E85 Ethanol Fuel Test - The E85 Solution

E85's increased volume requirement demanded we drill the secondary power valve channel restrictor from 0.070 inch to 0.080 inch to supply sufficient fuel to the engine. This equates to a 30 percent increase in flow area.

E85's increased volume requirement demanded we drill the secondary power valve channel res

The only real changes we made to the Quick Fuel 850 annular-discharge carburetor to use the E85 fuel was to swap in the Quick Fuel E85 metering blocks and change the high-speed air bleeds on top of the carburetor. We knew going in that E85 would demand a bunch more fuel, and that's exactly what transpired. The jetting combination actually knocked on the door of 100 secondary jets, and that's after we had already added a power valve to the secondary side that was not used on gasoline. With 99 rear jets, we decided to drill out the power valve channel restrictors in the secondary metering block from 0.070 to 0.080 inch in diameter to give us some jetting room.

In discussing this change with Quick Fuel, we were told the problem was likely a restriction after the main well, perhaps in the drilled passage leading to the annular boosters. Increasing the size of this passage would ultimately reduce our overall jetting requirements.

The following chart illustrates the massive increase in fuel-flow area required when running E85. Despite these changes, this did not require a dedicated methanol-style carburetor. All we did was mildly modify both metering blocks. Otherwise, this was a typical Quick Fuel Technology gasoline 850-cfm carburetor. As an example, just changing from a 72 to an 80 primary jet is a jet area increase of 39 percent.

As you can see from the horsepower chart, the E85 surprised us with a sizeable midrange power increase over the race-gas blend that Quick Fuel claims is typical for an ethanol or methanol type of blend.

E85's greater fuel-volume demand will also place a greater load on fuel pumps. This small Mallory 140 pump did a great job. Mallory also makes a 140 A pump for straight alcohol.

E85's greater fuel-volume demand will also place a greater load on fuel pumps. This small

We also noticed that once we increased the E85 fuel flow sufficiently to make the engine happy, it seemed like the engine was much less sensitive to small changes in fuel flow. Duttweiler said this is also typical of a methanol engine. Generally, a gasoline engine will respond to a jet change of two jet sizes, but once the fuel flow was close, it seemed the E85 package was more forgiving and less touchy in terms of power gained or lost. We did not get into timing requirements with E85 because of time constraints. Total timing was maintained at 34 degrees.

Overall, the test was successful, and it's clear E85 has earned a high-octane place in the performance-fuel market. There are still several issues that are as yet unclear in terms of how well gasoline fuel delivery systems will react regarding long-term use of E85. Our research on the subject has uncovered conflicting information. We spoke to a couple of fuel-pump companies, and they claimed their pumps should not have a problem with E85, since ethanol is not nearly as corrosive as methanol. More experience over a longer period of time will dictate any extended-use limitations with E85, but the future for an alternative fuel that can make big power is certainly bright. And now you can let those tree-huggers know they're not the only ones using yellow to go green.

Click here for the E85 fuel test dyno chart

By Jeff Smith

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