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.