Nobrainer’s Think Tank

So, you’re looking for a PDMS solvent. I bet you’re having a difficult time, and mostly finding scholarly articles that you either can’t access or that don’t actually have what you’re looking for. Well I’m going to provide some summary data for a very useful paper published in 2003 by Jessamine Ng Lee, Cheolmin Park, and George M. Whitesides. In their paper, Solvent Compatibility of Poly(dimethylsiloxane)-Based Microfluidic Devices, (you may be able to access the abstract and full text versions here), they report on the efficacy of various solvents for cross-linked PDMS.

For 38 different potential solvents, they immersed their samples of cross-linked PDMS and measured the amount of swelling. Most solvents won’t dissolve PDMS. The best solvents and the measured swelling ratios are listed below, along with a few very common, but less efficacious solvents. (Below all that are the chemicals that can completely dissolve the PDMS.)

If you actually want to dissolve PDMS, the paper says that 3 different items will do it: dipropylamine, sulfuric acid (18.0 mol/L), and trifluoroacetic acid (13.4 mol/L). It also notes that it took 39 days for the dipropylamine to completely dissolve the PDMS. It is important to note that these processes may all take days or weeks to complete.

UPDATE [2010-03-07]: A copy of the paper I was referring to has been uploaded to Scribd.

In the whole debate about whether or not acetone can improve your fuel mileage, there is some conversation about whether or not acetone will damage your fuel system, particularly seals, hoses, and gaskets. I think everyone who comments is really just speculating, and I am going to chime in on the basis that I have no idea whether or not damage is actually occurring. However, there are several, potentially mistaken although somewhat logical, hypotheses being floated around. Here I’m just addressing what those ideas are and why they aren’t necessarily reliable.

Here, off the top of my head, are the 4 things that I’ll focus on.
1.) I’ve used acetone for years and never had a problem.
2.) I put fuel system parts in a jug of pure acetone for an extended time (years?) and there has been no problem.
3.) Gasoline is a solvent. Acetone is a solvent. Gasoline doesn’t destroy a fuel system, ergo acetone won’t, either.
4.) Acetone comes in plastic bottles, ergo it doesn’t destroy polymers.

Let’s address these items:
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I’ve previously cast my thoughts on the acetone improves mileage concept. I still think it’s a myth, but like the good little scientist I am, I’m always up for being proven wrong. It turns out that the main propagator of the idea, Lou LaPointe (who also goes by C. L. LaPointe, and Louis LaPointe), updated his files sometime in 2006. There is a lot of stuff to read, but not very much useful information; it’s rather long winded, ill organized, and full of entirely too much conspiracy theory. To avoid being long winded myself, there are 4 main points I want to hit on today.

1.) Have you read the finer details of his testing?
2.) Did you notice he says that it’s not just acetone that works as a mileage enhancing additive? Let’s look more at xylene, and some of the others.
3.) There’s a researcher at Clemson University who has confirmed positive results?
4.) If it’s a surface tension problem, let’s study that.

To some extent this is incomplete and ongoing research. This is the presentation of what I’ve found thus far.

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[Editor's note: In recent tests, I got only a moderate, 5%-8% (if that much), improvement due to acetone. Also, click the above Acetone & Gasoline link to see the most recent posts on the topic.]

Mythbusters finally tackled the issue and tested car performance with acetone mixed with gasoline. Was the mileage improvement touted by Louis Lapointe confirmed? Plausible? No. And no. Totally busted.

They didn’t test the full range of mixtures, but said they used about a 500:1 gasoline:acetone ratio. That’s about 2.56 fluid ounces per 10 gallons.

Just like the engineers at Kettering University, no improvement due to acetone was found. In fact, it looked as though mileage was decreased in all four of their scenarios (2 speeds times 2 cars) on the dyno.

I’m SHOCKED!

UPDATE: whoops! I thought tonight’s episode was new. I was wrong, according to Wikipedia it aired on May 10, 2006. And crazy ol’ LaPointe defends himself in his FAQ (seriously, read it and decide for yourself that the guy is nuts): (more…)

Happily, I get a slightly decent number of hits relating to acetone in gasoline. As noted in “Better mileage with acetone? I doubt it,” I cast my doubts on the, how shall I say, less than scientific “findings” of a Mr. Louis LaPointe (whose crew is also “developing devices to extract electricity from the air“).

Today I followed a search which led to an article. The main source was Dr. Greg Davis, of the Mechanical Engineering Department at Kettering University (formerly known as the General Motors Institute). It seems that someone is actually trying to reproduce the “data” previously provided.

(following blockquote from the article added here on 7/7/06)

To find out, we went to the Mechanical Engineering Department at Kettering University, in Flint. Dr. Greg Davis thought it would be good experience for his students to verify the claims about acetone in the department’s test engine, a Buick 3.8 liter V-6 that is equipped with all kinds of probes and sensors.

For several weeks the students experimented with various strengths of acetone in gasoline. The findings were disappointing.

“Our current preliminary data suggests essentially no improvement running acetone in the fuel,” Davis said.

To the surprise of no one, preliminary data show no benefits from adding the recommended levels of acetone.

This is will prove inconclusive, however. Reasonable people with reasonable abilities of scientific understanding and interpretation would expect little to no change. The conspiracy-theorist type, however, would also expect any type of study coming from Kettering, with it’s ties to the Big 3 and big oil, to be completely biased.

Of course, if you are the conspiracy-theorist type, I encourage you to buy the hype, with skepticism, of course, as that should be your modus operandi. Now, I would test the hype, except that I expect it to cost me money. You, the conspiracy-theorist should expect to save money, right? So go for it. When you do it scientifically, and prove a 5%+ improvement, you’ll be published in major journals and possibly even legitimately world renowned.

I’m not holding my breath, but my mind can be changed.

UPDATE (7/3/2006): Engineers at Kettering University have yet to replicate the claims of Louis Lapointe.
UPDATE (1/3/2007): Mythbusters was unable to validate claims that acetone will increase your fuel mileage.
UPDATE (1/21/2007): Acetone probably can’t improve the surface tension of gasoline.
UPDATE (1/21/2007): Oil companies make most acetone.

Note: This was the first in what became a series of posts about the purported benefits of adding acetone to gasoline. As such this is perhaps the least useful of all the posts I wrote. The most salient points are that only an extreme few are able able to get a 25+% increase in mileage and no one with any widespread credibility has been able to get significant improvements under laboratory conditions.

The original post continues below:

In a few instances, I have seen fark reference some work suggesting that adding small amounts of acetone to your fuel will increase your fuel mileage by up to 30%.

Today’s link goes to RealTechNews. That’s just the same information posted at PureEnergySystems. That information was written by a guy named Louis LaPointe. Both show the same graph, which is pretty non-descript. It’s the kind of graph that would earn you an F in most high school classes, let alone a college class with a professor like Leo Gaddis.

The links all use this same graph. It shows no data points. It does not tell us what kind of cars were used, although in one article it is explained that curve D is for a diesel engine. All the graph really tells me is that someone drew some pretty lines.

There really isn’t much methodology to be digested. Most of the information isn’t even brought close to your plate. The best you can get is that someone is adding acetone to their vehicles and basing the information off of runs done somewhere at 50 mph.

More links:
DIY Live
PureEnergySystems Wiki
FuelSaving.info

The DIY link is the same as the first 2 links but with less. The PES Wiki link involves numerous user testimonials, some good, some bad. It also took me to a link about calculating fuel mileage savings, which used an erroneous formula. (A hint: getting a 100% increase in mileage won’t reduce your fuel costs by 100%.)

There is some good information about being consistent while you test. But still, I don’t really trust individuals looking for results to give very good data. The article at fuelsaving.info is a counter to the pro-acetone group. I’m inclined to side with that article.

Here’s something that caught my eye:

Many products claiming to improve mileage are expensive and do not really help much. Others are fakes. For instance, a SMOOTH flow of air into a carburetor or injector is far better for mileage than turbulent air. Turbulence is bad. Yet many people deliberately introduce turbulent air into their engines. There are many silly myths floating around the car industry to fool the average person. Another is that cold intake air improves mileage. NO. Warm air improves mileage.

If I’m not mistaken, fluid flows much better under turbulence. Everyone from ship to airplane builders and golf ball designers know this. Per Parviz Moin and John Kim in the SEAS at UCLA:

In the cylinders of an internal-combustion engine, for example, turbulence enhances the mixing of fuel and oxidizer and produces cleaner, more efficient combustion.

Also, cold intake air, I believe should increase motor efficiency. The idea is that cold air is more dense. Thus each volume of intake air has a greater mass of oxygen. Oxygen, of course, is completely necessary for combustion of organic materials like gasoline. However, cold air will, due to its density, increase the air drag on a vehicle. So in real world conditions, there is a trade-off to be made.

So why should we trust Louis LaPointe?

FACTS. Absolute true facts. My Scan Gauge does not lie and neither do I. What data do these people show? Actual data. Actual test results.

Well his facts and test results aren’t that good. For example:

My 1995 Neon that is now 10 years old at 130,000 miles and runs with acetone all the time. It runs perfectly. Absolutely perfect. Just averaged 45 MPG IN TOWN last week. And just last weekend we averaged 50 to 73 MPG on a test run through Wisconsin with special mileage devices attached. Never had engine work.

50 to 73 MPG? That’s a huge variation. Is that for a whole trip? Is the 73 MPG just from that 1 mile where you tailgated an 18-wheeler? His FACTS, are pretty much anecdotal in my opinion.

Personally, I believe the guy is just try to sell the ScanGuage (Evan & Bear, you ought to offer to revamp their website). Damn near every link names this singular device and suggests that you should buy it to test your car.

Does acetone really work? I don’t have the guts to find out for myself. The risks of voiding a warranty, corroding my fuel system, or even spilling the acetone on my paint and ruining it are just too much for me to take.

If you are interested in improving your mileage, your best bet is still to be a good driver with a well maintained vehicle. Keep your tires inflated properly. Don’t run the AC. Keep your engine tuned. Don’t carry around unnecessary weight. Perhaps most importantly, accelerate and brake as slowly as possible. Gunning your engine and braking hard will probably do more to hurt your mileage than anything else. The key is to be gentle with the pedals. And remember, in this house, we obey the laws of thermodynamics!