Increase Your Corvette's Fuel Economy - Corvette Econo-Nomics 101
Increasing The Fuel Economy Of Your Favorite Ride
From the March, 2007 issue of Corvette Fever
By Tom Benford
Photography by Tom Benford
One thing's for sure, no one ever accused the Corvette of being an economy car. Even during the late '70s into the early '80s when the gas crunch was hitting all of motoring America hard and the Corvette was putting out as little as 190 hp, it still wasn't a star performer when it came to getting more miles to the gallon.
While there are those who say if you have to worry about the mileage you shouldn't be driving a Corvette, that kind of thinking is foolhardy. After all, why spend more money on anything than you have to? As of this writing here in New Jersey, high-test gas is slightly over $2.50 a gallon, steadily inching its way up to the $3 mark. Back in the day when I started driving, you could almost fill your whole tank for $3, and now it barely buys enough fuel to prime the carburetor on my '67 big-block coupe! The whole idea is to get the biggest bang for the buck, so if there are some ways you can get more miles to the gallon, why not pursue them? The money you save on gas can be better spent on bling or other things, right?
So, you ask, what can you do to increase your Corvette's fuel economy? Well, there are a number of things; some of these are common-sense measures that will definitely increase your miles per gallon, while other measures may entail some physical adjustments, maintenance, or mods to better your mileage. And, lastly, there are the devices and products that make claims to increase your mileage that certainly seem to be too good to be true-whether they are legit or "snake oil" is the question.
Let's take a closer look at all three of these approaches to getting better mileage. bear in mind that they can and should be used in concert with each other to really make a noticeable difference in your bottom-line fuel economy.
Lay Off The Loud Pedal
Sure, nailing the accelerator on your Vette and getting that adrenaline rush as you're pushed back into the driver seat is a lot of fun, but it's also an expensive kick when you look at what it does to your mileage. Jackrabbit starts cause the engine to literally gulp fuel in copious amounts rather than ingesting a smooth, civilized stream. While we're all guilty of engaging in the stoplight drags, next time you feel the temptation, ask yourself if it's really that important to show the dude in the 5.0-liter Mustang who the real king of the boulevard is. Remember, it's your wallet, so why is it so important to impress a total stranger (who's driving a Ford, no less).
Keeping your highway speed at 55 mph can improve your gas mileage by as much as 25-percent, compared to 75 mph. Bear in mind that over 50-percent of the energy required to move a vehicle down the road is spent overcoming aerodynamic drag (pushing air out of the way). The faster your drive, the more the aerodynamic drag and rolling resistance increases. Consequently, the fuel economy decreases rapidly at speeds above 60 mph. As a rule of thumb, you can assume that each 5 mph you drive over 60 mph is like paying an additional $0.21 per gallon for gas. Do the math, it adds up in a hurry.
Things You'll Need
- Accu-pressure valve caps, wireless tire monitor system, AccuTire digital tire gauge (Prime Time Solutions)
- Digital tire pressure gauge with hose and auto-off (Mid America Motorworks)
- NoLoss tire valve caps and ExtremeAire Outback portable compressor (Extreme Outback Products)
- TornadoFuelSaver and tire Minder max valve caps with tire gauge (TornadoFuelSaver)
A good tire-pressure gauge...
A good tire-pressure gauge should be standard equipment in the glovebox of your Corvette or at least in your garage. Digital units like this one from Mid America Motorworks have a handy hose and turn off automatically after a few seconds to conserve battery life.
If your Corvette is equipped with an overdrive transmission, use it. With overdrive gears, it's possible to still drive at highway speeds, but the engine speed decreases. Overdrive gears reduce both fuel consumption and engine wear. Also, if you have cruise control, use it on highway trips to help maintain a constant, steady speed rather than a variable speed. Maintaining a steady speed helps to reduce fuel consumption. One caveat to using cruise control applies when you're traveling through hilly terrain. Avoid trying to increase speed while climbing a hill, since your engine is already working hard trying to overcome gravity. If you have the cruise control engaged when ascending a hill, the car will try to compensate for the increased gravity and use more fuel, so disengage the cruise control when climbing hills.
Anticipating traffic conditions ahead and not tailgating can improve gas mileage by 5-10 percent. This driving strategy is not only safer, but it will also reduce wear on tires and brakes. When driving in the city, nearly 50 percent of the energy needed to power a vehicle is for acceleration, and unnecessary braking wastes that energy. Also, accelerating quickly causes the engine to enter a less efficient "fuel enrichment mode," whereby additional fuel is delivered to increase the rate of acceleration; in most instances this is overkill, since a lot more fuel than required is actually delivered. Avoid stop-and-go traffic by taking alternative routes or less congested travel times. Consolidate your daily trips and errands.
Avoid unnecessary idling; idling gets 0 mpg. Later-model Corvettes (C3 and newer) do not need to be warmed up. In fact, no matter how efficient your car is, unnecessary idling wastes fuel, costs money, and pollutes the air. If waiting for more than a few minutes in a drive-through lane (e.g., at the local burger joint), turn off the engine. Also, do not leave the car idling while running into a store for a quick errand. This is especially hard on a Vette during the hot summer months and is an open invitation for auto theft.
Valve caps that indicate tire...
Valve caps that indicate tire pressure at a glance are convenient and a wise, inexpensive investment. Available from several manufacturers, the Accu-Pressure caps from primetimesolutions.com indicate danger, caution, and safe pressures, while the Tire Minder Max caps from TornadoFuelSaver.com come with an analog, dial-type tire-pressure gauge.
Be a sensible patriot. Everyone loves the flag, but show your patriotism by affixing a decal rather than hoisting a large flapping U.S. flag or attaching one to your radio antenna, which increases wind resistance. And while we're on the subject of wind resistance, keep your windows closed when possible. your mileage should improve if you keep the windows closed at highway speeds, since air drag is reduced. This is true even with the air conditioning on, assuming the system is in good working order. If possible, try to avoid using your air conditioner in heavy, stop-and-go traffic such as traffic jams or holiday weekend back-ups. Remove any external accessories, such as a luggage rack, surfboard carrier, or other items that lower the aerodynamics of your vehicle.
Get rid of excess weight by removing unnecessary items from the vehicle. You should store only essentials in the trunk, since less weight means better mileage. After a vacation or a trip, make sure you remove all unnecessary items in your vehicle, especially heavy ones. An extra 100 pounds in your vehicle could reduce your mpg by up to 2 percent. The weight reduction can be realized by eliminating socket sets, jumper boxes, or other such tools you probably won't use anyway if your Corvette is in good running order. This brings us to the next point.
This digital Accutire gauge...
This digital Accutire gauge from primetimesolutions.com features a comfortable rubber pistol grip and large, easy-to-read LEDs that are easy to see, even at night.
Keep your engine operating at its peak efficiency. A well-maintained engine will help you maximize gas mileage. Incorrect fuel ratio, bad spark plugs, and incorrect spark timing can have a big effect on gas mileage. Follow the service schedules listed in your owner's manual. Replace filters and fluids as recommended; have engine performance problems (rough idling, poor acceleration, and so on) corrected at a repair facility unless you're qualified and have the requisite equipment to do the job right yourself. Studies have shown that, depending on a car's condition, a poorly-tuned engine can increase fuel consumption by as much as 10-20 percent.
Slip Sliding Away
Always use a good engine oil, preferably a synthetic with a friction-reducing additive. These have been known to improve fuel economy by as much as 12 percent. I'm personally a big fan of Royal Purple for my C5, and in independent dyno tests I conducted, I established beyond any doubt this oil increased my horsepower and mileage by a measurable degree. Well-lubricated engines don't have to work as hard, so they produce more power while using less fuel. And don't forget the importance of a clean oil filter, too (I like K&N filters, but that, again is personal preference). The oil filter removes harmful dirt and grit from the engine; clean engines run smoother and easier. The car's air filter keeps impurities in the air from damaging internal engine components. Not only will replacing a dirty air filter improve fuel economy, it will protect the engine. Clogged filters can cause up to a 10-percent increase in fuel consumption due to air-starvation.
If you're really into romping...
If you're really into romping around with your Vette on the racetrack or the autocross courses, or even if you just want to have some extra added insurance against air leakage from your tire valves, a set of these NoLoss captive tire valve caps are the way to go. Originally designed for NATO military use, they're now available to the public from Extreme Outback Products. they attach securely to the valve stem so you'll never lose them.
Tired Of Poor Mileage
Make sure your tires are properly inflated. Under-inflated tires cause more resistance to travel, and they force the engine to work harder. Let the tires cool down before checking their pressure. Car manufacturers are required to place a label in the car stating the correct tire pressure. This label may be found on the edge of the door or door jamb, in the glovebox, or on the inside of the gas cap compartment cover, depending on the year of your Corvette. If the label lists a PSI range, use the higher number in order to maximize fuel efficiency.
It's important to note that radial tires can be under inflated yet still look normal, so check the tires with a gauge-digital gauges are the most accurate. On average, tires lose about one psi per month and one psi for every 10-degree drop in temperature. I was curious as to why tires lose pressure for, what on the surface, would seem to be no reason at all. For the answer, I contacted Mark Cherveny, the tire product specialist at Goodyear.
Mark says, "Like a balloon, tires hold air pressure. for a tire, it is within the cavity between the tire and the wheel. However, changes in ambient temperature cause the tire pressure to fluctuate (this is why tire pressure should always be checked when the tires are cool, preferably in the morning before driving the car more than a few miles).
"Also like a balloon, the pressure difference between the inside of the tire and the outside of the tire creates a pressure gradient causing some small amount of air permeation to occur due to the size of the rubber compound molecules and the size of the air molecules inside the tire. A balloon loses a small amount of air pressure over time due to the microscopic nature of the rubber molecules and so does a tire.
"The special rubber compounds we use for the liner of the tire slows the air permeation, but it does not eliminate it. That is why tires need their air pressure checked at a frequency of about once per month or before a long trip."
If you want to have the convenience,...
If you want to have the convenience, safety, and security enjoyed by C5 and C6 owners, you can add a wireless tire-monitoring system from primetimesolutions.com to your Corvette for under $350, and that includes four tire-sending units and an LCD readout center that can be powered by your cigarette lighter outlet or hard-wired.
So how much does tire pressure effect mileage? A lot: under-inflated tires cause fuel consumption to increase by as much as 6 percent, cause the tires to wear quicker, and can make it difficult to handle the vehicle. And, while we're on the subject of rolling gear, be sure your wheels are aligned and your brakes are properly adjusted to minimize rolling resistance. Out-of-line wheels, as evidenced by uneven tread wear, should always be aligned by a professional.
Based on this information, monitoring your tire pressure is important, and there are several devices available for doing this. If you own a C5 or a C6, you've got it knocked already since your Corvette is already equipped with tire-pressure monitors, and the exact pressure of all four tires can be read on your DIC.
If you have an older Corvette, you can use tire valve caps that will indicate safe or low pressure at a glance; these are very inexpensive, available from a number of sources, and well worth the money. If you just want to get some additional insurance against tire-valve leakage, then you may want to purchase a set of NoLoss tire valve caps for under $13.
You can also install a wireless tire-pressure monitoring system in your older Corvette to endow it with the same high-tech tire-pressure monitoring enjoyed by C5 and C6 owners. The system comes with four tire-valve transmitters that are installed in each of the Corvette's wheels, and an LCD monitor screen that can be mounted noninvasively on the dash or console. The monitor screen is powered via a cigarette lighter plug (or you can hard-wire it, if you wish), and it provides a readout of the pressure in all four tires with the push of a button.
Installation of the TornadoFuelSaver...
Installation of the TornadoFuelSaver consists of dropping it inside the air cleaner and putting the cover back on. It really doesn't get any easier than this.
If you do a lot of autocrossing, chances are you frequently drain or add air to your Corvette tires for better performance on various courses. To add air, you probably bring a portable air tank with you, or, if you really want to be on top of your game, you have a 12V-powered compressor like the one available from Extreme Outback. This small compressor comes with cables to hook it up to your battery, a tire gauge, a flashlight, and it all fits compactly into the nice powdercoated steel case that tucks away in the trunk of your Vette. Even if you don't want to take it along with you, it's an excellent small compressor for garage use, and, since it uses 12V DC power, you don't even need an electric outlet to use it.
So as you can see, none of these tips and suggestions is rocket science, just good old common sense. But they can add up to a significant increase in the mileage you'll get if you put them into practice. Now let's take a look at some of the gizmos you can employ to increase your mileage.
The Tornado FuelSaver is a...
The Tornado FuelSaver is a stainless-steel device that comes in a variety of sizes and configurations for both carbureted and fuel-injected engines. The slots and grooves of the device create a swirling vortex of air that causes the air/fuel mix to atomize better for more efficient combustion.
As Seen On TV
Unless you're living in a cave, you've undoubtedly seen the infomercial for the TornadoFuelSaver on TV. This device (and several of its copycat imposters) purports to deliver better mileage, increased horsepower, savings on fuel costs, and an installation that requires no skill and takes less than 5 minutes. Sounds like quite a package of goods, right?
Being a natural-born skeptic is a good thing when you're a journalist, so I set out to see if the TornadoFuelSaver really does deliver on its claims. As part of my initial research, I spoke with my friend, Craig Van Wickle, who is also a Corvette guy and the owner of the local NAPA store, Van Wickle Auto Supply, in nearby Point Pleasant, New Jersey. He sells the TornadoFuelSaver (TFS) in his store, and he has sold dozens of them. He told me the device actually does work, and his customers have all reported positive results from using it. Some have gotten moderate gains in performance and mileage, while other have gotten really spectacular results, depending on the vehicle it is installed in. Several of his friends, who also own Corvettes, are using the TornadoFuelSaver too, and they all seem to be happy campers according to what they've told him.
Armed with this knowledge, I thought, "what the hey, I'll give one of these gizmos a try," so I went to the company's web site, www.tornadofuelsaver.com, to look up the model I'd need for my '98 C5. Bad news here-the device won't work on a C5 because its air-induction system is oval rather than round, which is a requisite of the TFS. That's too bad, indeed. However, if you have a C6 (which has round air induction), you're in luck, since there's a model (KI-90) that works with it.
I wasn't about to be deterred by this minor detail, however. I also have a '67 427 coupe, so that was the next model number to look up. Aha! The KC-50-C is the puppy I needed for my Bad Boy, so that's the one I ordered. Suggested list price on the TornadoFuelSaver is $69.97.
Now for the manufacturer's claims, starting with the installation. On the '67, which is normally aspirated, it was truly a no-brainer, consisting of removing the air cleaner's wing nut and lifting off the cleaner cover, dropping the TFS in place within the air filter (following the orientation on the label), and replacing the cover and wing nut. That's all there is to it.
On an injected engine (including C4s and C6s), you simply remove the air-inlet hose between the throttle body and the air-filter box, install the unit (making sure it fits snugly inside the hose), then replace the hose, and secure the clamp.
Every well-equipped garage...
Every well-equipped garage should have an air compressor, and this compact-yet-powerful portable unit from Extreme Outback Products is really the cat's meow. Powered by your Corvette's 12V battery, at less than 14 pounds, the unit is small and light enough to take with you, yet it delivers an incredible sustained volume of air. It comes with hoses, cables, a tire-pressure gauge, and a flashlight-all in a nice powdercoated steel box that measures a scant 16x7x7 inches.
Their under-5-minute installation claim held water. But a large part of my skepticism was based on the fact that this device has no moving parts, so just how is it supposed to increase power and mileage?
The manufacturer explains the slots and grooves in the TFS create a vortex with the air coming into the intake system, and this turbulence produces a more finely-atomized air/fuel mixture in the combustion chamber, which, when exposed to the ignition, results in more complete and efficient burning of the fuel. This, ostensibly, produces more power from less fuel consumption. End result: less gas used, more miles per gallon, money saved at the pump.
It all sounds good, but does it work? Bottom line: yes, it does. I actually could feel a bit more pep in my off-the-line acceleration, and my average mileage increased from about 15 mpg to 18 mpg-that's a 20-percent mileage increase. At that rate, the TornadoFuelSaver will have amortized itself in less than seven tankfuls; after that, it's all gravy!
There are several competitive products on the market that are pretty much copies of the original, but since I haven't tried them, I can't say whether they work or not. But the TornadoFuelSaver definitely lives up to its claims, so if you want to improve your mileage this is a good way to do it.
On injected engines, the device...
On injected engines, the device mounts inside the air-inlet hose between the throttle body and the air filter box, but due to the oval inlet configuration on C5s, it won't work with them. The really nice thing is, it's a noninvasive installation that can be removed at any time if you decide to sell the car, and it's also undetectable for you purists out there.
Snake Oil, Blue Smoke, And Mirrors Department
There are lots of other products that all claim to improve power, mileage, and fuel economy, but I tend to view them with suspicion. These include devices such as bolt-on gasoline vaporizers, "super turbulator" modules, engine ionizers, fuel pills, and combustion-increasing enzymes. just do a quickie search of "fuel saving devices" on the Internet using Ask.com, Google, or any other search engine, and you'll find a plethora of products that all claim to increase your mileage, deliver more power, and save you money. Do these items work? to be honest, I don't know. But because of my innate skepticism and reluctance to do any kind of invasive stuff to my Corvettes, I'll never know firsthand. You won't see me installing any kind of additional plumbing to my engine, nor dropping pills and tablets into my gas tank; I just don't like these approaches and I'm the one who has to foot the repair bill if something goes awry with these gizmos. That's why I always advise on the side of caution rather than bravado. If you're more adventurous than me, by all means go for it. But give it a little thought before using any of these products and ask yourself some questions, such as: What's this stuff going to do to my fuel system? is this going to do anything permanent to my engine? what if this really screws up my Vette? if your vehicle is still under warranty, how will adding/ installing/using these things effect it?
Personally, these invasive products are not for me, and I don't recommend them for you either. Play it safe by modifying your driving habits, using some common sense, keeping your Corvette properly tuned, and your tires properly inflated. These are rock-solid ways of improving your mileage without putting yourself or your vehicle at risk. Now, go gas up and go for a spin, but as I said earlier, try to take it a little easier on the loud pedal.