Maximum Supported Turbo Mass Flow Rate Based on HPFP

[zfgracing]

You can find this in my facebook group "boosted ecoboost (ecoboost tuning and tech)" but I thought I would post it here to for those of you that are like me and running out fuel.

This document tells you the maximum turbo mass flow rate that the HPFP can support at the given lambda, rpm, fuel temp and fuel pressure.

If you are having trouble maintaining fuel pressure log turbo mass flow rate actual, and compare at the trouble spot to this document. If you are showing a higher flow rate than what this document says at that particular point than you have likely exceeded the fuel pump capacity and that is what is what is causing the fuel pressure drop. Remember the HPFP is a positive displacement fuel pump, one you exceed the flow rate the pressure will drop like a rock!

Also take note, if you are seeing Insufficient fuel flow in your Drive Demand Limit Source and your fuel pressure is not falling like a rock, you need to adjust your injection window.

F150 Supported Air Flow.pdf

[metroplex]

http://www.ecoboostperformanceforum....p?topic=1248.0

Based on the data above for the F-150's HPFP, it looks like with stock airflow limits on the turbos on the F-150 3.5 EB, you could actually run E85 unless your LPFP/injectors aren't sized to match. But the HPFP should be fine. I can't run richer than ~0.82 lambda with E10 on my SHO without running into HPFP pressure drops and insufficient fuel flow errors.

[zfgracing]

Absolutely not these calculations are for pump gas only.... If i plug in e85 the supported air flow number will drop significantly.

Just to be clear the LPFP means nothing on these trucks. Change it does nothing the HPFP other than maybe, increase the ve 1-2% from the added pressure. When it comes to fuel pumps and the direct injection you have to realize you are dealing with a positive displacement pump. The GDI pump will suck right through that LPFP if push comes to shove. All the LPFP is there for is to prime the HPFP and keep the inlet pressure up to prevent capitation.

Injector wise it also misnomer that you'll need bigger injectors. You will eventually but in reality there is alot of room, you can increase the fuel pressure, and increase the injection a significant amount over stock. Enough to run e85. Again you have to look past convention MPI theory.

http://www.ecoboostperformanceforum....p?topic=1248.0

Based on the data above for the F-150's HPFP, it looks like with stock airflow limits on the turbos on the F-150 3.5 EB, you could actually run E85 unless your LPFP/injectors aren't sized to match. But the HPFP should be fine. I can't run richer than ~0.82 lambda with E10 on my SHO without running into HPFP pressure drops and insufficient fuel flow errors.

[zfgracing]

This is what it looks like on e85 at .85 lamba. As you can you can support it some degree (basically a little more than stock boost levels) but that is it. not worth it. Now I'm getting an rtr pump in soon like tomorrow that will support e85 in the sameish way the stock pump supports pump gas.

Just a note there are a lot more calcs in the FB group, basically one for ever ecoboost out right now. Also another not is these calcs are pretty damn close my truck is running out of within 1-2 lbm/min of the calculation, you can see the pressure start to dip off and then recover.


Capture.PNG

[zfgracing]

http://www.ecoboostperformanceforum....p?topic=1248.0

Based on the data above for the F-150's HPFP, it looks like with stock airflow limits on the turbos on the F-150 3.5 EB, you could actually run E85 unless your LPFP/injectors aren't sized to match. But the HPFP should be fine. I can't run richer than ~0.82 lambda with E10 on my SHO without running into HPFP pressure drops and insufficient fuel flow errors.

and the here are the calcs for the sho, it's a different fuel pump (and cam 4 cam lobe vs 3 in the f150) than the F150. Like I said though all this info is in the docs in the FB group SHO HPFP Max Supported Air flow.pdf.

Monitor your mass flow rate for air and line it up with this and see where you are at.

[metroplex]

What happens above 2200 psi with E30 and a lambda of 0.90? Say at 2500, 2700, and 2900 psi?

[zfgracing]

The ve of the fuel pump drops a little. If you go look at the 2.3l calculations they go up to 2900psi stock granted it's a different engine but it will give you an idea of how the ve drops. In general ve will get down in the mid 70% at that pressure (this often referred to add pump slip). So to explain ve let's say the fuel pump displacement is 1.23cc per cam revolution. That means at 75% ve you getting .9225cc of flow per camonth revolution.

[metroplex]

How much air mass flow would the SHO pump support at the higher PSI's with E30 and 0.90 lambda? I've been logging air mass flow since day 1 and have made several observations. The data you provided for pump gas seems to correlate with that, but I'm curious to see the max flow numbers calculated for the higher PSIs and E30/0.90

[zfgracing]

I can run some numbers and get back to. I'll take a little bit to do though since the stock fuel pump ve is only defined our 2200 psi. I'll pull in some other data though and should give me some results in the ball park anyway.

[zfgracing]

Alright here is the e30 numbers at stock fuel pressure.

I couldn't do the 2900 psi yet. However it is a safe assumition that you will lose between 1-5lbm/min going from 2200 to 2900

[metroplex]

Thank you. I might be reading the data incorrectly... if I increase the pressure, then the max air mass flow is reduced? But if I run the pump at a lower pressure, the VE is higher so it can flow more fuel/air?
How should I use the data? Is there any benefit in allowing the pump to run at a higher pressure?

[zfgracing]

Correct, remember this is what the fuel pump can support not what the injectors can support. Ideally you want to run the pump at the pressure where you have the highest VE. However, that's not possible because of the injectors. As you increase the pressure the injector flow go's up relative to injector pulsewidth but the total fuel pump potential goes down because the ve decreases as the pressure increases.

[metroplex]

How would I tell if I need to run the HPFP at a higher pressure to keep the injector flow at the right amount, or when to just keep the max at the stock pressure?

Based on my own testing, any lambda richer than say 0.85 with pump gas would result in insufficient fuel flow at WOT when running higher-than-stock boost levels. Looking at your numbers, it seems that I want to ensure that the air mass flow from at least 1000 psi needs to be the same or higher than the actual air mass flow. I heard that if your fuel pressure drops below 1200 psi or so, then you've run out of fuel but I know the Insufficient Fuel Flow error can come on above 1200 psi and the injection angle wouldn't help if it drops that much.

[zfgracing]

Re read the very first post!

The insufficient fuel flow limit is directly related to the fuel pump. It is directly related to the amount of fuel getting into the cylinder. Basically if the calculated fuel mass from the injection system is less than what you need for the afr you are at it triggers the IFF.

This happens when the injector is injecting for the entire injection window. If you see IFF and your fuel pressure is steady at the setpoint then that means you are at the limits of your injector. So you can do one of 2 things or both. Increase the injection window by spreading eoi and soi apart and increasing injection angle or increasing fuel pressure.

Now if you see IFF or if you see your fuel pressure drop more than 300-400psi off your setpoint you're out of fuel pump.

[metroplex]

How should I spread the EOI and SOI? Have it start earlier (smaller) and end later (larger)? There's SOI Minimum (383*), and then EOI Clip vs Pressure (700*) - and the SHO has a setting for Intake Valve Open at 360*. The 2015-up EcoBoost have a different format, but the 2014 F-150 shares the same settings (or similar) to the SHO.

[zfgracing]

Well that's what you have to play with, SOI and EOI clip can be moved out and MIA is the actual window max. So you need to make sure MIA fits into soi and eoi clip.