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2020 XT5, 2017 ATS-V M6,1968 Corvair, 1974 Corvette, 2003 HD Road King
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Discussion Starter · #1 ·
Hey all,
I don't have immediate access to E85, although the internet says there is a station ~20 miles up the freeway. I have been contemplating flex fuel or meth injection. I favor the flex fuel for the perceived engine safety but would likely not use the E85 often.

So for those that have done this, is it worth the cost and effort to go flex fuel.

Or is it safe to run MI?

This is a semi daily. I live in FL and ride the bike about 50% of the time and do not race the car - only the bike so far.

Thanks!
 

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LF4 Platform Master Tuner
2018 ATS-V M6
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706 Posts
Hey all,
I don't have immediate access to E85, although the internet says there is a station ~20 miles up the freeway. I have been contemplating flex fuel or meth injection. I favor the flex fuel for the perceived engine safety but would likely not use the E85 often.

So for those that have done this, is it worth the cost and effort to go flex fuel.

Or is it safe to run MI?

This is a semi daily. I live in FL and ride the bike about 50% of the time and do not race the car - only the bike so far.

Thanks!
In round numbers, we typically see 520 to 540 whp on our Blue Belt Performance Packages. These consist of intercooler fill/bleed kit, spark plugs, intake, catless downpipes and remote tune, running on 93-octane fuel. Adding the basic fuel system modifications allows you to run ethanol fuel blends and this results in 615 to 640 whp. You can also get to 600 whp using methanol injection, but the risks are much higher.
 

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2020 XT5, 2017 ATS-V M6,1968 Corvair, 1974 Corvette, 2003 HD Road King
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474 Posts
Discussion Starter · #4 ·
Thanks Scott. I basically have the Blue belt minus the intake and I love it. But I have an addiction so...

For the E Blends, do I need LPFP and both HPFP mods? Do I need the cam and the pump?
 

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2016 ATS-V
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176 Posts
Hi there,
For starters, just the HPFP and E85 won't be of much use without an upgraded in-tank LPFP.
  • Conversely, the LPFP isn't of much use without an HPFP unless you only want a bit of extended range at the current performance level up to higher mph/load.
  • Assuming you upgrade both HPFP and LPFP and run E85 via a flex fuel kit, you can expect airflow in the ~62lb/min range, and around ~21* of timing advance. This is enough to support 600whp without sacrificing any factory protection mechanisms. I won't quote any numbers since dynos and environmental conditions can vary.
  • If you do the HPFP and fuel cam, you'll be in the realm of diminishing returns, because HPFP + LPFP is all you need to support full E85 with the stock turbos. If you drive the car especially hard, to where it commands full enrichment more often than not, then maybe it's worthwhile to you.
Good luck
 
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2017 ATS-V 6MT CWT Sedan, Tuned 2016 Explorer TT
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819 Posts
I go up to E30 on a stock fuel system. This is just an arbitrary number I feel comfortable with as far as issues with ethanol are concerned. Technically I can run e85 or whatever comes out of the ethanol pump but the car wouldnt be any faster as it will need to be dialed back due to the lack of fuel flow and pressure.
 

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I've been seeing some interesting warnings (and pictures) about running higher lobe fuel cams with the AutoTech high volume HPFP internals kit.

My understanding is that the Tapout fuel cam is actually the XDI fuel cam, which offers 21% more flow. What's the cutoff? At this point, which cams do we know won't work? When I looked at this a while ago, I remember reading debates about whether the ZZP fuel cam (+40%) was safe or not on the stock internal HPFP (and also whether the extensive machining went through the hardened depth of the cam). Since that's the biggest fuel cam on the market, THAT cam is clearly UNSAT. Do we know whether the Weapon-X fuel cam (+30%) is safe with the AutoTech HPFP kit?

Switching gears slightly, my understanding is that the LPFP offered by everyone is either 1) the CTS-V or ZL1 pump, or 2) the XDI Stage 1 pump. Is there really any difference? XDI claims that their unit has a modified pressure limiting valve (opening at 85-90 psi vs. stock 70-75 psi). Over the past year or so, I've quietly watched a number of vendors withdraw their LPFP options that utilize off the shelf pumps, so there may be something to this. Coming from the world of LS series motors (58 psi), I don't understand why the LPFP portion of the system is running at such high pressure.
 
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