I was driving through an unfamiliar town yesterday when my low fuel light came on, so I stopped at the next gas station. They had two different premium fuels...91 octane and 92 octane with 10% ethanol. Which gas should you choose if you have a SuperChip? I didn't really think the SuperChip would have any problems with the ethanol blend, but I filled up with the 91 octane just to be safe and didn't have problems with it.

Thanks,
Matt

------------------
99 F150 X-Cab 4x4 SB, 5.4L V8, Deep Wedgewood Blue/Dark Graphite, ORP, 3.73 LS, Tow Pkg, Captain's Chairs
AIRAID, Luvernve Stainless Nerf Bars, BedRug Bed Liner
Lund: Frontrunner bug deflector, Eclipse taillight covers, Eclipse quarter window shades all painted to match

Sony: Mobile ES CDX-C7850 head unit, Mobile ES XDP-U50D DSP, MDX-65 MiniDisc changer
Rockford Fosgate: Punch 600a5 amp, 2 Punch XLC 4 Ohm 8" subs
Infinity: Kappa 63.1i's in the front, Kappa 62.1i's in the rear
StreetWires: Zero Noise 5.0 patch cables, UltraFlow Power cable, Power Distribution Blocks, speaker wire

 

Hi Matt,

You made the right choice!

Ethanol blends have a lower energy content, and you're almost always better off with pure gasoline instead of those blended fuels, commonly referred to as "gasahol".

What happens is, alcohol generally has a high octane value, but only a fraction less than half the relative energy value (BTU's per lb. of fuel) of gasoline. For example, in Indy car racing, where methanol is routinely used for fuel, they have to burn 2.1 gallons of methanol for every 1 gallon of gas you would normally burn.

So anytime you have a choice like this, 91 octane gas versus 92 octane gasahol, use the 91 octane gas instead, just like you did. You'll get a little bit better fuel mileage by doing this, basically.

The gasahols are OK to use, as by law they cannot use more than 10% alcohol by volume, and your vehicle owners manual will tell you that you can use those gasahol blends in concentrations of alcohol up to 10%, just as the law allows.

Actually, if the fuel system were engineered for alcohol-based fuels, both from a volume delivery standpoint and to withstand the additional corrosiveness of alcohol on fuel system components, it would be a lot better for the environment, alcohol-based fuels could very easily work in place of gasoline. But since the vehicles are not engineered for, nor are mostly-alcohol fuels even available, you're better of sticking to gasoline only if it's available. And if not, you'll be fine, just get a little bit less fuel mileage with gasahol, basically.

------------------
Mike Troyer
Performance Products, Inc.
National Distributor of Superchips
(540) 862-9515
Email: mtroyer@compuserve.com
Performance Products F150Online Superchip ordering system: F150Online Superchip Ordering System
First National F-150 Online Rally Event Organizer

 

Mike,

FYI, here in Ontario most, if not all the gas has up to 10% ethenol blended in. I use Pioneer brand and their 93 Octane has 9% and their mid-grade 90 Octane has 7% and thier 87 Octane has 4.5%. Would using Michigan Gas without Alcohol improve the 1/4 mile times?

Regards

Jean Marc Chartier

------------------
00 F-150 XLT SC Flairside 4x4 4.6 w/5spd 3.55LSD
Warn XD9000i, skid plates, Draw tite class III,
Rancho RSX Reflex shocks,
Borla Cat Back, Headman Headers,
Modified Air Cleaner Outlet Tube
and air box, Shortened MAF sensor tower,
K&N air filter,
Superchips





[This message has been edited by JMC (edited 10-05-2000).]

 

Hi JMC,

Excellent question!

The honest answer is, it would have to be tested to know for sure.

However, I can tell you that virutally any all-gasoline formulation is going to have a higher energy content (# of BTU's per lb. or gallon of fuel) than any "gasahol" blend, due to the extremely low energy content of the alcohol component. Alcohol, methanol, what have you, has about half the relative energy value of gasoline, and in the case of Indy racing cars, they have to burn 2.1 gallons of methanol for every 1 gallon fo gasoline you would normally burn. Alcohol can have a relatively high octane number, but a very low energy content, so this does have an impact.

Personally, I feel that you could potentially improve 1/4 mile times a bit if scientific back-to-back testing was done, but I don't think it would be a *big* improvement, maybe a tenth or so, I'm guessing. I could be worng and it might be more, that's just what I'm guessing in your situation, with your vheicle.

Let me know if you ever try that, but of course it would requrie back-to-back testing the same day, close together in time, so you'd have to have a way to completely change fuels while at the track to do the proper testing, and that isn't convenient, though it certainly can be done.

------------------
Mike Troyer
Performance Products, Inc.
National Distributor of Superchips
(540) 862-9515
Email: mtroyer@compuserve.com
Performance Products F150Online Superchip ordering system: F150Online Superchip Ordering System
First National F-150 Online Rally Event Organizer