47 replies to this topic

[ThePluck]

Hello,

I've searched but I keep finding different opinions on whether the Green LSJ injectors are ok for a supercharged vx or if the VXR injectors are a must, also most posts I found were quite old. I plan on using OBD tuner.

Any guidance?

 

Thanks in advance!

[The Batman]

Vxr are best but plenty are running the green lsj ones

[smiley]

After your SC build you are going to do some logging anyway.

That will tell you if the lsj ones are up to the job, or if you will have to upgrade to bigger ones.

 

[Exmantaa]

That will depend on your SC goals;

Only basic stage 2 with 250-255HP/ 7K rpm limit; LSJ green ones are fine and a direct fit. (Just make the fuel pressure "boost referenced".)

 

Above that and higher rpm's you'll need bigger injectors.

[chris_uk]

Dont bother they are crap. They work yes.. but if you start looking at the duty cycle of the injectors you have to drop the rev limit quite low before they are constantly working at 90% duty cycle.

[Acidpopstar]

I had to change from green to blue VXR injectors as was maxing them out on my 250bhp S/C engine Sent from my iPhone using Tapatalk

[ThePluck]

Thanks for all the quick replies! My original plan was to use the LSJ ones first and buy VXR injectors later on if I they were close to maxed out (I have no plans to increase the rev limit, and will have the standard stage2 ~250hp setup).

Where's the best place to get VXR injectors?

[siztenboots]

iirc these are only 310cc , so worse than LET black ones 370cc

[chris_uk]

I would use z20let over lsj greens. And you cant buy the vxr's as easily now, Germany is probably your best bet.

Edited by chris_uk, 03 April 2017 - 11:28 AM.

[smiley]

Tried matching the forum injector names to the ones in obdtuner.
Is this about right?

 

[CHILL Gone DUTCH]

As smiley indicates greens are better than black and blue better than both But to answer question you would be over 90-95% duty cycle with the green ones @ 6500 rpm ish Ideally you should be aiming for a duty cycle of around 80% max this will be at around 245-250 hp

[CHILL Gone DUTCH]

I had to change from green to blue VXR injectors as was maxing them out on my 250bhp S/C engine Sent from my iPhone using Tapatalk

This is because your car before water injection was injecting extra fuel because of your inlet temps with smal rad So everything is not black and white but the blue vxr injectors also the size of the pulley effects duty cycle

Edited by CHILL Gone DUTCH, 03 April 2017 - 05:14 PM.

[CHILL Gone DUTCH]

You could also change fuel pressure to help

[Exmantaa]

This is what is actually measured for the various injectors on a flow bench at the NA's standard 3.8bar pressure:

 

Z20LET: 365cc/min @ 3.8Bar LSJ: 406cc/min @ 3.8Bar  (+ 11%) Blauwe VXR injectoren: 442cc/min @ 3.8Bar (+21% / +9%)

 

The Z20LET's used to be the standard on all Courtenay Stage 2 Sc conversions and I get a straight 0.8 Lambda (11.8AFR) till the 6800rpm redline with those giving 249.8HP on the dyno.

The LSJ's give 11% more fuel above that, but if you feel unhappy touching ~90% dutycycle at the rev limit, by all means fit the blue VXR's.

 

Edited by Exmantaa, 03 April 2017 - 05:41 PM.

[CHILL Gone DUTCH]

Was this with CS " modded fuel pressure "

[smiley]

The dutch don't bang their fuelrail

[Exmantaa]

Was this with CS " modded fuel pressure "

 

No, bog standard Courtenay Stage 2 with the standard 3.8 bar fuel rail. Boost referenced pressure off course.

(Still untouched like that in my black street Speedster; although feels a bit slow if I drive it after the Yellow Harrop 2.0. )

[oakmere]

Don't the vxr blue have the incorrect single spray pattern? I know they work but wasn't there a GM SC upgrade injector for the LSJ?

[smiley]

The vxr ones have to good spray pattern.

Only the Siemens 680 have single spray.

Not sure about the 550's and  860's.

[CHILL Gone DUTCH]

I would use z20let over lsj greens. And you cant buy the vxr's as easily now, Germany is probably your best bet.

Why are blacks better than green ??