I don't run it straight.

I have run it on my bike and my Audi (B5 TT). Both of those made a big difference.

On the P, I only run some 100 to clean out the gas a little or to average out the OCT of the 91 so that I may have a rating of closer to what the car wants.

I don't do it all the time, only when I am close by to woodside.

 

Is that gas station near 101 and 92? I wonder how fresh is that gas? I'm sure the gas station owner knows.

 

There are only a few 100 oct unleaded pumps in the area... the ones that I know of:


1. 76 On woodside road. In between 101 and 280, used to be close to where Doc Wong had his office before he moved. For those that ride.
2. 76 In San Jose, Almaden 76 & Race Fuel. 3010 Almaden Expressway
3. Sears point. No, not Infineon. It will always be Sears Point.

The 76 on woodside is more than likely pretty fresh as I know it is used often by bike and cars alike and it is a good fill up on the way to the hills.

 

Octane ratings are related to detonation temperature and nothing else. High-octane isn't any "better" or "worse" than low-octane, it just means that the fuel ignites at a higher temperature to avoid premature detonation in high-compression engines.

So unless you have a high-compression engine -- either a turbo with a high-boost map, or an aggressive timing map -- you'll just be wasting your money or worse, not getting a complete burn of your fuel which leaves carbon in the motor and reduces fuel economy.

The rule of thumb is that you need to run only as high an octane as is necessary to avoid knocking (premature detonation)

 

Thanks! The Woodside Rd 76 station website HERE.

 

Cool. I updated the list with the San Jose location.

 

This is very true.

On my Audi, it loves it. Can't get enough. The turbos and the tune.. gets me a roid rage AWD monster..

My ZX6R, likes it also.. hi compression rice rocket.. Also tuned slightly.

When I had my Monster, it HATED hitest. If I put anything over the 87 that it called for, it would tard like a suma*****.

 

Right. ECU-controlled Porsche engines run fine on 91 and up. However, the engine maps are optimized for 93. So, I suppose a blend bringing up the octane rate to 93 should be ideal. That means 3.5-4 gallons of 100/101 on a 16 gallon tank.

 

I'll have to try that at my next DE. I always run 91 from Shell or Chevron. The track has race gas.

 

Just make sure the high-octane offering is unleaded...

 

Hah! Yeah.

 

I used to fill a couple of gallons of 100 octane @ around $15 a gallon. After not noticing a big difference in the performance, I stopped and started to add 100 ethanol. The engine sound and performance with the 100 ethanol is much better than the 100 octane and way less per gallon.

 

Adding ethanol above the E-10 level may be asking for trouble.

 

This needs to be quoted again... great information.

And even if your car/bike is "tuned", unless it is tuned specifically for 100 octane this gas will not make a difference. Matter of fact, your car will probably run worse. 99% of street cars will run their best on the grade of fuel specified by the manufacturer.

 

Uh, not exactly.

Octane is related to how well the fuel is at *resisting* forming pre-ignition compounds in front the advancing flame front.

The fuel ignites as soon as the flame front reaches the tiny droplets of fuel surrounded by air. The fuel burns at the same speed. High octane gasoline is kind of like dynamite in that it is hard to ignite but once ignited burns very quickly.

In the context of this discussion the OP was asking about 100 racing fuel and whether is worth running. As I mentioned in my earlier post racing fuel has benefits above and beyond its higher octane rating. Whether the cost of the fuel and the benefits one notices is worth it can only be determined by the driver of the car, with the caveat the fuel be safe to use with modern engines and their O2 sensors and converters.

However, I seriously doubt the OP would find that much improvement to make the $8.99/gallon price acceptable, at least on the street. If he did we would have heard about it and we'd all be using at various times.

On the track again while there is the benefit of the higher octane -- granted 100 octane is way above what the engine is tuned to need/use but better to use too much octane on the track than too little -- there is also the benefit of the way the fuel burns especially at higher RPMs were track engines spend most of their time.

Comparison tests of gasolines including racing gasoline have confirmed this. IOWS, it is *racing* fuel.

I use 91 octane in both my Porsches. This is really all that is available where I live and drive and while there might be a station still out in Tracy that carries 100 octane I am not ready to spend God only knows how much over the $2.999/gallon I spent today filling up one of my cars' gas tank even if the station was right next door.

With 91 octane the engines run ok. But I have also run at least one engine, the Turbo engine, on 93 octane. The engine really reacts favorably to 93 octane. This makes sense as this is the octane the engine was deisgned/intended to use.

Now for the Boxster, some years ago just before a smog test I ran the fuel tank down real low and put 6 gallons of 100 octane racing fuel in the fuel tank. This was a station located in Tracy CA.

With 6 gallons of 100 octane racing gas in the tank I then took the car out where I could really accelerate the car hard through the gears and noticed no change for better ( or worse ) in the way the engine ran. I also drove the car more sedately around town and on the freeway and again I couldn't notice any difference.

Once back to Livermore the engine passed smog just fine but it had passed smog just fine on 91 octane gasoline before and since, too, so the 100 octane didn't help in that regard.

Even so, I would use 100 octane on the track. I would not worry too much about trying to blend it with 91 to get right at 93 but would just put in enough 100 octane fuel in the tank to ensure the average octane rating was at least 93 (and a bit higher is not a bad idea for as an engine ages its octane requirements goes up) and enough fuel in the tank to ensure the engine would have plenty of fuel during the session and on the way home or at least enough fuel to get me to a gas station that sold something less exotic than 100 octane racing fuel.

IOWs, on the track I would run as close as I could get to 100% 100 octane racing fuel in order to derive the full benefits of the *racing* fuel over and above the benefit arising from the very real benefit of the higher octane rating.