Chevyboi09

Just upgraded to an MS3 cam and not sure what size inectors to go with. It's my daily driver but don't care about gas, Obviously. I currently do not have any fuel system upgrades but that can change if needed. If you need any other info bout my setup in order to answer my question, ask away and I'll do my best to answer ASAP. Thanks again for any help

Chevyboi09

75 views and no responses? Nice LoL

ZL1Killa

iTrader: (17)

is all you have a MS3 cam on a stock what? LS1/LS6 /LS2 ?

Do you still have the stock injectors? stock fuel pump?

Stock fuel pump will be fine with just basic bolt ons. If still stock injectors, have you scanned or checked your peak duty cycle? If not, and you have stock injectors, I recommend 36# injectors or just slightly larger from FIC, Fuel Injector Connection. You can also have yours re-flowed.

Chevyboi09

Performance: LS1 out of an 02 Vette, Magic Stick v.3 cam w/112LSA, PRC dual vale springs w/titanium retainers, seals and seats, TSP Hardened pushrods, SLP Double Roller timing chain, SLP Fully ported oil pump, TCI flex plate, Comp lifters kit, BBK Performance 85mm throttle body, Taylor Cable TB spacer, SLP Flowpac intake package(whisper lid, smooth bellow, forced induction, K&N filter), headman headdress, pacesetter performance off-road Y pipe, SLP Loudmouth ll exhaust, 3:73 gears, Jet performance mass airflow sensor.

That's about it. Sry bout any unnessecary parts listed above. Just copie and pasted from my BIGGER list. Far as I know, the entire fuel system is stock. The car was slightly modded when I bought it last year. How much WHP are 36s good till?

ZL1Killa

iTrader: (17)

stock pump is 190Lph, this will make it up to 32# @ 43.5psi (38# @58psi)

see sticky here

The optimum setup would be to go ahead and purchase a Racetronix PnP kit w/wiring harness & 255Lph pump and also purchase 36# injectors. -- great for more bolt ons, pumps maximum is 51# injectors.

what are you future plans? if you are thinking about forced induction, I suggest as a base, getting 42# & the listed pump above.

this is kind of a loaded question, what is the application? Naturally aspirated = nearly 500rwhp; Forced Induction = 450 likely.

See this website for details
scroll to the bottom of the page and read the print.

A good place to start is Racetronix / Lonnies / NastyN8 sponsors for quotes/parts. Fuel Injector Connection for injectors.

Blackpanther99

iTrader: (8)

I think #30s are good for your car, dont go over 40s

Chevyboi09

Well with my comp thumper series, before the MS3 cam n spring kit, SLP oil pump & TC kit, before the stock 308s being milled and the engine being bored 30 over, I put down 396whp 390tq. Idk what it's going to put me at but I am runnin N/A for a while... I'm sure Santa threw my twin setup out the window already haha

TeEnAgE pHeNoM

iTrader: (6)

As a reference my car is a ms3 cam only car and the stock injectors are at 105% duty cycle.

elephantrider

iTrader: (2)

i went with 42lb'ers and made 415 on my ls1 gto.
same cam with modded 241 heads.

we tried the stockers just to see how they would
act, and of course they were maxed out.

ZL1Killa

iTrader: (17)

explain this. a stock car can idle perfect with 42# injectors from racetronix/lucas/delphi/bosch with just the IFR table changed. Further tweaks can be made to better control the injectors, but they work & idle fine. Sure, the duty cycle may only be 40% or 50%, but what is wrong with that

elephantrider

iTrader: (2)

thats what my 42lb'ers were at during wot pulls when we were tuning
it. 55% cycle. just gives you room to grow !

Chevyboi09

Not going to lie. I have no clue what the cycle% is. With that being said, what is better? Higher or lower % or what range x%-x%?

ZL1Killa

iTrader: (17)

it is suggested to be equal or less than 80% duty cycle. Above this number, the injector can become static, or always open instead of closing as its time off to time on is very minimal. This may have changed over the years, but I look at it as if you are getting high duty cycles 85% or 90%, you need to upgrade your fuel system.

a good % is between 50 and 70%, but being 75% or being 45% isn't bad either.

Chevyboi09

Ok cool thanks for the info. So how do i go about finding out the duty cylce for my injectors? Could AutoZone tell me? Or is this something only dyno shops can tell me? My car & I have a date on the dyno some time before January. If anything, I guess they can tell me what I'm at and then go from there. More advice/info is appreciated. I will let yall know what the duty cycle is once i find out and then see what needs to be done

elephantrider

iTrader: (2)

go with the 42 lb ers

ZL1Killa

iTrader: (17)

if you know someone at advance/autozone that is willing to ride with you and ask then to view the duty cycle, lol. they usually don't leave the parking lot.

a scan tool or even a shop that has efi live or hptuners nearby usually shouldn't mind a quick ride around the block WOT pull to log the duty cycle.

Exidous

iTrader: (11)

Inj cycle is based on how long it is open. 105% is not possible as 100% is always open(static). You cannot have more open than always open. The ECU may show 105% but it's still 100%. It would show 105% because the calculation says the engine needs more fuel than 100% can provide(injectors are too small by about 25%). 50% inj duty would mean that the injector is open 500ms for every one second past. The max recommended duty cycle is 80%. Some may go to 90% but never more. It gives the ECU VERY little flexibility in fueling.

I suggest the LS3/7 injectors. They are shorter so a different rail or spacers(the top style by FIC) will be needed. They can be had on eBay for under $150.00 and flow about 42lb's with a perfect idle in a stock car. They will also support up to about 550fwhp. Mine run at about 65% inj duty cycle at 420whp. New injectors REQUIRES tuning.

Like ZL1 said, HPTuners or EFILive are your best bet to display duty cycle. Some of the better scanners may be able to as well.