[UltraMagneticAL]

At Bimmerfest West this year, i was talking w/ Brandon from Dinan, and he said that their LPFP should fix the HPFP crashes we see in our datalogs for those of us in the 400whp club. that would be a relatively cheap mod (compared to upgraded HPFP) for extra reliability when upgrading the turbo. but since i was talking to a Dinan rep about a Dinan product, i need to take his recommendation w/ a grain of salt.

anyone w/ the Dinan LPFP have logs showing the HPFP meeting its target pressures?

[ZM2]

Before the confusion begins, let’s call this a LPFP mod. It’s not a higher flowing LPFP. It just flows more fuel into the saddle tank via some hose rerouting to resolve the fuel pick up/limp mode issues when running under a half tank of gas on track.

I used to have fuel pick-up issues constantly on track, but it went away after I did Dinan’s LPFP mod, and I’m able to run the tank dry in hour long sessions.

All of this out of the way, I do not know the answer to your question. I’m only Stage 1 right now and have not had any HPFP crashes. I will be Stage 4 in a couple weeks tho, and at an open track day in Aug, so I’ll find out.

To make another point, a few of the Stage 4 guys that track have commented on HPFP crashes, but they’re also running aftermarket downpipes. I’m hopeful Stage 4 with all other stock bits will not cause HPFP issues. We will see.

[DrKevM5]

BS. I've got Stage 4 and I've done the mod and it still goes into limp mode on the track like clockwork. On 400+hp applications it's a fuel flow issue, not delivery.

[horsepower_and_hounds]

LPFP will not have HPFP failures....or lets say I have yet to see it

[SeanWRT]

Originally Posted by DrKevM5

BS. I've got Stage 4 and I've done the mod and it still goes into limp mode on the track like clockwork. On 400+hp applications it's a fuel flow issue, not delivery.

Your issue is Dinan tune specific. Wherever boost goes, Dinan follows stock AFR which is super rich.

JB4 can have similar problem but less likely. Because unlike Dinan, JB4 allows for AFR leaning out with additional boost. Still it's too rich.

It's kinda funny how hard JB4 has been trying to have N55 run richer all these years and now with M2 it just can't lean out enough.

Flash tunes suffer much less on LPFP/HPFP issue. That's why.

[DrKevM5]

Fewer issues with Stage 3 map

[Yiruna]

There's the new HPFP upgrade if you need it

[SeanWRT]

Originally Posted by DrKevM5

No issues with Stage 3 map

That's because STG3 see less boost. Same AFR, less fueling stress.

[ZM2]

Originally Posted by DrKevM5

BS. I've got Stage 4 and I've done the mod and it still goes into limp mode on the track like clockwork. On 400+hp applications it's a fuel flow issue, not delivery.

Aren’t you also running an aftermarket downpipe?

[DrKevM5]

Yessir

[ZM2]

Originally Posted by DrKevM5

Yessir

Dinan Stage 4 is right there with the 400-whp tunes, but pushes more of the power up top. I wonder if your DP is just enough to tip it over the edge and cause HPFP crashing on track.

My car is stock, except for the Stage 4 bits going on soon. I’ll find out if it holds up on track or not.

[DrKevM5]

Could be. Frustrating as hell when it happens though.

[UltraMagneticAL]

Originally Posted by SeanWRT

Your issue is Dinan tune specific. Wherever boost goes, Dinan follows stock AFR which is super rich.

JB4 can have similar problem but less likely. Because unlike Dinan, JB4 allows for AFR leaning out with additional boost. Still it's too rich.

It's kinda funny how hard JB4 has been trying to have N55 run richer all these years and now with M2 it just can't lean out enough.

Flash tunes suffer much less on LPFP/HPFP issue. That's why.

so you think the lpfp mod with bm3 will fix the hpfp crash? the dinan rep said because the lpfp is able to fill the saddle better, i shouldn't see the hpfp struggling to meet the target psi. of course i want to see logs to confirm, but what he said also makes sense.

[SeanWRT]

Originally Posted by UltraMagneticAL

so you think the lpfp mod with bm3 will fix the hpfp crash? the dinan rep said because the lpfp is able to fill the saddle better, i shouldn't see the hpfp struggling to meet the target psi. of course i want to see logs to confirm, but what he said also makes sense.

I can't guarantee anything. But here are things I can tell.

1) HPFP and LPFP are completely different things. LPFP feed gas flow to HPFP to make pressure. It's the rail pressure that HPFP can't keep up, not the insufficient gas volume to make pressure. There is some pressure, albeit too low, when HPFP fails. And you can easily break HPFP at lower rpm with super high boost, when gas flow (GPM) demand is still low.

2) Any tune running lean can GREATLY relax LPFP. If you do your math, STG2 tune load with proper mixtur require about same amount of gas or even less (and thus lpfp stress) than the super rich stock tune. That's why you barely hear LPFP issue from flash tune user. I know a few tunes running richer (won't name them here) than others, but most certainly anything is better than stock.

However, things are two folded blade, with bad gas like in CA and the likes, vendors better play safe being rich with their OTS tune that do not offer datalog tracking ability. Running lean can cause way way more serious issues than lpfp starving with rich afr, especially with piggyback on bigger turbo.

[M-Supra]

BM3 Stage 2 Race Gas Tune NO HPFP CRASH!

http://f87.bimmerpost.com/forums/sho....php?t=1506904

I have not done any fueling mods to car.

[cookiesowns]

Originally Posted by UltraMagneticAL

so you think the lpfp mod with bm3 will fix the hpfp crash? the dinan rep said because the lpfp is able to fill the saddle better, i shouldn't see the hpfp struggling to meet the target psi. of course i want to see logs to confirm, but what he said also makes sense.

Sent you a text allen

Short answer: a LPFP will not solve any HPFP specific crashes due to tune.

A LPFP could solve fuel pickup issues with an appropriate fuel pickup upgrade like the holley hydromats.


A proper track tune should target the minimal amount of boost, with a good AFR curve to not run super rich, and have appropriate consistencies in place for IAT/Timing to prevent additional stresses on the motor. This will all keep HPFP happy, as the car will enrichen fuel if it detects knock which will exacerbate HPFP deficiencies.

[Oxymoron]

Originally Posted by M-Supra

BM3 Stage 2 Race Gas Tune NO HPFP CRASH!

http://f87.bimmerpost.com/forums/sho....php?t=1506904

I have not done any fueling mods to car.

You mention on your thread that the weather has been hotwhere you are. I would not be surprised if you start to see hpfp crashes in winter on this same tune. I have seen this myself on the e30 map. It's winter here now and I'm seeing regular crashes now, and I wasn't getting any 3 months ago. SeanWRT explained this in one of his posts recently from memory.

[M-Supra]

Originally Posted by Oxymoron

You mention on your thread that the weather has been hotwhere you are. I would not be surprised if you start to see hpfp crashes in winter on this same tune. I have seen this myself on the e30 map. It's winter here now and I'm seeing regular crashes now, and I wasn't getting any 3 months ago. SeanWRT explained this in one of his posts recently from memory.

All other tunes that I downloaded (Stage 1 93, Stage 2 93, and Stage 2 E30) were tested in same weather and HPFP almost always crashed, it got better on E30 tune but it's pretty darn stable on the latest tune...Stage 2 Race Gas using 93 plus 1 to 1.5 cans of Torco.

[Oxymoron]

Nice!

[M-Supra]

Originally Posted by Oxymoron

Nice!

Yes, it is quite nice and I'm too old to be thrown under the jail

[MagnusT]

Originally Posted by ZM2

Before the confusion begins, let’s call this a LPFP mod. It’s not a higher flowing LPFP. It just flows more fuel into the saddle tank via some hose rerouting to resolve the fuel pick up/limp mode issues when running under a half tank of gas on track.

I used to have fuel pick-up issues constantly on track, but it went away after I did Dinan’s LPFP mod, and I’m able to run the tank dry in hour long sessions.

All of this out of the way, I do not know the answer to your question. I’m only Stage 1 right now and have not had any HPFP crashes. I will be Stage 4 in a couple weeks tho, and at an open track day in Aug, so I’ll find out.

To make another point, a few of the Stage 4 guys that track have commented on HPFP crashes, but they’re also running aftermarket downpipes. I’m hopeful Stage 4 with all other stock bits will not cause HPFP issues. We will see.

Is the Dinan LPFP mod kit the only available solution out there to saddle tank slosh pick-up issues?

[ZM2]

Originally Posted by MagnusT

Is the Dinan LPFP mod kit the only available solution out there to saddle tank slosh pick-up issues?

I think there are some higher flow LPFP’s out there that fill the saddle more quickly without the hose rerouting.