10 Things You Always Wanted to Know About Engines

This article is copied from the September 1999 issue of Hot Rod Magazine

By Ray T. Bohacz

    Here’s the old apples-and-oranges comparison. A port EFI system utilizes a dry-flow manifold that allows for more freedom of design than one that needs to carry both fuel and air. In theory, the electronic mapping of the fuel curve would appear to be the most accurate means of feeding the engine. But if the calibration is incorrect, many benefits of this design will never be realized.

    If emissions and feedback control are not an issue, the carburetor constitutes an excellent fuel-mixing device. It also enjoys the benefit of cooler charge air temperatures from the latent heat of vaporization that consumes heat from the intake manifold. The OEMs have embraced EFI for emissions and economy reasons, and these qualities are represented via intake manifolds designed with long-runner, torque biased characteristics. The problem arises when such a manifold design is asked to move large amounts of air very quickly. Since they don’t do this well, EFI has been labeled inferior to a carburetor, when it is really the intake manifold, not the theory that is the issue. As the enthusiast market embraces the microprocessor—tuning with a laptop instead of a screwdriver—this technology will allow engine output to reach new levels.