Your opinions, if I may...

[James86]

Hello, I have a 99 flex fuel Ranger. After I read the "rebuilding the 3.0" tech piece, I found out that ethanol engines have different shaped combustion chambers than a standard 3.0 engine. Also, I have heard from mechanics and a coworker with a 2000 flex ranger that I have an octane sensor in the fuel line so the ECM knows how to advance/retard spark, etc. for the ethanol. SO with that in mind, I have a few questions I'd like to hear thoughts or opinions on:

1.) Does the shape of the combustion chamber have a detrimental effect on efficiency when running gas versus a standard chamber?
2.) Does that difference (if any) equal any power gains with E85 versus regular gas in a flex engine (there feels a subtle difference to me from the seat...)
3.) If there is an octane sensor, what would happen if I put 110 octane gasoline or some other 100+ octane fuel (which is available around here - my dad used it in his '77 Corvette) in my Ranger? Could the ECM theoretically be "tricked" into thinking its E85 and advance/retard spark for more power and exploit the higher octane while still achieving the mileage that gasoline gets versus E85? (I'm not asking whether its cost effective per say, I just want to know if it would work )

BTW, I regularly burn E85, and average 17mpg a tank, vs. 19-20mpg if i mix 89 octane and E85 50/50 (the best combo ive stumbled on, since E85 is 1.86 and gas is about 2.50 for regular)....

Ive been pondering this for a while and figured this was the place to ask.

 

[triumphrider-1]

1. I don't know about the shape of the chamber, but I do know that the chamber is smaller. FF heads are 47cc and the standard is 49cc.

2. I would more call it releasing the power potential.

3. E85 has octane value of about 108, so depending on the summer (E85) or winter blend (E70) it would be fairly close to running 110 race gas. I do know however, if the computer can adjust beyond the E85 ratings; I would think so, but can not say for sure.

 

[hartwrenches]

flex fuel

From what my friend at ford tells me the sensor doesnt actually read octane, it reads the alcohol content. Ethonal reads different than gas. It reads a percent and adjusts timing to match.

He says the computer can't tell the octane of the gasoline itself. And there are several other sensors involved for timing control.

He also says the flex fuel engines run lower compression, the heads are different to provide for better flame front.

The only way to get the power out of the 110 gas only fuel would be to tell the ecu to advance the timing manualy past normal peramiters with a chip or custom fuel maps.

I asked him because I run methanol engines and thought that might be a nice short cut, but not so much. Alcohol is high octane but has different burn characteristics than gas.