[JasonBVHS]

1: which is better a Diable or Jet chip?
2: if i get a custom program, should i go ahead and upgrade my fuel injectors, TB, and other stuff before i order it?
3: Could my 99 vulcan engine handle upgraded Fuel injectors, and if so what size, and lbs. should i go with?

 

[silvapain]

1: Dablo. It is custom programmed for your SPECIFIC box code. Jet just does a generic code.

2: You can upgrade your TB anytime without a re-burn. The MAF and injectors will need a reburn, unless you get a MAF that is already calibrated for the injectors.

3: Yes, the vulcan can handle upgraded injectors. I would start with 19 lb/hr injectors. If you go too high, you will have throttle response issues.

 

[JasonBVHS]

thanks, so if i get bigger injectors say 19 like you suggested, would i have to get a different fuel pump? And would duratec injectors swap? if not where can i get bigger injectors that fit my car?

 

[silvapain]

Duratec injectors will swap. So will mustang injectors (also 19 lb. for the 3.8L). The stock 60 PLH fuel pump will barely support the 19 lb injectors. I got my fuel pump off of ebay for $40 (I think). IT is a bit of a pain to drop the tank and install it, but I would definately suggest replacing the in-tank pump rather than putting an in-line pump in. the in-lin pumps have a tendancy to cause the in-tank pump to cavitate (suck it dry and make it burn up).

 

[mikehawk]

I'm almost positive duratec injectors won't work. AFAIK duratecs use the skinny oval injectors, and vulcans use the fat round injectors.

 

[Bob Gervais]

Originally posted by mikehawk@Jan 25 2004, 09:00 PM
I'm almost positive duratec injectors won't work. AFAIK duratecs use the skinny oval injectors, and vulcans use the fat round injectors.

You are correct. Up to 99, Vulcans had the longer style injectors. The easiest route is to find some from a 5.0 Mustang up to the mid-90's.

 

[americanmotorsport.com]

Originally posted by silvapain@Jan 25 2004, 07:35 PM
1: Dablo. It is custom programmed for your SPECIFIC box code. Jet just does a generic code.

2: You can upgrade your TB anytime without a re-burn. The MAF and injectors will need a reburn, unless you get a MAF that is already calibrated for the injectors.

3: Yes, the vulcan can handle upgraded injectors. I would start with 19 lb/hr injectors. If you go too high, you will have throttle response issues.

On automatic cars, you MUST reburn for a TB. They affect shifts.

If a tuner is good, it DOES NOT matter what size injectors you have, it WILL idle perfectly. I have made Focus cars idle perfectly with 55# injectors and such.

EVEN if you get a MAF calibrated for the injectors, you MUST get a chip or a flash. If not, load will be off, and thus you will have too much timing...this is a not-so-well-known fact...

 

[silvapain]

As for the TB, I am going by what I have been told by Ken at Motorhaven. As for the injectors, I asked some people on this site who have done it. Just out of curiosity, why would you put #55 injectors in a Focus, unless it was forced induction? If they were on an otherwise stock engine, the duty cycle on the injectors would be incredibly small. But hey, I'm no programmer, so I am just making an educated guess.

sorry about the wrong info on the injectors. I got mine from a mustang.

 

[americanmotorsport.com]

It was a turbo SVT Focus. That's a problem for most other tuners...I can get it to idle perfectly as it should be, even if it was N/a. I tune a little differently than everyone else...and my software and hardware allows me to make changes others can't or won't.

We once did a V6 Mustang with a blower and a Lightning MAF and a blower. He broke the blower belt (it was a powerdyne) and the car was tuned well enough that he was able to drive it as such until he fixed his blower; perfect idle and driveability. Injectors are about capacity, not about whether you will "use enough of the fuel to allow it to idle properly." However, clearly there is no point in putting in a large injector unless you need it...

Trust me on the TB. We have lots of experience with transmission calibration....

 

[JasonBVHS]

so if i get the 19lb injectors and get a chip calibrated for them, would the overall performance be better, than if i were just to leave the stock 16lb injectors and pump in.

 

[JasonBVHS]

And since The flex fuel is essentially a vulcan, could i swap out the 23.5lb injectors and or swap out the pump?

 

[americanmotorsport.com]

If you have not made any mods requiring more fuel, there is no need.

 

[dant98]

FYI... Alberto knows his stuff.

But anyway, IIRC, adding injectors alone will not add power. The only reason to add injectors is if you have another power adder that is maxing out your stock injectors. I think there's probably a chart somewhere that tells you if you have so many cylinders and so many horsepower, you need such and such a size of injector.

-Dan

 

[Bob Gervais]

Injector sizing

Here's one I came across on the V8 SHO mailing list. Seems that the stock 14 lb. Vulcan injectors are fine.

Alberto, I will be in touch with you this week, nice job on Dan's car from what I hear.

 

[americanmotorsport.com]

For a general idea, use the folowing formula:

(sqrt(actual flow/pressure at rated flow)) x rated flow x (#of injectors/BSFC)

-Actual flow is the current delta P or pressure drop across the injectors
-Pressure at rated flow is roughly 39.5
-Rated flow is the injector rating at 39.5, i.e. 19#
-# of injectors is self-explanatory
-BSFC is brake specific fuel comsumption. Use 0.6 for a blpown car and 0.5 for an
-N/A car if unknown

This will give you the rough power level that the system will support froma fuel standpoint, granted an adequate fuel pump.

 

[americanmotorsport.com]

p.s.

This is just a guideline. The horsepower numbers that result are flywheel horsepower numbers or BHP, not RWHP.

Most non Ford injectors are rated at 42.5 psi. Most Ford systems run fuel pressure of 39.5 psi. Clearly then you must use 42.5 for rated fuel flow for most injectors and 39.5 for actual fuel flow.

 

[dant98]

Now that it's perfectly clear...

Alberto, I'm not sure how to use your forumula because there isn't any equals sign... Does that calculate horsepower or what?

Now the link I saw from Bob I understood better.

If I read that correctly, the stock Flywheel horsepower on a duratec is 200HP..

So you get:

(200 X .5) / (6 X .8) = 20.833# injectors

So, Alberto, does this mean the stock injectors are just barly cutting it for the duratec, or is my formula wrong, or is ford just lieing about the stock HP rating?

-Dan

 

[americanmotorsport.com]

Originally posted by americanmotorsport.com@Jan 26 2004, 11:11 AM
This will give you the rough power level that the system will support from a fuel standpoint, granted an adequate fuel pump.

I apologize if it is unclear. As I wrote above, "this will give you a rough power level that the system will support from a fuel stanpoint."

So I guess you would re-write is as such:

BHP supported = (sqrt(actual flow/pressure at rated flow)) x rated flow x (#of injectors/BSFC)

That being the case, for 19# injectors in an N/A taurus you get

BHP = (sqrt(39.5/42.5))x19x(6/0.5)
=0.964x19x12
=219bhp

 

[Bob Gervais]

OK then, using that formula I come up with 14lb. injectors supporting roughly 161 HP.

Alberto, what duty cycle is this calculated at, and how much does that matter?

 

[americanmotorsport.com]

Yes but rememeber that is only a guide...

Here goes a little diatribe, bear with me:

Most calculations are done at at 100% injector duty cycle. I know what you're thinking, but that's not a problem for a street engine or a drag race engine. If you are stuck only wanting 80% duty cycle then most everyone needs bigger injectors or they are on the edge. There are a bunch of fairly stock GT's making around 260 at the wheels with 19# injectors. Do the math with .5 BSFC, that's only enough for 304 crank HP, if you then take 80% of that, they are only good for like 240 at the CRANK.

Should all these guys switch injectors? Let's take a stock GT with 260 crank HP, that's even under the 80% of the 304 number. Does that mean that Ford doesn't know what they are doing and the injectors are too small? No. A Cobra with 8 24's, 8 times 24 divided .5 is 384 FWHP, 80% of this is 307 FWHP, again, Ford is violating "the 80% duty cycle rule." There are also a lot '01 Cobra's with stock injectors, making over 300 RWHP. Are all these on the edge and in danger of blowing up? No.

One final example: lets use a '03 Cobra. Eight times 39.6 divided by .6 (and if you see the a/f ratio on stock cobra's, it's way greater than this) is 528 FWHP. 80% of this is 422 FWHP. How many '03 Cobras are more than this at the wheels, are they on the edge?

The thought of only 80% injector duty cycle came from people thinking the injector needs enough time to cool off. And this is true, but to overheat an injector it takes 60-90 seconds minimum at 100%, how fast do you think you'll be going in 90 seconds? And it's almost impossible to be at 100% duty cycle for extended time. It's a calculated game that almost everyone plays, including the OEM's. Now, in a road race motor, this is very, very true about giving it enough time to cool off and then maybe you want to size for 80% so it does have that cool off time.

It is virtually impossible for an injector get unstable over 80% duty cycle unless it's there for an extended period of time. I knwo most will disagree, but they have no data to the contrary. Clearly the OEM's run their injectors way past 80% and there are very, very few injector failures.

Now if you ran a car at WOT ALL the time when you are "on the egde" it may go lean..." but again, howmuc time CAN you spend at WOT?