New Car, More ethanol data

[treekiller]

Car 1991 Volvo 940 Turbo.
Boost Controler set for 7PSI
Controlled Speed over varing terain and temparure.

1100 miles so far.

1st tamk 15 Gallons E10 87 Tampa $2.83 21.3 MPG @$2.83 $.132/mile

2nd Tank 15 Gallons 87 Gasoline South of Savannah GA (part tank no mileage recorded but 22 is est.) @$2.66 $.12/mile

-------------Begin ethanol recording---------------

3rd Tank Topped off with 6.4 gallons of E85 (15 Gallopn Tank) ~35% Ethanol blend Mileage Decreased to 18.5 MPG $2.33/gal .868 yeild.

8.6 gallons E0 @ 2.66 22.876
6.4 Gallons E85 @ 2.33 14.912

Cost per gallon $2.52 per gallon $.136/Mile
-------------end---------------------------------

35% in the tank if I follow my old Data should have yeilded 9.45% or a 2.01 reduction in MPG (2.7% reduction per 10% blend) I went from 21.3 to 18.5 which is actually a 13% reduction in mileage for a 6% cost reduction.. the 35% blend does not work unless there is almost a full dollar difference in price. and from 2.66 to 2.33 it was a net loss.

Honestly I felt with a turbocharger the engine would be better capable of using the cooling effect and octane of enhanced ethanol blends but apparently the 20 year old computer is just not powerful enough to match my previous returns.

test 1 Ethanol 35% FAILURE

Net cost increase. and 3.7% decrease in mileage per 10% ethanol..

[treekiller]

Repeated test 4 more times with varying ethanol percentages. and got from 16-18 MPG. pretty much across the board. Not enough positive data.. but I can tell you the 1991 computer is smart enough to compensate and not pop a CEL, but it does not run as efficiently as a more powerful computerized newer car.

In South Carolina using a 70% ethanol mix cost effective at $2.30 a gallon + $2.85 regular. even with the 4 mpg loss.

[SixCylinders]

Not surprising at all. The energy content of ethanol is less than gasoline. Ethanol is more knock resistant (octane).

When doing these "tests" (the information is already out there if you just google for it) you have to keep in mind that your engine is made for gas. If you want to take advantage of the ethanol you need to make sure the car is tuned for it (ignition timing, air:fuel, compression, etc)

[treekiller]

oh yea I've been following the buick Regal turbo that actually makes more horsepower on ethanol and the economy is similar to gas.. it's the most powerful ECU in any passenger car so i'll dig it. b

[SixCylinders]

Well you can make more power on ethanol but I highly doubt that you'll make "similar" economy at the same time.

Ethanol contains 76,000btus per gallon
Mid-grade gasoline contains 125,000btus per gallon

Running a similar tune will therefore (theoretically) give you 60% of the fuel economy on ethanol that it would on straight gas

Now where ethanol retrofitting is useful is turbo cars running more than 12lbs of boost (in my opinion) because at that point (depending on the car) it's usually getting close to the limits. The conversion is not for saving money....unless E85 is $1.50 and gas is like $2.50.