anotheraznguy

iTrader: (1)

i currently have a 418 ls3 block
w/ 1 3/4 header
ud pulley
tsunami cam
ported stg 2.5 ls6 heads
3 inch dual exhaust

currently have 36lb ford injectors but dont know if those are good enough.

will most likely run what i have to break in the motor w/ the oem ls6 intake
however i will swap it out to a fast 102 once its broken in.. anyone recommend injector size? 50lb?

Thanks

litle88

iTrader: (20)

I calculated 54 lbs'rs with the mods in my sig.

Russ K

iTrader: (1)

Those 36 lb injectors will support 650+ HP at 58 psi fuel pressure. Verify the wot fuel pressure by taping a fuel pressure gauge to the windshield.

I also have a TSP 418, TFS 215 heads (valve pockets opened up to match the bore), YT rocker arms, LG G5X3 114 cam installed at 114 ICL, LG long tube pro headers & HF cats, LG big 3 mufflers and a Mamofied 90 mm Fast intake. I'm going with the Fast 36 lb injectors.

Russ Kemp

Tech

iTrader: (1)

Seems excessive.

ducatisl

iTrader: (1)

At what pressure drop should one start to be concerned?

Gray86hatch

iTrader: (83)

42 would be sufficent at 40 psi

I have 60 in mine and they are at 63% now 40 psi with about 650hp

Tim

Russ K

iTrader: (1)

A 5 psi pressure drop @WOT is normal.

Russ Kemp

Chris10an

iTrader: (1)

are you rising the RPM on the engine?

TransWS6Am

iTrader: (41)

im over 100% duty cycle with 42# injectors on my 416 LS3, mods are in my sig. I'm going to have to pick up some bigger injectors soon. I'd say 36# is going to be way to small for you.

Gray86hatch

iTrader: (83)

One thing to keep in mind you need to have a stable fuel delivery.
I see 3 psi drop from idle during a pass but it stays right at 39 all the way down.

The injector may not be to small if the volume is not there.

If you can find a way to monitor fuel pressure during a pass to make sure it is rock solid it would be worth the time

Tim

anotheraznguy

iTrader: (1)

i have an aeromotive fpr and a decent walbro pump. i havent seen any fuel pressure drop at wot on the dyno however i have not seen it in real life conditions...
the 36's are rated at the lower fuel pressure so realistic pressure of those 36's are close to 40 ish... at this point i am unsure if i should go try and get it tuned or should i wait and pick up some 50's

but at the same time.. i don't want to oversize my injectors either.

WKMCD

iTrader: (2)

FWIW: I run Ford 42's with a Walbro 255 wired to the alternator and an Aeromotive 1006 regulator set to 59psi on a return style fuel system. Duty cycle is fine.

TransWS6Am

iTrader: (41)

hmmmm maybe i need to monitor my fuel pressure..... I have the racetronix pump with the hot wire kit, ran to the alternator..... and my 42# injectors are definitely over 100% duty cycle. I have the FAST fuel pressure gauge on my fuel rail, but that don't help much... lol.

litle88

iTrader: (20)

Here is a formula, you must remember that the injectors max out at 80% duty cycle.
http://www.rceng.com/technical.aspx

hymey

I have tuned LS7s that rev up to 8000 rpms with solid rollers with factory 42 pounders and still have room to move. 42 is more then enough, 36 is plenty in a 6500 rpm hydro roller engine. Hydro roller engines with plastic intakes are pushing **** up hill to keep making power past 7000rpm no need for it.

Last engine I built/tuned 4.010 x 4 large heads very large hydro roller plastic intake 82% duty cycle, remember poor efficiency means higher BSFC requiring larger injectors. 63s would be needed on a gasoline engine that is making power still at 7800 rpm plus.

80's all you require for e85 4XX cube setup.

36s will just scrape in by I would go 42lb bosch.

hymey

That engine would make a real 600HP(genuine) the heads are to small for it to keep making power up top so the 36s should do it.

miami993c297

iTrader: (6)

My engine is equipped with Lucas High impedence flowing 42.5 lb at 43.5 psi...
measured pressure is 58 psi
DC is 95% on a good DA at 7150 rpm

Christian