The subject of converting your vehicle to flex-fuel or E85 fuel comes up a lot. More car owners are looking for ways to conserve and get better performance. This has led to an increased interest in learning how to convert to E85 fuel.
Although E85 has advantages over standard E10 or non-ethanol gasoline, it also presents some disadvantages. We’ll go through the most frequently asked questions concerning switching to E85 to help identify where you will need to upgrade components for the switch.
- Does E85 burn more volume than regular gasoline?
- Does E85 have the same energy as regular gasoline?
- What octane rating does E85 have?
- Is E85 gasoline cheaper than regular gas at the pump?
- What components are required to convert to E85 fuel?
- Can any vehicle be converted to E85 fuel?
- Can I store my vehicle with E85 in the gas tank?
- How will E85 affect my original fuel system?
- Is E85 more prone to pre-ignition detonation?
- Does E85 Reduce Gas Mileage?
- Does E85 fuel harm catalytic converters?
- Is it worth it to switch to E85 fuel?
- Where do I get a fuel pump to convert to E85?
Does E85 burn more volume than regular gasoline?
Yes. Most E85 cars require 30-40% more fuel flow compared to a regular gasoline fuel system. Using that extra volume of fuel means your fuel tank won’t last as long as before.
Does E85 have the same energy as regular gasoline?
No, E85 does not. It has approximately 26-28% less energy per gallon compared to regular E10 or non-ethanol gasoline.
What octane rating does E85 have?
You can find regular gasoline at the pump with 87 to 94 octane, depending on your location. E85 typically has an octane value of ~104.
340LPH Fuel Pump w/ Installation Kit – E85-Compatible Automotive Performance, QFS-352FT-511
Is E85 gasoline cheaper than regular gas at the pump?
Yes, you can typically find E85 at a lower price at the pump.
What components are required to convert to E85 fuel?
Due to the extra fuel volume required, you will need at minimum a fuel pump that can pump the required extra volume, fuel injectors that can also handle the extra volume, and a re-tune of your engine management system (basically re-flash your Engine Control Module) to accommodate the larger volume of fuel.
While the minimum components will get you off on the right foot, many of us want to add more horsepower and torque to our vehicles. Beyond the fuel pump, injectors, and computer re-flash, you should add other supporting components that will flow the required fuel amount to meet your goals.
You may choose to replace your vehicle’s 100LPH fuel pump with a 255LPH pump instead of the minimum 155LPH pump required for E85. You can also increase the size of the injectors equally, plus replace your fuel regulator, fuel filter, fuel lines, and fuel pump wiring for the extra required fuel flow.
Here are some of the Quantum Fuel System fuel pump options:
| Part Number | Part Description | Application Notes | Horsepower Support |
| QFS-344FT | 265LPH E85 IN-TANK EFI FUEL PUMP | Universal | 500 |
| QFS-342FT | 340LPH E85/FLEX IN-TANK EFI FUEL PUMP | Universal, can be doubled for 900+ hp | 640 |
| QFS-343FT | 340LPH E85 INTANK FUEL PUMP | Universal | 640 |
| QFS-350FT | 340LPH E85/FLEX IN-TANK EFI FUEL PUMP | Universal | 640 |
| QFS-353FT | 340LPH E85 INTANK FUEL PUMP | Universal | 640 |
| QFS-450-FT | 450LPH E85/FLEX IN-TANK EFI FUEL PUMP | Universal | 840 |
| QFS-606FT | 380LPH INLINE EXTERNAL E85 FUEL PUMP | Universal, external mounting | 716 |
Can any vehicle be converted to E85 fuel?
The complete fuel system must be prepared for E85, even though any car can run on E85 gasoline. Ethanol is corrosive to most fuel system components. The United States has incorporated 10% ethanol into gasoline since the late 1970s, but higher levels of ethanol weren’t prevalent before 2008.
It is safe to assume that any vehicle before 2008 cannot run on more than 10% ethanol unless the fuel system components and computer system are prepared for higher ethanol content. We recommend that you prepare each fuel system component, or at least verify that your current system can handle a higher ethanol content, before switching to E85.
Can I store my vehicle with E85 in the gas tank?
For some drivers that face extended winter cold months, they have to put their vehicles in storage. That requires preparing the fuel system to sit for a while. Ethanol is hygroscopic, meaning it absorbs water.
E85 is very hygroscopic, meaning it can absorb a large number of water molecules that can corrode fuel system components. You can store E85 in the fuel tank of your vehicle, but you will need to add a fuel stabilizer specifically designed for E85 to protect against its added hygroscopic properties.
How will E85 affect my original fuel system?
If your original fuel system is not rated for E85 fuel, that means the materials in your fuel pump and fuel lines will degrade quickly when E85 runs through the system. We go into all the details about How E85 and Other Fuels Impact Your Fuel System in another blog.
Is E85 more prone to pre-ignition detonation?
Yes, E85 is more likely to ignite before the piston reaches the top dead center and the spark plug ignites the fuel due to the higher ethanol content. An engine management computer re-flash and potentially colder spark plugs can compensate for this.
Does E85 Reduce Gas Mileage?
Yes, it can reduce gas mileage. E85 requires 30-40% more fuel volume compared to regular gasoline. This reduces your mileage by approximately 30-40%.
Does E85 fuel harm catalytic converters?
No, E85 won’t harm your catalytic converters.
Is it worth it to switch to E85 fuel?
This answer is very subjective. Consider why you are thinking of making the conversion. The higher octane levels can be an added bonus for making more horsepower and torque, but the switch also comes with a cost for replacement parts and labor.
When starting a new fuel system build, plan for E85 compatibility. Converting later can be more costly in components and labor.
Where do I get a fuel pump to convert to E85?
We continuously receive questions about switching to E85 or making a particular vehicle flex-fuel capable. The temptation of higher horsepower always lures, but you should only make the switch if you intend to incorporate changes that enable the entire system to be E85 compatible.
When you convert to E85 fuel, it requires more than a fuel pump, injectors, and a computer re-flash. Double-check every component in the system before deciding to make the switch.
You can order a better-designed replacement pump or complete assembly from Quantum Fuel Systems. Our customer service team is available Monday through Friday, 7:00 a.m. to 4:00 p.m. PST. Find your perfect fuel pump over the phone or browse our extensive catalog.
