From a performance standpoint, the next obvious questions are: will E-85 cut the mustard in terms of performance, and how difficult is the changeover? The answers are: yes, it is a great high-performance fuel, and the changeover is pretty straightforward. So if you are struggling with today's pump premium in your street car, or interested in a lower cost race fuel, or even contemplating adding forced induction to your higher compression ride, read on.
We wanted to know what happens if we take a car that we are driving today-one that is working just fine on readily available 91-octane-and change it over to run on E-85.
We set the '73 Charger up with two complete fuel systems for our test so we could rapidly
For the gasoline fuel system, we used a Magna Fuel ProTuner 625 fuel pump and dash 8 fuel
By adding a completely separate fuel system, testing with our supercharged 440 was as easy
To find the answer, we took The Supercharger Store's test mule-a '73 Dodge Charger with an F-1 Procharger mounted on a 440-and added a complete second fuel system. This allowed us to make rapid changeovers and do back-to-back testing with two different fuels. This particular Charger also has some useful instrumentation onboard, which will be handy when we try to sort out what is going on as we change between the two fuels. We will measure intake temperatures above and below the carburetor, exhaust temperatures, and where differences occur.
We enlisted the help of Eddie and Ron at Performance Carburetors in Ontario, California, and Robbie at Magna Fuel in Colorado Springs, Colorado, to put together proper blow-through carbureted fuel systems for our tests. We were concerned about obtaining consistent results, and consistency at the strip is a tough game, so we also enlisted the services of Tim at Xact Dyno in Tempe, Arizona. Xact Dyno utilizes a Dynapack hydraulic chassis dyno. The Dynapack is unique in that it uses hydraulic load units that bolt directly to the axles. Obviously, there is no tire slip here. Also with the Dynapack, you can conduct steady-state pulls and a number of other tests that are not practical with roller chassis dynos.
Test day arrived, and it was a typical September afternoon in the Phoenix area: sunny and about 98 degrees Fahrenheit. While Tim bolted the Charger to the Dynapack, we checked to make sure the E-85 fuel system was ready to go. We made two quick pulls with E-85, and recorded rear wheel torque, rear wheel horsepower, lambda values (rich/lean), supercharger boost in the intake manifold, maximum air temperature above the carburetor, and maximum temperature of the fuel/air mix in the intake plenum. The two E-85 pulls felt strong, and we had a lot of data to study later, so we set about changing the fuel system over to 91-octane pump premium fuel. We made two quick pulls with pump premium, and again, they felt good. despite the fact we lost the lambda readings on one pull, we had the data we desired.
We were convinced the Charger would be running lean in Phoenix because the carburetors were jetted for 4,600 feet above sea level, and Xact Dyno is in Tempe, which is around 1,300 feet above sea level. We didn't take time to study the data we had just gathered, but immediately changed to larger jets, thereby making what turned out to be an already rich mixture even richer. We did this for both the E-85 carburetor and the 91-octane pump gas carburetor. Subsequent pulls for both fuels were not as good as the earlier pulls and, for all practical purposes, a waste of time.
By now we were out of dyno time, so we removed the Charger from the dyno and headed for home. We were later told by Eddie and Ron at Performance Carburetor that properly calibrated blow-through carburetors are not sensitive to altitude changes.