“Weight and Power (Continued)”
AS we said in our previous article, power and weight are related, in order to increase power, think about shedding as much useless weight as you can. Have you ever considered the option of avoiding giving lifts? It is stunning that, many people reason that, “even if I drive the vehicle empty, I will burn the same fuel”, far from the truth. The heavier your vehicle gets, the more fuel it will consume because, it has to overcome more resistance as a result of the added weight. I will not indulge in the mathematics but the truth is, for every kilogram of weight added, there is an additional drag as a result.
If you load say three passengers in a car as opposed to a single occupant (the driver), you are likely to consume more fuel. Statistics show that, an addition of about 50kg could result in about 2% consumption, if you add four passengers with an average of 300kgs that could translate to 12% or more. Are these passengers paying for that additional cost or it is just a goodwill lift? For those that travel upcountry, the food stuff you load into that vehicle could end up being much more expensive than if you had bought them in the city!
Alternatively, in an ideal world, the engine in your car would do one thing - propel you forward. In real life of course it’s doing a lot more than that. It’s driving the alternator to charge your battery and in most cars now, it’s also driving the air conditioning compressor (when active). Both of these items increase the load on the engine. As a rough guide, every 25amps of load on the alternator equals 1hp of load on the engine, whilst running the A/C can typically sap 5% of the engine’s power.
So imagine you have a 150hp engine in a vehicle in the summer with the A/C on, running the radio and the seatback DVD player and LCDs for the ankle-biters. You’re dropping a couple of horsepower for the electronics in the vehicle (electric power steering, power seats, radio, LT circuit, lights etc) and 7½hp because you’re running the air conditioner. Your 150hp engine is now performing like a 140hp engine - you’ve lost a lot of power there. But what can you do? Well the most obvious thing is turn off the A/C. unless it’s genuinely hot outside, don’t use it.
For example, on a chilly day or night, when you’re warming the windows on a cold morning - don’t turn the a/c on - leave it off. Ok the air won’t be so dry but you’ll also not be sapping that power from your engine. After that you can look at separate charging and battery circuits for things like the radio or ICE install that only load the engine when they need to charge. Upgrade your alternator to a super lightweight item with professional grade ball bearings on the alternator shaft; this makes the alternator easier to turn and induces less drag on the alternator belt (fractionally).
The use of Turbos and superchargers, most people know that a turbo or supercharged engine is more powerful, but do you know why? In simple terms, they give more suck before the squeeze, bang and blow of your engine. The basic idea behind both devices is a turbine that sits in the intake airflow. As it spins, it physically sucks more air in than the normal induction of the engine and compresses it further down the line resulting once again in more air in the intake charge, which means better burn which means more power. Both devices are known by the common description of forced induction systems. The difference is the way the two devices are driven.