Are they larger than the LSJ? I'm assuming so since the boost is higher.

 

You can't compare the two because the application is completely different. The LNF is direct injection running over 2000 psi at WOT. From what I understand, DI also limits the available window for having the inector open to less than 40% duty cycle.

 

QFT.

The Supercharged Cobalt had XX lbs. injectors and the stage kits upped the lbs. of the injectors. The Cobalt SC was not direct injected like the new LNF Turbo Cobalt. The injectors are not comparable.

 

aaaaand CUT, PRINT.

 

im not positive, but i think the LNF runs around 2,000psi at idle, and under WOT, it steps up closer to 12,000psi.

 

doesn't go that high hunter, its technically a 150 bar nominal (or 150* 14.4 = 2160 psi) system, max pressure the fuel rail pressure sensor can read is 20 MPa (2900 psi)

 

hmm. maybe i just added an extra zero to the numbers i looked up a while ago...lol idk.

 

actualy its not over 2000psi at WOT the system maxs out at 1900psi. The pcm will not let the system build more then 1900psi. at WOT is roughly 1200-1300psi and at idle is 400-500psi the pressure is never constant its always fluctuating

 

I see 2150 all the tim eon the dashhawk. At idle it's about 650.

 

winna!

trying to compare the two different style of injectors and idc of conventional style will end up in a blown motor. watching idc is a moot point on the lnf cars. watch the time itself

 

Yup, the DI injectors aren't going to spray outside of cat warmup while the exhaust valves are open, it has to be precise and timely. Can't be open 100% of the time for safety sake.

 

we should write a new duty cycle PID that references intake valve open time vs PW.

 

go for it. it would give people the real number and facts.

i don't do enough lnf cars to warrant writing it myself

 

And I hate writing PIDs hahaha. Not sure how you would write one to only refence valve angle.

 

Not really so much valve angle as intake stroke.
BTW to the original poster, they are 122lbs/hr @2000psi nominal using heptane.

 

Does the LNF inject fuel during the compression stroke under light load conditions?

 

Not to my knowledge, homogenous charge is the preferred injection strategy for cruise, injection events are completed during the intake stroke under this strategy. While multiple injection events do occur under certain parameters(catalyst warmup, injection mode transitions, etc) injection times are essentially limited to 5milliseconds.(roughly the duration of an intake stroke at 6000rpm) and max rail pressure is stated as 2.176ksi in service information.

 

I got some INFO for you guys on the SIDI if you love to read i work for gm and this is straight from gm on accessable by gm employees.

Several GM engine families presently use Spark Ignited Direct Injection (SIDI) technology -- the LNF 2.0L turbocharged 4-cylinder and the LLT 3.6L V-6 (fig.1). Some projections indicate that in a few years, one in six engines will be built with this technology.

The injection system used on SIDI engines differs from standard fuel injection in one important way. With SIDI, the fuel is injected at a much higher pressure (up to 2176 psi or 15000 kPa) because it's injected directly into the combustion chamber rather than into the intake manifold (port injection).

BENEFITS OF SIDI

When compared with port injection, benefits of SIDI include:

- lower emissions, particularly at startup

- higher compression

- better fuel economy (particularly on turbocharged engines)

- increased horsepower

All gasoline engines depend on atomizing the fuel before combustion. But with carburetors, throttle bodies, and even port injection, the atomization takes place at a distance from the combustion chamber. By the time the atomized fuel and air reach the combustion chamber, some of the fuel has separated out and collects on intake surfaces. SIDI eliminates all of this by atomizing the fuel directly in the combustion chamber. As the fuel atomizes, the air and fuel mixture are cooled, enabling the use of a higher compression ratio.

Better atomization contributes to a reduction in pre-ignition and detonation, which is why the SIDI engine can operate at a higher compression ratio and consume less fuel. SIDI allows the engine to run on a leaner mixture (more air, less fuel) at full power. SIDI also allows a higher compression ratio, which in turn provides better fuel economy at part and full throttle.

Direct injection permits controlling a richer mixture around the spark plug, making it easier to ignite when the engine is cold. The SIDI engine runs smoother and generates lower emissions during cold start and warmup.

COMPONENTS

The fuel delivery components of SIDI are divided into two groups, the low pressure system and the high pressure system.

Low Side

Low side components are essentially the same as those in a port injection system. The fuel tank (fig. 3) contains a modular reservoir assembly (fuel pump). Fuel pressure in the low side is approximately 60 psi (410 kPa).

The high pressure pump incorporates the fuel rail pressure (FRP) regulator. The FRP is operated by the ECM, using pulse width modulation, to provide the fuel pressure commanded by the ECM. And the high pressure pump also incorporates a pressure relief valve.

The fuel rail (fig. 7) delivers fuel from the pump to the injectors. A fuel pressure sensor is attached to the fuel rail, and it contains a diaphragm and strain gauges. Both the fuel rail and pressure sensor are made of stainless steel.

The ECM contains a converter that steps up voltage from 12V to 65V and charges a capacitor. The capacitor provides 65V to open the injector. Then the ECM provides pulse width modulated 12V to hold the injector open for the prescribed time.

SIDI OUTPUT CONTROLS

The Tech 2 can be used to perform the following (see SI for details):

- Cylinder Power Balance

- Fuel Injector Balance

- Fuel Pressure Control

- Fuel Pump on/off

- Fuel System High Pressure Reduction

SIDI SERVICE HIGHLIGHTS

See the appropriate section of SI for details.

Low side system pressure relief is the same as with standard fuel injection systems.

High side system pressure relief can be done two ways:

- Shut engine off and wait at least 2 hours, then cover high pressure fitting with a shop towel and loosen

- Use Tech 2 to command fuel pump relay OFF, run engine until it stops (approximately
30 seconds). Turn off ignition and confirm fuel pressure with Tech 2.

To remove injectors, it may be necessary to use tool J-37281-A if there is high carbon buildup. If there is high carbon buildup, use EN-47909 to clean the injector bore.

IMPORTANT: This tool can remove cylinder head material.

When removing injectors, the following must be discarded and replaced:

- fuel injector hold-down clamps

- O-rings

- plastic spacers

- fuel injector seal

The Teflon seal on the tip of the fuel injector must be installed and sized using EN-48266. See the appropriate section of SI for details.

When removing the high pressure fuel pump, the following must be discarded and replaced:

- fuel pump bolts

- fuel pump gasket and O-ring

- high pressure fuel pipe

When installing the high pressure fuel pump, be sure the roller lifter is oriented properly,
the camshaft is at base circle, and the number 1 piston is at top dead center (TDC) on the exhaust stroke.
- Thanks to GM Powertrain

SOME IMAGES TO GO WITH THE DOCUMENT

 

techlink

 

u bet haha

 

Awesome find!

 

Techlink is weaksos

If you could post engineer sheets, that would be impressive

 

idle is around 750 psi and WOT is 2250 psi.

 

If you read the document its up to 2176psi not over. for one the pcm won't let it. I data logged the injector pressure readings at idle and the lowest was 486psi to 710psi being highest at idle.

And i got two documents from the engineers i will post up later. No one has these documents i recieved them from area manager for school perposes. Its got every info on the system from every single design they tested to the one we are using. They are very large files. I will post the documents up and anyone who thinks theie dam knowledge is better then the ppl who designed and built the system and think it rises aboive 2176psi and idle is retarded high better buy some approved testing tools not some cheap shity ones and test it and you will find out for yourself! is you got an extensive tune with high boost ran u may just may see over 2176 but thats pushing it.

I logged a entire 1/4 mile down the track and i never ran over 2176psi stock, very close tho

 

okay, so you can't compare by numbers, but the fuel delivery of the tc is a lot higher than the sc stock right?