[fortywater]

Hi All,

I have been trying to search for this answer, but have had no luck. What type on increase in demand is there, if any, on the HPFP when tuning? Say you are going from stock tune to a stage 2+ tune with MHD, I assume there is an increase in fuel supply to the engine due to the higher boost etc, but how does this correlate to HPFP utilization?

I ask because I am wondering how taxing it is on the stock HPFH to flash a tune like a MHD 2+. I am wondering if a HPFP was close to its end of life, if this would greatly accelerate that end of life.

Obviously, I have my assumptions that yes, its more demanding and will accelerate the end of life, but I may be mistaken and MHD stage 2+ may not be that aggressive. Appreciate the input.

[BazIRL]

I don't think you will run into issues on the stock turbo on pump fuel, looking at my cars logs the pump ran the same 2200ish psi at stock psi as it does at 16-18 peak tuned. But in saying that the pump is only 5000 miles old and it seems failure is inevitable with them, mine got to 75K before it wouldn't hold pressure anymore.

[anjuna]

HPFP
RPM is X axis
Load is Y axis

Stock tune


Most definitely NOT MHD's HPFP table *wink*


The HPFP table I have been running for over a year....



Fueling AFR
RPM is X axis
Load is Y axis

Stock tune


Most definitely NOT MHD's HPFP table *wink*


Fueling I run (Meth inject tho)


EDIT - I never see a deviation from commanded vs actual fuel pressure, and I run 1.5bar boost. I only saw deviation when I went to ~40% ethanol (~30% E85) and higher.

[fortywater]

Originally Posted by anjuna

HPFP
RPM is X axis
Load is Y axis

Stock tune


Most definitely NOT MHD's HPFP table *wink*


The HPFP table I have been running for over a year....



Fueling AFR
RPM is X axis
Load is Y axis

Stock tune


Most definitely NOT MHD's HPFP table *wink*


Fueling I run (Meth inject tho)


EDIT - I never see a deviation from commanded vs actual fuel pressure, and I run 1.5bar boost. I only saw deviation when I went to ~40% ethanol (~30% E85) and higher.

Thank you for the info and detail!

[ky0u]

My HPFP is hitting low 3k PSI in certain cases :|

[wheela]

Originally Posted by ky0u

My HPFP is hitting low 3k PSI in certain cases :|

Holy moly. I'm curious, what kind of tune are you running?

[9krpmrx8]

2011 E90. I am on the stock HPFP, stage 2.5 LPFP (Walbro 535) on an upgraded turbo (N55+) and custom E50 tune and I see over 3000psi, never really drops below 2400psi at WOT.

[ky0u]

Originally Posted by wheela

Holy moly. I'm curious, what kind of tune are you running?

Originally Posted by 9krpmrx8

2011 E90. I am on the stock HPFP, stage 2.5 LPFP (Walbro 535) on an upgraded turbo (N55+) and custom E50 tune and I see over 3000psi, never really drops below 2400psi at WOT.

I wonder if ethanol has something to do with it.
I'm running an e20 mix, MHD stage 2, 93octane map. Fuel pump set up is stage 2 LPFP, stock HPFP

I noticed during cold starts, my car hits like 2900psi on the first turn over then settles to like 2200 until the revs decrease to normal 600 rpm. During this time my injectors will tick loudly and my pressures gradually decrease to the standard 700psi. My idle pressure has always been within spec when at proper operating temp

[9krpmrx8]

Originally Posted by ky0u

I wonder if ethanol has something to do with it.
I'm running an e20 mix, MHD stage 2, 93octane map. Fuel pump set up is stage 2 LPFP, stock HPFP

I noticed during cold starts, my car hits like 2900psi on the first turn over then settles to like 2200 until the revs decrease to normal 600 rpm. During this time my injectors will tick loudly and my pressures gradually decrease to the standard 700psi. My idle pressure has always been within spec when at proper operating temp

HPFP targets are based on load. So once the cars warms up and it settles down, it should be around 750psi if you AC is off, etc. Injector tick is not for every direct injected engine. It will be louder if your engine covers are removed.

[ky0u]

Originally Posted by 9krpmrx8

HPFP targets are based on load. So once the cars warms up and it settles down, it should be around 750psi if you AC is off, etc. Injector tick is not for every direct injected engine. It will be louder if your engine covers are removed.

Yea it's sitting in the right spot at idle. It's just under moderate to heavy throttle, it'll go to around 2600+. Highest I've seen so far is 3300psi

[anjuna]

Originally Posted by 9krpmrx8

HPFP targets are based on load. So once the cars warms up and it settles down, it should be around 750psi if you AC is off, etc. Injector tick is not for every direct injected engine. It will be louder if your engine covers are removed.

It also depends on the injection window.

If the window starts earlier and ends later, there's NO need for such high pressures. but t00ners just haven't figured this out.

There is ZERO need for HPFP rail pressure being over 2.5ksi