Looking for advice on larger than ID1000 injectors

[03Steve]

Another rub is the AD counts themselves. When approaching 980 AD counts on an EEC-V, the MAF and PCM as a system start to lose accuracy. Ford put 980 as a max number for MAF counts with reasoning behind it.

I've worked with lower power cars and counts above 1000 before with no issues. But I would be inclined to have a meter in the 900 range for a max output on a higher caliber car.

 

[MalcolmV8]

Alright, at 979 counts with that meter and 5.1" tube, you are looking at roughly 2750 kg/hr of air, or 101 lb/min unscaled. That is 6062 lb/hr of airflow.

With E85 and let's say a .78 lambda, that is an air fuel ratio of 7.7:1. Ethanol scale, not gasoline. 6062 lb/hr air with respect to a 7.7:1 air fuel ratio is 787 lb/hr fuel required from the pumps and injectors. Divide by 8 injectors, and you get 98 lb/hr required fuel from each injector to hit the target lambda. That's at 100% duty cycle, which is roughly the size of the ID1000s at 39.15psi base pressure.

Thanks Steve. So my PID is correct and I truly am at 100% duty cycle on the injectors. Have you tuned the larger ID injectors? Is there any reason to not just get 2000s? is there a reason I'd want to pick 1700 or 1300s? BTW I'd like to hit you up one of these days on the formulas and math to work out air flow and fuel volume. I find that stuff very interesting.

 

[MalcolmV8]

Another rub is the AD counts themselves. When approaching 980 AD counts on an EEC-V, the MAF and PCM as a system start to lose accuracy. Ford put 980 as a max number for MAF counts with reasoning behind it.

I've worked with lower power cars and counts above 1000 before with no issues. But I would be inclined to have a meter in the 900 range for a max output on a higher caliber car.

Good to know. I was not aware of a 980 limit where the ECU starts loosing accuracy. I'll keep an eye on that and possibly have to get a larger MAF sensor too.

 

[03Steve]

You may be getting close to their limit with that fuel at 39.15psi base pressure.

There are other factors at play. The specific gravity of E85 is 12% greater than non-oxygenated gasoline. Tune a car perfectly on gasoline, put E85 in it, set stoich to 9.85, and the wideband will tell you a story due in part to gravity.

I have worked with 1300s and 2000s. The limiting factor on our combos in that injector non-linear range below 2ms and the fact that we have 281ci engines. So a big injector like a 2000 with c16 fuel can be cranky on a 281. Put e-fuel in it where the injector output needs to increase, and it isn't as cranky.

I would probably run the 1300s at 50psi base (or a little more) with your combo. I would work up some numbers before making a final decision.

 

[MalcolmV8]

Thanks Steve. I've personally experienced the below 2 ms issues myself when I had SD 80s. I know what you're talking about. I need to figure out some of that math so I can work out what 1300s at 50 PSI for example would support to see how well it covers my setup. Given how much of an investment ID injectors are I don't want to have to buy again in the near future.

 

[03Steve]

Yep, $1/cc!

Here is the math I would use...

1300cc / 10.5 = 124 lb/hr injectors (@ 39psi base fuel pressure)

(Sq Rt (50psi / 39psi)) * 124 lb/hr = 140lb injectors (@ 50psi base fuel pressure)

140 lb/hr * 8 injectors = 1120 lb/hr total fuel

1120 lb/hr * 7.7 = 8624 lb/hr (max supported air flow in lb/hr) (fuel times air/fuel ratio on Ethanol scale)

8624 lb/hr / 60 = 144 lb/min (max supported air flow in lb/min)

(Current airflow from previous post calculation was estimated at 101 lb/min)

144 lb/min / 101 lb/min = 42% additional fueling with ID1300 injectors @ 50psi base vs current airflow



This is a ballpark estimate, but at a glance...you can see that an ID1300 can provide a LOT more headroom. The raised base pressure may not be necessary, but we have found a little more HP with elevated fuel pressures (see direct injection engines for extreme example).

 

[badcobra]

Sorry for the hijack Malcolm!

Steve, what does that 980 MAF counts equate to in voltage? When I log a run, I usually just tap into my Dynojet WBC and get A/F and MAF_V. I want to take a look at my log from Texas when I had it turned up to 28lbs. I'm worried I'm approaching the end of capacity on my HPX in a 3.75" tube size. Thanks

 

[03Steve]

Divide counts by 204.6 to get volts.

 

[MalcolmV8]

Thanks again for the math and info there Steve. Badcobra just incase you're interested where the 204.6 comes from. Scale is 0-1023 counts and voltage would be 0-5 volts. So 1023 / 5 = 204.6

 

[TRBO VNM]

This is a ballpark estimate, but at a glance...you can see that an ID1300 can provide a LOT more headroom. The raised base pressure may not be necessary, but we have found a little more HP with elevated fuel pressures (see direct injection engines for extreme example).

Yup, seeing that right now with the Focus ST's. I'm actually doing an aux fuel system on mine with a bigger turbo to spray directly on the valves for cleaning and support more power.

 

[03Steve]

Also I'm wondering about...any limitations or issues using the larger injector data in my 03 Cobra ECU. Any high/low impedance issues to note?

Thanks

There are plenty of large high impedance injectors on the market. You probably already know about the requirement for an injector driver with the use of low impedance injectors on a stock PCM.

As far as stock PCM limitations go with injector size - there is at least one limitation. It is on the high/low slope scalars. With a stock PCM, you are limited to entering slope values that are no higher than 108 lb/hr. This translates to 0.03 lb/sec. The lb/sec is a unit commonly used on injector data sheets and in some tuning software. This limit is something that is easily worked around with scaling.

By the time most are putting a 108+lb/hr injectors on a stock PCM, the calibration has usually been scaled for something else. Whether it is due to returnless fuel flow limits or expressed MAF airflow limits, the injector slopes are probably subjected to the same scale factor as other things in the PCM.

One example - my car has a returnless fuel system. Of the variables in the PCM that require scaling, returnless fuel flow is always the leading item on higher power applications. With the calibration on the silver car scaled down to 40% of original, the PCM would STILL peg returnless fuel flow. When that happens the voltage table output actually reverts to something other than values in the farthest right column. It isn't pretty. So I had to scale my calibration down even farther than 40%.

By the time a file gets to this point, the injector slopes are a fraction of their non-scaled values, and no where near the 108 lb/hr limit.

One example I can think of where the injector slopes would be the leading item for scaling is on an otherwise stock car with ID1300s. Another is on a higher powered return car that is using the BP Modifier and adding larger than 108 lb/hr injectors.

 

[MalcolmV8]

Yes your last comment is my car. In the past I've used the BP Modifier method so I'm building a new tune now and scaling it due to new fuel pressure and injectors coming up and not having the best luck. I have to scale everything by 30% to get #/min to fit in of a stock MAF curve which seems crazy. However if I take my old somewhat hacked up MAF curve (which i was not planning on re-using) it really only needs to be scaled by 70% to fit. It's weird it's like the shape of the curve doesn't go up in proportion like the stock curve does. I think that's what's been throwing me off on trying to start with a new blank curve, the proportion of how the #/min goes up is way off than what my MAF sensor seems to do.

 

[Blown38]

I run the ID 1300 in the Marauder and they tune great. Idles great on 93 at 39psi base pressure. We have E85 in it now and running at .71-.73 WOT. I've been trying to get a config file onto the X4 so i can see where the duty cycle is.

I'll have to wait til I get home to find out the Mass Air Flow we are seeing to do the calculations. But we have a BA5000 in a 5" tube and seeing 690 counts at 7k and making 25psi. This is thru an unlocked converter with the calculators saying its making 7-750 hp to run 10.1's at 4200 lb race weight.

All I did to change the tune from the old siemens 80s to the IDs was scale the ID values by the percent that was already in the tune and then just fine tuned it from there. But it ran just great with the initial scaling.

 

[MalcolmV8]

I run the ID 1300 in the Marauder and they tune great. Idles great on 93 at 39psi base pressure. We have E85 in it now and running at .71-.73 WOT. I've been trying to get a config file onto the X4 so i can see where the duty cycle is.

I'll have to wait til I get home to find out the Mass Air Flow we are seeing to do the calculations. But we have a BA5000 in a 5" tube and seeing 690 counts at 7k and making 25psi. This is thru an unlocked converter with the calculators saying its making 7-750 hp to run 10.1's at 4200 lb race weight.

All I did to change the tune from the old siemens 80s to the IDs was scale the ID values by the percent that was already in the tune and then just fine tuned it from there. But it ran just great with the initial scaling.

That's pretty cool. I had a BA5000 several years ago in a 5.1" tube and idle resolution on the meter was a little course. It made nailing a good idle A/F hard although car seemed to idle fine with varying A/F. That's what made me change to the GT500 slot sensor. The low end resolution was greatly improved.
I'm currently leaning towards ID1700s so I have room to grow.

 

[badcobra]

Has anyone tuned some ID1700's yet on a Cobra? Wondering how good the driveability is?

 

[03Steve]

I'll have to wait til I get home to find out the Mass Air Flow we are seeing to do the calculations. But we have a BA5000 in a 5" tube and seeing 690 counts at 7k and making 25psi.

690 A/D counts with a BA5000 in a 5" tube is roughly 88 lbs/min of airflow. That MAF arrangement will support somewhere in the neighborhood of 270 lb/min of airflow.

88 lbs/min with a decent brake specific, along with the track times for the weight, is definitely over 670hp at the tires.

 

[03Steve]

That's pretty cool. I had a BA5000 several years ago in a 5.1" tube and idle resolution on the meter was a little course. It made nailing a good idle A/F hard although car seemed to idle fine with varying A/F. That's what made me change to the GT500 slot sensor. The low end resolution was greatly improved.
I'm currently leaning towards ID1700s so I have room to grow.

I'm sure MAF output at hot idle was a double digit number. Probably got into the range of the meter where noise and output stability become factors.

The VMP 3500 is a good choice when the Ford slot meter runs out of headroom in the bigger tubes. It will support about 150 lb/min of airflow in a 5" tube before pegging.

1300s or 1700s should both work fine. Either should be able to support more than the 2.9 can put out.

Has anyone tuned some ID1700's yet on a Cobra? Wondering how good the driveability is?

I haven't yet. Most EEC-V people I run into are switching from stock PCMs when they get to the point where they run 1700 and greater sized injectors. I'm sure the stock PCM will work fine with them.

 

[Blown38]

I had varying AFR at idle when I didnt have a PCV valve in the car. I just put a ME Wagner adjustable PCV in and the AFR is rock steady now and the car is able to idle lower too. I want to say the counts are right at 100 at 900 rpm neutral idle.

 

[Fast Willy]

http://www.billetatomizerinjectors.com/

You will thank me after you call and talk to them.

 

[MalcolmV8]

http://www.billetatomizerinjectors.com/

You will thank me after you call and talk to them.

Care to elaborate? Their website says they are low impedance injectors which means I'd have to get an injector driver module to interface between the ECU and the injectors to make them work. I'd rather avoid that headache.