HCI setup with 19lb injectors?

[Strype]

93 Notch 5speed, 66k miles
-gt40X heads (58cc combustion chamber)
-b303
-SSI intake
-76mm MAF (I have both tubes, 19lb is in now)

Hey dudes/dudettes,

My 93 notch is now fully operational (it was timing and a couple of tight rockers). I'm running the stock fuel pump and 19lb injectors...

The car is running fine. We took it up to 6500 rpm and no popping or backfiring of any kind. Should I go ahead and change out to my 24lb injectors and 190lph fuel pump anyway?

My neighbor got the timing issue fixed on the car. He told me "Now that we've got it running right, if you touch anything I'll skin you alive". And he's a redneck so I believe him.

Am I leaning this car out???

My guess is that YES I AM... But it seems fine.

 

[NIKwoaC]

2 things:

1. The stock RPM limiter is 6250RPM. I'm guessing you were basing your reading off the factory tach and your factory tach is off... As is pretty common with these cars.

2. You can look up the calculators online, but the stock fuel pump and fuel injectors are working above safe limits once you get past 250~260 flywheel HP. In fact, if you look in the 2010 FRPP catalog, Ford rates the 19lb injectors for 258 flywheel HP at 85% duty cycle, assuming you're using the stock fuel pressure regulator. I'd be inclined to believe your engine is making much more than that, so yes, you need a bigger pump and bigger injectors.

 

[Strype]

2 things:

1. The stock RPM limiter is 6250RPM. I'm guessing you were basing your reading off the factory tach and your factory tach is off... As is pretty common with these cars.

2. You can look up the calculators online, but the stock fuel pump and fuel injectors are working above safe limits once you get past 250~260 flywheel HP. In fact, if you look in the 2010 FRPP catalog, Ford rates the 19lb injectors for 258 flywheel HP at 85% duty cycle, assuming you're using the stock fuel pressure regulator. I'd be inclined to believe your engine is making much more than that, so yes, you need a bigger pump and bigger injectors.

I actually looked at the autolite tach... Maybe that's when I shut my eyes!

I'm running an adjustable fpr. So basically what your saying is "yes it will work, but it's not good for it". I think since I'm the one with a few grand under the hood I'll take your advice and beef it up

And given the dyno sheets I've seen from other guys on here I'm guessing it has around 330 at the flywheel, maybe a hair more.

 

[NIKwoaC]

I think since I'm the one with a few grand under the hood I'll take your advice and beef it up

Yea, I mean if you're going to put all that money into the engine... Might as well make sure it's getting enough fuel, right? If it's starving for fuel, worst case is you blow it up, best case is it doesn't perform as well as it should. Both of those options suck if you ask me, haha.

 

[stykthyn]

personally I think you would be fine running the 19's but 24's with the matching maf wouldnt hurt it. Since you have them already put them on.

 

[skunk21]

This has been hashed out so many times about the max hp limited of 19s and what duty cycle they are running at. I have even gotten my head lopped off with my charts. chances are you are good but I agree stykthyn you have the parts use them it's not going to hurt and will probally put you in a better range IMHO.

 

[Strype]

 

[Chrome_Rust]

I am kinda in the same situation, My car runs hard, but at idle is pig rich. I have the stock injectors, a fuel tank from a SVO with a stock walbro fuel pump (not a GSS or anything, just says walbro on it). Using a MAF from a Lincoln (70mm) and an A9L. My car pulls past 7k (don't tell me I am wrong, tried 3 different Tach's), and I have no popping, nothing, but I am scared that I might melt a piston. I have no oxygen sensors right now (I know I know) and Like I said before, the car runs pig rich at idle... any thoughts?

Sorry for the hijack....

 

[f8tlfiveo]

My brother is running a similar setup with ported gt-40x heads and a ported gt-40 lower and explored upper.. Got dynoed at 335 at the wheels.. Air/ fuel was fine.. But if you have the parts it wouldn't hurt to put them in.

 

[NIKwoaC]

I am kinda in the same situation, My car runs hard, but at idle is pig rich. I have the stock injectors, a fuel tank from a SVO with a stock walbro fuel pump (not a GSS or anything, just says walbro on it). Using a MAF from a Lincoln (70mm) and an A9L. My car pulls past 7k (don't tell me I am wrong, tried 3 different Tach's), and I have no popping, nothing, but I am scared that I might melt a piston. I have no oxygen sensors right now (I know I know) and Like I said before, the car runs pig rich at idle... any thoughts?

Sorry for the hijack....

Assuming that the MAF meter is compatible, your computer is in failure mode if for no other reason than the missing O2s. In other words, it's assuming values for the O2s that are missing, and since your motor is modified, those values are most likely incorrect.

Pulling past 7K on ported stock heads is... Hard to digest.

My brother is running a similar setup with ported gt-40x heads and a ported gt-40 lower and explored upper.. Got dynoed at 335 at the wheels.. Air/ fuel was fine.. But if you have the parts it wouldn't hurt to put them in.

 

[Strype]

I just read that the stock rev limiter starts to drop fuel at 6250

 

[Night Shifter]

completely different motor but i have heads and stage 2 cams on my car and im running the stock maf and injectors and i wasnt even close to maxing out my injectors.. they were giving me more than enough fuel all the way up to 6,800 rpms when it was being tuned.. im around the 320hp mark so your 19's would be completely fine..

 

[NIKwoaC]

I just read that the stock rev limiter starts to drop fuel at 6250

What exactly does that mean?

 

[NIKwoaC]

OK, I just googled it.

This is all off the internet, so you have to take it with a grain of salt. All the books I've read about the 5.0 Mustangs claim a rev limiter of 6250... But here are a few examples of people saying that is not the case.

Also note the inaccuracies of stock tachs.

The following taken from: Factory rev limiter [Archive] - Hardcore 5.0 - The Hardcore Ford Drag Racers Forum

January 17th, 2009, 10:32 PM
Your stock tach is off way more than 200rpm. Typically the error increases as rpm increases. When my Autometer tach reads 4000, the stock tach reads 4200. At my 6200rpm shift point my stock tach is past 7000rpm. I'm sure Ford error'ed on the high side on purpose.....warranty. I guess they hoped it would discourage high rpm use. I also guess it hasn't discouraged you. (me either LOL)

January 18th, 2009, 01:10 PM
Some Fox computers (like the A9L & A9M) have a factory rev limit set at 7000RPM.
The A9P is set at 6200.

However, there are 2 rev limiters on these computers. The Minimum PIP Period is the 2nd limiter & needs to set very low (I normally set it at 250 or 300). In the SCT software you can adjust this, I don't know about Diablo.

A9P PIP is set at 700, which calculates to a 2nd limiter of over 8000RPM.
A9L & A9M PIP is 961 which calculates to a 2nd limiter of 6500RPM

Both limiters work the same, however the 2nd PIP limiter is calculated based on the PIP signal (clock speed).

I have run into a few foxes that seem to have no limiter.....with a stock computer & no chip. Very strange. These cars don't respond to limiters when I program the chip to limit the motor. (I do this for 'baseline' tunes & set limiters to ~4000RPM till the customer can bring the car in to dynotune it)

January 28th, 2009, 11:13 PM
That's right, the A9L will limit at 6504 RPM unmodified based on the MNPIP8 setting of 961. X3Z ('93 Cobra) has the limiter set at 6250 & the A9P is set at 6200 as stated. It has been assumed that A9L is 6250 for a looong time for some reason.

The person who put the ignition in showed that when many people think they have a rev limit below 6500 RPM in A9L, it's usually due to spark blow-out or valve float.

The following taken from: EECTuning.org • View topic - A9L rev limiter?

The rev limiter as set in the stock ECU for A9L is 6504 RPM. This is set by the MNPIP8 setting.

You are better off setting the MNPIP8 much higher than needed, then setting the rev limit using NLM_SH. This is a fuel cut rev limiter. Set NLM_CL below NLM_SH - this is the point where the fuel is turned back on.

The following taken from: EECTuning.org • View topic - A9L rev limiter?]Rev limit of A9P is lower than A9L [Archive] - Corral Forums

10-03-2004, 10:53 AM
When you are looking at the rev limiter in the software on a stock A9l file, that's what the value is set at (7000), but in an EEC-IV like an A9l, the rev limiter is also controlled by the minimum PIP function, which in the case of the A9l is 961. Once you calculate this and convert it to RPMs for a V8, the actual rev limiter is 6500 for an A9L. The minimum PIP for an A9P is 700 which translates to roughtly 9000 RPMs. Does this mean the A9P has a limiter of 9000? No, in this case the limiter IS controlled by the rev limiter function which is 6200. The processor will limit the revs based on whichever function's trigger occurs first. Hope this helps.
Don

 

[Strype]

Clear as mud

I didn't say anything but I thought my monster tach actually went closer to 7,000. My shift light is set to 6,000.

 

[NIKwoaC]

Clear as mud

Hahaha, seriously. SO, if what I'm hearing is correct, the A9L (manual trans computer) has a rev limiter of ~6500, and the A9P (auto trans computer) has a rev limiter of ~6200.

But yet, by some sort of black voodoo magic, some cars made it out of the factory with no rev limiter whatsoever.

 

[Chrome_Rust]

Assuming that the MAF meter is compatible, your computer is in failure mode if for no other reason than the missing O2s. In other words, it's assuming values for the O2s that are missing, and since your motor is modified, those values are most likely incorrect.

Pulling past 7K on ported stock heads is... Hard to digest.

OK on the 1st part. Totally understand.

Part 2, I ported the heads myself, not just removing the thermactor bump, but complately went through and opened up the exhaust to as close as the same size all the way tp the seat. I cleaned up the bowl area, dropped the floor and re radiused the valve stem area, on the intake they are cleaned up and gasket matched to a fel-pro 1250. smoothed the intake bolt protrusion removed all casting bumps and irregularities. Also cleaned up the bowl area, valve stem, and dropped the floor. I Know I am not a reconized pro on porting, and not asking to be, but the thing flat rev's NOW, and pulls forever. I have no valve float and have not hit any limiter of any kind.


Thank you for the time to reply though.

 

[Strype]

Just looked on mustangworks.com at the fuel system analyzer. It said I am in safe limits as long as I bump the fuel pressure up to 66psi


FUEL SYSTEM ANALYSIS
Total fuel consumption under wide open throttle: 170 lbs/hr
Minimum fuel pump volume required: 102 L/hr
Optimum fuel pump volume required: 122 L/hr
Injector size needed at stock pressure (40 psi): 24 lb/hr
Pressure required on current injectors to simulate needed size: 66 PSI
FMU Required on Current Injectors: N/A
Your current injector status is: IN THE SAFE ZONE

 

[NIKwoaC]

Just looked on mustangworks.com at the fuel system analyzer. It said I am in safe limits as long as I bump the fuel pressure up to 66psi


FUEL SYSTEM ANALYSIS
Total fuel consumption under wide open throttle: 170 lbs/hr
Minimum fuel pump volume required: 102 L/hr
Optimum fuel pump volume required: 122 L/hr
Injector size needed at stock pressure (40 psi): 24 lb/hr
Pressure required on current injectors to simulate needed size: 66 PSI
FMU Required on Current Injectors: N/A
Your current injector status is: IN THE SAFE ZONE

OK, yes, you can bump the fuel pressure up to make undersized injectors work. Couple things you need to know about that, though- 1. Part throttle and idle may end up running rich, since the injectors are kicking out more fuel than what they would be at stock fuel pressure. The computer may be able to compensate for some of that after a few operating cycles by narrowing the injector pulse width. 2. Fuel pumps are flow rated at ~39 psi. As you increase fuel line pressure above 39 psi, actual fuel flow from the pump lowers from what it is rated at. That is one of the reasons why, all else equal, forced induction cars require a bigger fuel pump than a NA car at the same horsepower level.

In other words, just buy a fuel pump way bigger than you actually need and forget about it, haha.