E85 conversion for C5Z?
Thread Starter
Heel & Toe
Joined: May 2018
Posts: 19
Likes: 0
E85 conversion for C5Z?
Hopefully this is the right section for this question. What does it take to convert a blown C5Z to E85?
Is it as simple as something like a proflex commander, possibly bigger fuel pump, bigger injectors, and a tuner familiar with E85?
Or is it way more involved than that?
Can someone point me in the right direction?
I know the meth injection is a lot more common, but I’m trying to avoid having to hide the methanol injection line every other year for smog visual inspections here in CA. I don’t want to have to rely on a guy that knows a guy who knows a guy for smog either.
Thanks in advance for any help.
Is it as simple as something like a proflex commander, possibly bigger fuel pump, bigger injectors, and a tuner familiar with E85?
Or is it way more involved than that?
Can someone point me in the right direction?
I know the meth injection is a lot more common, but I’m trying to avoid having to hide the methanol injection line every other year for smog visual inspections here in CA. I don’t want to have to rely on a guy that knows a guy who knows a guy for smog either.
Thanks in advance for any help.
Thread Starter
Heel & Toe
Joined: May 2018
Posts: 19
Likes: 0
Flex fuel would be nice, but straight E85 would be just fine too.
The car is not a daily driver and I have E85 near me. So the only thing I’d potentially lose is out of town trips. Which we don’t really do those any more since the kids.
Also, it’s not a track car. Just an around town fun car. Not likely to ever be a track car, but who knows how I’ll feel in the future.
The car is not a daily driver and I have E85 near me. So the only thing I’d potentially lose is out of town trips. Which we don’t really do those any more since the kids.
Also, it’s not a track car. Just an around town fun car. Not likely to ever be a track car, but who knows how I’ll feel in the future.
Burning Brakes
Joined: Oct 2016
Posts: 1,209
Likes: 363
From: Massillon Ohio
I would go straight e85. Because converting to flex fuel on these cars is no simple task. The proflex is not true flex fuel.
So with that said, pump, injectors, and possibly an external regulator depending on pump.
So with that said, pump, injectors, and possibly an external regulator depending on pump.
Acct Suspended APR 2026 by request
Joined: Dec 2010
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2020 Corvette of the Year Finalist (performance mods)
C5 of Year Winner (performance mods) 2019
for straight e85 just build a system for it with compatible pumps and injectors that won't corrode and get it retuned, you will need to keep an eye on the mixture you put in the tank though since your tune won't make changes like a flex setup will... I have been running mine for close to 2 years on e85 full time and haven't had any issues, luckily the place I buy mine from is pretty consistent
Melting Slicks
Joined: Sep 2006
Posts: 2,721
Likes: 104
From: Florida
OT, would you suggest E85 for a non daily car? Maybe driven once or twice a week...
I was talked out of going E85 by my builder/tuner since I don't drive my car very often.
I was talked out of going E85 by my builder/tuner since I don't drive my car very often.
Last edited by chris308; Mar 25, 2019 at 01:47 PM.
Acct Suspended APR 2026 by request
Joined: Dec 2010
Posts: 10,367
Likes: 1,272
2020 Corvette of the Year Finalist (performance mods)
C5 of Year Winner (performance mods) 2019
I only drive mine on nice days so not all the time, nothing wrong with that as long as you have the right parts... if you leave injectors and pumps submerged in ethanol for extended periods of time and those parts don't have stainless internals then they could corrode and cause problems
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Drifting
Joined: Aug 2008
Posts: 1,399
Likes: 30
There’s an ecu hack/swap that brings some flex fueling to the c5 but otherwise it’s 3rd party ecu time. You can get away with running e85 and just monitoring the % via a sensor. If it deviates too far from what % you tunes it at you can just turn it off.
Instructor
Joined: Mar 2016
Posts: 125
Likes: 2
From: Las Cruces, NM
I was able to find a true Flexfuel sensor for Fbody/C5 Stock PCM, our PCM only reads up to 14psi of boost if you’re FI.
I have a friend running it, and works fine between pump 91 and corn. He has a 01 base, H/C/I
our tuner was able to flash 04 z06 tuning tables to the car through some kind of wizardry, he was able to adjust off of the 04 tables as they included flex fuel tables in 04+ for tuning.
i will be going in for Tune Tuesday with my LS3 swapped C5 with a little boost..
Ill be using the same flex fuel sensor so I’ll keep some results posted around once I get them, I’m on Snakeeater Performance 1500CC’s, a walbro high pressure 450 e85 pump, and “TheTuningLab” flex fuel sensor, I have upgraded Holley rails but the sensor worked fine with stock rails/system
here is the link for all my C5 friends to unlock the solution to the flexfuel issue..they also have a p59 pcm upgrade option for more boost!
https://www.thetuninglab.com/product...r-99-02-f-body
I have a friend running it, and works fine between pump 91 and corn. He has a 01 base, H/C/I
our tuner was able to flash 04 z06 tuning tables to the car through some kind of wizardry, he was able to adjust off of the 04 tables as they included flex fuel tables in 04+ for tuning.
i will be going in for Tune Tuesday with my LS3 swapped C5 with a little boost..
Ill be using the same flex fuel sensor so I’ll keep some results posted around once I get them, I’m on Snakeeater Performance 1500CC’s, a walbro high pressure 450 e85 pump, and “TheTuningLab” flex fuel sensor, I have upgraded Holley rails but the sensor worked fine with stock rails/system
here is the link for all my C5 friends to unlock the solution to the flexfuel issue..they also have a p59 pcm upgrade option for more boost!
https://www.thetuninglab.com/product...r-99-02-f-body
Drifting
Joined: Mar 2011
Posts: 1,823
Likes: 43
From: East Aurora NY
Site says 2 bar is 14psi but that's only 1 bar. It doesn't work with an OS flash for 2 bar?
I was able to find a true Flexfuel sensor for Fbody/C5 Stock PCM, our PCM only reads up to 14psi of boost if you’re FI.
I have a friend running it, and works fine between pump 91 and corn. He has a 01 base, H/C/I
our tuner was able to flash 04 z06 tuning tables to the car through some kind of wizardry, he was able to adjust off of the 04 tables as they included flex fuel tables in 04+ for tuning.
i will be going in for Tune Tuesday with my LS3 swapped C5 with a little boost..
Ill be using the same flex fuel sensor so I’ll keep some results posted around once I get them, I’m on Snakeeater Performance 1500CC’s, a walbro high pressure 450 e85 pump, and “TheTuningLab” flex fuel sensor, I have upgraded Holley rails but the sensor worked fine with stock rails/system
here is the link for all my C5 friends to unlock the solution to the flexfuel issue..they also have a p59 pcm upgrade option for more boost!
https://www.thetuninglab.com/product...r-99-02-f-body
I have a friend running it, and works fine between pump 91 and corn. He has a 01 base, H/C/I
our tuner was able to flash 04 z06 tuning tables to the car through some kind of wizardry, he was able to adjust off of the 04 tables as they included flex fuel tables in 04+ for tuning.
i will be going in for Tune Tuesday with my LS3 swapped C5 with a little boost..
Ill be using the same flex fuel sensor so I’ll keep some results posted around once I get them, I’m on Snakeeater Performance 1500CC’s, a walbro high pressure 450 e85 pump, and “TheTuningLab” flex fuel sensor, I have upgraded Holley rails but the sensor worked fine with stock rails/system
here is the link for all my C5 friends to unlock the solution to the flexfuel issue..they also have a p59 pcm upgrade option for more boost!
https://www.thetuninglab.com/product...r-99-02-f-body
Pro
Joined: Apr 2006
Posts: 534
Likes: 82
From: Charlotte NC
I'm guessing they can't do a 3 bar setup with the flex fuel segment because the older PCM doesn't have enough room for the expanded 3 bar table.
Acct Suspended APR 2026 by request
Joined: Dec 2010
Posts: 10,367
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2020 Corvette of the Year Finalist (performance mods)
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mine is setup for 3bar using a zr1 map and my tuner had to rewrite the os and scale the table... there is an option in hptuners to upgrade to 3bar sd os, is this not possible on some cars?... I have no idea just curious
Melting Slicks
Joined: Nov 2016
Posts: 2,306
Likes: 1,582
From: East Metro (Twin Cities) Minnesota
St. Jude Donor '21
Hopefully this is the right section for this question. What does it take to convert a blown C5Z to E85?
Is it as simple as something like a proflex commander, possibly bigger fuel pump, bigger injectors, and a tuner familiar with E85?
Or is it way more involved than that?
Can someone point me in the right direction?
I know the meth injection is a lot more common, but I’m trying to avoid having to hide the methanol injection line every other year for smog visual inspections here in CA. I don’t want to have to rely on a guy that knows a guy who knows a guy for smog either.
Thanks in advance for any help.
Is it as simple as something like a proflex commander, possibly bigger fuel pump, bigger injectors, and a tuner familiar with E85?
Or is it way more involved than that?
Can someone point me in the right direction?
I know the meth injection is a lot more common, but I’m trying to avoid having to hide the methanol injection line every other year for smog visual inspections here in CA. I don’t want to have to rely on a guy that knows a guy who knows a guy for smog either.
Thanks in advance for any help.
Burning Brakes
Joined: Sep 2016
Posts: 979
Likes: 102
Some Operating Systems have limits to what they can run. Some cars can only run a 2 bar some 3, some none.
Melting Slicks
Joined: Mar 2006
Posts: 2,754
Likes: 380
From: South Florida FL
simply put, you need injectors and a tune, if you're going to run straight E85.
I have a secondary fuel system. but that only comes on on the demand. My oem system have been doing the primary work since 2014. I only just replace my stock intank because I wanted a bigger pump.
the downside to E85 is if you dont drive the car. people experience injector clogging, and that's the smallest part of the system.
I drive my car weekly, so i've never experience that. if im doing a build, generally i'll pull the injectors as a precaution, and have them flow checked every year or so.
I have a secondary fuel system. but that only comes on on the demand. My oem system have been doing the primary work since 2014. I only just replace my stock intank because I wanted a bigger pump.
the downside to E85 is if you dont drive the car. people experience injector clogging, and that's the smallest part of the system.
I drive my car weekly, so i've never experience that. if im doing a build, generally i'll pull the injectors as a precaution, and have them flow checked every year or so.
Acct Suspended APR 2026 by request
Joined: Dec 2010
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Likes: 1,272
2020 Corvette of the Year Finalist (performance mods)
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or get good injectors with stainless internals, they won't be cheap though as we all know lol... personally I have had good experiences with fic
Melting Slicks
Joined: Nov 2016
Posts: 2,306
Likes: 1,582
From: East Metro (Twin Cities) Minnesota
St. Jude Donor '21
simply put, you need injectors and a tune, if you're going to run straight E85.
I have a secondary fuel system. but that only comes on on the demand. My oem system have been doing the primary work since 2014. I only just replace my stock intank because I wanted a bigger pump.
the downside to E85 is if you dont drive the car. people experience injector clogging, and that's the smallest part of the system.
I drive my car weekly, so i've never experience that. if im doing a build, generally i'll pull the injectors as a precaution, and have them flow checked every year or so.
I have a secondary fuel system. but that only comes on on the demand. My oem system have been doing the primary work since 2014. I only just replace my stock intank because I wanted a bigger pump.
the downside to E85 is if you dont drive the car. people experience injector clogging, and that's the smallest part of the system.
I drive my car weekly, so i've never experience that. if im doing a build, generally i'll pull the injectors as a precaution, and have them flow checked every year or so.
Last edited by Toys4Life C5; Apr 11, 2019 at 07:30 AM.
Melting Slicks
Joined: Mar 2006
Posts: 2,754
Likes: 380
From: South Florida FL
My 87 3800 supercharged fiero has been on e85 for 5 years. I was told it would eat the rust out of my tank and clog my fuel filter and clog my injectors. I simply added 60lb injectors, ethanol compatible hoses and have had no issues. The car is rarely driven from Dec - April each winter. With that backdrop, I call BS on the injector clogging issue. Just make sure your new injectors are E-85 compatible. https://www.youtube.com/watch?v=XcFNm7F7GwU
Burning Brakes
Joined: Sep 2016
Posts: 979
Likes: 102
Agreed. It’s not BS about the clogging. I’ve seen it on multiple cars. If you let it sit, it WILL clog. I’ve been running E85 since 2006. It takes awhile to coagulate, but it will and ruin parts of your fuel system if it sits.