E85 flex tune for 350

[65sohc]

I agree 100%. If I had the time to enjoy my car more I'd definitely be using E85
I received my car on 12-2-15 and to date I have 217 miles on it lol. That's hopefully going to change soon.

Holy shite! You've got more than ten posts per mile. Mine is my DD. Having said that my daily commute is 11 miles roundtrip so I am always looking for excuses to "run errands."

Sponsored

 

[swedensky]

I was told I need LU47 injectors for my flex fuel tune...all the ones I'm looking at online are optimized for 5.0 motors...they are still the right ones correct?

 

[Derek@Lethal]

The 5.0L and 5.2L share the same injector heights, so the traditional 47's would work, however, the stock injector on the GT350 is probably a 47 already. You should not need injectors for a bolt on application doing flex fuel/E85.

 

[superman07]

what he said.

 

[65sohc]

I was told I need LU47 injectors for my flex fuel tune...all the ones I'm looking at online are optimized for 5.0 motors...they are still the right ones correct?

Who told you that?

 

[swedensky]

Who told you that?

Friend of mine. So the stock are 47 and high flow enough?

 

[Derek@Lethal]

Friend of mine. So the stock are 47 and high flow enough?

We haven't had the stock injectors flowed, but Lund believes that stock injectors are around 47 lb based on the power and RPM they have shown to support already.

 

[RubyRedBoost]

Hope this helps

 

[swedensky]

From my tuner, on another forum:

I've been getting a lot of questions lately about this, so I'm going to lay out the cold hard numbers.

Ford has laid out the fuel flow characteristics of the stock injectors, in fact they use airflow via Maf readings to calculate fuel flow, so we can accurately calculate the maximum lb/min of airflow an injector can support given a known stoich.

The high slope of the injectors is programmed as 0.0121999997645617 in pounds per second. To convert to lb/min simply multiply by 60, in this case .7312. Multiply this # by 8 (for the number of injectors) and you have the total volume of fuel the injectors can flow at *full* programmed fuel pressure at 100% duty cycle.
.7312 * 8 = 5.856 lb/min

Now we have the total fuel volume at full fuel pressure, which is regulated at the fuel hat in the tank. On the 15+ cars Ford has set this pressure at 59.595 psi at zero fuel flow. As fuel flow increases there is a pressure drop at the injector (basic physics) due to the location of the fuel pressure regulator. Ford has calculated this loss and programmed it into their fueling model, but it is only scaled to 4.0 lb/min fuel flow, however this model is linear so we can calculate the fuel pressure at the injectors at 100% duty cycle (5.856 lb/min), which would be roughly 55psi.

At 100% injector flow capacity pressure at the injector has been reduced 55psi. So what does a drop in fuel pressure at the rail do to injector flow? We need to recalculate the fuel volume thru the injectors at 55psi vs 59.595 at zero fuel flow. Ford has already done this calculation. The high slope multiplier is .9269 at 54.97psi.

So, at 100% pulse width on the injectors pressure drops to 55psi and fuel volume is calculated to 5.428 lb/min at 100% injector duty cycle.

Now that we have the maximum fuel flow at 100% injector duty cycle we can calculate maximum airflow the injectors can support, the variables being stoich of the fuel and the programmed lambda at WOT.
Stoich of the average ethanol blended gasoline in the US is calculated to be 14.08 by Ford. If you know the lambda commanded at WOT the math gets very simple.

Lambda at WOT * Stoich * fuel flow = lb/min Airflow

Below are examples:
.820 lambda * 14.08 * 5.428 = 62.6
So, on average gasoline with a commanded lambda of .820 at WOT the injectors can support 62.6 lb/min airflow.

Now lets look at E85:
.850 lambda * 9.7 * 5.428 = 44.75
On true E85 at 100% duty cycle on the stock injectors they can support 44.75lb/min airflow at .850 Lambda.

Looks pretty good right? Well, not really once we start looking at a few other variables.
1. Factory injector tolerance is +/- 6%
2. Factory fuel pressure regulators vary as well
3. Running at 100% duty cycle on the injectors leaves no room for error
4. Ethanol blends vary, we do see over 90% in the summer time in some places around the country

The tolerances can stack up against you just as easily as for you. 90% ethanol and 6% lower flowing factory injectors and you're out of fuel on a factory stock setup.

Food for thought, but it's why AED requires larger injectors on ALL coyote E85/Flex Fuel applications. Better safe than sorry is how we roll.

 

[superman07]

if your cars injectors were not up to par, I assume they would fail to reach the commanded Lamda and you would see this on the nguage?

 

[swedensky]

if your cars injectors were not up to par, I assume they would fail to reach the commanded Lamda and you would see this on the nguage?

Not sure, as he will be using an SCT with my car but also because we won't even try stock ones. Like he said I'd rather be safe than sorry.

 

[65sohc]

If that is food for thought, here is some dessert. Scrolling about 1/4 of the way down there is an interesting chart of AFR for common fuels:

http://www.hotrod.com/how-to/engine/1307-wideband-oxygen-sensor/

In light of the AED comments it would seem that running ethanol in the 50-60% range (flex tune, obviously) would comfortably take into account any "tolerance stacking" effect while retaining the high octane, high oxygen benefits.

 

[superman07]

Excuse my inexperience,

Does the 9.5-10.5 hp per lb/min formula the FI guys use have any relevance here? that would suggest that at max airflow with e85 despite octane we would not be able to make the HP folks have shown on the dyno. I could see where this multiplier would be wrong for NA due to efficiency differences however I did not see any multiplier that is used for NA.

Is there a way to estimate the upper HP bound supported with bolt-ons given this injector info. I would definitely consider bigger injectors when I add the CAI and ARH long tubes.

 

[superman07]

will the 60lb injectors work? if your going to get a new set it would seem best to buy once cry once and go big.

 

[Johnb-5.0]

The 5.0L and 5.2L share the same injector heights, so the traditional 47's would work, however, the stock injector on the GT350 is probably a 47 already. You should not need injectors for a bolt on application doing flex fuel/E85.

Fordparts.com the 5.0 and 5.2 share the same fuel Injector part number 9F593 (CM-5187). If they are the same injector, Its safe to say they are not 47's.

Sponsored