When is PI needed?

[TopJimmy]

Hi Guys,

I have a F80 6MT that I love to build and improve 60-130s. I'm playing with some ideas of advanced fuels & fueling and I'm wondering when Port Injection (PI) becomes helpful or necessary. For the sake of my questions here let's keep any bung or port Meth out of the discussion because I don't want a separate tank to manage...unless we're talking about mixing Meth/Eth/93/RaceGas in the gas tank.

1) Using stock turbos are there any fuels or mixes that could benefit from PI, or require it? I'm hearing that the stock fuel system is good for all gasolines and E30-85, but running E90-98 or a tank Meth mix would overtax the stock HPFPs. PI might help with these high E mixes but any top end HP benefit is not worth the investment cost.

2) What about PI needs after installing PS2/PS2+ or GC/GC+ turbos...with basic or advanced fuel mixes? This is the really important question, since I'm thinking about the GC+ and racing on E85. I'm hearing that E50 is the limit for the stock fuel system at this level.

3) When would the PI need the Stage4 LPFP (with a secondary Walbro 450 & Hobbs switch), and when is the Fuel Pressure Regulator and return line a benefit?

4) Which injectors and why...the 550cc, 750cc or 950cc?

Just trying to plan ahead... I always appreciate your help!

-TopJimmy

[Detoxified]

Very interested in this thread. Following...

[Sejo5]

I went with the Fuel-it Pi platinum kit Minus the Pumps. My plan was to go for Max amount of HP without building motor my tuner and i discussed in length for what we needed to make the power safely. I did 50/50 mix before PI and now 100% e85 which was alot easier to deal with as i go to alot of race events and its easier to lug with me Ignite Red and Straight E85 Jugs.

Pure Turbo HF
Fuel It Pi Platinum 750CC
VRSF CP and J Pipe
ARM Resonated DP
MPE Titanium Exhaust with Secondary Cat Removal.
Mishimoto Top Air and Front Radiator
NGK - .019
Stock Clutch and Engine

Let me know if you have any more questions.

[TopJimmy]

Originally Posted by Sejo5

Let me know if you have any more questions.

Thanks!

When you said "minus the pumps" do you mean you use the stock LPFP +PI and no problems fueling E85?

Hybrid turbos but not plus, right?

Are you 6MT or DCT?

Any dyno info?

Thanks again!

[E92TiAg335i]

Following

[M4XS55]

What kind of power did you end up making?

Originally Posted by Sejo5

I went with the Fuel-it Pi platinum kit Minus the Pumps. My plan was to go for Max amount of HP without building motor my tuner and i discussed in length for what we needed to make the power safely. I did 50/50 mix before PI and now 100% e85 which was alot easier to deal with as i go to alot of race events and its easier to lug with me Ignite Red and Straight E85 Jugs.

Pure Turbo HF
Fuel It Pi Platinum 750CC
VRSF CP and J Pipe
ARM Resonated DP
MPE Titanium Exhaust with Secondary Cat Removal.
Mishimoto Top Air and Front Radiator
NGK - .019
Stock Clutch and Engine

Let me know if you have any more questions.

[Detoxified]

Originally Posted by TopJimmy

Thanks!

When you said "minus the pumps" do you mean you use the stock LPFP +PI and no problems fueling E85?

Hybrid turbos but not plus, right?

Are you 6MT or DCT?

Any dyno info?

Thanks again!

Excuse me if I'm not mistaken. Doesn't the car have 2 HPFP stock? Do people add another LPFP as a third pump for full E85 PI?

[whitstap]

Hey Jimmy, while PI is a legit way to add fuel for alcohol tunes/bigger turbo requirements the controllers are slow to respond/compensate compared to the stock ecu and can be tough to get right... Dorch engineering is working on 3 diff levels of upgrade for the s55 hpfp and stage 2/3 for big power will require upgrades to the lpfp as well... stage 1 is super trick and simple and should flow approx 20% more volume while retaining the oem hpfp but we’ll have to wait for a bit more testing before he releases and shares the exact details... even stock turbo e85 tunes will benefit from this as load/torque values need to be manipulated to get e85 to work on totally stock fuel system and then the ecu has no ability to adapt (compensate) and power is not consistent in all conditions like the factory tune or mild e10 tunes are...basically the car loses power with anything less than ideal conditions (i.e. dyno pulls at low IAT’s, sea level, first few street pulls on a cool day et...) hope that makes sense

[///BMW Junkie]

Originally Posted by whitstap

Hey Jimmy, while PI is a legit way to add fuel for alcohol tunes/bigger turbo requirements the controllers are slow to respond/compensate compared to the stock ecu and can be tough to get right... Dorch engineering is working on 3 diff levels of upgrade for the s55 hpfp and stage 2/3 for big power will require upgrades to the lpfp as well... stage 1 is super trick and simple and should flow approx 20% more volume while retaining the oem hpfp but we'll have to wait for a bit more testing before he releases and shares the exact details... even stock turbo e85 tunes will benefit from this as load/torque values need to be manipulated to get e85 to work on totally stock fuel system and then the ecu has no ability to adapt (compensate) and power is not consistent in all conditions like the factory tune or mild e10 tunes are...basically the car loses power with anything less than ideal conditions (i.e. dyno pulls at low IAT's, sea level, first few street pulls on a cool day et...) hope that makes sense

Thanks for sharing. Do you have any links where I can further research these upcoming Dorch upgrades?

[TopJimmy]

Thanks @whitstap !!!
Always great advice from you.

Originally Posted by Detoxified

Excuse me if I'm not mistaken. Doesn't the car have 2 HPFP stock? Do people add another LPFP as a third pump for full E85 PI?

The Fuel-It "Stage 4 LPFP" is an OEM in-tank fuel pump with a smaller Walbro pump attached beside (on a separate power circuit). This smaller secondary pump is activated by a separate Hobbs pressure switch, and feeds added fuel through a Y-filter to up front for when PI is about to kick in. This up-front line feeds both the HPFPs and the PI fuel rail. The Stage 4 setup also uses a boost-adjusted fuel pressure regulator and return-to-tank fuel line so the extra fuel pressure from double-pumping doesn't surge and affect the HPFPs. The regulator also protects from surges as PI turns on and off. For best performance the low-pressure side PSI must remain consistent as HPFPs and PI demands snap on and off.

[///BMW Junkie]

Originally Posted by TopJimmy

Thanks @whitstap !!!
Always great advice from you.

The Fuel-It "Stage 4 LPFP" is an OEM in-tank fuel pump with a smaller Walbro pump attached beside (on a separate power circuit). This smaller secondary pump is activated by a separate Hobbs pressure switch, and feeds added fuel through a Y-filter to up front for when PI is about to kick in. This up-front line feeds both the HPFPs and the PI fuel rail. The Stage 4 setup also uses a boost-adjusted fuel pressure regulator and return-to-tank fuel line so the extra fuel pressure from double-pumping doesn't surge and affect the HPFPs. The regulator also protects from surges as PI turns on and off. For best performance the low-pressure side PSI must remain consistent as HPFPs and PI demands snap on and off.

It does sound complicated when comparing to these upcoming straight high/low pressure fuel pump upgrades (Spool already available) and just having ECU do all the work. OEM++

[Detoxified]

Originally Posted by TopJimmy

Thanks @whitstap !!!
Always great advice from you.

The Fuel-It "Stage 4 LPFP" is an OEM in-tank fuel pump with a smaller Walbro pump attached beside (on a separate power circuit). This smaller secondary pump is activated by a separate Hobbs pressure switch, and feeds added fuel through a Y-filter to up front for when PI is about to kick in. This up-front line feeds both the HPFPs and the PI fuel rail. The Stage 4 setup also uses a boost-adjusted fuel pressure regulator and return-to-tank fuel line so the extra fuel pressure from double-pumping doesn't surge and affect the HPFPs. The regulator also protects from surges as PI turns on and off. For best performance the low-pressure side PSI must remain consistent as HPFPs and PI demands snap on and off.

This was a super helpful explanation. I really want to go Fuel-It stage 4 but use EOS intake manifold for my PI.

[TopJimmy]

@///BMW Junkie
I considered this but some of the top guys tell me that even though aftermarket HPFPs can flow 150% what OEM can their weak link is that the stock fuel injectors still flow at their normal rate (no bigger injectors...yet, maybe retrofits are WIP).

[///BMW Junkie]

Originally Posted by TopJimmy

@///BMW Junkie
I considered this but some of the top guys tell me that even though aftermarket HPFPs can flow 150% what OEM can their weak link is that the stock fuel injectors still flow at their normal rate (no bigger injectors...yet, maybe retrofits are WIP).

True, good point! Hopefully XDI or Dorch upgrades will have injectors as well 🤷🏼🙏

[TopJimmy]

@Detoxified
Exactly! I'm thinking the EOS manifold fed by a regulated Fuel-It Stage 4 (and port-matched to a VAC Stage 3 CNC head!!!). Vargas GC+

[Bluer2]

Originally Posted by TopJimmy

@///BMW Junkie
I considered this but some of the top guys tell me that even though aftermarket HPFPs can flow 150% what OEM can their weak link is that the stock fuel injectors still flow at their normal rate (no bigger injectors...yet, maybe retrofits are WIP).

What about putting in M5 injectors? Those European shops put in M5 injectors even before touching the LPFP and HFPF. I read somewhere that it only flows 5% more than stock but the pulse width and injector angle is improved also. I'm planning on getting Spool LPFP and HPFP with M5 injectors on my Krato turbos.

[TopJimmy]

Originally Posted by Bluer2

What about putting in M5 injectors? Those European shops put in M5 injectors even before touching the LPFP and HFPF. I read somewhere that it only flows 5% more than stock but the pulse width and injector angle is improved also. I'm planning on getting Spool LPFP and HPFP with M5 injectors on my Krato turbos.

I hear you but that's at least $5K in parts, then labor on top, for just 5-10% more fueling. $5K gets me the EOS PI intake, the FI Stage 4 LPFP kit, injectors and the install work. With that setup I'd have a ton of accurate fueling.

[///BMW Junkie]

Originally Posted by TopJimmy

I hear you but that's at least $5K in parts, then labor on top, for just 5-10% more fueling. $5K gets me the EOS PI intake, the FI Stage 4 LPFP kit, injectors and the install work. With that setup I'd have a ton of accurate fueling.

Thinking about it too, but in that case why not just do meth for fraction of a cost? Talked to few guys running Pures on E85/meth pushing mid 700's with no problem.

[TopJimmy]

Originally Posted by ///BMW Junkie

Thinking about it too, but in that case why not just do meth for fraction of a cost? Talked to few guys running Pures on E85/meth pushing mid 700's with no problem.

Meth usually has the risk of uneven distribution and I also don't want to manage a separate fuel tank. PI is pretty darn accurate and distributes evenly. I would have no problems running a Methanol fuel mix in the tank, since F80Paul has shown that M85 and even M100 is possible with PI.

[TopJimmy]

Okay, the word back from Steve at Fuel-it is the only real way to know when PI is needed is when logs show the HPFPs can't meet requested PSI. And to know when increased LPFP is needed also watch logs for a PSI drop.

[Bluer2]

Originally Posted by TopJimmy

Okay, the word back from Steve at Fuel-it is the only real way to know when PI is needed is when logs show the HPFPs can't meet requested PSI. And to know when increased LPFP is needed also watch logs for a PSI drop.

Has anybody has found the limit of the stock injectors yet because the HPFP limit is reached first? In order to find the limit of the stock injectors somebody needs to upgrade the HPFP and to push those stock injectors to the limit so i think adding M5 injectors to upgraded HPFP will add more than 5-10% more fueling.

[E92TiAg335i]

Originally Posted by Sejo5

I went with the Fuel-it Pi platinum kit Minus the Pumps. My plan was to go for Max amount of HP without building motor my tuner and i discussed in length for what we needed to make the power safely. I did 50/50 mix before PI and now 100% e85 which was alot easier to deal with as i go to alot of race events and its easier to lug with me Ignite Red and Straight E85 Jugs.

Pure Turbo HF
Fuel It Pi Platinum 750CC
VRSF CP and J Pipe
ARM Resonated DP
MPE Titanium Exhaust with Secondary Cat Removal.
Mishimoto Top Air and Front Radiator
NGK - .019
Stock Clutch and Engine

Let me know if you have any more questions.

Do you run an intake or drop ins?