Biodiesel as gasoline additive
 

Before ethanol for fuel leaves the plant a small amount (around 2%) of gasoline is added to denature it. In a paper comparing the economy of various ethanol blends, an E10 that didn't use gasoline as a denaturant was also tested. Instead, it was denatured with iso-butane and biodiesel. In the test, the cars got the same or slightly better fuel economy than straight gas.

Now, I can't get a hold of iso-butane, but biodiesel is pretty straight forward to make.
https://biodiesel.infopop.cc/6/ubb.x?a=tpc&s=447609751&f=719605551&m=857600061

I figure the final concentration of a denaturant at the pump to be around 0.2%. That makes the initial amount of biodiesel to add about 125mL or 4oz to the HHR's 16.5gal tank. I'll add around 60 to 100 mL with each fill up after that. If it has an affect, I don't think a precise concentration will be critical for it to happen.

Biodiesel mixes with gasoline, but I'm mixing it with mineral spirits first. This will thin the biodiesel out, but mainly I'm doing it for use as a carrier. To leave less biodiesel behind in the bottle.

Since A-B-A testing isn't practical with additive testing, I'll post some tank averages for comparison.

The last three fills: 31.11mpg
2010 Oct and Nov: 30.88mpg
2009 Oct and Nov: 31.79mpg

I did not include any of the road trip tanks from those times.
I currently have the stock air intake in place. For at least part of the 2009 2010 averages, I had the warm air intake and engine bay insulation installed. Unless the temperatures take a deep dive, I'll stay with stock.
The HHR got new spark plugs at the beginning of the last tank, and an oil change at the end of it.

That's about it. I'll try reporting the daily trip economies from the scangauge, but hard numbers won't be had until I fill up, which is about every 7 to 10 days.

Re: Biodiesel as gasoline additive
 

I'm subscribed. I used to toy around with biodiesel a bit. I wonder what the science behind it is? I mean, I know that bio higher btu's per unit, which is why diesels get better FE for the amount of weight they move (not to mention turbos). How much does it cost to make a gallon of bio (or are you buying the commercial product?) plus the cost of your thinner?
B

Re: Biodiesel as gasoline additive
 

At .2%, the BTU content is a non-issue, so there'd definitely need to be some other scientific explanation if there was a true FE increase.

I'll be interested to see how this experiment works out.

Re: Biodiesel as gasoline additive
 

Oops, I should have rechecked the paper before posting. The other ingredient is isopentane.
https://www.ethanol.org/pdf/contentmg...yStudy_001.pdf
The RVP is the measure of the gasoline's volatility, and what makes summer blend different from winter blends. This additive might increase starting difficulties for carbuerated vehicles during the winter. However, most of the testing in the paper was done at below 60F.

The only thing to report on the test is that I notice fuel consumption increase during the neutral coasts at 30 to 45 minutes into the trip. The idle consumption drops by a tenth of gph according the scangauge. I'm guessing the fuel in the tank or engine bay has been warmed up to some critical point for the biodiesel. Since I've never seen this behavior before. Fuel injector cleaners have given a slight boost to economy in the past, but never the 200 to 300 insantaneous mpg at 60mph I saw. Can't rule out an error in the sensor readings or scangauge calibration at this point.

PS: Is there a limited time frame in which to edit posts.

Re: Biodiesel as gasoline additive
 

Yes, there is a time limit for editing posts.

Re: Biodiesel as gasoline additive
 

Can you clarify this part. Sorry I don't understand???:o

Re: Biodiesel as gasoline additive
 

One of the read outs I have set on the scangauge is for instant mpg. When I go into neutral for a coast at 60mph, the display goes from around 30mpg to 200mpg. With the biodiesel, and after a certain amount of time into the trip, that 200mpg will be at 300mpg instead.

Re: Biodiesel as gasoline additive
 

Got 33.3mpg on the trip into work this morning. Not my highest, but not bad considering I didn't use EOC or FAS, and the highest temp was 51F during the drive.

Re: Biodiesel as gasoline additive
 

First tank is 31.10mpg.

It includes a day with heavy traffic from accidents.

Re: Biodiesel as gasoline additive
 

What kind of driving is that? Lengths at what speed I mean. Amount or type of slopes you might encounter would be useful too. Also, please to post the average or a selection of daily temperatures for each tank too.

I am very interested in your results.

Re: Biodiesel as gasoline additive
 

I'm about an hour north of Philadelphia and work right outside it. The commute is a little over 30 miles one way. Except for the little bit of surface streets at the beginning and end, I'm on a 4 lane highway, route 309. It's roughly split into thirds along my trip.

The first going in to work is expressway with rolling hills. My home is at a higher elevation than work. By the one GPS it might be has much as 500ft, but this GPS once said I was below sea level at the beach. What ever it is, most of the change occurs along this stretch with 2 big, steep hills. I do EOC down these hills in general practice. With the colder mornings and headlights on at night, I decided to be kind to the new battery and haven't been during the test. I do neutral coast them, and pulse and coast between 50 and 60 mph on the express way sections.

The second section is a business district, with lights and heavier traffic. Speed drops to 35 to 45 here. I coast when I can, and try to time lights. I might FAS at the railroad crossing and one long light, but It's not as long as during summer as battery voltage drops quicker.

The final section is expressway again. Still rolling hills, but without any major individual slopes.

Recently, temperatures were around 50F in the morning and around 60 on the trip home. It's going to be dropping. I had wanted to start this experiment sooner, but had some problems with my first batch of biodiesel. After the current tank, I think I'll try the insulation and WAI with the biodiesel. Then I'll do some tanks without the biodiesel.

Re: Biodiesel as gasoline additive
 

Finished with 30.1mpg yesterday. Had plenty of rain and temperatures dropped. Got 32.4mpg in 35F temps this morning. It looks like the near 60s weather is gone for the year. I might actually be shoveling snow this Sat.

Re: Biodiesel as gasoline additive
 

The latest tank came in at 30.22mpg.

For most of the past week the temperatures were at or near freezing for my morning commute. It would have been another week before I saw such temps in previous years. Despite being uphill, my commute home in milder temps returns a higher trip economy now.

I removed the tube between airbox and fender wall, and put some insulation in the engine bay. I'll get the tube shield in that intakes above the exhaust, behind the engine, in place this weekend. In absolute terms, this WAI setup doesn't help improve fuel economy for me, but it does speed up warm up and holds some warmth while parked. If I hadn't been trying to keep the tank conditions consistent, I'd have put it in place last weekend.

Re: Biodiesel as gasoline additive
 

Final tank with biodiesel came to 32.32mpg.
That's an average of 31.21mpg for those three tanks.

Slightly better than the previous tank average, but in the middle when compared to previous years.

The report claimed near or better fuel economy with alcohol free gas. So I think it's safe to say I had no improvement with my mix; 1:1 biodiesel to paint thinner with a final concentration of biodiesel of 0.2% to 0.3% in the tank. That is if my mileage doesn't plummet in the next couple of tanks.

I think I might try going up to a 0.5% final concentration. I don't think going would be a problem, it's just any more and it starts getting impractical for me to make enough biodiesel in these tiny batches. Another consideration is that with more added, energy content of the biodiesel might be factor. If so, for most of us, it would be more practical to try experimenting with ultra low sulfur diesel.

Of course, the isopentane might be the key. I'm going to look into other ready available solvents to use in place of the paint thinner while doing 2 to 3 biodiesel free(I'll keep adding the paint thinner) tanks. Any suggestions?

Re: Biodiesel as gasoline additive
 

If I remember correctly, toluene and xylene (available at home depot in gallon cans) are what refiners use to adjust octane rating and are used for DIY octane boosting; regardless of octane, they would therefore be safe solvents to use. Also, people have posted on this site about using acetone.

For your biodiesel, why not buy some instead of making it or buying ULSD?

Re: Biodiesel as gasoline additive
 

I checked for nearby sources of biodiesel before starting off. The only available stuff was blends which may or may not be heating oil. If it seems to be the btu content is the factor, I'm willing to try ULSD. Heating oil had a magnitude more sulfur than the old road diesel. I don't think it would be good for the cat.

It may be an issue of too much biodiesel though. There was still over a quarter of tank left when filled up with just gas and a little paint thinner. The little driving I have done so far is staying above 32 mpg.

Re: Biodiesel as gasoline additive
 

First tank without adding biodiesel came to 31.85mpg.
There was some leftover biodiesel, but more importantly, the weather has been pleasant here for the last week. Highs around 60 with my morning commute at the mid 40's to 50.

Re: Biodiesel as gasoline additive
 

It's been awhile. I had an issue that may of had an affect on the previous testing. Still had some biodiesel left, so I'm taking another try at it.

Since a bottle of injection cleaner is usually 12oz., I'm sticking with 10oz. total of additive. It will be 5oz(150mL) of the biodiesel and the rest the solvent.

The three previous tanks were 30.98, 30.86, and 31.47 mpg with an average of 31.1mpg. In first tank with additive, the biodiesel was mixed with the paint thinner, and the mpg was 30.37.

I'm now using acetone instead of the the paint thinner. Of the readily available solvents, it has the lowest density and boiling point, and thus closest to isopentane. The tank with the acetone/biodiesel mix returned 31.56mpg.

Re: Biodiesel as gasoline additive
 

The three tanks with a biodiesel mix were 30.37, 31.56, and 33.27. The first tank without is 32.93. Still might be some residue biodiesel there. So we'll have to wait for the next to call it, but with the effort of making the biodiesel, it is looking like how I'm doing it isn't worth the work.

The mild winter, with some spring like days, didn't help in controlling the temperature variable. So it might be worth revisiting. Without knowing the specifics of the mix in the paper though, it will still be a lot of guess work.

Based on some rough calculations, it'll take 1 to 2 quarts of biodiesel or diesel in 10 gallons of e10 to raise the btu content to straight gas. At that concentration, diesels might effect viscosity. They will lower the octane.

Re: Biodiesel as gasoline additive
 

At those concentrations I would be concerned with the possibility of oil fouling the plugs, O2 sensor, and the Cat converter over the long term.

Re: Biodiesel as gasoline additive
 

I was going to look at the procedure for making bio diesel but the link is no longer active. Could you post it?

Re: Biodiesel as gasoline additive
 

https://biodiesel.infopop.cc/6/ubb.x?...51&m=857600061

That's a procedure for making small batches of around a liter. If you are looking to make more, it is a bit wasteful on the reagents.

Re: Biodiesel as gasoline additive
 

Thanks for the link.