High ethanol mixtures

On 2008-05-30, Don Stauffer in Minnesota <[email protected]> wrote:
> Somewhat related to an ongoing thread, but different-
>
> Our local newspaper had an article today about folks who do not have
> flex fuel vehicles, but do burn high ratios of ethanol. They fill
> from two pumps, one E85, one gasoline, and so tailor their own
> mixtures.

> Since ethanol requires a much richer mixture than gasoline, doesn't
> this substantially lean out the mixture? I know ethanol will burn
> quite rich, but how LEAN will it go? Also, doesn't this risk valves
> and pistons? I remember cases of folks with race cars running lean
> mixtures and doing a lot of damage.

All they need to do is keep the mixture within the range that their
car's O2 sensors, computer, and injectors can handle. If they do this,
then the computer will hold the mixture correctly and nothing bad will
happen wrt mixture. as far as higher % of ethanol doing bad things to
the seals, plastics, etc... that's another story.

> Also, this brings up a question. I understand flex fuel cars have a
> sensor in the fuel system that measures the gasoline/ethanol mixture
> ratio so ithe EFI can adjust the mixture accordingly. What kind of
> sensor is that? I used to work in sensor R&D, but chemical sensors are
> not my strong point.

I thought it was all software using a wider band O2 sensor in a typical
FFV. I suppose a fuel mix sensor might be needed so there aren't
stumbles right after a fillup with a drastically different mixture.

The systems that advance timing and otherwise take advantage of
ethanol's octane advantage probably do have some sort of fuel mix
sensor but I have no idea how it would work.

Brent P wrote:
> On 2008-05-30, Don Stauffer in Minnesota <[email protected]> wrote:

>>Also, this brings up a question. I understand flex fuel cars have a
>>sensor in the fuel system that measures the gasoline/ethanol mixture
>>ratio so ithe EFI can adjust the mixture accordingly. What kind of
>>sensor is that? I used to work in sensor R&D, but chemical sensors are
>>not my strong point.

> I thought it was all software using a wider band O2 sensor in a typical
> FFV. I suppose a fuel mix sensor might be needed so there aren't
> stumbles right after a fillup with a drastically different mixture.
>
> The systems that advance timing and otherwise take advantage of
> ethanol's octane advantage probably do have some sort of fuel mix
> sensor but I have no idea how it would work.

The flex fuel sensor is basically a capacitor, the capacitance
changes because the dielectric constant of ethanol differs from
gasoline.

"Don Stauffer in Minnesota" <[email protected]> wrote in message
news:43540c82-dd5f-4b52-8566-4b8f1d341fde@x35g2000hsb.googlegroups.com...
> Somewhat related to an ongoing thread, but different-
>
> Our local newspaper had an article today about folks who do not have
> flex fuel vehicles, but do burn high ratios of ethanol. They fill
> from two pumps, one E85, one gasoline, and so tailor their own
> mixtures.
>
> Since ethanol requires a much richer mixture than gasoline, doesn't
> this substantially lean out the mixture? I know ethanol will burn
> quite rich, but how LEAN will it go? Also, doesn't this risk valves
> and pistons? I remember cases of folks with race cars running lean
> mixtures and doing a lot of damage.
>
> Also, this brings up a question. I understand flex fuel cars have a
> sensor in the fuel system that measures the gasoline/ethanol mixture
> ratio so ithe EFI can adjust the mixture accordingly. What kind of
> sensor is that? I used to work in sensor R&D, but chemical sensors are
> not my strong point.

I havent researched it, but I doubt these sensors are chemical specific;
i.e.,
I suspect they measure some other parameter like thermal conductivity which
can be related back to blends of hydrocarbon fuel with ethanol. That is
often
the case. It wouldnt, perhaps, be impossible to develop a specific sensor,
but I suspect that would be expensive and troublesome.

I have always thought that an alcohol flame was a cooler flame than a
gasoline
one, but maybe this is just a preconception. Also, alcohol has a reasonably
high
octane rating, so maybe this offsets some of the preignition and temperature
issues.. It is not an area that I have had any reason to research before
now.

I tried running on 1/3 E85 and 2/3 normal E05 (gas here have 5%
ethanol) in my 1996 audi, and it had no problem adapting to the
resulting E32 (by my calculations).

As long as the mixtures AFR for lambda 1 is within the permissable
range of the engine management system, it shouldn't be a problem.

Don Stauffer in Minnesota wrote:
> Somewhat related to an ongoing thread, but different-
>
> Our local newspaper had an article today about folks who do not have
> flex fuel vehicles, but do burn high ratios of ethanol. They fill
> from two pumps, one E85, one gasoline, and so tailor their own
> mixtures.
>
> Since ethanol requires a much richer mixture than gasoline, doesn't
> this substantially lean out the mixture? I know ethanol will burn
> quite rich, but how LEAN will it go? Also, doesn't this risk valves
> and pistons? I remember cases of folks with race cars running lean
> mixtures and doing a lot of damage.

If (theres a loaded word) they can keep the mix within the range that
the engine and sensors can tolerate it will work BUT they will be losing
a lot of power because of the leaner mix. It also is likely to be doing
some damage to the engine as well.


>
> Also, this brings up a question. I understand flex fuel cars have a
> sensor in the fuel system that measures the gasoline/ethanol mixture
> ratio so ithe EFI can adjust the mixture accordingly. What kind of
> sensor is that? I used to work in sensor R&D, but chemical sensors are
> not my strong point.
>

They use a fuel composition sensor in the line feeding the engine. On GM
flex fuel equipped vehicles it is installed near the fuel filter under
the vehicle. On the trucks it is just below the drivers seat location on
the cars it is either in the rear near the tank or up front just below
the master cylinder.

It looks at conductivity and a couple other items to determine the
alcohol content. It is basically preset to look for a few blends though.
Straight gasoline - E10 is one mix, Then it looks for E15-about E50 as
another step, then E50 - E85 is another step. It then tells the computer
to use the sensor maps and mix tables for those different blends.


--
Steve W.

"Steve W." <[email protected]> wrote in news:g1phup$2ti$1@aioe.org:

> Don Stauffer in Minnesota wrote:
>> Somewhat related to an ongoing thread, but different-
>>
>> Our local newspaper had an article today about folks who do not have
>> flex fuel vehicles, but do burn high ratios of ethanol. They fill
>> from two pumps, one E85, one gasoline, and so tailor their own
>> mixtures.
>>
>> Since ethanol requires a much richer mixture than gasoline, doesn't
>> this substantially lean out the mixture? I know ethanol will burn
>> quite rich, but how LEAN will it go? Also, doesn't this risk valves
>> and pistons? I remember cases of folks with race cars running lean
>> mixtures and doing a lot of damage.

>
> If (theres a loaded word) they can keep the mix within the range that
> the engine and sensors can tolerate it will work BUT they will be
losing
> a lot of power because of the leaner mix. It also is likely to be
doing
> some damage to the engine as well.


It should do no eng damage, why you think it should I don`t
understand. It will not run lean, the O2 sensor will enrichen it as long
as it is within range of the fuel inj to richen it up. it my have a
slight power loss because of non specific achalol software but other
than less milage and power it should do no harm. KB


>
>
>>
>> Also, this brings up a question. I understand flex fuel cars have a
>> sensor in the fuel system that measures the gasoline/ethanol mixture
>> ratio so ithe EFI can adjust the mixture accordingly. What kind of
>> sensor is that? I used to work in sensor R&D, but chemical sensors
are
>> not my strong point.
>>
>
> They use a fuel composition sensor in the line feeding the engine. On
GM
> flex fuel equipped vehicles it is installed near the fuel filter under
> the vehicle. On the trucks it is just below the drivers seat location
on
> the cars it is either in the rear near the tank or up front just below
> the master cylinder.
>
> It looks at conductivity and a couple other items to determine the
> alcohol content. It is basically preset to look for a few blends
though.
> Straight gasoline - E10 is one mix, Then it looks for E15-about E50 as
> another step, then E50 - E85 is another step. It then tells the
computer
> to use the sensor maps and mix tables for those different blends.
>
>



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