[AT] GM Flex Fuel vehicles

[charlie hill]

Thanks Henry,

It seems to me that since GM builds my truck in both a Flex Fuel and regular 
version with the same engine that they would have a way to convert between 
the two.  Anyway I was just curious.

Charlie
----- Original Message ----- 
From: "Henry Miller" <hank at millerfarm.com>
To: <at at lists.antique-tractor.com>
Sent: Saturday, August 12, 2006 10:01 PM
Subject: Re: [AT] GM Flex Fuel vehicles


>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.
>
> 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.
>
>> 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 seearch 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)
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