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Maximum ethanol %?

sbviir

New member
Location
Moore, OK
Car(s)
2017 VW Golf R
I'm currently on an e30 tune. Have a gauge and all necessary thing to run and monitor levels, but had a question in my head most of the day.. what is the maximum percentage of ethanol our cars can run on the stock hpfp? I usually stay +/-2% on 30%, but I've heard some running around e40.
 

cr_sti

Go Kart Newbie
Location
IA
Knowing there is some variability to each car, is there a way to monitor if your HPFP can't keep up? I know you can watch rail pressure, but what's a red (or even yellow) flag that the HPFP is struggling?
 

JerseyDrew77

Autocross Champion
Location
Virginia & NC
Knowing there is some variability to each car, is there a way to monitor if your HPFP can't keep up? I know you can watch rail pressure, but what's a red (or even yellow) flag that the HPFP is struggling?

Not exactly the same but close enough. When I had a failing LPFP, on WOT pulls, shortly after flooring it, my car would start shuddering due to fuel cutting out.
 

cr_sti

Go Kart Newbie
Location
IA
Not exactly the same but close enough. When I had a failing LPFP, on WOT pulls, shortly after flooring it, my car would start shuddering due to fuel cutting out.
I don't know you, but can already tell your balls are bigger than mine. Testing lean conditions with fuel cut, especially on a build like yours, is ballsy.

I was hoping for something more like, "Watch for rail pressure to drop below 2,xxx PSI above 5xxx RPM."
 

JerseyDrew77

Autocross Champion
Location
Virginia & NC
I don't know you, but can already tell your balls are bigger than mine. Testing lean conditions with fuel cut, especially on a build like yours, is ballsy.

I was hoping for something more like, "Watch for rail pressure to drop below 2,xxx PSI above 5xxx RPM."

Lol... Those pulls were done prior to knowing about my failing LPFP and after looking at the logs associated with them, saw that the lpfp duty cycle was dropping as the rpms went up.
 

El_bigote_AJ

Autocross Champion
Location
Las Vegas
Car(s)
2019 GTI bunny
I don't know you, but can already tell your balls are bigger than mine. Testing lean conditions with fuel cut, especially on a build like yours, is ballsy.

I was hoping for something more like, "Watch for rail pressure to drop below 2,xxx PSI above 5xxx RPM."
You need to be looking at rail pressure VS set rail pressure to actually know if it’s dropping due to the pump being inadequate, since other factors will play with saying a specific percent is safe. Like the tunes requested boosts, and the ambient temps/egts. In some scenarios e30 will even be able to max out the hpfp.
 
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