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Acetone in your gas tank = more MPG???

Curb Hucker

I am an idiot
Feb 4, 2004
3,661
0
Sleeping in my Kenworth
This is take from a post in a land rover forum:
_____________________________________________
Well, damn GP, that's about the most coherent thought I've heard from you since you pulled the Jag tail lamps outta your ARB.

FWIW, I started an Acetone experiment a couple of months ago on the D2.

I'm running between 8-10oz per full tank (24gal), sometimes a little less acetone. Truck specs:
99D2, 88K miles, orig O2 sensors
PowerChip
STI plug leads
Bosch Plat (2)
Safari Snorkel
4.11 gears
3" RTE lift
285/75-16 on stock alloys
Warn 15K, RTE sliders/bumper, Greg Davis rear bumper, Engle and full pelican are always in the truck.

I'm an easy driver with the right foot and rarely exceed 75mph on the hwy.

NO ACETONE, country roads, town driving, pre-MAR:

264 miles/19.5 gal = 13.54mpg
292 miles/19.7 gal = 14.82mpg

This was around MAR and right about here, I put in new plugs and wires (Still no acetone):

322 miles/20.7 gal = 15.55mpg (about 85 miles here was hwy)
319 miles/19.9 gal = 16.03mpg (about 90% hwy miles here )

WITH ACETONE, 80% hwy / 20% city (Knoxville, TN)

348 miles/20.3 gal = 17.14mpg
369 miles/20.7 gal = 17.83mpg
358 miles/19.7 gal = 18.17mpg

I'm driving around 70mph on the hwy and I only use the cruise on the areas up here on 81 where it's flat. This was my second trip to Knoxville.

336 miles on 20.3 gal with a 15knot direct headwind down 81S running 75mph all the way
Back last night, last two tanks of the weekend:

311 miles/20.3 gal: ~15.32mpg, 90% city driving, NO Acetone ( I forgot to put it in)
375 miles/21.5 gal: ~17.44mpg, 85% hwy driving, 8oz Acetone, tried to keep it under 75mph.
334 miles/20.3 gal: ~16.5mpg, about 50/50 hwy/city (ran 75-80 on the hwy mostly)
_______________________________________________

Has anyone else put acetone in with their gas? It seemed to help this guy and a few others out quite a bit.
 

PatBranch

Turbo Monkey
Sep 24, 2004
10,460
8
wine country
Sounds crazy, but its working. Acetone is about 3/4 isopropyl. I read a while ago that its used in rocket fuel.

Thase are some good increases. I wonder how it affect performance (torque,acceleration,top speed, reliability?
 

BigMike

BrokenbikeMike
Jul 29, 2003
8,933
0
Montgomery county MD
I've heard of this also, but i'm scared to try it. If I had some old beater than maybe, but not in my pretty new (to me) Pathfinder :blah:


I've heard a lot of reasons it works, it has somthing to do with breaking the surface tension of the gasoline and using it all, instead of wasting some........ somthing like that
 

Toshi

Harbinger of Doom
Oct 23, 2001
27,757
2,293
i'd like to see a systematic study of this, not 3 tanks on uncontrolled roads with variable driving style (influenced by the "study" not being blind at all), weather (temperature!), fuel cutoff on the pump at the station...

i'd also like to see verification of this surface tension claim. fwiw a thread on nasioc (the subaru board) stated that gasoline already has negligible surface tension. from a handwavy perspective this seems plausible -- after all, why do you think gasoline fumes are so widespread at the pump if not for the volatility? (might be conflating unrelated concepts here, but i'll defer to the professional chemists :D)

the final thing i'd like to see is whether adding 2 or 12 oz of anything to a full tank has any effect at all beyond the placebo influence on driving style. :D
 

Curb Hucker

I am an idiot
Feb 4, 2004
3,661
0
Sleeping in my Kenworth
Toshi said:
the final thing i'd like to see is whether adding 2 or 12 oz of anything to a full tank has any effect at all beyond the placebo influence on driving style. :D

Well I can tell you one thing, there is NO way to pull 17-18mpg out of one regular tank of gas on one of these trucks no matter how you drive, trust me, I know :dead:
 

Toshi

Harbinger of Doom
Oct 23, 2001
27,757
2,293
there are still way too many variables. i bet temperature affects the auto cutoff on the gas pump, for instance...
 

MMike

A fowl peckerwood.
Sep 5, 2001
18,222
85
just sittin' here drinkin' scotch
Transcend said:
exactly. Acetone is far from cheap, is highly explosive (more so then gasoline) and works REALLY well to strip just about anything gunky off of anything shiny. :)
You may be onto something right there. Maybe the acetone just cleaned out the accumlated gunk in the fuel system!
 

Transcend

My Nuts Are Flat
Apr 18, 2002
18,045
0
Towing the party line.
MMike said:
You may be onto something right there. Maybe the acetone just cleaned out the accumlated gunk in the fuel system!
Ya that's a good point. Acetone is pretty nasty stuff. When it gets really cold out, i use it to light my woodstove. It burns hot enough to force all the cold out out of the chimney and I don't get smoke in the house.
 

Wumpus

makes avatars better
Dec 25, 2003
8,163
154
Six Shooter Junction
Toshi said:
after all, why do you think gasoline fumes are so widespread at the pump if not for the volatility? (might be conflating unrelated concepts here, but i'll defer to the professional chemists :D)

Water has high surface tension but evaporates readily.
 

urbaindk

The Real Dr. Science
Jul 12, 2004
4,821
0
Sleepy Hollar
Interesting. I'm a chemist (actually materials engineer but close enough). I was trying to look up some data to shoot this acetone idea down but didn't really find anything definitive against it.

From a chemical point of view acetone has some good properties. In gasoline (spark driven) engines we are looking for a high autoignition temperature and a low flash point. Basically you want the fuel to vaporize in the combustion chamber and not ignite before the spark plug fires.

Here are some numbers:

octane (not really gasoline but close enough)
Flash point: -45 C
autoignition temperature: 257 C
vapor pressure @ 25 C = 13.95 mm Hg

acetone
Flash = -18 C
autoignition = 538 C
vapor pressure @ 25 C = 229 mm Hg

Ok so based on these numbers, I've come up with the following conclusions.

Adding acetone should ignite similarly to gasoline. It wouldn't pre ignite due to it's high autoignition temperature and as such might limit knocking and pinging somewhat.

With its (very) high vapor pressure one might expect that it would vaporize more easily than gasoline which should make it burn more efficiently and evenly in the combustion chamber. I suspect that this effect would be negligible with modern fuel injector systems though.

Acetone would have a slightly lower fuel value (energy/mass) than gasoline. Its chemical formula contains some oxygen and as such is already in a slightly oxidized state from the get-go. (combustion = oxidation). This might cause horse power to suffer somewhat.

I suspect the main issue regarding its use as a fuel boils down to (no pun intended) its terribly high vapor pressure / volatility. It's just not safe to have a whole lot of it stored up in your gas tank.

Also not mentioned is that it is a damn fine solvent and would probably eat rubberized fuel lines over time.
 

rooftest

Monkey
Jul 10, 2005
612
0
OC, CA
jdschall said:
Acetone would have a slightly lower fuel value (energy/mass) than gasoline. Its chemical formula contains some oxygen and as such is already in a slightly oxidized state from the get-go. (combustion = oxidation). This might cause horse power to suffer somewhat.
Wouldn't using a less efficient fuel make your milage per gallon decrease?
 

urbaindk

The Real Dr. Science
Jul 12, 2004
4,821
0
Sleepy Hollar
Wumpus said:
20 cents per gallon

Wumpus is pretty much right. From what I understand it's a bunch of hooey.

Petrol engineers came up with a nifty way to compare fuels. You and me call it the octane rating system. Take your good old 87 octane gasoline. It is formulated with lots of various additives and other junk to run in a test engine like a mix of 87% 2,2,4 methylpentane (they call it octane and it has same chemical formula but different structure than octane) and 13% heptane.

2,2,4 methylpentane has very good running characteristics, no knocking, pinging or any of that. Heptane runs like absolute crap, knocks like crazy, etc.

Anyway. The petrol engineers come up with these formulations that match the running characteristics on their test engines and that's how we get octane ratings.

Now, comes along the auto engineers. They design really live put'em in your truck and drive around town engines (not test engines!!!) These folks being pretty smart people design their engines so that run optimally at 87 octane. No knocking no pinging, just smooth running engines.

So basically anything above 87 octane (unless your engine specifically requires it) is a waste of your money and may actually cause harm. Higher octane rated fuels tend to burn hotter and over time this can damage the engine.
 

justsomeguy

Monkey
Oct 3, 2005
723
0
jdschall said:
So basically anything above 87 octane (unless your engine specifically requires it) is a waste of your money and may actually cause harm. Higher octane rated fuels tend to burn hotter and over time this can damage the engine.
Some would argue that the premium blends can be beneficial due to superior detergent additives. Some would argue that the better detergent claim is marketing hooey.

Cars can still use gas with an ocrtane rating that is lower than the recommended rating but the ECU will retard timing and you'll be getting less power.

Re: Additives

In areas where high octane (93 or 100) fuel isn't available you can use an octane booster (no, not the crap found at auto parts stores, I'm referring to Toluene) to get to the desired octane. That is if you're willing to mess around with rubber gloves and be willing to be suspected of running a meth lab every time you buy it in quantity.