100 Octane?

[hellyvin]

I mixed two gallons of 100 Octane with my usual 91 V Power, the butt dyno feels the difference. Just wondering if anyone else has had experience with higher octane fuel? Is it safe? What if the whole tank is 100 octane? lol

Just found this and pumped some by the 76 in Saratoga just before heading up 9 to Alice's.

[TheRipler]

Unless your car is tuned for it, you will start to lose performance if the octane rating gets too high. Bringing 91 CA gas up to 94-95 can be a good thing, but straight 100 will probably be a waste of money. If you normally put in 10gal, try 3 gal 100 w/ 7gal 91. That should put you in the high 93 range, and the car will love it. Most I would go is 4gal:6gal using 100:91 without a tune.

[PMok]

yeah a bunch of us did the 94 octane or 91 + 100 octane mix this weekend, and we were all talking after about how we could feel the difference. What a shame we have to live with 91 all the time here or pay through the nose to get the hi octane stuff. Everyone else in the country gets that extra bit of power on a regular basis.

[BlaineWasHere]

Extra octane in your fuel does NOTHING unless you're tuned for it. Octane is just how fast, and hot the fuel burns.

Running 100 octane without a tune is more likely to cause damage than gain performance.

PLUS if you really knew what you were doing you'd just be tuned for E85 (which is about 104 octane) because it's a million times cheaper than race fuel and slightly easier to find.

Even the autoX 86 cars running E85 or 100 octane WITH A TUNE for it are only seeing it give them 3-6 WHP, this is not something you could likely feel with a "butt dyno" especially since none of you are tuned for it.

[OldGuyBRZ]

I've been mixing for the past few weeks, and can definitely tell the difference. Which actually surprised me, cause I didn't think I would (I didn't think our engines have enough compression to make a difference). First time I tried it was right before the last Mt Ham drive, and now I'm doing it for even for around town 'normal driving'.

[CamryDS]

There's a couple of places with 100octane I know and there's another near almaden expressway. The problem is that there's so few and far between stations with racing fuel let alone flexfuel (e85). If there's a way we can consistently obtain flexfuel i'd probably be doing the tune right now for it.

[sdlynx]

Originally Posted by PMok

yeah a bunch of us did the 94 octane or 91 + 100 octane mix this weekend, and we were all talking after about how we could feel the difference. What a shame we have to live with 91 all the time here or pay through the nose to get the hi octane stuff. Everyone else in the country gets that extra bit of power on a regular basis.

PMok is right. I hadn't said anything to them yet, but I certainly felt, and am still noticing the difference (not quite done with that tank yet). When you drive a particular route regularly at 91, then you bring the car to its desired 94, you definitely notice it. It's not so much "extra" power, but a better responsiveness.

Gotta agree with Blaine too. If you start going higher, you're not really going to notice anything more. The only reason we noticed the increase to 94 is because the car is tuned for that.

[Clipdat]

From the owner's manual: "The engine is designed to operate at maximum performance using unleaded gasoline with an octane rating of 93 or higher. If 93 fuel is not readily available in your area, unleaded gasoline with an octane rating of 91 may be used with no detriment to engine durability or driveability. However, you may notice a slight decrease in maximum engine performance and you may hear some knocking (pinking) of an engine while using 91 fuel."

Interesting wording, and hints that the stock tune may have some wiggle room when it comes to octane. I've definitely noticed improvement with filling up with full tanks of 94 or 100, or when mixing 91 and 100. It's not crazy dramatic, but it really smooths out the powerband, and the engine feels especially rev happy above 4k.

I hadn't heard that running 100 could damage anything. I would think that they would make a note of that in the manual versus saying "93 or higher". Also, they ran 100 octane in the cars at the Scion celebrity racing event:

"The cars run on 100-octane race fuel -- there's no performance gain, but it levels out the knock sensors for even running."

http://www.autoweek.com/article/2013...NEWS/130319965

[BlaineWasHere]

The celeb race cars where tuned.

Trust me guys, the butt dyno is not scientific and you guys are pretty much just pissing in the wind here.

Even with a few extra ponies a V6 Caravan or Odyssey will still smoke you on the highway. If you bought this car for power and straight line speed you have the wrong car.

[Clipdat]

I'm not sure anyone that's posted about their experiences in this thread has claimed a measurable horsepower increase. It's more about how the engine responds and behaves, not like "oh it gives me +10 hp".

Also, I'm not seeing where it talks about the celebrity race cars being tuned. Link?

[BigFatFlip]

Originally Posted by Clipdat

I'm not sure anyone that's posted about their experiences in this thread has claimed a measurable horsepower increase. It's more about how the engine responds and behaves, not like "oh it gives me +10 hp".

This is exactly what I thought after filling up at Sunol, no extra power, just better response. My guess would be that at 91, the ecu just pulls the timing just slightly to compensate.

Also, food for thought, our ecu's have a learning span to safely adjust itself on the local fuel. So a tank of 93+ won't really give you any immediate gains (if any) since it has been calibrated to run on all those tanks of 91 we'll already been running. Some people post gains after a tune, but that could possibly be the ecu just being reset and not getting the chance to "re-learn" yet.

[icemang17]

100 octane fuel will LOSE HP in a stock car....... When tuned for it, there will be a gain from increasing timing due to reduced knocks.... Yes our crappy CA gas is only 91....but with a modern fuel injection system like our cars have its fine....

[Clipdat]

How does it lose hp?

[RC51ed]

I don't know about hp but my mpg seems a little bit better with my heavy foot on 94 octane than 91.