At 07:14 PM 3/18/96 -1000, you wrote:
>
>There has been quite a lot of stuff on this topic just recently. I
>must admit I was 100% convinced it was just a snake oil scam until I
>read the article below. I presume that the device you have been
>talking about is the same or similar to the one described below
>although it is a *lot* cheaper here...
>
>This device is based on the leaching of tin into the fuel to act as a
>Tetra Ethyl Lead substitute. The tin is purported to both improve
>combustion control and lubricate valve seats etc. There appears to be
>supporting evidence for this in the article below.
>
>Perhaps some chemists on the list might comment?
>
As a "chemist on the list", I guess I need to comment. And I am also
skeptical of these miracle devices for many reasons.
The theory of the tin as a lead replacement sounds plausible. But since the
tin won't stay in solution for any period of time, this gizmo is supposed to
allow tin contained inside of it to leach into gasoline shortly before the
fuel reaches the carb(s). This brings up several questions. Won't this tin
also tend to settle, in the float bowls or jets? And how long does the tin
in the gadget last before it needs to be replaced? And third, isn't gasoline
more likely to coat or deposit material on the tin instead of leaching or
corroding it? (maybe there is a magnet!)
The study quotes BTEX analysis of the emissions. The BTEX compounds are the
lighter volatile aromatics in the gasoline that tend to evaporate first.
Thus, aged gasoline is recognizible on a gas chromatograph by its reduced
BTEX compounds (benzene, ethylbenzene, toluene, and xylene).
Elevated BTEX in car emissions (as well as CO) merely indicate inefficient
combustion. The one advantage to testing BTEX is the good sensitivity of a
gas chromatograph with a PID (photo ionization detector) - these compounds
can be quantified accurately to part per billion levels.
Thus the study only indicates improved combustion. It would be easy to
improve combustion a number of ways - such as altering the fuel mix or
timing after installing the gizmo under the pretense that certain settings
must be optimized. The key is how controlled this experiment was in the
before and after tests. The details in the post do not elaborate on how
identical the conditions were. And it would be easy to give credit to a
university even if they only tested the actual samples.
I would have to see the complete study before I was convinced. And if this
device really did all this, why sell it to the average consumer - the low
volume, high maintenance type sales? Wouldn't you sell it to volume
customers like car manufacturers and such?
Fortunately, I live in Montana where we don't have to worry about car
emissions. And I would be reluctant to add these foreign devices to the car
anyway. Its a fine car in its original state. Why ruin a good thing?
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David Councill
dcouncil@imt.net
http://www.imt.net/~dcouncil/home.html
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