N54Tech.com - International Turbo Racing Discussion
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Rob@RBTurbo's Avatar
Rob@RBTurbo Rob@RBTurbo is offline
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Default 05-28-2013, 03:34 PM

Well it seemed like the Stage 3 car was great on the fuel. But he did have a pretty elaborate LPFP feeding the HPFP on that car if memory serves, not sure if you're LPFP is good to go as well but based on what you've been through it sounds like you'd be well aware if it were not. Only thing left is that he had a much more laggy setup (than say a stock framed turbo car would be) so I'd guess the whole issue lies there. It seems odd that the pump mods would not do anything until very high RPMs though, I'd think the improvements would work well throughout the entire pump RPM range if done correctly.

The bottom line is that things need to be tested and proven to work in the environments they are being marketed in. Not everything is going to always go right, but you live and you learn. Hopefully there is some resolve that can be done to get these smaller twin setups the fuel they need to maximize the midrange.


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lecsoman lecsoman is offline
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Default 05-28-2013, 11:53 PM

I did not mail him because its not installed yet. But now i lost all hope... stupid meth kit kills me...

Hope at least the complete turbo setup what he offers works like promissed.


Slow, stupid and angry...

2007 E90 335i AT, G5 ISO, FSB, BMS flash, RB's, RB PCV, **'s, ER OC's, Injen DCI, BMS OCC, FMIC, ER CP, Tial Q BOV, Walbro 455 LPFP, Snow meth kit injecting E85, runnung on E40-50, Alpina TCU flash, Wavetrac LSD.

Coming: BT FMIC, bigger better water rad.

Last edited by lecsoman; 05-29-2013 at 12:01 AM..
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(#28)
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G.I.Joe G.I.Joe is offline
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Default 05-29-2013, 01:51 AM

I have my VTT HPFP upgrade pump/rail sitting here as well. Won't go in until next week, as my mechanic doesn't have time before then. My current HPFP is on it's way out anyway, so the upgraded pump will go in, and I will test it. I had also hoped to be able to run with 100% E85, mostly so I don't have to mix fuel all the time, but it seems that is not going to happen
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enrita enrita is offline
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Default 05-29-2013, 02:49 AM

you guys should first testing it out before loosing hope LOL


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G.I.Joe G.I.Joe is offline
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Default 05-29-2013, 04:50 AM

Quote:
Originally Posted by enrita
you guys should first testing it out before loosing hope LOL
Good point... However NJz already did on stock turbos on E85 and the VTT HPFP update didn't really do any good in the midrange as far as I understand.

Will have mine installed next Wednesday, and I'll take it from there.
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chuckd05 chuckd05 is offline
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Default 05-29-2013, 09:11 AM

you dont really need 100 percent though... if you can get away with e70 and no drop thatll net you all the power you need


e92
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dfjaws dfjaws is offline
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Default 05-29-2013, 09:43 AM

I think their point of trying to be able to use 100% E85 is so that there is no mixing of fuel to worry about. It just makes life simpler.


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chuckd05 chuckd05 is offline
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Default 05-29-2013, 11:05 AM

But what in life is easy?


e92
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Kollegga Kollegga is offline
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Default 05-29-2013, 12:12 PM

Quote:
Originally Posted by chuckd05
But what in life is easy?
Made my day


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NJz NJz is offline
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Default 05-29-2013, 12:30 PM

there are afr tuning concerns when you start to mix fuels with different stoich points to keep in mind as well. It is not all about ease of refilling the tank.
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G.I.Joe G.I.Joe is offline
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Default 05-29-2013, 12:52 PM

Plenty of reasons to just go with E85 straight from the pump I think, but it probably isn't going to happen with 21 psi on the RBs in the midrange when apparently it doesn't work with stock turbos.

Before my current HPFP went south, it managed to "only" drop to ~1300 psi in the midrange, and only at 4000-4200 rpm but now it's hitting ~900 psi and over a wider rpm range as well. My first HPFP managed 80k km, this one is now @ 67k km, but the last 17k with RBs.

I'll be logging away with the VTT HPFP upgrade at the end of next week, and I'm hoping to be able to cope with ~E70 levels in order to maximize power, but even if I can run an E50 mix reliably at this point with all the stuff I had to replace over the last 6 months (VANOS, coils, injectors, plugs, DME) I'll be fairly happy.

Last edited by G.I.Joe; 05-29-2013 at 12:54 PM.. Reason: spelling....
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Terry @ BMS Terry @ BMS is offline
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Default 05-29-2013, 12:55 PM

Quote:
Originally Posted by G.I.Joe
Plenty of reasons to just go with E85 straight from the pump I think, but it probably isn't going to happen with 21 psi on the RBs in the midrange when apparently it doesn't work with stock turbos.

Before my current HPFP went south, it managed to "only" drop to ~1300 psi in the midrange, and only at 4000-4200 rpm but now it's hitting ~900 psi and over a wider rpm range as well. My first HPFP managed 80k km, this one is now @ 67k km, but the last 17k with RBs.

I'll be logging away with the VTT HPFP upgrade at the end of next week, and I'm hoping to be able to cope with ~E70 levels in order to maximize power, but even if I can run an E50 mix reliably at this point with all the stuff I had to replace over the last 6 months (VANOS, coils, injectors, plugs, DME) I'll be fairly happy.
~1300psi in the midrange is in the "acceptable range" although just barely. Have a log of the boost, AFR, & IAT there? How was high pressure rowing through the gears? Are you sure the high pressure pump itself stopped performing as well and its not just a weather change, etc?


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Default 05-29-2013, 01:28 PM

The stock HPFP and fuel system are perfectly capable to maximize nearly 100% of the HPFP output at low engine speed (<5000rpm) it seems. However, HPFP output is dependent on engine speed, so output is too low for E85 and big power down low. If it's already working at 100% efficiency, no changes to any part of the system will increase output. Only two things can help here: spinning the pump faster, or increasing the size of the fuel chambers in the HPFP. Neither are performed by VTT because this was not his need for stage 3.

The fuel system is not able to perform at 100% efficiency at higher engine speeds for a few reasons. Firstly, LPFP pressure drops without upgraded pump(s), taking HPFP pressure with it as the HPFP is unable to fill its internal chambers at high rpm with low inlet pressure (the pump spins too fast for the low pressure fluid velocity to fill the chambers, especially if the pressure is dropping). When you fix the LPFP, you still run into internal restrictions inside the pump/rail that keep the HPFP from increasing fuel output linear with engine RPM (if it was in fact operating at 100% efficiency here, the VTT upgrade wouldn't have worked). The stock HPFP output increases linear at first, then tapers off at high RPM much like our turbo's. The VTT upgrade is to address this issue. He ported and modified the passages (I believe) so that as RPM increases, HPFP output remains linear. His upgrade works as intended.

To be honest, I'm interested to see how the booster pump and FCV control works with this issue. 60% PWM (max Terry has monitored IIRC) and 70psi is fine for keeping the pump at 100% output at low RPM from recent testing I've seen, but maybe the VTT upgrade isn't even necessary. 90+ PSI (booster pump) and 80-90% PWM to the FCV may raise the fuel pump output at high RPM where it's not already maxed out, where the factory never saw a need.

Rest assured though, you're in a better position fueling wise with the VTT pump than without, just mostly for later in the power band.
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G.I.Joe G.I.Joe is offline
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Default 05-29-2013, 02:13 PM

Quote:
Originally Posted by Terry @ BMS
~1300psi in the midrange is in the "acceptable range" although just barely. Have a log of the boost, AFR, & IAT there? How was high pressure rowing through the gears? Are you sure the high pressure pump itself stopped performing as well and its not just a weather change, etc?
Well, I'm not entirely sure, but it happened at the same time that my MSD80 DME died on me and had a coil/injector go bad. No problems before the DME failure and problems from day 1 after the new DME. Don't really know if it is related, but seems very likely to me. Weather has gotten a bit warmer around here, but I would kinda expect that to actually help, not hurt? I've tried to lower the Ethanol content, but it doesn't seem to do much, which it used to before if I was getting these "symptoms".

Don't have any logs handy atm unfortunately.
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NJz NJz is offline
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Default 05-29-2013, 02:54 PM

Tony@Vargas has contacted me and took care of me. Quality companies like BMS and Vargas taking care of their customers (good or bad) makes me confident in my vendor choices.
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NJz NJz is offline
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Default 05-29-2013, 02:55 PM

Quote:
Originally Posted by v8bait
The stock HPFP and fuel system are perfectly capable to maximize nearly 100% of the HPFP output at low engine speed (<5000rpm) it seems. However, HPFP output is dependent on engine speed, so output is too low for E85 and big power down low. If it's already working at 100% efficiency, no changes to any part of the system will increase output. Only two things can help here: spinning the pump faster, or increasing the size of the fuel chambers in the HPFP. Neither are performed by VTT because this was not his need for stage 3.

The fuel system is not able to perform at 100% efficiency at higher engine speeds for a few reasons. Firstly, LPFP pressure drops without upgraded pump(s), taking HPFP pressure with it as the HPFP is unable to fill its internal chambers at high rpm with low inlet pressure (the pump spins too fast for the low pressure fluid velocity to fill the chambers, especially if the pressure is dropping). When you fix the LPFP, you still run into internal restrictions inside the pump/rail that keep the HPFP from increasing fuel output linear with engine RPM (if it was in fact operating at 100% efficiency here, the VTT upgrade wouldn't have worked). The stock HPFP output increases linear at first, then tapers off at high RPM much like our turbo's. The VTT upgrade is to address this issue. He ported and modified the passages (I believe) so that as RPM increases, HPFP output remains linear. His upgrade works as intended.

To be honest, I'm interested to see how the booster pump and FCV control works with this issue. 60% PWM (max Terry has monitored IIRC) and 70psi is fine for keeping the pump at 100% output at low RPM from recent testing I've seen, but maybe the VTT upgrade isn't even necessary. 90+ PSI (booster pump) and 80-90% PWM to the FCV may raise the fuel pump output at high RPM where it's not already maxed out, where the factory never saw a need.

Rest assured though, you're in a better position fueling wise with the VTT pump than without, just mostly for later in the power band.
Agreed
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