Friday, August 10, 2007

How to Get More Engine Power & Better Performance

There are lots of different ways to make an engine perform better. The better an engine performs, the more power it delivers. We’re constantly asked by customers how they can best increase horsepower and performance. Playing with the many variables to make an engine more powerful can be a daunting task. There is a lot of information to disseminate, and many theories and “favorites” to consider. Cost and fuel efficiency are big considerations. And, the biggest question of all…where to start.

First, let’s look at some of the tried-and-true methods of getting more power. We’ll start with the engine itself. If you’re considering beefing up your vehicle with performance horsepower, we highly recommend that you get help from experts such as a quality performance or machine shop. They not only have the level of expertise needed, but the professional equipment you’ll need to get the job done right. A machine shop can help you with an existing engine, or in the design of a new engine (often including engine balancing and blueprinting) for your vehicle. You’ll need to discuss what your goals are for horsepower, as well as your intended use so that they can get the right match for you. We'll discuss this more in the next article.

An alternative to a performance or machine shop is to go with a performance crate motor, available from Chevy, Ford and Dodge. Turnkey motors are affordable and come complete with everything you need, including hot cams, big heads (usually aluminum) and beefy intake manifold. Turnkey crate motors are designed to simply drop in, hook up and go. A great alternative if you don't currently have an engine.

Increase your Compression Ratio - Higher air/fuel compression ratios produce more power. However, the more you compress, the more likely it is to spontaneously combust before the spark plug ignites it. This is why high-performance vehicles (with engines that use higher compression ratios to get more power) need higher octane gasoline. Octane prevents early combustion.

Increase Displacement – Simply put, more displacement gives you more power because you are able to burn more gas during each revolution of the engine. Making the cylinders bigger or adding more cylinders increases displacement. This is why an 8 cylinder engine creates more power than a 6 or 4 cylinder engine.

Stuff your Cylinders - Cram more air/fuel into a cylinder and you’ll get more power (in the same way as increasing the size of the cylinders as we described above). This is one reason enthusiasts have turned to turbochargers and superchargers, which pressurize the incoming air. When the incoming air is pressurized, it literally stuffs more air into each cylinder.

Cool your Incoming Air – Your goal is to have the coolest air possible in your cylinders. The hotter the air, the less it will expand when combustion takes place and the less power created. Compressing air raises its temperature. The higher your compression ratio, the more you’ll need to cool your air. If you turbocharge or supercharge your vehicle, you’ll need a special radiator (called an intercooler) which the compressed air passes through to cool it off before it enters the cylinder.

Let your Engine take a Deep Breath – Air resistance robs power from the engine. It keeps your engine from taking a nice deep breath. It would be like an asthmatic person trying to suck in a deep breath while their throat is tight and restricted. Your engine is trying to take a deep breath as the piston moves down during the intake stroke. Air resistance can be lessened dramatically by using polished intake manifolds to eliminate air resistance there, by putting two intake valves in each cylinder, or by using bigger air filters, ram air and many other systems that are specifically designed to improve air flow.

Let your Engine Exhale Easily – Now imagine what it’s like to take in a really big breath and having your mouth and nose covered. It would be very difficult to exhale. Just as we need maximum air into the engine, we need an effective way for it to leave the engine. If air resistance makes it hard for the exhaust to exit a cylinder, it robs power from your engine. If your exhaust pipe is too small or your muffler has a lot of air resistance, it can cause back-pressure. High-performance exhaust systems use headers, big tail pipes and free-flowing mufflers to eliminate back-pressure in the exhaust system. Dual exhaust improves flow by having two exhaust pipes instead of one. Adding a second exhaust valve to each cylinder improves performance as well (a car with two intake and two exhaust valves has four valves per cylinder).

Make Everything Lighter - Lightweight parts help the engine perform better. Each time a piston changes direction, it uses energy to stop the travel in one direction and reverse it to the other direction. The lighter the piston, the less energy it takes. Aluminum heads and other lightweight components, although expensive, can give you added power and performance.
Ok, now that we’ve covered the basics, where do we start? A common misconception is that one would start at the beginning (the front), and work our way back. This, however, will give you problems if you are doing an upgrade in stages.

Imagine upgrading your intake system so that your engine can now breathe freely. Perhaps you’ve even upgraded the engine a bit, adding a bigger cam and increasing your compression ratios! (Wow, your thinking, I’m really doing great!) Things are going well until your engine tries to exhale. All the exhaust becomes bottled up at the rear end and all your power gains are out the window because it has nowhere to go. This is why we begin at the end (the rear) and work our way forward!

You’ll get the best bang for your buck if you start at your exhaust system and work your way forward to the intake. Do yourself a favor a resist the urge to do the work which will give you the dazzle you desire (who wouldn’t like that shiny new dual quad performance intake manifold), but won’t do a thing for improving power or performance. If you’re not sure where to begin, seek advice from a professional shop. Motorheads Performance specializes in performance upgrades for street or strip.

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