Why Are Superchargers So Rare?
[ September 24th, 2008 ] By: Mark Ozimek Posted in » Ramblings
One thing that I’ve noticed a lot is that rally cars seem to use turbochargers almost exclusively over their supercharger counterparts.
I have gone into detail on turbochargers in the past on how they work, and why they’re used to increase the amount of power an engine puts out. What is different about a supercharger? Well, both compress the intake air to increase power, but the supercharger’s compressor is driven mechanically (usually a belt off the crankshaft) instead of by the energy in the exhuast gas. So instead of reducing the efficiency of the engine by increasing exhaust pressure, energy is taken directly from the engine to increase power.
There are some plus sides to this, mainly no lag in waiting for the compressor to spin up. The compressor speed is directly related to the engine speed. This predictability makes design simpler, and the engine’s power response much more consistent.
However, ultimately a turbocharger setup can make more power with a similar amount of weight added to the car. The pressure increases non-linearly with engine speed, and can hit a high pressure before the supercharger would.
Each setup has it’s pros and cons, but to me, it seems like turbochargers are winning in popularity by a long shot. I know Charles and I both prefer turbochargers, and own turbocharged cars, mainly for the power efficiency and fun torque curve. Which do you prefer, turbochargers, superchargers, or even normally aspirated, and why?
September 25th, 2008 at 8:57 pm
I used to fear turbos, based on the Porsche 930 “widowmaker” effect of lag-into-holy-cow-this-car-is-trying-to-kill-me. Having had a SC in a MINI Cooper S and a turbo in my WRX - I really prefer the turbo.
It’s much simpler to control boost with a turbo to dial in levels of performance and economy balanced with reliability.
I have gotten over my 930 anxiety after driving plenty of 911s. NOS? Yeah - THAT concerns me.
I’m not in the “car making” business, but I’m willing to bet that the cost/benefit of a turbo is superior to a supercharger when considering the extra parts needed to make it work efficiently.
MINI (BMW) went from a supercharger in the Cooper S to a Turbo for that very reason - cheaper to make bigger gains.
September 25th, 2008 at 11:06 pm
Yea, the fear of OH MY GOD MY CAR IS GOING TO KILL ME goes away once you figure out how to drive it (just as you found).
I still have yet to drive a 911, although i know a few people who own them. Hrmm….
September 26th, 2008 at 8:18 pm
I’ve owned a couple (both naturally aspirated) and the snap oversteer is largely over-hyped. It can happen if you’re going flat-out into a bend and lift the throttle, but my second 911 was a Carrera4 and the AWD made the car very forgiving in that regard.
The 930 was tricky because you ran the risk of coming on boost (boost was not even close to gradual) suddenly and could really upset the car if not pointed straight. Aside from that issue (which you can learn to manage) the 930 is a wonderful car - tactile, expressive, responsive…