Month in, month out, you plunge all your hard-earned duckets into aftermarket accessories that, in theory, should make your car a bit quicker down the quarter mile.
As you're well aware, anything from an air intake to a turbo system for an import application will cost you an arm and a leg, so it's imperative you get the best bang-for-the-buck. But all too often, we hear stories or come across vehicles that are lit up with all sorts of power-proven products but aren't running as well as they should. More often than not, the problem lies with good, old, basic maintenance.
Think about it. You can upgrade your ignition to dish out more spark than a Fourth of July fireworks display, but if you're still running on the same plugs that came with the car three years ago, you can hardly expect to gain anything. The same applies to other bolt-on products such as air filters. How well can your high-flow filter actually flow when it's clogged thick with dirt? Not only do you lose potential performance, you also decrease the longevity of your engine over time.
Those of you who follow testing procedures no doubt have noticed that every vehicle we select as a test bed, we always establish a baseline run on the dyno before we begin the installation and testing. Of course, this allows us to evaluate power gains or losses once the product is installed, but it also allows us to assess whether or not the vehicle is running up-to-par beforehand. This is an important procedure that's often overlooked by entry-level enthusiasts. If you purchase your import ride brand-new, it's generally safe to assume the vehicle performs to its full potential. However, if you purchased a used vehicle--which is often the case--a basic maintenance overhaul is the first upgrade you should make.
If your vehicle is in desperate need of a thorough tune up, it could be as much as 20 hp down from the factory rating. A basic tune up consists of spark plugs, plug wires, cap and rotor, oil and filter, air filter, fuel filter, transmission fluid and checking the tire pressure. It'll cost well under $100 and is quite possibly the best bang-for-the-buck you'll ever get. Even if your newly revived powerplant doesn't exactly pin you in your seat at the touch of the throttle, at least you can be content in knowing that it's running up to its full potential and is ready for some serious bolt-on performance.
What happens after you modify your ride? When you add high-performance products and start to drive the car harder, basic maintenance becomes preventive maintenance. Regular and thorough maintenance should be on the top of your priority list once you've built a high-performance vehicle. Optimum running condition is imperative if you want your additional power to last.
Of course, the basics remain the same--regular oil changes, plugs, cap and rotor all need to be maintained and replaced when necessary. Aside from the visual inspection or scheduled maintenance, another worthwhile and informative procedure is a compression and leak down test.
A compression test will tell you whether or not the cylinders are performing equally at an optimum level. The compression tester is a gauge that fits into the spark plug thread, then, when you crank the engine over, the gauge will give you a reading. You repeat this process on each cylinder with the throttle wide open.
Unfortunately, there's no standard reading, as compression differs from engine to engine, but if your engine is in good shape, you should end up with a similar reading across all cylinders. If not, then something is probably amiss.
This is where the leak-down test comes into play. If you're familiar with using a leak-down tester, you can actually pinpoint where the problem lies. The leak-down test works similar to the compression test, only this time you begin at the number-one cylinder with the engine at top dead center (TDC).
For the leak-down test, the engine does not need to be cranked over. Instead, the leak-down tester pressurizes the cylinder and then measures the amount of cylinder pressure lost through worn piston rings.
Known as blow by, it can indicate a defective valvetrain or blown head gasket. This procedure is repeated across the cylinders, only this time, you test each cylinder in the engine firing order.
Also, a coolant pressure tester, which attaches to the radiator, will allow you to test the coolant system for leaks around any of the hoses, head gasket or radiator. If you don't have the necessary tools to perform these tests yourself, any automotive service center should be able to do it for no more than about $50.
Hopefully, we provided enough information and insight to enable you to take advantage of the horsepower gains available through the aftermarket, so use this advice to keep your ride running to its fullest.