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Basically, it is a very subjective matter to define a truth power or an
“ability” of car engines. It is very complicated because it relates to sooooo
many other factors. Here we are to conclude all of the factors.
What are some of the factors? It will be the engine torque, engine rpm, Time to
reach peak RPM, Fuel Consumption, Ability to have high peak power within wider
range of RPM, an external factors (car weight, transmission system, car
stability & aerodynamics, and too many external factors) and characteristic of
dyno performance chart.
Basic calculation is:
An engine produces POWER by providing a ROTATING SHAFT which can exert a given
amount of TORQUE on a load at a given RPM. The amount of TORQUE the engine can
exert usually varies with RPM.
HP = Torque x RPM ÷ 5252
If you dont want to know the details about the 5252, it’s ok and it is
negligible. Because it involves a longer calculation to have that 5252. But the
amount is correct and the formula to calculate the horsepower also correct
specially for automotive sector.
What you see in the car manufacturers catalog regarding the HP and Torque is
actually a max output of the engine only. Means it is not calculated including
external factors. Which we called an “engine dynamometer test“.
To have a truth result, you can go to any dyno tester and make a “Chassis
Dynamometer test” to include all the external factors to determine true ability
of a car. Because some manufacturer claims they have a very high HP compare to
other car HP but if you test the car on track, they lose. Why? because of the
external factors and the different characteristic on their dyno performance
chart!
This may be lack of weight management or stability, lack of smoothness of gear
transmission, higher output resistance such as higher drag or tyre friction etc.
This is all depends on the overall technologies of a car to be compatible with
each other’s main factors. Not the engine output only!
If you have a car with slightly lower HP, don’t worry. Your car characteristic
might be different. If your torque or HP is at low RPM, it is very good for fuel
economy. Means you did not have to push further to reach peak HP.
But if you have a car with higher HP, don’t be too happy. Because you may want
to watch your peak RPM and torque because HP really depends on them (HP = Torque
x RPM ÷ 5252). If you have higher HP at higher RPM, you need to check whether
you have shorter time to reach that RPM while other car that has slightly lower
HP at lower RPM already reach it’s high peak and smoked you on the track on
certain speed.
But if you are able to reach high RPM faster, then you are the man! Thats what
makes VTEC, VVTI and other variable valve timing so special. They allow for fuel
to be burned more to helps you reach higher RPM faster. This will make you have
wider RPM range for peak power. And this technologies makes your car fuel
consumption more over a specified RPM to activate this stuff. Don’t complain if
your car fuel consumption have an obvious wide range of lower and higher
consumption.
But again, its all depends on the characteristic of a car on a dyno performance
chart. A car may be driven slower 0-100kmh but they perform well over 100kmh or
vice versa. Depends on settings of engine. This makes the engine tuner an
important person for you to reach your target. To be a drag racer 0-100, top
speed racer, or a fuel efficient car driver.
If your car is designed to be driven in a city and less fuel consumption, then
high torque at low RPM is better. But if your car is designed to race, then high
torque at higher RPM is better because it generates more horsepower again with
the formula that moves you further in a faster time. If your car is designed to
have both, then the VVT (variavle valve timing) is better for you to set your
driving style. But in case of VVT, you will have lower hp at normal operating
engine. You can have higher hp only if you rev up your engine up to specific RPM
normally RPM 3000 and above.
Category:
Type: Ailments
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