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| Fuel's resitance to knock (less than 10%) https://www.slantsix.org/forum/viewtopic.php?t=34522 |
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| Author: | Bren67Cuda904 [ Thu Mar 26, 2009 3:15 pm ] |
| Post subject: | Fuel's resitance to knock (less than 10%) |
Most fuels now have the "less than 10% ethanol" added at the pump. I was talking to a guy that races VW's and he is telling me that the added ethanol at that level will cause an engine with a border line knock/pinging problem (due to CR only) to not get better, but get worse with 10% ethanol. Now I believe that yes fuel mileage is not as good and the power will fall off a bit, but to have more tendency to knock/ping seems wrong to me, especially if a little extra fuel is added (jet up) to bring the calorie count back up as to avoid a lean condition. I know alcohol race cars run a very high CR. It would seem to me the more alcohol you run the higher the CR you can run. Or is the problem with this theory that fact that there is still gasoline in the mix that is doing the knock/pinging? |
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| Author: | GENT [ Thu Mar 26, 2009 3:20 pm ] |
| Post subject: | |
It must just be the gas. The ethanol has a higher octane rating,but like you said they ad 10% or less. I dont really see why it would get worse??? My buddy has a big block car with 10-1 comp and with correct fuel and timing tuning he can run it on 89 pump. No ping with gas,and still no ping with the 10% ethanol blend. |
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| Author: | MitchB [ Thu Mar 26, 2009 4:41 pm ] |
| Post subject: | |
I have seen published data and correspondence with oil companies supporting the fact that actual ethanol percentage varies greatly and ranges anywhere from 5% to 15%. 10% ethanol will lean an engine by 4%. This alone could push an engine into lean detonation. Mitch |
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| Author: | THOR [ Thu Mar 26, 2009 9:13 pm ] |
| Post subject: | |
Ethanol only has about 75% of the energy in it that gasoline does. Therefore, as many notice, you have to add alot more fuel to keep from experiencing a lean condition, and subsequent detonation. If you add enough extra fuel, it will take care of the detonation, but you will obviously get less miles per gallon. Ethanol will also raise the volatility of the gasoline it is mixed with, so it will cause detonation where there was none before, and make existant detonation worse. ~THOR~ |
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| Author: | dakight [ Fri Mar 27, 2009 5:22 am ] |
| Post subject: | |
At the correct air/fuel mixture and ingition timing, a fuel with ethanol added will be LESS likely to detonate than on gasoline alone. Ethanol raises the Octane rating which was significantly lowered by the removal of lead additives. It does not, howver, protect the valve seats, which was the primary funtion of lead additives. |
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| Author: | Rug_Trucker [ Fri Mar 27, 2009 6:03 am ] |
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I do know someone that has a slant that was over carbed with too much compression, not enough cam that topped off with E-85 and his pinging went away and the car ran better! When I was in Florida I was able to run 87 in my van and no ping. Now I have the blend it pings under hard acceleration. It may be in part to a loose primary throttle shaft on the Qjet. All I can say is ethanol is BS technology and the big corporate corn farmers are laughing all the way to the bank! Our governer in here was in my store a week or 2 ago buying gardening supplies. He is a big proponent of bio fuels. Didn't think to bust his chops when I was assisting him. Ethanol doesn't make sense. I like the smell of the B-20 diesel. Just my mileage sucks on it. It's hard to find, and is expensive. |
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| Author: | coconuteater64 [ Fri Mar 27, 2009 6:17 am ] |
| Post subject: | |
Sounds like it is too lean. Alcohol is virtually detonation-resistant by nature. I know guys who run it in their race cars because of the octane, running as high as 13:1 with no detonation. Just gotta richen it up and bump the timing. |
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| Author: | Bren67Cuda904 [ Fri Mar 27, 2009 6:27 am ] |
| Post subject: | |
Quote: Sounds like it is too lean.
The VW guy and I where just shooting the sh*t. I no longer have a pinging problem. Whenever I hear anything about knock/pinging I start listening. I am still a little scared from about a year ago when it seemed like i turned my slant into a diesel. 
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| Author: | Rug_Trucker [ Fri Mar 27, 2009 6:39 am ] |
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Quote: Sounds like it is too lean. Alcohol is virtually detonation-resistant by nature. I know guys who run it in their race cars because of the octane, running as high as 13:1 with no detonation. Just gotta richen it up and bump the timing.
What you talking about the slant or my 360?If the slant? The guy is running a mild Comp cam. Similar to the MP cam. a 450 Holley circle track carb. 10:3:1 compression. |
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