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Supercharging vs. Turbocharging
By: Jon Zenker Zank77@purehonda.com
For years there have been
debates over which form of forced air induction is the overall best.
Whether it's turbocharger, supercharger or nitrous oxide they all
greatly increase horsepower in small displacement engines. Which one
that is best for your car depends on how much money you want to spend
and what type of car you want to have.
For easy installation,
instant power, and low cost, nitrous gives you the most bang for the
buck! That would be the way to go if you wanted your car to be a drag
racer or an occasional mustang spanker at your local street corner. If
you want nitrous power everyday, this is where the turbocharger/supercharger
debate comes in.
For absolute peak power
where drivability, turbo-lag, emissions and long engine life is not an
issue, turbo is the way to go. With a properly designed turbocharger
system you have the ability to produce huge amounts of boost and horsepower
easily. The problem with all that boost is once the turbo spools, it
goes to full boost. There is no linear delivery of boost. If the turbo
spools at 3000 rpm, you have full boost at a valve speed that is very
low, so the turbo has a lot of time to create cylinder pressure on the
rods and piston because of the long duration that the valves are open.
This is what creates the huge rush of power when the turbo spools. This
is what also causes so many turbo engine failures. This is also combined
with the fact that the turbo sits roughly two inches from a 1300 degree
exhaust manifold. The charged air temperature is always high.
This leads to the rumor
that anything that is forced air inducted must be intercooled. The air
temperature of the intake of a turbocharger system is about 200 degrees,
even after it is intercooled. The intercooler drastically reduces intake
temperature, as long as there is a steady air flow over it. If your
doing a lot of starts and stops this diminishes the effect of the
intercooler. Once the air is cooled it must be re-routed back to the
intake manifold. This means it must come back to the engine compartment
and the tubing is reheated by the hot engine compartment. You have to
also fill all that tubing with boost, then when you shift the bypass
valve blows open, it empties the tubing, and then you have to refill the
tubing. This is the main cause of poor throttle response and classic
turbo lag in an intercooled turbocharged car. Then you have to stop and
once you stop you have to cool the turbo. The heat circulating from the
hot turbo is the enemy of your engine.
continued...
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