One of the most common areas of confusion in performance fuel systems is the difference between E85 compatibility, PTFE fuel lines, and true flex-fuel capability.
These terms are related, but they do not mean the same thing.
The easiest way to understand them is to separate two questions:
What fuels can the fuel system safely handle?
and
Can the vehicle automatically adjust for different ethanol content?
Standard Rubber Fuel Hose
Traditional rubber-core AN fuel hose is commonly used with conventional pump gasoline.
At JBtuned, our 250 Series hose is our standard rubber-core fuel hose option.
This type of hose is intended for pump gasoline applications. It is not the hose option we recommend for vehicles that will regularly run E85 or other high-ethanol fuels.
Ethanol can degrade fuel-system materials that were not designed for long-term exposure to it.
So if your vehicle is staying on conventional pump gasoline, standard rubber fuel hose may be the correct choice.
PTFE Fuel Hose
PTFE fuel hose is different.
Our 350 Series PTFE hose is compatible with a much wider range of fuels, including conventional pump gasoline and E85.
One of the biggest misconceptions we hear is:
“If I choose PTFE lines, does that mean I have to run E85?”
No.
PTFE fuel hose can be used with regular pump gasoline too.
Choosing PTFE simply gives the fuel system compatibility with fuels such as E85 that standard rubber hose is not intended to handle long term.
In simple terms:
250 Series rubber hose = pump gasoline
350 Series PTFE hose = pump gasoline or E85
What Does “E85 Compatible” Mean?
When a fuel system is described as E85 compatible, that is referring to the materials used in the fuel system.
The hose, seals, filter components, and other parts that come into contact with the fuel need to be suitable for ethanol.
An E85-compatible fuel system can physically handle E85.
That does not automatically mean the vehicle is flex fuel.
This distinction is important.
What Is a Flex-Fuel System?
A flex-fuel vehicle uses a flex-fuel sensor to measure the amount of ethanol in the fuel.
The ethanol percentage can change significantly from one tank of fuel to another.
A properly configured flex-fuel system sends that ethanol-content information to compatible engine management or electronics. The tune can then compensate for the changing fuel mixture.
This is what allows a properly tuned vehicle to operate on different mixtures of gasoline and ethanol without the driver needing to know the exact ethanol percentage every time they fill the tank.
PTFE Does Not Mean Flex Fuel
A vehicle can have a complete PTFE fuel system without being a flex-fuel vehicle.
For example, you could have:
- A PTFE fuel system running conventional pump gasoline.
- A PTFE fuel system running E85 all the time with an E85-specific tune.
- A PTFE fuel system with a flex-fuel sensor and a proper flex-fuel tune.
All three can use PTFE fuel lines.
Only the third example is a true flex-fuel setup.
The fuel-line material determines which fuels the plumbing can safely handle.
The flex-fuel sensor and tuning determine whether the vehicle can automatically compensate for different ethanol percentages.
E85 Compatible vs. Flex Fuel
Here is the simplest way to look at it:
E85 Compatible
The fuel-system components are capable of safely handling E85.
Flex Fuel
The vehicle can detect changing ethanol content and the engine management system is configured to adjust for it.
A fuel system can be E85 compatible without being flex fuel.
Which Fuel Line Should I Choose?
If you plan to run conventional pump gasoline only, our standard 250 Series rubber hose may be the appropriate choice.
If you plan to run E85, choose the 350 Series PTFE option.
If you want the ability to run changing mixtures of gasoline and ethanol without being locked into one specific ethanol content, you will also need a flex-fuel sensor and compatible tuning solution.
And remember:
Choosing PTFE does not require you to run E85.
It simply gives your fuel system broader fuel compatibility.
Still Not Sure?
Choosing the correct fuel system depends on more than just hose material. Your vehicle, engine, fuel pump, fuel rail, regulator, intended fuel, power level, and tuning strategy can all affect the right configuration.
If you’re unsure which JBtuned fuel-system option is right for your build, contact us with your setup and we can help point you in the right direction.
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