7UP YERS

is running strait 110 gonna hurt anything?i have no cats or o2 sensor so im not worried about that,but motor wise is it gonna hurt anything?

Samps

Why are you not using an O2 sensor? 110 will probably make your car run worse. Unless you're running nitrous, or some sort of forced induction, then stick with the lowest octane available. If you have advanced your timing, you may want to step it up to about 91-93.

Mr Rotary

I'm a new owner of a Base 87' RX-7. What's a O2 sensor? My brother put 100+ octane in my car just a couple days ago. I am concerned if anything would go wrong also. I have a single exhaust though (that's how I purchased it) and I also have no cat.

Samps

Oxygen sensor. I don't think the higher octane will damage anything except your wallet, and feelings when you find out your car is not going any faster. Leave the big octane for the turbo guys.

FPrep2ndGenRX7

If your N/A car isin't running right on the 87-91 octane gas there is something wrong with it. I've used the 87 octane for years and have never had any problems.

Stepdaddy

so your sayin since i have a turbo i should run higher octane, i usualy by lowest myself

Evil Aviator

The octane rating is an anti-knock rating, and has nothing to do with performance. Racing fuels (not pump gas) are made from different compounds, which will yield more hp per pound, and will possibly have a higher octane (anti-knock) rating. Highly compressed and/or heated air has a higher tendency to cause engine knock, so this is why turbocharged cars and race cars use the higher octane. Your owner's manual will tell you which octane to use if your car is somewhat stock.

cymfc3s

unless your car is pretty modded up or your running a lot of boost, running race gas wont make your car any fast. It will run pig rich. I made the mistake of running 103 at palmdale (high elev) with the fcon all the way up. Needless to say the car was totally flooding out down the track and billowing black smoke.

baix2

100% agree on that
i also remembe reading somewhere that all these 89,92,110 ratings are actually based on the strength of the chemical bonding inside those propane, methane, (all those crap)

sorry not a chemistry major here

DC350

yeah, with my mazda manuel, it says, recommended 84 :P nothing to powerful

Evil Aviator

From the Colombia Encyclopedia in reference to US standards:
"The octane number of a sample of fuel is determined by burning the gasoline in an engine under controlled conditions, e.g., of spark timing, compression, engine speed, and load, until a standard level of knock occurs. The engine is next operated on a fuel blended from a form of isooctane that is very resistant to knocking and a form of heptane that knocks very easily. When a blend is found that duplicates the knocking intensity of the sample under test, the percentage of isooctane by volume in the blended sample is taken as the octane number of the fuel. Octane numbers higher than 100 are found by measuring the amount of tetraethyl lead that must be added to pure isooctane to duplicate the knocking of a sample fuel. At present three systems of octane rating are used in the United States. Two of these, the research octane and motor octane numbers, are determined by burning the gasoline in an engine under different, but specified, conditions. Usually the motor octane number is lower than the research octane. The third octane rating, which federal regulations require on commercial gasoline pumps, is an average of research octane and motor octane."

In the US, the gasoline is marketed by the Pump Octane Number (PON), which is the averaging method listed above. You may have noticed the "R+M/2" on your local gas pump. Much of the rest of the world uses the RON only.

Not a chemistry major here, either. Just a simple aeronautical science degree.

Evil Aviator

LOL, it is quite possible that an 84 octane fuel is more powerful than a 91 octane fuel. Iso-octane is not as powerful as heptane, so the more octane in an octane/heptane mix, the less powerful it is. Of course, most of the modern higher octane fuels have other additives, so this is not necessarily true in actual practice. Like I said, octane is a knock rating. Power (heat energy) is rated in BTU/lb, and I have yet to see this posted at any fuel pump in the US.

From the US Federal Trade Commission. Knocking is more dangerous to rotaries, but everything else applies:
http://www.ftc.gov/bcp/conline/pubs/autos/octane.htm

NZConvertible

Running rich is too much fuel, it has nothing to do with the fuel's octane. Like Evil Aviator said, it's just resistance to detonation. Your mistake was mucking around with the F-Con, not what fuel you ran.
A higher octane fuel will allow more boost and/or ignition advance, which will provide more power.

Josepi

Just thought i'd bore you guys, the octane measurement is a relation to how the gasoline burns. Higher octane normally gives an even burn, while lower octane, burns like a tree branches. Doesn't make sense? I'll ask my GF when she gets back from class, she's taking organic chem now...

87GTR

iTrader: (61)

thats why 4 rotor car ran low octane and still made like 900hp

Evil Aviator

Hehehe, yes, that is somewhat correct. What he didn't realize was that racing fuel has a different air/fuel ratio than pump gas. The reason it ran rich was because unleaded pump gas has about a 12:1 best power AFR, while racing unleaded is around 13:1. If nothing were changed from its street tuning, the engine would have ran 8% rich.

Edit: Add an additional 1% difference in the specific gravities between the two fuels if you are running open loop. The high altitude will make this even worse. The bottom line is that not all fuels are formulated the same, and you need to re-tune when using race gas.

Evil Aviator

"Clean burning" is marketing BS. Here is the FTC link again for those who missed it:

http://www.ftc.gov/bcp/conline/pubs/autos/octane.htm

turbotwista

this is what I know you can run race fuel that is unleaded (if you have cats and O2 sensor). Whether or not it does anything for you is another story. If you have no O2 sensor or cats than you can run leaded gas (in a piston engine atleast don't know what it would do to the rotary). I run 100 octane cam 2 when I go to the strip ( I am running 12psi on the stock IC) and then I only put in like 5 gallons (cost around $20) but it is cheap insurance aginst detonating to death.

blu_gxl

race fuel is LEADED there is no other way to get it that is how they get the higher anti-knock it will mess with your o2 and cats but only if you run it every day there is no reason to run it in an n/a unless your squeesing. i have advanced my timing to the freakin moon and can still run 89 in my car, but i run 91 for the added peace of mind.

james

Evil Aviator

Yes, there is. It's called MTBE (oxygenates), Toulene, Xylene, Methanol, Ethanol, as well as many other additives.

See unleaded racing fuels here:
http://www.racegas.com/Racegas/fuelspecs/default.asp
http://www.vpracingfuels.com/main.html

Dyre

I can get upto 110 unleaded in town...
100 unleaded only costs $3.35/gal down at the 76 station.

Not all race fuel is leaded.

RETed

There seems to be a lot of misconceptions on what stupid-high octane fuel does and doesn't...

Yes, you are technically right - octane rating has nothing to do with rich/lean.&nbsp BUT, in reality is does - the slower propogation of flame front of super-high octane stuff MIMICS a rich condition.&nbsp If there is ANYTHING you get out of this thread, remember this:&nbsp to take advantage of higher octane, you need to advance your ignition.&nbsp This is HOW super-high octane gets you power - it's through a more advance ignition timing.&nbsp Running normal octane and retarding the ignition timing will look exactly like running slightly rich, and it will show all the signs (blackened plugs, gas burning in the exhaust system - i.e. popping, etc.)...


-Ted

RETed

That is correct, but some of the lower octane race gas (under 110) is actually unleaded.&nbsp All the higher octane race gas (over 110) are either "LL" (low lead) or straight-up EPA busting, brain damaging leaded gasoline...

Most of the Unocal stations in Vegas offer 100 octane unleaded stuff at the pump!&nbsp $4/gallon - sheez!


-Ted