Bigger injectors

[Get_Sum]

Hey guys anyone knows where i can get a the best quality injectors that are a lil bigger than the stock ones ???

[jmc007]

I purchased some barely biggers injectors than stock friday and I received them this morning. Unfortunately, we didn't have the chance yet to see if they fit. Also the connectors aren't the same. Also, we are not sure of the stock injectors flow, unless someone got it measured.

EDIT : remove some asumed datas.

[clevelander2002]

I thought someone on here tested them and they were 42LBS/hr. I could be wrong though.

[jmc007]

Finally I get the true result for the injector flow test: My stock Cobalt SS/SC injector filled a 95 cc graduated cylinder in 30 seconds flat, BUT THE DUTY CYCLE OF THE TEST WAS 50% (it was a dynamic test). So it means that stock injector flow is 380 cc/min @ 43,5 PSI ! (380 cc/min divided by 10.5 = 36 lb/hr @ 43,5 PSI).

Don't forget that the stock LSJ fuel pressure runs somewhere between 50 and 62 PSI (highest numbers at WOT). For those who want to make some calculations, since this car is a forced induction one, you MUST use the differential pressure (I mean if there is 62 PSI in the fuel rail at WOT with the stock supercharger pulley running at 12 PSI, the differential pressure through the injectors (bone stock) to be used for calculation is 62-12 = 50 PSI).

I have myself done a lot of calculation, the Brake Specific Fuel Consumption (BSFC) of the car seems to be 0,585. Stock maximum injector duty cycle seems to be around 90 %.

Remember that the SS averages 210 WHP stock (4th gear dynojet); plus the 14-15 % drivetrain loss, that gives roughly a 240 SAE BHP number to be used in the formula.

As an example, here is the injector flow calculation for the stock SS.

240BHP x 0,585 (BSFC) / (4 (number of injector) * 0,9 (90% duty cycle)) = 410 cc/min (at a 50 PSI differential pressure).

To know how they flows at the standard rate of 3 BAR (43,5 PSI), you must multilply 410 cc/min by the square root of (43,5 / 50). The results gives 380 cc / min (36,2 lb/hr) @ 43,5 PSI, as I saw on the flow bench.

Now I am in the process of choosing the right injectors for my car, since the 38 lb/hr I had purchased are too small.

Hope this help.

Have a nice day !

[jmc007]

Bump ... see my previous post please ...

[korax123]

So thats how the stage 1 kit produces so much HP....your bigger injecters should make a lot of HP also of course tuned that is with the Mini AFC.

[jmc007]

Post deleted, excuse me there is something that doesn't match.

[dL_RL]

Originally Posted by jmc007

.. but when doing some calculation at 58 PSI ...

Square root of 58/43,5 x 190 cc/min only gives 255 cc/min !!!

Unless I am not using the good formula ... ???

255cc/min. i've heard of honda's with bigger injectors..

[jmc007]

Post deleted, excuse me there is something that doesn't match.

[jmc007]

OK just see my corrected post #4 for the results.