View Full Version : Fuel Injector Question

12-29-2005, 10:05 PM
This is one I have never been able to get a good answer on

Lets say that I have a 30lb fuel injector and a 45lb fuel injector

How does the 45lb injector deliver more fuel?
the same number of fuel droplets but with larger droplets
Or the same sized droplets and just more droplets?

12-30-2005, 12:53 AM
Bigger pintle / orfice combo. So, yeah- more droplets.

12-30-2005, 07:33 PM
Ok that makes my idea not work...
I was thinking of using 2 20 lbs injectors instead of 1 40 lbs injector to get better atomization.

12-30-2005, 11:34 PM
The problem with that would be that you would have two injector nozzles in the combustion chamber instead of one which could hamper combustion maybe?

12-30-2005, 11:52 PM
Lowend- Is this for the 383 in your sig?

Rumblee- the injectors aren't in the chamber, they squirt into the intake tract, or on LSX engines, they squirt right down at the intake valve. Diesels do have injectors in the cylinders, though...

12-31-2005, 10:11 AM
Back in the old days (5-10 years ago) large injectors were not capable of switching on/off quick enough for a good idle on high power motors (especially boosted applications) and staged injectors were almost required. Now they have lightened the components so they can react faster and you can get a good idle even with 75lb. injectors.

Fuelie Fan
12-31-2005, 12:10 PM
For droplet size, it's the pintle design that matters. Response time has improved as well, the dynamic range of modern high impedance is approaching that of older low impendance injectors. Most new injectors are of the multi-orifice disk design, and can be custom tailored to the application with anything from a "pencil" pattern to dual cones for 4 valve engines.

12-31-2005, 03:24 PM
FuelieFan got it right- the newer injectors are way better than the older designs- you can no longer (if you ever did) assume that "injectors are injectors".

01-02-2006, 11:06 AM
Is just an idea I've been kicking around for awhile... I'm on a spending hiatus for my Camaro until Spring so this wouldn't be happening any time soon

ProStreet R/T
01-02-2006, 04:53 PM
Also remember that idle quality has a lot to do with the power of the injector drivers in the PCM configuration. It's not an issue till you get up in the 80# + range but with the right setup even 160's are tolerable.

Though for a true street car I would run (on a V8) 16 injectors and stage the 2nd set to come in at a certain rpm or boost pressure.

The injector size refers to the amount of fuel in #'s that is flowed per minute, similar to how you size a turbo.