This is a long way around to the answer for your question, Steve, but all oxygen sensors operate on the lambda principle. Plus, according to Innovate Motorsports' engineer Klaus Allmendinger, the Bosch wide-band air/fuel sensors are fully capable of reading E85, gasoline, or any mix of ethanol and gasoline. If you read the two dyno-test stories we did on E85, you know we must use roughly 30 percent more E85 than straight gasoline to compensate for ethanol's lower Btu rating. While lambda for the stoichiometric ratio for E85 is still 1.0 for this fuel, to put it in perspective, this is an air/fuel ratio of 9.7:1. For max power, E85's lambda number is between 0.72 (rich best power) and 0.85 (lean best power).
To run E85 in closed-loop, you still must adjust your fuel map to increase the injector pulse width to compensate for the lower Btu heat output of the fuel. Once your base fuel map is compensated, the narrow-band oxygen sensor should be able to adjust the air/fuel ratio to a lambda 1.0 reading. The closer your map is to true lambda, the more efficiently the oxygen sensor will adjust to the proper air/fuel ratio.
This also assumes your injectors are large enough to deliver sufficient fuel. As an example, let's say at wide-open throttle (WOT) your engine is making 450 hp and your engine uses 210 lb/hr of gasoline. Let's also assume your engine is equipped with 36-lb/hr injectors. These injectors are capable of 288 lb/hr of fuel at 100 percent duty cycle (36 x 8 = 288). At an 80 percent duty cycle, the injectors are capable of safely delivering 230 lb/hr of fuel. To use E85, for the same power, the fuel delivery to the engine must increase by 30 percent. This means the engine will need roughly 273 lb/hr of fuel (210 x 1.3 = 273). It also means increasing the fuel-injector size enough to increase fuel flow. A set of 44 lb/hr injectors would fulfill this requirement at an 80 percent duty cycle (44 x 8 = 352 x 0.80 = 281 lb/hr) to produce sufficient fuel-delivery capacity. There are other shortcuts, such as operating the injectors closer to 90 percent duty cycle, which would lower the required injector size down to 40 lb/hr. You can also raise the fuel pressure from the standard 43 psi to 55 psi, which increases fuel delivery by 13 percent. Regardless of which way you go, you will probably have to increase injector capacity to run E85 with your EFI system.
According to Edelbrock's tech information, your Pro-Flo system uses 29 lb/hr injectors but is designed to handle up to as much as 480 hp on gasoline. If your engine is making more than 400 hp, you will probably have to increase the size of the injector up to around 36 lb/hr. Otherwise, the system is designed to handle the part-throttle operation assuming your system has been tuned to deliver the proper amount of fuel. This means going into the global fuel map and increasing the injector pulse width to compensate for the ethanol-based E85 fuel. Once that has been done, your system will operate just as it does on gasoline, but with the advantages of the higher-octane, E85 fuel.
More InfoEdelbrock; Torrance, CA; 800/416-8628;
edelbrock.com
Forged pistons, like this Federal-Mogul, are also a definite suggestion for any nitrous engine. Cast pistons are very brittle, and when subjected to high nitrous loads, these pistons can snap off a ring land very easily, with even a trace of detonation. We know. We've done it-more than once.
Nitrous vs. Blowers
Thomas Shane Taylor, via CarCraft.com: I have a couple of questions to ask about the engine from the June '06 issue ("445 HP for $3,995"). I want to build a similar but different version. I want to use nitrous. What would be the best pistons to use? What's the best combo to use? Which system would be best for the application? What kind of horsepower do you think I could get out of this motor with spray? I'm planning on bolting it into a Malibu Classic station wagon with a strong Turbo 350, but then what stall would be best? I think this would make for a pretty quick and cool grocery getter. Thanks for everything, and keep up the good work on the mag, it's great.
Jeff Smith: The story you're referring to is the original budget blower motor, where we bolted a Weiand 142 miniblower on a cast-piston 350 short-block with a set of unported Vortec iron heads. On pump gas, this motor made 455 lb-ft of torque at 3,800 rpm and 445 hp at 6,000. This package also used a Crane PowerMax 288 cam (226/234 degrees duration at 0.050-inch tappet lift with 0.488/0.473-inch lift) using 1.6:1 Crane rockers.