PI or HPFP upgrade?

[ASTATENATE]

Current mods: Front mount intakes, cat less DP’s, single mid, SSR 4 pin crank hub fix w/ CH capture, stage 3 brushless LPFP, EU5, charge pipes, NGK gapped at .021 , GC+ turbos , BM3 Flex Fuel kit, BM3 and XHP tuned.

I am at a cross roads. Stock engine and trans. Not really wanting to go much more than 700-750. I have 2 friends running upgraded HPFP, one is at 778 and the other is 746 whp .

Is there any true benefit to PI over HPFP? Seems like both have pros/cons. My tuner will only tune PI if I have Reflex PLUS. Will not tune via AIC or Reflex LITE.

Pros to PI - more injectors, less of a lean condition possible, A/I software in the Reflex PLUS has added safety nets
Cons to PI - adding 6 more injectors (more parts = more possible failures) , have to splice into factory wiring, 6 more injectors that will require swapping/maintenance at some point.

Pros to HPFP - fairly simple hardware swap, no wiring/splicing, can easily support my power goals
Cons to HPFP - if DI injector fails there is no other injector to keep that cyl happy, no safety nets if hardware fails, etc

Anyone running PI or HPFP upgrade that can give me their .02 cents. My tuner recommended PI, which is what I was leaning towards, but said he can tune for HPFP upgrade as well. And I’d personally rather do HPFP upgrade

[wheela]

I may be biased, because I have no plans to ever go PI unless somebody comes up with a way to control the PI injectors with the stock DME...

But I would like to say that regarding your Cons to HPFP, I think this con is over-stated. If an injector fails to inject properly, it only takes 1 combustion cycle to go lean and get catastrophic detonation. If that happens, the damage could be done before your O2 trims have a chance to compensate via the other injector. With 6 additional injectors, you increase the odds of a cylinder having an injector failure. It's probably still only a remote possibility, but still...

[DeTh]

I've been told by a few different shops and tuners that 750whp on E50 is doable on the stock HPFP. I will be doing this soon once I am done with break in miles on my built motor.

[astris]

HPFP. I wouldn’t even consider PI. You can make 700whp+ easily with DI only.

People used PI when the platform was new-ish since it was available and DI related upgrades weren’t. Seems to happen with each new model iteration (see G8X platform now).

[ASTATENATE]

Originally Posted by wheela

I may be biased, because I have no plans to ever go PI unless somebody comes up with a way to control the PI injectors with the stock DME...

But I would like to say that regarding your Cons to HPFP, I think this con is over-stated. If an injector fails to inject properly, it only takes 1 combustion cycle to go lean and get catastrophic detonation. If that happens, the damage could be done before your O2 trims have a chance to compensate via the other injector. With 6 additional injectors, you increase the odds of a cylinder having an injector failure. It's probably still only a remote possibility, but still...

Yeah I do agree with that logic. Thanks for your input. I’m definitely leaning towards upgraded HPFP. For what the engine can handle and what the HPFP can supply. I def thinks this route is best for my goals.

Originally Posted by DeTh

I've been told by a few different shops and tuners that 750whp on E50 is doable on the stock HPFP. I will be doing this soon once I am done with break in miles on my built motor.

650whp on stock HPFP is doable. I am currently on stock fuel system and my HPFP is begging for mercy on E50 in the data logs to my tuner. It dips out too. Which I, nor my tuner like. No way it would support 750 wheel.

Originally Posted by astris

HPFP. I wouldn’t even consider PI. You can make 700whp+ easily with DI only.

People used PI when the platform was new-ish since it was available and DI related upgrades weren’t. Seems to happen with each new model iteration (see G8X platform now).

Def appreciate the response. Sounds like the crowd favorite is HPFP upgrade. It’s a little cheaper as well (if you go nice PI setup, I.e, plate kit, Motiv reflex+ , and 750cc injectors) it’s like $2100 for what PI setup I was looking at. HPFP from dorch is like $1800 and you get your $400 core back. HPFP Seems like more things to remove to install and little more physical work. But less time on labor since you don’t have to splice into anything like PI controller install.

[ASTATENATE]

I told my tuner I’d like his input on PI vs HPFP upgrade. His response

“So for me PI is best always. I see multiple people chasing DI numbers and then having to blend OR run the car VERY lean to hit the power goal is not worth it. Running Port injection allows you to have all the fuel and run the car richer which is safer. also all the aftermarket calibration for EU5's and hpfp upgrades is never as good as OEM. Pi has no effect on any of that.”

So seems like he prefers PI. But I’d rather just run HPFP upgrade. For a hardware upgrade. Not have to worry about splicing into factory DME. No additional injectors to fail, etc. I believe my goals 720-740 wheel are possible without mixing or leaning the car out. Am I wrong in that assumption? Am I missing something?

[DeezBluBallz]

HPFP,LPFP,EU5 injectors, and Bend Calibration Filter kit. Tried and true. All DME controlled.

[wheela]

Originally Posted by ASTATENATE

I told my tuner I’d like his input on PI vs HPFP upgrade. His response

“So for me PI is best always. I see multiple people chasing DI numbers and then having to blend OR run the car VERY lean to hit the power goal is not worth it. Running Port injection allows you to have all the fuel and run the car richer which is safer. also all the aftermarket calibration for EU5's and hpfp upgrades is never as good as OEM. Pi has no effect on any of that.”

So seems like he prefers PI. But I’d rather just run HPFP upgrade. For a hardware upgrade. Not have to worry about splicing into factory DME. No additional injectors to fail, etc. I believe my goals 720-740 wheel are possible without mixing or leaning the car out. Am I wrong in that assumption? Am I missing something?

I don't know all the technical details, but comparing AFR targets between DI and PI is apples and oranges; they can't really be directly compared. With DI, you have finer fuel atomization due to the higher injection pressure, and your injection window is no longer limited to the time the intake valve is open. These things impact charge mixing and cooling, so a particular AFR target on PI will have different combustion characteristics and knock resistance compared to the same AFR target on DI. Here's a Wikipedia link with some information about DI.

https://en.m.wikipedia.org/wiki/Gaso...rect_injection

One of the results is with DI the engine will generally like leaner AFR targets than with PI. So even though the AFR may be leaner on DI, that doesn't necessarily mean it's not as safe as a richer target on a PI motor.

[wheela]

Personally, I'd trust the aftermarket calibration for upgraded HPFP's and larger DI injectors more than I'd trust adding an additional controller to my engine management scheme. But to each their own

[-Eidos]

Originally Posted by ASTATENATE

I told my tuner I’d like his input on PI vs HPFP upgrade. His response

“So for me PI is best always. I see multiple people chasing DI numbers and then having to blend OR run the car VERY lean to hit the power goal is not worth it. Running Port injection allows you to have all the fuel and run the car richer which is safer. also all the aftermarket calibration for EU5's and hpfp upgrades is never as good as OEM. Pi has no effect on any of that.”

So seems like he prefers PI. But I’d rather just run HPFP upgrade. For a hardware upgrade. Not have to worry about splicing into factory DME. No additional injectors to fail, etc. I believe my goals 720-740 wheel are possible without mixing or leaning the car out. Am I wrong in that assumption? Am I missing something?

If you have to blend or lean things out to hit a power goal on DI, then your DI setup is insufficient (LPFP, HPFP, and injectors). OR you're shooting for built motor numbers and maxing out the currently available Nostrum Stage 3 injectors (Conservatively rated for 730whp on E85).

If you're the latter, then yeah, I can see PI being useful to avoid blending down or leaning things out especially when paired with ECUTek and Motiv Reflex.

If you're the former, then it's unfair to bash on DI-only if it's ultimately a setup issue.

The only absolute win I see for PI is if you live in an aggressive SMOG check state like California. With PI, you can still run your stock tune and pass the normal route if you can pass the visual, which isn't difficult.

[JustAnothaM4]

Originally Posted by DeezBluBallz

HPFP,LPFP,EU5 injectors, and Bend Calibration Filter kit. Tried and true. All DME controlled.

This!!

There is no need for PI for 700-750 power goals.

[ASTATENATE]

Originally Posted by -Eidos

If you have to blend or lean things out to hit a power goal on DI, then your DI setup is insufficient (LPFP, HPFP, and injectors). OR you're shooting for built motor numbers and maxing out the currently available Nostrum Stage 3 injectors (Conservatively rated for 730whp on E85).

If you're the latter, then yeah, I can see PI being useful to avoid blending down or leaning things out especially when paired with ECUTek and Motiv Reflex.

If you're the former, then it's unfair to bash on DI-only if it's ultimately a setup issue.

The only absolute win I see for PI is if you live in an aggressive SMOG check state like California. With PI, you can still run your stock tune and pass the normal route if you can pass the visual, which isn't difficult.

I mean my current setup is S3 LPFP, EU5 and if I ran Dorch HPFP I see my goal of 720-740 being possible. Also not in any SMOG compliant state so no worries about any of that. I was just under the impression PI is outdated and was only used until HPFP upgrades became available, now everyone is jumping ship to HPFP+ instead of PI. It’s gonna cost me roughly the same amount either route I go. And my power goals of sub 750. Stock motor. I don’t think I’ll ever use the full capabilities of PI. But it goes back to, is it safer. I’m so 50/50 on it. It hurts my head

Originally Posted by wheela

Personally, I'd trust the aftermarket calibration for upgraded HPFP's and larger DI injectors more than I'd trust adding an additional controller to my engine management scheme. But to each their own

This is kinda where I stand with it, more parts = more failures. But when 3 different tuners (2 with this platform, 1 with LT platform which is also DI) tell me PI is much safer. It’s hard when I’m not a tuner.

Originally Posted by DeezBluBallz

HPFP,LPFP,EU5 injectors, and Bend Calibration Filter kit. Tried and true. All DME controlled.

Is fuel filter kit required ? I only know 1 person running a filter and wasn’t sure why. Also with this setup. What was your WHP #’s if you don’t mind sharing?

Originally Posted by wheela

One of the results is with DI the engine will generally like leaner AFR targets than with PI. So even though the AFR may be leaner on DI, that doesn't necessarily mean it's not as safe as a richer target on a PI motor.

Yeah I was looking at my friends data logs with Dorch HPFP, S4 LPFP, EU5 full E85 who made 780 whp. And his AFR’s look pretty lean 13.0-13.4 at WOT in 3rd and I didn’t like that. I came from a ZL1 that ran 10.5-11.5 WOT AFR’s. Seeing my F82 at 12.5-13.0 right now on E50. It scares me. As my previous tuner popped my engine on bolt on’s alone. PI is all new to me. So I don’t quite understand the full principle of it. You know?

[ASTATENATE]

Originally Posted by JustAnothaM4

This!!

There is no need for PI for 700-750 power goals.

That’s what I hear. But from tuners PI is “safer” you can run the same power safely than you can with DI/HPFP+ only. I’m more about safety. Since it’s roughly the same amount coming out of my pocket. Even if PI is “overkill” for my goals. Is it safer. That is the true question for me.

[JustAnothaM4]

Thats BS...find a different tuner. The amount of extras you need to run PI can be a liability.

[TopJimmy]

Only do PI if you’re going all out, otherwise beef up the DI system. Less cost, less boxes, less risk.

Biggest DI, HPFPs and the LPFP. I’m thinking the Nostrum Stage 3 kit with injectors and HPFPs.

[ASTATENATE]

Originally Posted by JustAnothaM4

Thats BS...find a different tuner. The amount of extras you need to run PI can be a liability.

My tuner is RK, who to my knowledge has no blown engines on the F series. As well as my previous tuner who blew my engine (and many more) F80 Paul recommended PI as well.. he said you have to run the DI system pretty lean to make power. And a third tuner I reached out to (who is LT4 platform) similar to our DI system also said PI is the best/safest route to go.

[-Eidos]

Originally Posted by ASTATENATE

My tuner is RK, who to my knowledge has no blown engines on the F series. As well as my previous tuner who blew my engine (and many more) F80 Paul recommended PI as well.. he said you have to run the DI system pretty lean to make power. And a third tuner I reached out to (who is LT4 platform) similar to our DI system also said PI is the best/safest route to go.

If you have to run your AFRs in the 13s on DI only and E85 to make north of 700whp, then your fueling is insufficient, you don't have enough turbo, or you need a new tuner.

[ASTATENATE]

Originally Posted by -Eidos

If you have to run your AFRs in the 13s on DI only and E85 to make north of 700whp, then your fueling is insufficient, you don't have enough turbo, or you need a new tuner.

Well I knew that. That’s why when I was running 13.0+ with F80 Paul and popped an engine. I switched. I’m current in the low to mid 12.2-12.6 range with RK. And I’m OK with those #’s since it’s DI.
He said with HPFP you have to run leaner and/or blend fuel to hit my power goals. He said PI is the safest route and leaves me room on the table to push more if I ever wanted to go that route. Almost sounds like a no brainer. But everyone on here is so pro HPFP. And so against PI. It makes the decision hard. I feel like the only true con of PI is just more parts possibly having more failure. I spoke with Motiv. And their reflex+ has a lot of safety nets and ties into DME. Not sure how true that is. But seems pretty safe.

My friends AB performance tuned F82 made 780 wheel with HPFP and his AFR’s are 13.0+WOT on full e85 (70% +) (with upgraded turbos I believe Kratos, EU5, stage 4 LPFP with filter, and all bolt on’s) which I don’t like AFR’s in his logs either.

The others friends AFR’s are 12.8+ WOT on full E85, with HPFP upgrade. GC+ , EU5 , stage 3 LPFP, and all necessary bolt on’s as well. Wedge performance tuned. Made 740+ whp.

But this just further shows multiple different tuners running lean AFR’s with HPFP. And proving my tuner, RK Tunes right. HPFP requires leaner conditions where as PI can run safer richer #’s

[-Eidos]

Originally Posted by ASTATENATE

Well I knew that. That’s why when I was running 13.0+ with F80 Paul and popped an engine. I switched. I’m current in the low to mid 12.2-12.6 range with RK. And I’m OK with those #’s since it’s DI.
He said with HPFP you have to run leaner and/or blend fuel to hit my power goals. He said PI is the safest route and leaves me room on the table to push more if I ever wanted to go that route. Almost sounds like a no brainer. But everyone on here is so pro HPFP. And so against PI. It makes the decision hard. I feel like the only true con of PI is just more parts possibly having more failure. I spoke with Motiv. And their reflex+ has a lot of safety nets and ties into DME. Not sure how true that is. But seems pretty safe.

My friends AB performance tuned F82 made 780 wheel with HPFP and his AFR’s are 13.0+WOT on full e85 (70% +) (with upgraded turbos I believe Kratos, EU5, stage 4 LPFP with filter, and all bolt on’s) which I don’t like AFR’s in his logs either.

The others friends AFR’s are 12.8+ WOT on full E85, with HPFP upgrade. GC+ , EU5 , stage 3 LPFP, and all necessary bolt on’s as well. Wedge performance tuned. Made 740+ whp.

But this just further shows multiple different tuners running lean AFR’s with HPFP. And proving my tuner, RK Tunes right. HPFP requires leaner conditions where as PI can run safer richer #’s

Your EU5s are probably tapped out and is your limiting factor. RK would need to lean you out further for more injector headroom if you wanted to push more.

You can have more power at the same AFR target with the Nostrum Stage 2 injectors. They flow 12% more than EU5s. Nostrum Stage 3s flow another 19% on top of that.

No need to "require" a leaner condition. You can upgrade your injectors further.

The Dorch lift kit for S55s is rated for 800+whp on E85 so that's not the bottleneck.

[ASTATENATE]

Originally Posted by -Eidos

Your EU5s are probably tapped out and is your limiting factor. RK would need to lean you out further for more injector headroom if you wanted to push more.

You can have more power at the same AFR target with the Nostrum Stage 2 injectors. They flow 12% more than EU5s. Nostrum Stage 3s flow another 19% on top of that.

No need to "require" a leaner condition. You can upgrade your injectors further.

The Dorch lift kit for S55s is rated for 800+whp on E85 so that's not the bottleneck.

I’m confused. Everywhere states EU5 is good for 800 whp on E85…

Furthermore, Stage 3 ones you speak of. Is only rated at 730whp. And that’s from their direct site.

[-Eidos]

Originally Posted by ASTATENATE

I’m confused. Everywhere states EU5 is good for 800 whp on E85…

Maybe for people that don't care about running lean or for a kill map meant for one or two hits.
Some tuners also like to run them at higher pressures, but this reduces their longevity.

Ultimately it comes down to the application and tuning strategy, which is what noone really mentions. People just see a horsepower number and don't know what that number consists of.

[ASTATENATE]

Yeah I want to do things right and safe. I don’t like the idea of running leaner on HPFP. But I also don’t like the idea of PI having extra components that can go bad. Which is why I’m so 50/50. I do like the ease of install and headroom PI provides though. The PI kit and LPFP that I have are good to 1000whp. Well beyond the capabilities of the S55 stock block.