[AT] GM Flex Fuel vehicles

Steve W. falcon at telenet.net
Sat Aug 12 22:25:50 PDT 2006



Henry Miller wrote:
> I wasn't home for a couple weeks, so I'm late, sorry.   (I work 100 miles from 
> home)  A few minor corrections need to be made though, because I'm an 
> engineer who hates to see mistakes.
> 
> On Monday 31 July 2006 21:18, Steve W. wrote:
>> Charlie,
>>   There are three major differences in them. One is the gas cap itself.
>> Besides being Yellow it has a different vent valve in it because alcohol
>> is hygroscopic so the venting is set up to only vent pressure. The
>> second is the fuel line assembly. There is a 700.00 flex fuel sensor in
>> the line that tells the computer what the mix in the tank is. The sensor
>> is the same for all the flex fuel vehicles made from 2002 and up. The
>> line itself is also made of a different material.
> 
> Maybe, maybe not.   Not all flex fuel cars have the sensor - some cars can 
> figure things out without the sensor.   The main difference is the air/fuel 
> ratio, and you can get a good clue about this ratio by reading the oxygen 
> sensor that is already there.  All cars need to be able to adjust between E10 
> and straight gas (often one of the many different types that each city 
> mandates), this is just an extension.  

I have not seen a single vehicle made to run as a flex fuel that doesn't 
have a fuel composition sensor in it unless you want to look at the 
military vehicles. GM, Ford and Dodge all use sensors in their vehicles.

> 
> The fuel line being made from a different material can be an important factor.  
> (but only when they don't change all cars of that type over to avoidproblems 
> where the lines puts the wrong line on a car)   Most people who experiment 
> (illegally) have not seen a problem with the wrong line though.
> 
>> The last change is in 
>> the injectors. Since alcohol has less energy than gasoline they
>> increased the flow rate for the flex vehicles to accommodate the higher
>> rate of fuel flow.
> 
> WRONG!    Yes the injectors are bigger, but it is not because ethanol has less 
> energy (though it does).  Injectors are bigger because ethanol needs to run 
> richer than gasoline.   Gas needs an air/fuel ratio of about 14:1, while 
> ethanol is about 9:1.   Without the bigger injectors your engine runs too 
> lean.   Over time (thousands of miles, one tank of E85 is not problem) this 
> can burn a hole in your pistons.

Same thing different wording. The lower energy of the alcohol means that 
in order to generate the same power and tolerate the different mix 
requirements they need to flow more fuel.


> 
>> Now for the REAL problem. It is Illegal to convert any unleaded fueled
>> vehicle to a different fuel unless you have the DOT do a test on the
>> entire vehicle and can prove that it meets or exceeds the emissions
>> standards for that vehicle type. That test is about 10,000.00 to have
>> done. There are NO approved kits or methods out there to convert a
>> vehicle to E-85 or other fuel. Get caught driving a converted vehicle
>> and you get to pay a BIG fine for tampering with the emissions system of
>> the vehicle.
> 
> Yep, but if you search you will find conversion kits.  The state of MN is 
> considering getting involved in certifying these kits, so you might want to 
> revisit this issue in a couple years.   In MN E85 is about $2.59/gallon, so 
> there is money to be saved if you can use it.   (MN has more Ethanol than we 
> use, and we are not able to transport enough to other states that have a 
> shortage, thus there is a large spread in ethanol prices depending on where 
> you live)

You can find ILLEGAL kits. Until the EPA and the Feds change the law 
they will remain illegal to use without the required certification which 
is VERY difficult to achieve.


Steve W.
Near Cooperstown, New York

Pacifism - The theory that if they'd fed
Jeffrey Dahmer enough human flesh,
he'd have become a vegan.



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