redz2899

iTrader: (1)

what size will i need for a 383 stroke motor for an ls1. Not sure on the dyno #s yet

ZL1Killa

iTrader: (17)

what numbers you think you will be looking at.... obviously above 450hp so **** try sticking in some numbers of what you think on the sticky on the top of this main page. Sorry I'm not much help.

redz2899

iTrader: (1)

hopefully between 450-500

TeeKay

OK, this is just what I was trying to check too. I have a 383 LS1, mild cam and good heads (~300cfm @.600 intake lift). It should make about 550 hp crank N/A (BSFC @ .5). I will use 53psi as fuel pressure and 85% duty cycle. My calcs say 40 pph injectors.

The next step is turbo @ 6 psi (about 680 crank hp) and 52+6 = 58 psi fuel pressure WOT. My numbers say ~ 50 pph at 85% duty cycle and BSFC at .6.

Looking for opinions, experience, estimates. This should help both of us RedZ!

white2001s10

iTrader: (4)

Using hillbilly method I come up with 30.99 lb/hr rated at 4-bar.

redz2899

iTrader: (1)

thanks

TeeKay

Well, Hillbilly, I came up with this (I admit your answer made no sense to me), 38 lb/hr injectors (43.5 psi static rated) make 42.x @ 52 psi x 80% duty cycle = 34 lb/hr delivery x 8 = 272 lb/hr x 2 = 545 hp) seem to be the ones to use. That's what I ordered. Excuse my ignorance, just what is 4 bar anyway? Thanks for the info.

white2001s10

iTrader: (4)

1 bar = 1 atmosphere of pressure which is 14.7 psi.
Stock injectors are rated 28 lb/hr at 4 bar 58.8 psi, or round on up to 60psi.

383 cubes - 346 cubes = 37 additional cubes to feed
37 / 346 = 0.1069 (the percent increase in cubes)

0.1069 * 28 lb/hr = 2.9942 additional lb/hr of flow needed
28 lb/hr + 2.9942 lb/hr = 30.99 lb/hr

The proportionally larger injector to match the additional cubes is 30.99 lb/hr.
Most people will move on up to the next larger available size so they can stay in the more "comfortable" zone of 80% max duty cycle.

Considering the stock 28 lb/hr injectors can support an additional 300 lb/ft of torque and 200hp of additional power (a 66% increase) over a stock LS1 engine within the factory rev-range, you realistically do not have to increase injector size in most cases of building a 383 cube engine.
That's why people were asking about your predicted power output with the new engine.

white2001s10

iTrader: (4)

To take into account your future turbocharger and approx 700hp,
my hillbilly method says that a 65 lb/hr (at 4 bar) is about right for the power level, but you have to either increase injector size and/or fuel pressure when you start dealing with boost pressure in the intake manifold. Many people tack on another 10% or so with boost, which would be about 72 lb/hr.

Obviously the bottom line depends on just how much boost pressure the injectors have to fire into, and how much power the engine will be making.

SMOKINV8

iTrader: (6)

I'm not meaning to be an *** here, but do you guys ever look at the sticky within the forums? There's an injector calculator at the top of this very forum.

white2001s10

iTrader: (4)

Yep and there's dozens of others out on the net. I think he was just looking for some additional input from people who have done it.

TeeKay

Dead on. There are so many folks out there that seem to defy the calculations, that I wanted to poll the real world to see who was making what with what size (if that makes sense.). My calculations are accurate according to the calculators, but is it real? In addition, not everyone talks about injector capacity at 100% at test pressure (43.5 psi), but that's the way they are advertised: so how to come to a common rating? That's why all the tedious questions. Thanks for all you guys being patient with me.