4.62VNA

I have a prety well moded NA 4.6 and changing the lower intake due to cracking and was wondering if i have it appart is it worth going from 19lb to 24 lb injectors or will it give me no gain.

on a side not my head on the passanger side front and last cilender seem to have more build up on them then the other 6.

Thank

mrtstang

What's pretty well modded? Details???? If the 19's are supplying enough fuel now, there will be no gain in upgrading.

4.62VNA

top end is JBL cold air, accufab 75mm upper, 80mm tb. and all the rest under drive pullies x pipe 2 chanber flow master still stock headers shifters and alot alot more. Realy the only thing i can do is long tube headers vortech supercharger. I have all the rest.

4.62VNA

o and some head work can be done too.

Thanks again

MU71L4710N

why are you under the impression fuel injectors will give you more power?

cliffyk

The 19lb/h injectors were upgraded to 21lb/h in the mid 2002 MY, because they were operating at 90% to 95% duty cycle (which is essentially static) at high revs and WOT. The 21s run 85% to 90%, which is still too high by most "rules of thumb".

So if you are not all of a sudden dropping dead lean at the top-end (WOT and 6k rpm), and your AFR is what you want, then higher capacity injectors won't add a bit of power--they just won't be working as hard.

That said, if I was running the 19lb/h injectors I would upgrade to at least a set of 21s from a bone yard, or someone who upgraded a late model new-edge; or to 24s if I couldn't find a set of 21s (which will likely cost less).

You will need a tune to adjust the low and high fuel slopes, breakpoint, and minimum pulse width...

4.62VNA

ty ? cliffyk, for all the knowlage.

asiansensation78

I'd say upgrade them if you have FI plans. If you're going nitrous (wet), a they'll be fine but a bigger fuel pump is always a good idea.

janine

Injector upgrades are done when the engine is modified to take in more airflow. Unless you've done some internal engine work, or added a FI, you don't need to upgrade to 24lb or larger injects. Your engine can only take in so much fuel in it's factory form.... Now if you had your Intake and heads ported and added a set of high lift cams, that would call for more fuel flow as your motor would be drawing in more airflow....

Motors are basically air pumps. The more Air and fuel, the more power it will make. A engine can only pump in a given amount of air N/A according to it's CI and head cfm. You can make a motor breathe better by doing the following: cylinder boring to increase displacement, crank swapping, porting/polishing the intake, porting the heads to allow more cfm, and of course by forced induction. There are also other methods to open air flow as well.

Larger injects (and if warranted a high volume fuel pump or pumps) would then be needed to meet the demand for the larger airflow. Otherwise the motor would run lean.

A larger Mass Air Meter, pipe, and better exhaust system can help a motor breathe to a lesser degree and would be mandatory with any major airflow upgrades.... However, those relatively minor upgrades by themselves without getting into the motor would not necessitate larger injectors. Just minor air/fuel tweaking on a dyno.

cliffyk

However, the 19lb/h stock injectors are known to be too small for even a dead stock PI 2V engine--Ford recognised this when they changed to 21lb/h injectors in 2002-1/2...