FAQ: Everything You Need to Know About Switching to E85

The subject of converting your vehicle to flex-fuel or E85 gasoline comes up a lot. 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?

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?

Regular gasoline can be found at the pump with 87 to 94 octane available depending on where you are in the country. E85 typically has an octane value of ~104.

QFS 525LPH E85 COMPATIBLE IN-TANK FUEL PUMP W/ INSTALL KIT OPTION, QFS-525FT

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Is E85 gasoline cheaper than regular gas at the pump?

In most cases, E85 can be found at a lower price at the pump.

What components are required to make the switch to E85 gasoline?

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.

If your vehicle has a fuel pump that is rated at 100LPH (liters per hours), you may choose to replace it with a 255LPH pump instead of the minimum 155LPH pump E85 will require. 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:

Can any vehicle run E85 gasoline?

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.

Unless the fuel system components and computer system are prepared for a higher ethanol content, we should assume that any vehicle before 2008 cannot run on higher ethanol content than 10%. 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 period of time. 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.

Is E85 more prone to pre-ignition or detonation?

Yes, E85 is more likely to ignite before the piston reaches near the top dead center and the spark plug ignites the fuel due to the higher ethanol content. This can be compensated for with the engine management computer re-flash and potential colder spark plugs. 

Does E85 Reduce Gas Mileage?

Yes, it can reduce gas mileage. E85 requires 30-40% more fuel volume compared to regular gasoline. That means you can expect your fuel mileage to be reduced by approximately the same 30-40%.

Does E85 gasoline harm catalytic converters?

No, E85 won’t harm your catalytic converters.

Is it worth it to switch to E85 gasoline?

This answer is very subjective. It can be worth the switch depending on why you are interested. 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.

If you are already upgrading or building a fuel system from scratch, it may be a good option to make it all E85 compatible from the beginning. If you just want to make your vehicle E85 compatible with cheaper gas at the pump, you may find the cost of parts and labor too high to recoup the savings.

Need help switching 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.

You should not assume that only a fuel pump, injectors, and a computer re-flash are all that is required. Double-check every component in the system before deciding to make the switch. If you have any doubts, or just need an expert to weigh in on your options, contact us at Quantum Fuel Systems.

You can order a better-designed replacement pump or complete assembly from Quantum Fuel Systems, Monday through Friday, 8:00 a.m. to 5:00 p.m. PT, over the phone or browse our extensive catalog.

For over 15 years, Quantum Fuel Systems has been manufacturing and distributing fuel system components for OEM and performance applications. Our mission is to manufacture fuel systems that are centered around longevity, accurate flow data, and hassle-free direct fitment.

Be sure to snap a few pictures during and after the installation of your E85 fuel system, or if you are a video creator, send us a link to your video on our ‘Submit Your Ride’ page. We love to see what you’re working on and hear about your experience.

Choosing A Fuel Pump to Meet Horsepower Goals

If you hang around any forums or look through automotive groups on any social media platform you will often see the question, “What fuel pump do I need to make XX horsepower?” Choosing a fuel pump with horsepower goals in mind can get complex with many different answers.

We’re going to break it down to help understand what fuel pump you may need and any other considerations to keep in mind as you make plans for your fuel system.

What Fuel Pump Do I Need?

Most of the time just making a few more horsepower can be accomplished with the current fuel pump you have in your vehicle. That’s true for a Ford Mustang, Dodge Hellcat, or Chevy Camaro or Corvette. At a certain level of horsepower, the fuel pump you have won’t be able to pump enough fuel though, and that is where Quantum Fuel Systems can offer a better option.

If you look at the chart below, we have multiple fuel pumps available that can support up to 1,000 horsepower at the engine. The chart uses the standard of 2.64 horsepower per LPH (liter per hour) as the conversion criteria.

Keep in mind that adding a larger fuel pump may require modification of your housing to clear a larger fuel pump. This could include creating windows in the assembly housing, or enlarging current windows or recesses currently in there.

Other considerations when adding a larger fuel pump:

What fuel will you be using?

Most upgrades are to flow standard or high-octane gasoline (such as E10 or E15 depending on your location). If you plan to move to a flex-fuel system that can handle E85, or make the switch to E85 primarily, you may need to account for the additional 40% volume required for fuel systems using E85. That will indicate you should purchase a fuel pump one or two sizes larger than you need for standard gasoline.

Can your current fuel tank enclose a larger fuel pump internally, or will the new system require an externally mounted pump?

Moving from an internal pump to an external pump may require a different inlet strainer and pre-filter to keep contaminants out of the new fuel pump. You may also need a new mounting system (such as insulated fuel pump mounting brackets) for an externally mounted pump.

Will your other fuel components handle the additional volume you plan to pump?

Are your fuel lines large enough to support 600 horsepower, 700, 800, etc.? Do you need a larger pre-filter or fuel filter for extra volume? Lastly, what size and type of fuel injectors are needed to meet your horsepower goals?

Would adding an external fuel pressure gauge be advantageous for tuning your new system or trouble-shooting future upgrades?

A gauge can be an easy addition while you complete the other work, and it can add some comfort in being able to see how your system is performing initially and months or years later.

The last thing to consider would be the minor details for a clean upgrade. Do you need an installation kit complete with electrical connectors, hose clamps, and protective sleeves?

QFS Is Here To Help

Looking through all of this information, it’s easy to feel overwhelmed when trying to add a few more horsepower. Some pumps are designed to drop in your current internally mounted tank and be ready to go within a few hours.

In other cases, you may need injectors, fuel lines, and some extra accessories to support the horsepower goal. Whichever situation you have, there’s no need to stress over what pieces and pumps you need.

You can order a better-designed replacement pump or complete assembly from Quantum Fuel Systems, Monday through Friday, 8:00 a.m. to 5:00 p.m. PT, over the phone or browse our extensive catalog. Be sure to contact us via our support page for any detailed technical questions, and we’ll get back to you as soon as possible.

QFS 340LPH FUEL PUMP HANGER -6AN/-6AN FITTINGS 1986-1997 MUSTANG 5.0L 4.6L + 340LPH PUMP

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Be sure to snap a few pictures during and after the installation, or if you are a video creator, send us a link to your video on our ‘Submit Your Ride’ page. We love to see what you’re working on and hear about your experience.

REVIVE YOUR GM 1500 SERIES WITH AN UPGRADED FUEL PUMP

Trucks have been a great starting place for restoration and modification projects. Many automotive brands have offered models over the last 70 years with differing chassis, engine, and drive combinations. If you’re looking for a low-cost option with a healthy aftermarket and restoration availability, you may find the 1997 – 2003 General Motors 1500 series trucks to be a perfect fit for your needs. During restoration, it’s incredibly important to consider replacing or upgrading your GM 1500 Series fuel pump.

Choosing the Low-Cost Budget Truck

Both Chevrolet and GMC half-ton truck lines have multiple trim levels available, different engine and transmission options, and come available in both 2WD and 4WD. There is something for everyone.

This model featured the LS-engine family that started a new revolution that saw these engines swapped into everything. Most restoration projects will choose the V8 models or swap one of them in though.

The 4.8-liter V8 (producing 255 horsepower and 285 pound-feet of torque), the 5.3-liter V8 (producing 270 horsepower and 315 pound-feet of torque), and the 6.0-liter V8 (producing 300 horsepower and 355 pound-feet of torque) were available as options from General Motors, and all three have immense potential for restoration or modification.

Assuming the truck runs and drives, one area of focus should be the fuel system. The truck could have sat at some point in its life, or it could have been a constant workhorse and now have a few hundred thousand miles on the odometer.

Whatever the case may be, the fuel pump and other fuel system components may be on their last legs. If you have concerns with either, now is the time to address them. A new fuel system is key for the next phase of the truck’s life.

Replacing the 1999 – 2003 Chevy & GMC 1500 Series Fuel Pump Assembly

Replacing the fuel pump or the complete fuel pump assembly on the 1500 series trucks isn’t a complicated process. Once the fuel tank is removed from the vehicle, the fuel pump assembly can be taken out from the top side of the tank with simple hand tools.

Some will simply replace the pump assembly with an OEM drop-in replacement, however, keeping the factory design will keep inherent design problems going forward. The factory design uses a problematic venturi design to keep the canister full during hard cornering.

If you plan to build a corner carving truck for autocross, keeping this design will have limitations. The venturi design was used in all 1995 – 2005 GM trucks, vans, and SUVs, which will only allow for OEM-style fuel pumps with limited fuel flow potential.

Combating OEM Design Limitations

If you plan to add more horsepower to your truck, the OEM fuel pump won’t flow enough fuel for a lot more power than the factory level. You can add a larger fuel pump for more flow. Doing so requires the fuel pump assembly to be modified by cutting windows into the sides of the bucket.

This completely disables the venturi function of the OEM housing and the ability of the canister to stay full during cornering or acceleration. It will eventually lead to fuel starvation and overheating of the fuel pump.

Fixing the poor venturi design and adding a larger fuel pump can be achieved by switching over to Quantum’s QFS-A81HV 340LPH (340 liters per hour) drop-in fuel pump assembly. This assembly was designed specifically for the 1999 – 2003 Chevy and GMC 1500 Series trucks to eliminate the problematic venturi canister design found in all 1995 – 2005 GM trucks, vans, and SUVs while offering significantly more fuel flow for larger engines or forced induction applications.

This clean sheet design also allows the fuel tank to be run down to empty as the OEM fuel assembly does.

QFS 340LPH IN-TANK FUEL PUMP ASSEMBLY, QFS-A81HV

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The assembly uses Ethanol safe PTFE / Teflon corrugated flex hose and Teflon-coated wiring throughout. They are 100% gasoline and E85 compatible. The new design features an updated 40-amp bulkhead connector to handle the additional amperage load of the high-volume pump, plus includes a new float arm, sending unit, tank seal, and 4-way wiring connector.

All QFS products come with a lifetime warranty. There’s no need to worry about paying for a replacement later.

Replacing Just The Fuel Pump

If you aren’t ready for a new complete assembly, you may just need to change the fuel pump only. A previous owner may have replaced or upgraded the assembly. In this case, you just need to add a new pump to meet your goals.

That’s an easy fix with Quantum’s varying selection of performance fuel pumps. Each pump in the line-up offers a different fuel flow to meet your horsepower goals. Check out the chart below to see which pump is rated at the horsepower level you need.

The chart uses the standard of 2.64 horsepower per LPH as the conversion criteria.

We Are Standing By For Your Order

If you plan to build or simply restore a 1999 – 2003 Chevy or GMC 1500 series truck, take the time to get the fuel system up to snuff. It’s most likely 20 years old, and if it was a previous work truck, it may not have been well maintained. The OEM design works well for simple replacement, but if you plan to modify your truck it will need a better fuel system.

You can order a better-designed replacement pump or complete assembly from Quantum Fuel Systems, Monday through Friday, 8:00 a.m. to 5:00 p.m. PT, over the phone or browse our extensive catalog. Be sure to contact us via our support page for any detailed technical questions, and we’ll get back to you as soon as possible.