One of the most consistent theories in building engine power dictates that the more air you can force into your engine, the more power it will make. There are several ways to accomplish this. One is to allow the air rushing into the intake to build velocity by making its path as smooth and obstacle-free as possible. Another is to ingest cold, outside air rather than air that has been trapped under the hood and heated. The reason for this is that as a gas (air in this case) is heated, its molecules become more random and less dense. Therefore, you can fit more colder, dense air than heated, less dense air into the same area (in this case, a cylinder).
Think of it like this: When you blow up a balloon in a warm building, it’s full. Set it outside on a cold day, and it will shrink, because the air inside it becomes more dense. You can then fill that same balloon with a lot more cold, dense air. Your engine is no different.
Yet another way to fill the engine is to literally force cold, outside air with some type of a ram-air induction system. These are all simplified explanations, but they make the point. Superchargers and turbochargers are mechanical means of accomplishing this, while hood scoops and “ram air” systems are a more passive method.
If you’ve looked at the induction system of your Magnum lately, you might think that Detroit never knew these theories existed. The air cleaner assembly can hardly be described as power friendly! We borrowed a friend’s ’99 Durango and installed this functional fiberglass cold-air hood on it for aesthetics as well as function. Available from Keystone Automotive Restyling products in Toledo, Ohio, the hood is available as either an aesthetic bolt on (closed “nostrils” on the scoop), or with functional air inlets and an air cleaner adapter to allow cold, outside air to be fed into the engine. And as we know, that means more power. The choice for us was easy.
One of the things that sets Keystone’s Good Hood™ line-up apart from other aftermarket offerings is that it features two-piece construction consisting of an inner skin and outer skin that are bonded together, creating a very strong component. Additionally, all mounting hardware is sandwiched between the two halves before they are bonded, allowing the use of factory mounting points that won’t strip or pull out. Finally, the two-piece construction allows for a finished underside, meaning there is no “raw” fiberglass visible, unlike the fiberglass hoods of yesterday. Due to the beefy construction of these hoods, they aren’t light, so you aren’t going to realize any performance gains from lightening the front of the vehicle. However, the looks are unrivaled, and it will last. We definitely don’t mind the weight.
One thing that doesn’t come with the hood and adapter is the actual air filter element itself. A complete assembly from K&N is recommended, but when we ordered it, we asked for the wrong one. The one we ordered had a four-inch tall filter, which interfered with the cowl—a two inch tall, 14-inch diameter filter is required, so we made a trip to the auto parts store due to deadline constraints, rather than waiting for the proper K&N unit to arrive. We’ve seen K&N units make more power on the dyno, so one will be going on in place of the white paper element shown. Another addition will be K&N’s Extreme air filter lid, which is actually a flat, round filter with a flange around the outer perimeter that replaces the conventional steel lid. It not only allows more air in, but it lets it go through the top and straight into the intake, rather than making the bends from the sides like a conventional air cleaner. It’s tailor-made for hood scoops!