where is the math behind that derivation. My stock ls1 on 6psi with a 60mm turbo took ~55 LB/min air.

what is that supercharger capable of airflow wise?

bmech211

ZL1,
That's at peak torque which I calculated @ 3200 rpm, VE @ (modest) 95 & PR @ 1.41

5.7 * 3200 * 95 * 1.41 / 5660 = 431.66 CFM = 30lbs/min

Change the numbers and put 6800 rpm and it's 61 lbs/min. Actually a little lower because VE is falling off at this point.

I never associated a HP number to that value, only provided him mass airflow at peak torque where I like to start sizing my injectors accordingly. Since he didn't post any HP numbers, whether measured or anticipated, the only other option I see to making the best determination is what can be calculated based on the info given, and that's MAF. Different than how you do it maybe? Does it work? I never popped a motor because of lack of fuel.

I'm just trying to help.

Droptopws6

iTrader: (13)

I'm not opposed to using an adjustable fuel pressure regulator. What kind do you guys run on the LS1?

JRENIGAR

iTrader: (37)

The "in tank" kind, J/K... Couldnt help it...

ZL1Killa

iTrader: (17)

That math is correct, and yes that is what I use, but what is the point in using the peak torque value, when what you need to use is your max RPM value? We are both saying the same thing, and both agree that he should use 42#, thanks also for the assistance in providing knowledge to better choose fueling components.


I have the Aeromotive 13101 and all hardware.