How far can I push the stock 19# injectors?

[stangboy]

Hey guys,
I'm finally about to do H/C/I swap on my car. I don't really have it in my budget to get the 24# squirters yet, so I was wondering if the stock 19s will be able to support what I'm gonna be doing. Here's what I'm getting:

AFR 165s w/58cc chambers
F303 cam(or maybe a Trickflow stage 1 if I can sell or trade the F303)
FRPP 1.6 stud mount RRs
Edelbrock Performer 5.0 intake
70mm TB
1 3/4" longtubes
2 1/2" x-pipe
and everything else in my sig.

 

[5.0CRAZY]

I think youll be at the very limit, if not exceding it. About 300hp is the limit and if you have a good tune I think youll be a little above that.

 

[Mike86Stang]

Well with....
Edel RPM 2.02 heads
1.7 RR
70MM TB
75MAF
Holleysystemax II intake
Steeda #19 cam
15/8th headers
full exhuast
60PSI of FP

It's still WAY lean... plugs look like frosted mini wheats lol
Does it run & drive fine....yeah it does but I still get a lean
miss about 3000 RPM on up

 

[Michael Yount]

General rule of thumb is somewhere in the 300-330 crank HP range for the stock 19's at stock fuel pressure (38-40 psi). Crank the pressure up and they'll flow more. At 61 psi, the 19's flow like 24's - which are probably good to the 375-425 crank HP range. Go to Pro M's website and under the meter sizing tab there's a bunch of info about HP ranges with injector size, and how actual peak flows vary with fuel pressure.

 

[stangboy]

Well with....
Edel RPM 2.02 heads
1.7 RR
70MM TB
75MAF
Holleysystemax II intake
Steeda #19 cam
15/8th headers
full exhuast
60PSI of FP

It's still WAY lean... plugs look like frosted mini wheats lol
Does it run & drive fine....yeah it does but I still get a lean
miss about 3000 RPM on up

DAMN!! i guess i need to get some 24# injectors as soon as I get some more money, huh?

 

[Mike86Stang]

This is probably true mike but doesn't volume go down as pressure goes up?

 

[Michael Yount]

For the same pulse width, volume delivered increases with increasing pressure. Go here for more info on how effective rate increases with increasing pressure......scroll down. http://www.pro-flow.com/tech info/sizing.htm

 

[91LX302]

hmm interesting, but would it be safe to run 61 psi of fuel through stock lines and injectors? That's alot more pressure than Ford intended.

 

[Michael Yount]

Don't misunderstand - I've simply tried to state the relationship between increased pressure and flow rates. Whether or not the systems/filters/injectors were intended to deal with that is a separate question in my mind. However, there are plenty of people out there that run increased pressures. And MANY people with superchargers and dry nitrous systems that use fmu's and rising-pressure systems to deliver the extra fuel necessary with boost or juice. I've never read a post related to a system or component failure attributed to running increased system pressures.

 

[91LX302]

I've never read a post related to a system or component failure attributed to running increased system pressures.

ahh very true, I was just curious if the system could sustain that much pressure.

 

[stangboy]

So, I CAN run the 19s for a while until I get some 24s?

 

[Mike86Stang]

You can but you'll be running alot of FP like me & she'll still be a bit lean IMO.
Atleast it is in my situation... I can only speak from my personal experiences.

 

[Michael Yount]

Sure you can run 19's - just know that you may be taxing them. If you run it out of fuel at high rpm and lean it out, you could have problems. I'd get it on a dyno with a wide band sensor so you actually know what your a/f ratio is doing. It's almost impossible to get a read on that on a street-driven car by looking at the plugs. Get some data and then make any corrections that might be necessary with either fuel pressure or by moving up in injector size.