If you compared same octane e-10 and non-ethanol (pure gas), is the pure gas more prone to detonation? I filled up (half tank)with pure gas yesterday, and this morning i had some knocking at part throttle. I filled up with 93 octane ($5.00 per gallon--ouch!) this afternoon, and the knock went away. Coincidence, or bad gas maybe the problem instead?
non-ethanol fuel more prone to detonation?
- Thread starter Blue'03SVT
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From what I have read, you need to get to E-30 to gain additional knock protection (tune required). Are you stock or on tune?
On tune from years ago with 91 octane at the time. I recently changed the fuel filter, cleaned the air filter, and made sure the maf looked clean.
What was octane rating of the "pure gas"?
It would make sense that E10 version of the same octane gas would provide more detonation resistance but I don't know if that's enough to actually notice. 91 is premium in KC so I fill up with E10 91 and I tuned on it too. I avoid the pure 91 stations for that exact reason but have no data to show if it really matters or not on such a little bit as 10%.
The octane rating tells you what the fuel's resistance to detonation will be. Whether it contains ethanol or not is of little consequence (91 octane is 91 octane). The higher the ethanol content the higher cooling effect the fuel will have so that would impact it's anti-knock capabilities most likely in hotter weather.
An NA engine can tolerate knock. It's a different story with an FI engine. Don't do that!
An NA engine can tolerate knock. It's a different story with an FI engine. Don't do that!
It does which is why I picked E10 and tuned on it and continue to use it. It's a small difference but it's there.
It was 91 octane, which is what is considered "premium" here in OKC.
Oklahoma City UNBRANDED 93 Red Rock Distributing Co 1 Nw 50th St N35.52308 W97.51319
^^^^ kinda off topic, but if these guys are close you can get 93 octane, couldn't find any other place that sells it. May help with the knock.
^^^^ kinda off topic, but if these guys are close you can get 93 octane, couldn't find any other place that sells it. May help with the knock.
Thanks, I'll drop by there in the next couple of days to see what their prices are like. I found another station about 8 miles away with it on pump for $5 a gallon. It did seem to fix the knock when I added it to half a tank of the 91 octane. I also found a place with 104 octane on pump for $8 a gallon--maybe I could add a gallon of it to 91 for the same effect? Not sure if it's a simple conversion of diluting 104 into 91 for a boost in total octane?
Knock is bound to bring sure death to your motor. I'd start adding cans of torco to your gas immediately or get your tune adjusted with less timing. Stay out of boost till you fix this.
Mixing in toulene with your fuel can also improve your octane. Formula 1 used this stuff a lot in the first turbo era when during qualifying the engines would run upwards of 70 psi.
Interesting you mention that. A buddy of mine has a twin turbo 911 running a lot of boost and that's what he does. He mixes in toulene. I'd never heard of it or know anyone else besides him doing it but apparently it's popular in the Porsche crowd from what I hear.
I dumped a bottle of "heat" into the tank this morning, and let it sit until this afternoon. It ran flawlessly! Maybe water in the 91 octane? I'll keep checking, and use 93 octane for the next couple of fill ups.
It came from the first Formula 1 turbo era. I recently read a little article on it. Supposedly the fuel F1 used was 70% or more toulene and exhaust was ducted to help heat the fuel, not unlike JP-7(?) for the SR-71.
Water suspended in the fuel shouldn't lower the octane. I intentionally inject water to raise octane and cool the air charge. On the other hand, water isn't supposed to be mixed with the fuel in your tank. That will lead to rust. It's more probable that the 91 octane has less of the long hydrocarbons mixed in it than the 93. FWIW I always use 93.
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