E85 Flex Fuel Mod
 

Hey all,

I’m new to the concept of flex fuel mods but am considering a used SS 1LE with a Phastek flex fuel mod and a tune. Are there any downsides I need to consider with the mod that I should be aware of or take into consideration before purchasing? The car is under a year old so warranty is one thing I’m weighing already...

Flex fuel should of been standard from the factory...no downside at all.

Cool. What about to the hoses and other ancillary parts not made for 85? Why is a tune required for the conversion?

Talk to a local tuner as that’s all you need after the kit install

Technically the flex fuel kit and tune invalidated the powertrain warranty. If you take the car to a dealer with a powertrain issue and they see the flex fuel kit and/or detect that the car was tuned then they may refuse to repair the car under warranty. You will want to know who did the tune and if the tune is locked before you buy the car in case you want to do additional mods down the road.

Thanks for the advice all - I appreciate it.

Our cars fuel systems are setup for E85. The tables are already in the ECM. You just need a tune to turn them on and some additional changes need made in the ECM to make proper use if it.

I'm going to go the other way here and say I'm surprised no one ever discusses the cons to e85. I reached out to several well known and respected tuners in Florida because I read all the rave reviews on here about e85 and was looking to have my car tuned and they won't even tune for e85 due to their belief that it is too likely to harm the engine and fuel system components. Both mentioned the need to go with bigger injectors to compensate for decreased efficiency of e85 and potentially changing the fuel pump and fuel filters, problems with corrosion, and stress on engine internals. Additionally, gas mileage is significantly reduced and then there is the hygroscopic nature of ethanol which could lead to rust and further damage within the engine. Also our cars were not built as flex fuel vehicles. Just jumping in here cause I never see anyone share this side to it. I'd personally love to do it for the added hp and torque with the tune but after talking with these guys and doing some reading I've decided to table it and watch to see how some of these cars hold up after years of running e85.

/\ I’m on the about E85 for the same exact reason.. I’m seeing pros but also some cons.. I might get it tuned for E85 but probably not use it as regular fill up..

About some of the cons listed:
Tune is needed so powertrain warranty is gone, yes that is true.

Will harm the engine, subjective opinion only, which I question.

Need bigger injectors, this one depends. If you are just doing bolt-on mods, then no, the system does not need to be upgraded. If you are doing a supercharger or turbocharger though, then yes, you will need an upgrade to the fuel system to keep up with the demands of E85.

Gas mileage reduced, yes that is true, the mpg will be noticeably worse.

Agreed. I like corn in my likker, not in my gas tanks.

Decreased gas mileage is true as it takes more e content gas to equal straight 91. That’s the first I’ve heard somebody say it harms the engine... injectors can be an issue for direct injection vehicles IF it sits for months.

Run a tank of e54 then a tank of 91 and you shouldn’t have a single issue Boosted application is 100% different than NA when it comes to running out of fuel so the whole needing more pump won’t come into play NA with a 6th Gen and simple bolt on’s (disclaimer the 1LE has a different low side but still I’ve been told no difference in an SS)

Also running full e85 vs an e50 mix most the time doesn’t make a power difference so an experienced e tuner can explain these things. Running e54 is a better mix with the same performance results. I’ll ever run full e85 for my bolt on application & will always back one tank with 91 pump to clean it out

So the l83 has flex fuel from the factory, and our l86 trucks do not. But we have the same fuel oem system components so that there is zero reliability issues with e85. Camaro’s might have it the same way.

This is FALSE.... except the fuel mileage but that is washed out because E85 is a 1.00+ per gallon less then 91 octane, so it still ends up being cheaper to run by a few dollars a tank. You don't need bigger injectors unless going forced Induction. Again these gen 5 engines were built with the capability to run E85. All of the tables to run it are already in the ECM. The 5.3 L83 truck engines are activated to run it, the LT1 and L86 isn't, but can relatively easy. It's been proven by enough people that have a clue. Anybody that claims otherwise is misinformed plain and simple.