LPFP support for HPFP rail pressure

[langsbr]

Due to the cooling properties of ethanol itself?

That and being direct injected. If you're bored, here's a paper from MIT about it...

https://energy.mit.edu/wp-content/uploads/2008/01/MIT-LFEE-08-001-RP.pdf

 

[doublespaces]

We could not count on two hands the number of times people told us the shotgun was not working properly, and we told them the issue was to be found in the LPFP system. if it can't keep up, you cannot possibly hope to keep good rail pressure. They would argue that LPFP looked fine in the logs, etc. We would insist its a feed issue, people who listened would upgrade the LPFP, and the issue would usually resolve. Others would say the shotgun doesn't work as advertised. This is a prime example, albeit on a different product that the LPFP side of things is just as important as the high side. If you cannot properly feed the HPFP spinning it faster is not going to help your rail pressure. Good work Tyler

Not to stray, but one of my upgrades was surely my issue all along. You guys took care of me there and I appreciate that very much.

Although I recall neither of us suspected the LPFP or EKP with words. There was no obvious indicators that suggested this. It was tuning we suspected.

This problem plagued me for so long I am actually tempted to put the dw400 into this bucket just to see what happens.

 

[Chris@VargasTurboTech]

Not to stray, but one of my upgrades was surely my issue all along. You guys took care of me there and I appreciate that very much.

Although I recall neither of us suspected the LPFP or EKP with words. There was no obvious indicators that suggested this. It was tuning we suspected.

This problem plagued me for so long I am actually tempted to put the dw400 into this bucket just to see what happens.

Tyler, I was not referring to you in this post. Its a rather common occurrence with shotgun customers to be honest. They want to run E85 as cheaply as possible, $799 seems like a good deal. They throw a cheap LPFP solution in the car if anything at all. We have had people try to run stock LPFP and complain the shotgun was not working as advertised. LPFP needs to be robust to keep up with an overdriven HPFP. A Single Walbro 450 is usually not enough stock is 100% not enough.

 

[doublespaces]

Tyler, I was not referring to you in this post. Its a rather common occurrence with shotgun customers to be honest. They want to run E85 as cheaply as possible, $799 seems like a good deal. They throw a cheap LPFP solution in the car if anything at all. We have had people try to run stock LPFP and complain the shotgun was not working as advertised. LPFP needs to be robust to keep up with an overdriven HPFP. A Single Walbro 450 is usually not enough stock is 100% not enough.

I agree, with ethanol and pure DI the low pressure system should probably be upgraded to stage 3 based on power goals rather than datalogging indicators or comparisons with people running PI.

Until we understand the answer to the question I asked @martymil there isn't always going to be a clear indicator when the LP pump isn't cutting the mustard. Upgrade sooner than later IMO, avoid tons of headaches.

 

[RNM]

How about a single 525 to overdrive a hpfp?

 

[Chris@VargasTurboTech]

How about a single 525 to overdrive a hpfp?

We still say no. In our opinion. Should be a minimum of 2 pumps, one primary, and once secondary that comes in with boost, or aftermarket EKP controlled. We have seen people barely get away with a single 450, but one thing not to do "just enough" for is your fuel system

 

[BOosted 335i]

Yeah wasn't having a dig at you, I just think the common stated octane of E85 needs revision.

I know

 

[BOosted 335i]

Ideally running higher pressures say a 100psi on low pressure side will help even more

So how do we achieve this for the lpfp?is it possible.

 

[RNM]

We still say no. In our opinion. Should be a minimum of 2 pumps, one primary, and once secondary that comes in with boost, or aftermarket EKP controlled. We have seen people barely get away with a single 450, but one thing not to do "just enough" for is your fuel system

I'm going to log soon to see how a walbro 525 controlled by the bpm4 will do with the spool overdrive on upgraded turbos.

 

[scrllock]

I'm going to log soon to see how a walbro 525 controlled by the bpm4 will do with the spool overdrive on upgraded turbos.

Eager to see those results. Particularly with a stock regulator/return setup. Got 2x450s just for safety since the big LPFP vendors agreed with Chris here that a single 525 wasn't always sufficient.

 

[yuli8466]

Correct me if I'm wrong but he's showing you that it clearly wasn't keep up with actual hard data. Simply changing the LPFP bumped the HPFP up 1000 psi at 6800 where it was running out of steam.

Also I was under the impression that 50-60's are actually low, and the system/HPFP as a whole was designed around 72psi?

yes you are correct. i was thinking another question before

 

[RNM]

Eager to see those results. Particularly with a stock regulator/return setup. Got 2x450s just for safety since the big LPFP vendors agreed with Chris here that a single 525 wasn't always sufficient.

I also have a precision raceworks fuel regulator assembly (not installed at the moment).

 

[aus335iguy]

I might be talking out of my arse... could it be that there’s cavitation in the system and although the presssure is ok the fuel is being displaced by air?

 

[fmorelli]

We know anyone running two pumps in a Z4? We are the bastard N54 children. LPFP setup goes in from the underside of the tank and actually the assembly "hangs" on an internal tank hanger. You'd think we owned an MG or some piece of British crap ... @BQTuning

Filippo

 

[PFS]

Haven't played with one yet, but it might be easier to just have that stock Z pump feed a surge tank with an aftermarket EKP controlling that, or a single/double pump activated in the surge via hobbs switch.

 

[iminhell1]

We still say no. In our opinion. Should be a minimum of 2 pumps, one primary, and once secondary that comes in with boost, or aftermarket EKP controlled. We have seen people barely get away with a single 450, but one thing not to do "just enough" for is your fuel system

So 2 450's should feed a DBBL fairly well?
I bought an adjustable Hobb's because the 14psi one I had just didn't feel right.

 

[PFS]

So 2 450's should feed a DBBL fairly well?
I bought an adjustable Hobb's because the 14psi one I had just didn't feel right.

That's wide open -depends on fuel, boost, how far you want to push DI, AF target, if those pumps are going through stock regulator or an external one, upgraded lines vs. stock, etc. but with the proper setup, dual walbros will get you north of 750 whp. The average user will find a dual-walbro to be adequate.

Chris

 

[Phat135i]

I have a 525 with the bmp-4 and I’m struggling with tuning the software. Any help? It’s dipping at 20-22psi in on full e.

 

[doublespaces]

I have a 525 with the bmp-4 and I’m struggling with tuning the software. Any help? It’s dipping at 20-22psi in on full e.

Got a log? Upload it here: https://datalogs.spoolstreet.com

 

[RNM]

Here is my log with upgraded turbos and full e85:

Bpm4
Single walbro 525 lpfp
Precision Raceworks intank fuel regulator with upgraded 8an fuel line
Spool Helix overdrive

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