Increasing Horsepower


Get More Horsepower and See the Results

Mr. Norm’s Grand Spaulding Dodge was one of the first new car dealerships to install a dynamometer in its service department.  (For more about the dynamometer see last week’s Horesepower – What is it?) Mr. Norm’s customers received a free performance tune-up that could take a factory 383 ci engine that produces 180 horsepower and turn it into and engine making a reliable 325 horsepower.  Artists often say that no piece is ever finished, only abandoned. Many muscle car enthusiasts probably feel the same way, because the mechanical upgrades didn’t necessarily end with Mr. Norm’s mechanics. Muscle cars would spend the week on the track, getting tuned and tweaked, and then returned to Mr. Norm’s dynamometer to see the results of all the tinkering. Getting more out of an engine is a tale as old as engines themselves, but the dynamometer meant the engine could be easily tested and the results measured to an exact figure. Muscle car culture owes a lot to that fact.

See this video by Jive Hive Jeff’s Café of a Legend X Challenger on the dynamometer at Mr. Norm’s Garage:

Engines can be tweaked and rebuilt to the owner’s specifications, and more than one muscle car mechanic has chased even minor improvements in horsepower by fiddling with the engine components. Some mechanics make a career out of it, straining for every last bit of power to get their cars across a finish before the competition.

Increasing horsepower means you’re trying to do one or more of the following:

1. Increase fuel  consumption (by adding air to the combustion chamber)
2. Increase engine efficiency (by increasing the compression ratio or reducing friction in the engine)
3. Increase engine RPMs
4. Reduce inertial forces

Another equation to determine horsepower is:
Horsepower = (Torque x RPM)/5,252

Here’s some of the common ways horsepower can be increased:

Cold Air Intake
Cold air is more dense and more air means more combustion power. By taking in cooler air, more oxygen can be pumped into the engine in the same amount of time. Modifying the air intake (assuming the existing one is a limiting factor) has the potential to increase horsepower.

Blowers manipulate the pressure differential of the air flowing into the engine. Finding an optimal and efficient boost level in the airflow can help the engine to reach its maximum potential. Larger blowers can produce the same boost level and airflow as smaller blowers, yet do so while spinning slower and requiring less engine power to operate.

Camshaft Swap
High lift, high duration and high RPMs all contribute to horsepower. A performance camshaft can manipulate lift and duration in the valvetrain to increase airflow into the engine. With more airflow, you can increase the RPMs if the engine is strong enough.

Exhaust Modifications
Upgrading the air intake of the engine with the methods above means that the stock exhaust may not be able to handle the extra airflow, increasing back pressure on the engine. Improving the efficiency of the exhaust removal can increase performance by the reduction of that back pressure.  The most common way to accomplish this is with a catback exhaust.

These are just a few ways that horsepower can be increased, but you should be getting an idea of what concepts are being manipulated to get more out of a performance car. The best way to increase horsepower can vary greatly based on what other equipment is present in the vehicle, creating a “give and take” relationship between components in the same vehicle. Playing with these elements is part of a culture that’s as old as engineering itself.


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